JP7847964B2 - Method for forming a glossy multi-layer coating film - Google Patents

Description

This invention relates to a method for forming a multi-layer coating suitable for creating an appearance with excellent metallic or pearlescent luster.

Traditionally, a subdued and unremarkable exterior design was preferred for buildings. However, the exterior materials and colors used in architecture are becoming increasingly diverse. For example, metallic exterior materials, which exhibit optical phenomena such as gloss and reflection, are gaining popularity as they allow for harmonious integration with the surrounding landscape without the use of flashy colors. In recent years, there has been an increase in highly designed metallic buildings using exterior materials such as metal panels, leading to a growing demand for metallic paints for their renovation.

Patent Documents 1 and 2 disclose metallic paints suitable for application to buildings, which include flaky metallic pigments and coloring pigments, and in which the non-volatile content and pigment volume concentration in the paint composition are within a specific range.

Furthermore, Patent Document 3 discloses a paint composition containing a specific amount of non-leafing type aluminum pigment, wherein the viscosity during application is within a specific range.

Patent No. 6121015 Patent No. 6182686 Japanese Patent Publication No. 2017-87144

The paint compositions described in Patent Documents 1 to 3, while capable of producing a high-gloss metallic coating even when applied by roller, have the drawback of potentially exhibiting noticeable metallic unevenness, thus requiring skilled application techniques.

For example, when applying a paint composition to an existing building, it is necessary to obtain a paint film with sufficient film properties even under room temperature drying conditions. However, when conventional metallic paint compositions are used to form a paint film under room temperature drying conditions, the slow evaporation rate of the solvent disrupts the orientation of the metallic pigments, leading to unevenness.

The objective of this invention is to provide a coating method that can form a coating film with minimal unevenness and excellent gloss even under room temperature drying conditions.

The inventors of this invention have diligently studied a coating method for easily obtaining a glossy coating film with a metallic and pearlescent appearance. As a result, they arrived at the conclusion that the coating process for obtaining a glossy coating film should be deliberately divided into a colored paint coating process and a glossy paint coating process.

In other words, the present invention relates to the following embodiments:
Item 1. The process includes steps (1) of applying a colored coating (I) containing a colored pigment and resin component to a substrate surface such that the thickness of the colored coating film is equal to or greater than the opacity film thickness, and drying to form a colored coating film, and step (2) of applying a glossy coating (II) containing a glossy pigment and resin component onto the colored coating film obtained in step (1), and drying to form a glossy coating film.
The aforementioned colored coating film either does not contain a lustrous pigment or contains less lustrous pigment than the aforementioned lustrous coating film.
A method for creating a glossy multilayer coating film in which the glossy coating film contains glossy pigment in the range of 0.05 to 15% by mass and has a thickness less than the opacity film thickness.
Item 2. The method for forming a glossy multi-layer coating film according to Item 1, wherein the substrate surface is the substrate surface of a building.
Item 3. The method for forming a glossy multi-layer coating film according to item 1 or 2, wherein the colored paint (I) is a room-temperature drying type paint.
Item 4. A method for forming a glossy multi-layer coating film according to any one of items 1 to 3, wherein the colored paint (I) is a paint that forms a colored coating film in which the lightness (L ^* ) is in the range of 40 to 95 and the saturation (C ^* ) is 40 or less.
Item 5. A method for forming a glossy multi-layer coating film according to any one of items 1 to 4, wherein a colored coating film made of colored paint (I) is formed by roller painting.
Item 6. A method for forming a glossy multi-layer coating film according to any one of items 1 to 5, wherein the glossy coating (II) is a multi-component coating containing a main component and a hardening agent component.
Item 7. A method for forming a lustrous multilayer coating film according to any one of items 1 to 6, wherein the lustrous pigment is an aluminum flake pigment and/or a light-interfering pigment.
Item 8. The method for forming a lustrous multilayer coating film according to Item 7, wherein the lustrous pigment includes an aluminum flake pigment, and the aluminum flake pigment is of the non-leafing type or the leafing type.
Item 9. A method for forming a lustrous multilayer coating film according to item 7 or 8, wherein the lustrous pigment includes an aluminum flake pigment, and the average particle size of the aluminum flake pigment is in the range of 5 to 250 μm.
Item 10. A method for forming a lustrous multilayer coating film according to items 7 to 9, wherein the lustrous pigment includes an optically coherent pigment, and the average particle size of the optically coherent pigment is in the range of 5 to 250 μm.
Item 11. A method for forming a lustrous multilayer coating film according to any one of items 7 to 10, wherein the lustrous pigment contains an aluminum flake pigment and a light-interfering pigment in a mass ratio of the former to the latter within the range of 10/90 to 90/10.
Item 12. A method for forming a glossy multilayer coating film according to any one of items 6 to 11, wherein the glossy coating (II) is a multi-component coating comprising a main component containing a hydroxyl group-containing acrylic resin and a glossy pigment, and a curing agent component containing polyisocyanate.
Item 13. A method for forming a glossy multilayer coating film according to any one of items 6 to 11, wherein the glossy coating (II) is a multi-component coating comprising a main component containing a hydrolyzable silyl group-containing acrylic resin, a polysiloxane resin, an epoxy resin, and a glossy pigment, and a curing agent component containing an amino group-containing alkoxysilane compound.
Item 14. The method for forming a glossy multilayer coating according to item 13, wherein the glossy coating (II) further comprises an organic solvent and/or a curing catalyst.
Item 15. A method for forming a glossy multi-layer coating film according to any one of items 1 to 14, wherein a glossy coating film made of glossy paint (II) is formed by a roller.
Item 16. A method for forming a glossy multi-layer coating according to any one of items 1 to 15, further comprising step (3) of applying a clear coating (III) different from the glossy coating (II) on top of the glossy coating formed in step (2).
Item 17. The method for forming a glossy multi-layer coating film according to Item 16, wherein a clear coating film made of clear paint (III) is formed by a roller.

According to the multi-layer coating method of the present invention, by thinly applying a glossy paint containing glossy pigments and resin components onto a colored coating so that the underlying surface is translucent, the lower colored coating and the upper glossy coating fuse together, easily obtaining a glossy coating with a metallic or pearlescent sheen even under room temperature drying conditions, and with suppressed unevenness.

The following describes the method for forming a lustrous multi-layer coating according to the present invention.

<Base material>
In the present invention, suitable substrates for providing a multi-layer coating include, for example, metallic inorganic substrates such as steel plates, galvanized steel, stainless steel, and aluminum; non-metallic inorganic substrates such as concrete, mortar, slate, siding, brick, gypsum, and wood; and organic substrates such as plastics and rubber; as well as combinations thereof. Specific examples of objects to be coated include buildings. Examples of buildings include houses, public facilities, office buildings, warehouses, gates, fences, and sculptures.

In this invention, the above-mentioned substrate may be directly coated with the colored paint (I) described later, or a sealer, primer, surface preparation material, intermediate paint, rust-preventive paint, etc., may be applied beforehand to form a base coat film. The shape of the base coat film may be flat or uneven.

<Step (1)>
In the present invention, step (1) is a step of applying a colored paint (I) to the substrate and drying it to form a colored coating film.

<Colored paint (I)>
The colored paint (I) used in step (1) can be any conventionally known paint, such as organic solvent-based, water-based, or solvent-free paints, as long as it contains a colored pigment and a resin component.

As the aforementioned coloring pigment, any coloring pigment known in the paint field can be used without limitation, depending on the preference and purpose. Examples of coloring pigments include titanium dioxide, carbon black, red iron oxide, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, surene pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, and any combination thereof. Furthermore, the pigment may also include extender pigments such as barita powder, precipitated barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white, gloss white, and silica.

In this invention, since the colored coating (I) plays the role of providing color, it is preferable that the colored coating film does not contain luminous pigments, contains less luminous pigments than the luminous coating film, or contains 0.5% by mass or less of luminous pigments in the colored coating film.

The aforementioned resin component can be any resin and curing agent known in the paint field without limitation. Specifically, examples include acrylic resins, urethane resins, polysiloxane resins, alkyd resins, fluororesins, polyester resins, epoxy resins, polyisocyanates, polyamines, amino group-containing alkoxysilanes, and combinations thereof. Particularly preferred resin components include acrylic resins, urethane resins, polysiloxane resins, and combinations thereof. Furthermore, the aforementioned resin component also includes modified resins composed of multiple of these resins.

The aforementioned colored paint (I) may contain paint additives such as organic solvents, water, curing catalysts, reactive diluents, adhesion promoters, UV absorbers, light stabilizers, anti-algal agents, defoamers, anti-settling agents, dispersants, and wetting agents.

In this invention, a room-temperature drying paint is preferred as the colored paint (I). Examples of room-temperature drying paints include lacquer-type paints, alkyd resin-based paints, two-component urethane resin-based paints containing hydroxyl group-containing resins and polyisocyanates, and two-component epoxy-based paints containing epoxy group-containing resins and amino group-containing resins.

In step (1), the colored paint (I) is applied to the substrate surface so as to conceal the base material, i.e., the thickness of the colored paint film is equal to or greater than the concealment film thickness, and then dried. In this specification, "concealment film thickness" is a well-known term in the paint field and refers to the minimum film thickness at which the color of the base material can no longer be recognized. Specifically, it refers to the minimum dry film thickness at which, when paint is applied to a concealment test paper specified in JIS K5600-4-1 (1999) with varying film thicknesses and then dried and cured, the white and black areas printed on the concealment test paper become indistinguishable to the naked eye.

In the present invention, it is preferable that the colored paint (I) is a paint that forms a colored coating film with medium brightness and low saturation. Specifically, it is preferable that the brightness (L ^* ) of the colored coating film is in the range of 40 to 95 and the saturation (C ^* ) is in the range of 40 or less. This is because having the brightness and saturation of the colored coating film within the above ranges makes the brilliance and color development of the multilayer coating film, which is fused with the brilliance coating film formed by the brilliance paint (II) described later, more pronounced.
More specifically, to achieve a metallic sheen, the brightness (L*) of the colored coating should preferably be adjusted to a range of 40 to less than 80, while to achieve a pearlescent sheen, the brightness (L*) of the colored coating should preferably be within the range of 80 to 95.

In this specification, lightness (L ^* ) and chroma (C ^* ) can be expressed using the CIE 1976 L ^* a ^* b ^* color system (compliant with JIS Z8729). In the ^L* a ^* b ^* color system, lightness is represented by L ^* , and chroma is represented by a ^* and b ^* . Lightness L ^* takes a value from 0 to 100, with larger values indicating brighter colors. That is, for example, a lightness L ^* closer to 0 is closer to black, and a value closer to 100 is closer to white. ^a* represents the red-to-green directional component. Larger negative values indicate a color closer to green, and larger positive values indicate a color closer to red. b ^* represents the blue-to-yellow directional component. Larger negative values indicate a color closer to blue, and larger positive values indicate a color closer to yellow. For ^a* and b ^* , larger numerical values (absolute values) indicate higher chroma. ^a* = 0 and b ^* = 0 represent achromatic colors. The formula C ^* = (a ^*2 + b ^*2 ) ^1/2 is used as an indicator of saturation.
L ^* , a ^* , and b ^* can be measured using a commercially available colorimeter (for example, the Konica Minolta CR-400 color difference meter). Furthermore, the conditions for preparing the colored coating film to measure lightness and saturation are as follows: a glass plate is used as the substrate, the colored paint to be used as the sample is spray-coated so that the colored coating film becomes an opaque film thickness, and it is dried at 23°C for one week.

The colored paint (I) can be applied using known painting methods. Specifically, it can be applied using painting equipment such as brushes, smear coats, trowels, rollers, spray paints, airless spray paints, texture guns, and all-purpose guns. It is particularly preferable to use a roller, as this minimizes paint splatter. Drying after painting is preferably done at room temperature, but forced drying or heat drying may be performed as needed. Room temperature refers to a temperature where no temperature manipulation such as forced heating or cooling is performed, although this varies depending on the ambient temperature of the painting environment; for example, it is between 5 and 40°C.

<Step (2)>
In the present invention, a glossy coating (II) is applied to the colored coating film formed in step (1) above, and dried to form a glossy coating film. The glossy coating (II) is a coating that has a sparkling appearance due to glossy pigments and is also transparent. In other words, in the present invention, when a glossy coating is applied on top of a colored coating film, the colored coating film underneath becomes visible through the glossy coating film on top.

Therefore, in this invention, applying the glossy coating (II) to a thick film that completely conceals the underlying colored coating is undesirable because it results in insufficient gloss and color development of the glossy multi-layer coating.

In the present invention, the glossy coating (II) is applied so that the substrate is translucent and the glossy coating film is less than the opacity film thickness. The amount applied is adjusted by the content of the glossy pigment and the application conditions, but the amount applied is preferably in the range of 30 to 85 g/ ^m² , more preferably 35 to 60 g/ ^m² , in terms of the mass of the nonvolatile content of the glossy coating (II).

In this invention, the glossy coating (II) can be any conventionally known coating containing a glossy pigment and a resin component, such as organic solvent-based, water-based, or solvent-free coatings. Among these, room-temperature drying coatings are preferred. In the case of room-temperature drying coatings, a multi-component coating containing a main component and a hardener component may be used from the viewpoint of coating film properties such as weather resistance.

<Luminous Pigments>
In this invention, the lustrous pigment is used to impart a metallic or pearlescent shimmer to the coating film, and pigments known as lustrous pigments in the paint field can be used. Specific examples of lustrous pigments include aluminum flake pigments, light-interfering pigments, and vapor-deposited metal flake pigments.

Aluminum flake pigments are primarily used to impart a metallic sheen to paint films. They are generally produced by grinding and grinding aluminum in a ball mill or attritor mill in the presence of a grinding medium and grinding aids. Grinding aids used in the production process of these aluminum flake pigments include higher fatty acids such as oleic acid, stearic acid, isostearic acid, lauric acid, palmitic acid, and myristic acid, as well as aliphatic amines, aliphatic amides, and aliphatic alcohols. The grinding medium used is typically an aliphatic hydrocarbon such as mineral spirits.

The above aluminum flake pigments can be broadly classified into leafing and non-leafing types depending on the type of grinding aid used, and both are usable. In addition, while those with no special surface treatment can be used, those with a resin coating, silica treatment, or surface treatment with phosphoric acid, molybdic acid, or silane coupling agents can also be used. You can use a product with one of the above surface treatments, or you can use a product with multiple types of treatments.
Furthermore, the aluminum flake pigment may be one in which a colored pigment is coated on the surface of the aluminum flake pigment and then coated with a resin, or one in which a metal oxide such as iron oxide is coated on the surface of the aluminum flake pigment.

From the viewpoint of brilliance and gloss, it is preferable to use aluminum flake pigments with an average particle size in the range of 5 to 250 μm, particularly 7 to 200 μm.

In this specification, the average particle size of the lustrous pigment is defined as the 50% volume-average particle size D50, which represents the median diameter of the volume-based particle size distribution measured by laser diffraction scattering using a Microtrac particle size distribution analyzer MT3300 (product name, manufactured by Nikkiso Co., Ltd.).

Optically interfering pigments are used in combination with the above-mentioned aluminum flake pigments to give a pearlescent sheen to a coating film or to impart a metallic feel to a coating film. Specifically, they are iridescent pigments in which a metal oxide with a different refractive index than the substrate is coated on the surface of a transparent or translucent flaky substrate such as mica, artificial mica, glass, iron oxide, aluminum oxide, and various metal oxides. A transparent substrate is specifically a substrate that transmits at least 90% of visible light, and a translucent substrate is a substrate that transmits at least 10% to less than 90% of visible light. Examples of the above-mentioned metal oxides include titanium dioxide and iron oxide, and by varying the thickness of the metal oxide, the optically interfering pigment can exhibit a variety of different interference colors.

Examples of such optically coherent pigments include metal oxide-coated mica pigments, metal oxide-coated alumina flake pigments, metal oxide-coated glass flake pigments, and metal oxide-coated silica flake pigments.

Metal oxide coated mica pigments are pigments that use natural or artificial mica as a base material, with the surface of the base material coated with a metal oxide. Natural mica is a flaky base material obtained by crushing mica (mica) ore. Artificial mica is synthesized by heating industrial raw materials such as _SiO₂ , _MgO , _Al₂O₃ , _K₂SiF₆ , _{and Na₂SiF₆ ,} melting them at a high temperature of approximately 1500°C, and then cooling and crystallizing them. Compared to natural mica, it has fewer impurities and is more uniform in size and thickness. Specific examples of artificial mica base materials include fluorinated phlogopite, potassium tetrasilicate mica, sodium tetrasilicate mica, Na teniolite, and LiNa teniolite.

Metal oxide-coated alumina flake pigments are pigments that use alumina flakes as a base material, with the surface of the base material coated with a metal oxide. Alumina flakes refer to flaky (thin flake) aluminum oxide, which is colorless and transparent. The alumina flakes do not need to be solely composed of aluminum oxide; they may also contain oxides of other metals.

Metal oxide-coated glass flake pigments are pigments that use flaky glass as a base material, with the surface of the base material coated with a metal oxide. Because the surface of the base material is smooth, these metal oxide-coated glass flake pigments exhibit strong light reflection.

Metal oxide-coated silica flake pigments are pigments in which a metal oxide coats flaky silica, which is a substrate with a smooth surface and uniform thickness.

From the viewpoint of brilliance and gloss, it is preferable to use optically coherent pigments with an average particle size in the range of 5 to 250 μm, particularly 7 to 200 μm. Examples of commercially available optically coherent pigments that can be used include the "Iriodin" series (product name, manufactured by Merck Japan), the "Sillaric" series (product name, manufactured by Merck Japan), and the "Twinkle Pearl" series (product name, manufactured by Nippon Koken Kogyo Co., Ltd.).

The aforementioned vapor-deposited metal flake pigment is obtained by vapor-depositing a metal film, such as aluminum or chromium, onto a base substrate such as a film, peeling off the base substrate, and then crushing the vapor-deposited metal film.

In the present invention, the luminous pigment preferably includes an aluminum flake pigment and/or a light-interfering pigment. When both are used in combination, from the viewpoint of obtaining a coating film with a sparkling luminescence while suppressing unevenness, the mass ratio of the aluminum flake pigment to the light-interfering pigment is preferably in the range of 10/90 to 90/10, more preferably 20/80 to 80/20.

In this invention, the glossy coating film contains 0.05 to 15% by mass of glossy pigment. This is from the viewpoint of the glossiness and luster of the final multi-layer coating film. The preferred amount of glossy pigment in the glossy coating film is within the range of 0.5 to 10% by mass. If the amount of glossy pigment in the glossy coating film is less than 0.05% by mass, the glossiness of the multi-layer coating film will be reduced. If the amount of glossy pigment in the glossy coating film exceeds 15% by mass, unevenness may occur in the multi-layer coating film, and/or the color development or light selectivity may be insufficient.

Furthermore, it is preferable that the glossy coating (II) does not contain the above-mentioned coloring pigment, or if it does, its content is within the range of 5 parts by mass or less based on 100 parts by mass of the non-volatile content of the glossy coating film. By having the pigment composition of the glossy coating film formed from the glossy coating (II) as described above, a glossy coating film appearance with excellent color development and glossiness can be obtained, while maximizing the use of the color of the underlying colored coating film. By changing the type of colored coating film, it becomes possible to provide a wide range of users with a rich variety of appearances through combinations of glossiness and color.

In this specification, "non-volatile content" refers to the residue remaining after removing volatile components such as water and organic solvents, and is the component that forms the coating film. For example, when measuring the mass of non-volatile content, a drying condition for the sample is to heat 1 gram of the sample in a 110°C dryer for 1 hour.

<Resin components>
The resin components included in the glossy coating (II) can be any resin and curing agent known in the coating field without limitation. Specifically, these include acrylic resins, urethane resins, polysiloxane resins, alkyd resins, fluororesins, polyester resins, epoxy resins, polyisocyanates, polyamines, amino group-containing alkoxysilanes, and combinations thereof. Furthermore, the resin components also include modified resins composed of multiple of these resins.

Acrylic resin:
The aforementioned resin component preferably includes an acrylic resin from the viewpoint of weather resistance. In particular, it is preferable that the acrylic resin is an acrylic resin having hydrolyzable silyl groups and/or hydroxyl groups.

In this specification, "hydrolyzable silyl group" is a group that generates a silanol group upon hydrolysis, and that silanol group undergoes dehydration condensation to form a siloxane bond. It is not particularly limited as long as it is a silyl group having both or either a monovalent hydrolyzable atom directly bonded to a silicon atom (an atom that generates a silanol group upon reaction with water) and a monovalent hydrolyzable group directly bonded to a silicon atom (a group that generates a silanol group upon reaction with water).

Specific examples of the hydrolyzable silyl groups mentioned above include, for example, halogenated silyl groups such as chlorosilyl and bromosilyl groups, alkoxysilyl groups such as methoxysilyl, ethoxysilyl, propoxysilyl, and butoxysilyl groups, and any combination thereof.

Examples of acrylic resins containing hydrolyzable silyl groups and/or hydroxyl groups include those containing monomer units of hydrolyzable silyl group-containing polymerizable unsaturated compounds and/or hydroxyl group-containing polymerizable unsaturated compounds, and monomer units of (meth)acryloyl group-containing compounds. (Meth)acryloyl group-containing compounds exclude hydrolyzable silyl group-containing polymerizable unsaturated compounds containing (meth)acryloyl groups.

When the acrylic resin has hydrolyzable silyl groups, it can contain 1 to 50% by mass, preferably 2 to 30% by mass, of the hydrolyzable silyl group-containing polymerizable unsaturated compound based on the total monomer units of the acrylic resin. On the other hand, when the acrylic resin has hydroxyl groups, it can contain 1 to 50% by mass, preferably 2 to 30% by mass, of the hydroxyl group-containing polymerizable unsaturated compound based on the total monomer units of the acrylic resin.

Furthermore, when the acrylic resin contains both hydrolyzable silyl groups and hydroxyl groups, in terms of room-temperature curability, it is preferable that the acrylic resin contains 1 to 50% by mass, preferably 2 to 30% by mass, of the hydrolyzable silyl group-containing polymerizable unsaturated compound and 0.1 to 40% by mass, preferably 1 to 20% by mass, of the hydroxyl group-containing polymerizable unsaturated compound, based on the total monomer units of the acrylic resin.

Examples of polymerizable unsaturated compounds containing hydrolyzable silyl groups include vinyl alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, divinyldimethoxysilane, divinyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, and vinyltris(methoxyethoxy)silane; vinyl chlorosilanes such as vinyltrichlorosilane, divinyldichlorosilane, and vinylmethyldichlorosilane; and γ-(meth)acryloxypropyltrimethoxysilane and γ-(meth)acryloxypropyltriethoxysilane. Examples include xysilane, β-(meth)acryloxyethyltrimethoxysilane, β-(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldiethylmethoxysilane, and other (meth)acryloxyalkoxysilanes; and any combination thereof.

In this specification, the term (meth)acryloxy group refers to an acryloxy group, a methacryloxy group, or both an acryloxy group and a methacryloxy group.

Examples of hydroxyl group-containing polymerizable unsaturated compounds include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2,3-dihydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; compounds obtained by ring-opening polymerization of the above hydroxyalkyl (meth)acrylates with lactones such as ε-caprolactone; and hydroxyl group-containing (meth)acrylates such as monoesters of polyhydric alcohols such as polyethylene glycol mono(meth)acrylate and acrylic acid or methacrylic acid; as well as any combination thereof.

On the other hand, the "(meth)acryloyl" group refers to an acryloyl group, a methacryloyl group, or both an acryloyl group and a methacryloyl group, and "(meth)acrylic acid" refers to acrylic, methacrylic acid, or both an acrylic acid and a methacrylic acid.

Examples of compounds containing a (meth)acryloyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tridecyl (meth)acrylate, and other compounds containing linear, branched, or cyclic alkyl groups. (Meth)acrylates; alkoxyalkyl (meth)acrylates such as N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, methoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxyethyl (meth)acrylate, ethoxypropyl (meth)acrylate; alkoxy group-containing (meth)acrylates such as polyethylene glycol monomethoxy (meth)acrylate and polyalkylene glycol monoalkoxy (meth)acrylate; epoxy (meth)acrylates such as glycidyl (meth)acrylate and 3,4-epoxycyclohexylmethyl (meth)acrylate. Xyl group-containing (meth)acrylates; carboxyl group-containing (meth)acrylates such as acrylic acid, methacrylic acid, and half-esterified hydroxyalkyl (meth)acrylates with acid anhydrides; sulfonic acid group-containing (meth)acrylates such as 2-acrylamido-2-methylpropanesulfonic acid; phosphate group-containing (meth)acrylates such as acid phosphooxyethyl (meth)acrylate and phosphate mono-[(2-hydroxyethyl)(meth)acrylic acid] ester; N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate Examples include amino group-containing (meth)acrylates such as acrylate, N-t-butylaminoethyl (meth)acrylate, and N,N-dimethylaminobutyl (meth)acrylate; quaternary ammonium base-containing (meth)acrylates such as (meth)acryloyloxyethyltrimethylammonium chloride and dimethylaminoethylmethyl methacrylate; and fluoroalkyl (meth)acrylates such as hexafluoroisopropyl (meth)acrylate, perfluorooctylmethyl (meth)acrylate, and perfluorooctylethyl (meth)acrylate; as well as any combination thereof.

Furthermore, acrylic resins having hydrolyzable silyl groups may contain monomer units of polymerizable unsaturated compounds containing hydrolyzable silyl groups, such as (meth)acryloxyalkoxysilanes, including γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, β-(meth)acryloxyethyltrimethoxysilane, β-(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, and γ-(meth)acryloxypropyldiethylmethoxysilane.

From the viewpoint of paintability, the acrylic resin preferably contains a (meth)acryloyl group-containing compound that, as a monomer unit, is a linear, branched, or cyclic alkyl ester of (meth)acrylic acid having approximately 4 to 18 carbon atoms.

Examples of linear, branched, or cyclic alkyl esters of (meth)acrylic acid having approximately 4 to 18 carbon atoms include n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tridecyl (meth)acrylate, and combinations thereof.

The above-mentioned acrylic resin may also contain other polymerizable unsaturated compounds as monomer units.
Other polymerizable unsaturated compounds include compounds other than (meth)acryloyl group-containing compounds, specifically aromatic vinyl compounds such as styrene and vinyltoluene; vinyl ethers such as cyclohexyl vinyl ether, nonyl vinyl ether, 2-ethylhexyl vinyl ether, hexyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, and t-butyl vinyl ether; allyl ethers such as ethyl allyl ether and hexyl allyl ether; vinyl carboxylates such as ethylene, propylene, and isobutylene; fluorovinyl ethers such as fluoroalkyl trifluorovinyl ether and perfluoroalkyl trifluorovinyl ether.

The above-mentioned acrylic resin can be manufactured by any known method, such as radical polymerization using azo compounds, peroxides, etc., as initiators, and is also commercially available.

Furthermore, while the weight-average molecular weight of the above-mentioned acrylic resin is not particularly limited, from the viewpoint of gloss, luster, and room-temperature curability, it is in the range of 1,000 to 100,000, and preferably in the range of 2,000 to 80,000.

In this specification, the weight-average molecular weight can be measured using, for example, the "HLC8120GPC" (trade name, manufactured by Tosoh Corporation) gel permeation chromatograph, four columns ("TSKgelG-4000HXL", "TSKgelG-3000HXL", "TSKgelG-2500HXL", and "TSKgelG-2000HXL" - all trade names, manufactured by Tosoh Corporation), a differential refractometer as the detector, under the following conditions: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 mL/min.

Polysiloxane resin:
From the viewpoint of weather resistance, the above resin component preferably contains a polysiloxane resin. As the polysiloxane resin, a hydrolyzable silyl group-containing organopolysiloxane having a hydrolyzable silyl group and a polysiloxane skeleton in the resin is preferred.

Hydrolyzable silyl group-containing organopolysiloxanes are, for example, those of the following formula (1)
(1): SiX _n Y _4-n formula (1)
(In the formula, X represents a hydroxyl group or an alkoxy group, Y represents a monovalent hydrocarbon group which may have substituents, and n represents an integer from 1 to 4.)
Examples include resins produced by the chemical bonding of two or more identical or different organosilanes, represented by [the formula shown].

When the hydrolyzable silyl group-containing organopolysiloxane is composed of organosilanes represented by formula (1) linked in a linear or branched chain, it is preferable that the hydrolyzable silyl group-containing organopolysiloxane resin has hydrocarbon groups that are directly bonded to silicon atoms.

Examples of organosilanes represented by formula (1) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and γ-(meth)acryloxypropyltri Methoxysilane, phenyltrimethoxysilane, phenyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, β-cyanoethyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, dimethyldichlorosilane, diphenyldichlorosilane, methylphenyldimethoxysilane, trimeth γ-Acinopropyltriethoxysilane, 4-Acinobutyltriethoxysilane, p-Aminophenyltrimethoxysilane, N-(2-Aminoethyl)-3-Aminopropyltrimethoxysilane, Aminoethylaminomethylphenethyltrimethoxysilane, 3-Glycidoxypropyltrimethoxysilane, 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropyltriethoxysilane, 4-Aminobutyltriethoxysilane, N-(6-Aminohexyl)aminopropyl Examples include propyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltrichlorosilane, (p-chloromethyl)phenyltrimethoxysilane, 4-chlorophenyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, styrylethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, trifluoropropyltrimethoxysilane, and any combination thereof.

Hydrolyzable silyl group-containing organopolysiloxanes are preferably those that have methyl and/or phenyl groups directly bonded to silicon atoms, from the viewpoint of paintability and other factors.

Epoxy resin:
Furthermore, the above resin component preferably includes an epoxy resin. Such epoxy resins are compounds having at least two epoxy groups in their molecules, and include, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenol-epichlorohydrin type epoxy resin, polyglycidyl ether of glycerin-epichlorohydrin adduct, resorcinol diglycidyl ether, polybutadiene diglycidyl ether, hydroquinone diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, neopentyl glycol diglycidyl ether, hexahydrophthalate diglycidyl ester, and hydrogenated bisphosphate. Examples include Nol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, dihydroxyanthracene type epoxy resin, polypropylene glycol diglycidyl ether, diphenyl sulfone diglycidyl ether, dihydroxybenzophenone diglycidyl ether, biphenol diglycidyl ether, diphenylmethane diglycidyl ether, bisphenol full orange glycidyl ether, biscresol full orange glycidyl ether, bisphenoxyethanol full orange glycidyl ether, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N-diglycidylaniline, N,N-diglycidyltoluidine; and compounds obtained by grafting glycidyl group-containing components onto acrylic polymers.

When the above-mentioned resin component has crosslinking reactive groups such as hydroxyl groups, hydrolyzable silyl groups, or epoxy groups, it is preferable that the resin component contains a compound that can react with the crosslinking functional group as a curing agent. Examples of such curing agents include polyisocyanates, amino group-containing alkoxysilanes, and polyamines.

Polyisocyanates:
Among these, polyisocyanates include, for example, aliphatic, aromatic, or aromatic aliphatic polyisocyanates. Specific examples include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methylcyclohexane diisocyanate, bis(isocyanate-methyl)cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, lysine diisocyanate, and modified forms of these isocyanate compounds. Specific examples of modified forms include biuret modified forms, isocyanurate modified forms, adduct modified forms (e.g., trimethylolpropane adducts), allophanate modified forms, uretdione modified forms, and combinations thereof. Various modified forms of hexamethylene diisocyanate are particularly preferred from the viewpoint of weather resistance.

Amino group-containing alkoxysilane compounds:
The above-mentioned amino group-containing alkoxysilane compounds are compounds having an amino group and an alkoxysilyl group in their molecule. Specific examples include N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-methylaminopropyltrimethoxysilane, and N-methylaminopropyltriethoxysilane. The above-mentioned compounds also include hydrolysis condensates of these listed compounds.

The resin component included in the above-mentioned glossy coating (II) is preferably a composition containing a hydroxyl group-containing acrylic resin and a polyisocyanate, or a composition containing a hydrolyzable silyl group-containing acrylic resin, a polysiloxane resin, an epoxy resin, and an amino group-containing alkoxysilane.

When the resin component in the glossy coating (II) is a composition containing a hydroxyl group-containing acrylic resin and a polyisocyanate, it is preferable that the ratio of isocyanate groups in the polyisocyanate to the hydroxyl groups in the resin component is 0.5 to 1.5 equivalents.

On the other hand, if the glossy paint (II) is a composition containing a hydrolyzable silyl group-containing acrylic resin, a polysiloxane resin, an epoxy resin, and an amino group-containing alkoxysilane as resin components, the proportion of non-volatile content contained in each component to the total non-volatile content contained in the hydrolyzable silyl group-containing acrylic resin, the polysiloxane resin, and the epoxy resin is:
A hydrolyzable silyl group-containing acrylic resin is present in an amount of 20 to 90% by mass, preferably 30 to 80% by mass.
The polysiloxane resin is in the range of 5 to 40% by mass, preferably 10 to 35% by mass.
The epoxy resin is preferably in the range of 5 to 40% by mass, more preferably 10 to 35% by mass.

The amount of amino group-containing alkoxysilane compound used is preferably in the range of 0.1 to 2.0, more preferably 0.3 to 1.2, of the equivalent amount of active hydrogen from the amino group relative to one equivalent amount of epoxy group contained in the resin component.

<Glitter paint (II)>
In the present invention, the glossy paint (II) may contain, in addition to the resin component and glossy pigment, paint additives such as organic solvents, water, fillers, modifying resins, curing catalysts, reactive diluents, adhesion promoters, ultraviolet absorbers, light stabilizers, anti-algal agents, defoaming agents, anti-settling agents, dispersants, wetting agents, and dehydrating agents.

Among these, weak solvents can be cited as organic solvents.
"Weak solvent" is a well-known term in this technical field and generally refers to a solvent with weak dissolving power. The above weak solvents include those listed as Class 3 organic solvents in the classification of organic solvents under the Industrial Safety and Health Act. Specific examples of Class 3 organic solvents include gasoline, coal tar naphtha (also known as solvent naphtha), petroleum ether, petroleum naphtha, petroleum benzine, turpentine oil, mineral spirits (also known as mineral thinner, petroleum spirit, white spirit, and mineral turpentine), and combinations thereof.

In this invention, from the viewpoint of the environment during painting, it is preferable that the proportion of weak solvent in the total organic solvent contained in the glossy coating (II) be 40% by mass or more, preferably 70% by mass or more.

Organic solvents that can be used other than weak solvents include known solvents, such as hydrocarbon solvents like n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, and cyclobutane; aromatic solvents like toluene and xylene; ether solvents such as ethylene glycol monoisopropyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and dioxane; ester solvents such as methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, methyl acetoacetate, ethylene glycol monomethyl ether acetate, and butyl carbitol acetate; ketone solvents such as acetone, acetylacetone, diacetone alcohol, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone; and combinations thereof.

Furthermore, as curing catalysts, examples include organotin compounds such as diacetyltin diacetate, dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, diacetyltin dioctoate, tin octoate, dibutyltin diacetate, and dibutyltin dioctoate; organoaluminum compounds such as aluminum trimethoxide, aluminum tris(acetylacetonate), aluminum tri-n-butoxide, aluminum tris(acetacetate ethyl), aluminum diisopropoxy(acetacetate ethyl), and aluminum acetylacetonate; organotitanium compounds such as titanium tetra(monoethyl ethoxide), titanium tetra(monoethyl ethoxide), titanium tetra(monobutyl ethoxide), titanium tetrakis(acetylacetonate), and tetran-butyl titanate; zirconium tetra(monomethyl ethoxide), zirconium tetra(monoethyl ethoxide), zirconium tetra(monobutyl ethoxide), zirconium n-propylate, and zirconium n-propylate. Organic zirconium compounds such as butyrate and zirconium tetrakis (acetylacetonate); organic zinc compounds such as zinc naphthenate; organic cobalt compounds such as cobalt octoate and cobalt naphthenate; trimethylamine, triethylamine, 2-(dimethylamino)ethyl methacrylate, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]-7-undecene, 1,5-diazabicyclo[4.3.0]-5-nonene, 1-methylpiperidine, 1-methylpyrrolidine, etc. Examples of suitable catalysts include aliphatic amines, pyridines, 4-dimethylaminopyridine, 4-(1-piperidyl)pyridine, N-methylimidazole, and N,N-dimethylaniline; lead, tin, zinc, and iron complexes of carboxylic acids; and boric acid compounds such as boric acid esters like trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, triphenyl borate, tri(4-chlorophenyl) borate, and trihexafluoroisopropyl borate. These can be used individually or in combination of two or more. Among these, amine catalysts are preferred from the viewpoint of gloss.

In the above-mentioned glossy paint (II), the paint form can be selected according to the type of resin component. Specifically, if the resin component is a composition containing a hydroxyl group-containing acrylic resin and a polyisocyanate, the glossy paint (II) can be a multi-component paint containing a main component containing a hydroxyl group-containing acrylic resin and a glossy pigment, and a curing agent component containing a polyisocyanate. Furthermore, if the resin component is a composition containing a hydrolyzable silyl group-containing acrylic resin, a polysiloxane resin, an epoxy resin, and an amino group-containing alkoxysilane compound, the glossy paint (II) can be a multi-component paint containing a main component containing an acrylic resin, a polysiloxane resin, an epoxy resin, and a glossy pigment, and a curing agent component containing an amino group-containing alkoxysilane compound.
This multi-component paint structure ensures good storage stability for both the main component and the hardener component. Furthermore, the resulting glossy paint (II), obtained by mixing the two, produces a paint film with excellent gloss, weather resistance, and minimal unevenness.

If the above-mentioned glossy paint (II) is a multi-component paint, the painting contractor will stir and mix the main component, the hardener component, and any diluent immediately before application to prepare the glossy paint (II) for painting.

The mass ratio of the main component to the curing agent component is not particularly limited, but generally, the mass ratio of the main component to the curing agent component is in the range of 99/1 to 70/30, preferably 95/5 to 80/20.

The above-mentioned glossy coating (II) can be applied using known painting methods. Specifically, it can be applied using painting tools such as brushes, smear coats, trowels, rollers, spray paints, airless spray paints, texture guns, and all-purpose guns. It is particularly preferable to use a roller, as this method minimizes paint splatter. After application, drying can be done at room temperature, but forced drying or heat drying may be performed as needed.

<Step (3)>
Furthermore, the present invention may further include a step (3) of applying a clear coating (III) on top of the glossy coating film formed in step (2). Since the clear coating (III) protects the glossy multi-layer coating film, any conventionally known clear coating can be used without particular limitation as long as it is highly durable and transparent. The composition of the clear coating (III) differs from that of the glossy coating (II), but the resin component included in the clear coating (III) can be the same as the resin listed in the description of the resin component included in the glossy coating (II). The clear coating (III) can be applied using known painting methods, and can be done using painting equipment such as brush painting, pouring, trowel painting, roller painting, spray painting, airless spray painting, stucco gun, and all-purpose gun, with painting using a roller being particularly preferable. Drying after painting can be done at room temperature, but forced drying or heat drying may be performed as needed.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" refer to "parts by mass" and "mass percent," respectively.

《Manufacturing of acrylic resin》
Manufacturing Example 1
44.7 parts of mineral spirit were placed in a flask equipped with a condenser and thermometer, and the temperature was raised to 95°C while stirring under a nitrogen stream. The following components were then added dropwise over 4 hours while stirring, and after 1 hour of aging, the solution was diluted with mineral spirit to a non-volatile content of 60% to produce acrylic silicone resin solution (A-1). The weight-average molecular weight of the acrylic resin was 25,000.
Styrene 10.0 parts i-butyl methacrylate 62.2 parts 2-hydroxyethyl acrylate 2 parts 2-ethylhexyl acrylate 15.8 parts γ-(meth)acryloxypropyltrimethoxysilane 10.0 parts Production Example 2
In the above-mentioned Production Example 1, an acrylic polyol resin solution (A-2) was prepared in the same manner as in Production Example 1, except that the monomer added dropwise was as follows. The weight-average molecular weight was 25,000.
30 parts styrene, 10 parts hydroxyethyl methacrylate, 30 parts isobutyl methacrylate, 30 parts 2-hydroxyethyl acrylate.

Manufacturing of high-gloss paints
Manufacturing Examples 3-25
The main component and hardener component were prepared according to the mixing ratios shown in Table 1, and the two were mixed to produce glossy paints (II-1) to (II-23). Note that the amount of acrylic resin solution listed in Table 1 represents the mass of the non-volatile content of the acrylic resin solution.

"coating"
Example 1
A 60cm x 90cm galvanized steel sheet, which had been pre-treated with a sealer, was coated with a weak solvent-soluble modified epoxy paint, "Super Saurus 2" (product name of Kansai Paint Co., Ltd.), in gray, using a roller at a rate of 120 g/ ^m². After curing at 23°C for one day, the colored paint (I-1) described in Table 3 was applied twice with a roller at a rate of 100 g/ ^m² , and dried at 23°C for one day to conceal the substrate. Next, a glossy paint (II-1) was applied with a roller so that the glossy coating film obtained by applying and drying the glossy paint was less than the concealing film thickness (amount of non-volatile components of the paint applied: 45 g/ ^m² ), and dried at 23°C for seven days to create a test panel.

Examples 2, 4-19, 24, 26, 28, 30, 32, 34-39
In Example 1 described above, a test plate was obtained in the same manner as in Example 1, except that the combination of paints used was shown in Table 4.

Example 3
A 60cm x 90cm galvanized steel sheet, which had been pre-treated with a sealer, was coated with a weak solvent-soluble modified epoxy paint, "Super Saurus 2" (product name of Kansai Paint Co., Ltd.), in gray, using a roller at a coverage rate of 120g/ ^m² . After curing at 23°C for one day, the colored paint (I-1) described in Table 3 was applied twice using a roller at a coverage rate of 100g/ ^m² , and dried at 23°C for one day to conceal the substrate. Next, a glossy paint (II-1) was applied on top of that, using a roller, so that the glossy coating film obtained by applying and drying the glossy paint was less than the concealing film thickness (amount of non-volatile components of the paint applied: 45g/ ^m² ). This was dried at 23°C for seven days, and then a clear paint (III) (Note 14) was applied as a topcoat, with an amount of non-volatile components of the paint applied of 45g/ ^m² , and dried at 23°C for seven days to obtain the test plate.
(Note 14) Clear coating (III): A clear coating with a composition obtained by removing the glossy pigment from the glossy coating (II-1) of manufacturing example 3.

Examples 20-23, 25, 27, 29, 31 and 33
In Example 3 described above, a test plate was obtained in the same manner as in Example 3, except that the combination of paints used was shown in Table 4.

Comparative Examples 1-3
In Example 1 described above, a test plate was obtained in the same manner as in Example 1, except that the combination of paints used was shown in Table 4.

Comparative Example 4
A 60cm x 90cm galvanized steel sheet, which had been pre-treated with a sealer, was coated with a weak solvent-soluble modified epoxy paint, "Super Saurus 2" (product name of Kansai Paint Co., Ltd.), in gray, using a roller at a rate of 120g/ ^m². After curing at 23°C for one day, a glossy paint (II-22) was applied on top of it using a roller, with a coating amount of non-volatile content of 45g/ ^m² . The sheet was then dried at 23°C for seven days to create a test panel.

Comparative Example 5
On top of the test board of Comparative Example 4 described above, a clear paint (III) (Note 9) was applied as a top coat so that the amount of non-volatile content of the paint was 45 g/ ^m² , and the board was dried at 23°C for 7 days to obtain a test board.

Comparative Example 6
In Comparative Example 4 described above, a test plate was obtained in the same manner as in Comparative Example 4, except that the glossy coating (II-22) used was changed to glossy coating (II-23).

Evaluation Test
Each test panel obtained in the above examples and comparative examples was evaluated according to the following criteria. The results are shown in Table 4. In Table 4, "-" means "none" (there is no coating because it was not painted).

(*) Luminousness: The luminousness of each test panel was visually evaluated according to the following criteria.
◎: Excellent metallic or pearly shimmer.
○: Good metallic or pearly shimmer.
△: The metallic or pearly shimmer is slightly lacking.
×: The metallic or pearly shimmer is undesirable.

(*) Unevenness: The presence or absence of unevenness in the glossiness of each test board was visually evaluated according to the following criteria.
◎: The luminosity is perfectly even.
○: Slight unevenness in luster is noticeable but not conspicuous.
△: Clearly noticeable unevenness in luster.
×: The unevenness in the shine is quite noticeable.

(*) Color development: The color development of each test panel was visually evaluated according to the following criteria.
◎: Excellent color development,
○: Good color development,
△: Slightly poor color development.
×: Insufficient color development.

(*) Gloss: The gloss of each test panel was visually evaluated according to the following criteria.
◎: Excellent gloss,
○: Good shine,
△: Slightly poor gloss,
×: Lack of shine.

(*) Weather resistance: Each test panel was subjected to accelerated weathering testing (xenon weather meter) for 3000 hours in accordance with JIS K 5600-7-7, and its appearance was visually observed afterward.
◎: No change whatsoever before or after the exam.
○: Slight loss of gloss or discoloration is observed after testing.
△: Discoloration or loss of gloss is observed after testing.
×: Significant loss of gloss or discoloration is observed after testing.

《Consideration》
Based on the results in Table 4, the effects of the present invention will be discussed below.
Examples 1 to 39 are multilayer coatings within the range defined in the present invention.
Comparative Examples 1 to 6 are multi-layer coatings that deviate from the present invention in that they contain a large amount of glossy pigment in the glossy coating.
Based on the results of the finish quality test of the multi-layer coating created as described above, the following can be said:
By applying a glossy paint with a low concentration of glossy pigments translucently over a colored coating, the colored coating and the glossy coating fuse together, resulting in a multi-layer coating that combines glossiness, color development, and shine, while suppressing unevenness. (Examples 1-39)
However, when a glossy paint containing more glossy pigment than specified in this invention is applied, although sufficient gloss is achieved by the glossy pigment, unevenness is noticeable and the gloss is insufficient. In addition, the underlying surface is visible, but the color development is poor. (Comparative Examples 1-6)
Furthermore, when a glossy coating containing a large amount of glossy pigment is present in the lower layer and a clear coating is applied on top of it, the glossiness, shine, and weather resistance are good, but unevenness is noticeable and the color development is insufficient. (Comparative Example 5)

Claims (14)

The process includes steps (1) of applying a colored coating (I) containing a colored pigment and resin component to a substrate surface such that the thickness of the colored coating film is equal to or greater than the opacity film thickness, and drying to form a colored coating film, and step (2) of applying a glossy coating (II) containing a glossy pigment and resin component onto the colored coating film obtained in step (1), and drying to form a glossy coating film.
The aforementioned colored coating film either does not contain a lustrous pigment or contains less lustrous pigment than the aforementioned lustrous coating film.
The aforementioned glossy paint (II) is a multi-component paint comprising a main component and a curing agent component, and further comprising a main component comprising a hydrolyzable silyl group-containing acrylic resin, polysiloxane resin, epoxy resin and glossy pigment, and a curing agent component comprising an amino group-containing alkoxysilane compound,
A method for creating a glossy multilayer coating film in which the glossy coating film contains glossy pigment in the range of 0.05 to 10% by mass and has a thickness less than the opacity film thickness. The method for forming a glossy multi-layer coating according to claim 1, wherein the substrate surface is the substrate surface of a building. The method for forming a glossy multi-layer coating according to claim 1 or 2, wherein the colored paint (I) is a room-temperature drying type paint. A method for forming a glossy ^{multilayer coating film according to any one of claims 1 to 3, wherein the colored paint (I) is a paint that forms a colored coating film having a lightness (L* )} in the range of 40 to 95 and a chroma (C*) of 40 or less. A method for forming a glossy multi-layer coating film according to any one of claims 1 to 4, wherein a colored coating film using a colored paint (I) is formed by a roller. A method for forming a lustrous multilayer coating film according to any one of claims 1 to 5 , wherein the lustrous pigment is an aluminum flake pigment and/or a light-interfering pigment. The method for forming a lustrous multilayer coating film according to claim 6 , wherein the lustrous pigment includes an aluminum flake pigment, and the aluminum flake pigment is of the non-leafing type or the leafing type. A method for forming a lustrous multilayer coating film according to claim 6 or 7 , wherein the lustrous pigment includes an aluminum flake pigment, and the average particle size of the aluminum flake pigment is in the range of 5 to 250 μm. A method for forming a lustrous multilayer coating film according to any one of claims 6 to 8 , wherein the lustrous pigment includes an optically coherent pigment, and the average particle size of the optically coherent pigment is in the range of 5 to 250 μm. A method for forming a lustrous multilayer coating film according to any one of claims 6 to 9 , wherein the lustrous pigment comprises an aluminum flake pigment and a light-interfering pigment in a mass ratio of 10/90 to 90/10 of the former to the latter. A method for forming a glossy multilayer coating film according to any one of claims 1 to 10 , wherein the glossy coating (II) further comprises an organic solvent and/or a curing catalyst. A method for forming a glossy multilayer coating film according to any one of claims 1 to 11 , wherein a glossy coating film made of glossy paint (II) is formed by a roller. A method for forming a glossy multi-layer coating according to any one of claims 1 to 12 , further comprising step (3) of applying a clear coating (III) different from the glossy coating (II) on top of the glossy coating formed in step (2). The method for forming a glossy multilayer coating film according to claim 13 , wherein a clear coating film made of clear paint (III) is formed by a roller.