JP2022165253A - Reddish multilayer coating and method of forming reddish multilayer coating - Google Patents

Abstract

To provide a reddish multilayer coating excellent in shininess, saturation and depth of color, and reduced in metal unevenness and color unevenness.SOLUTION: A reddish multilayer coating comprises a first base coating and a second base coating arranged next to each other in order. The first base coating contains a color pigment and a luster pigment. The second base coating contains a color pigment and substantially no luster pigment. The mean light reflectance of a clear coating in a coating A which comprises an electrodeposited coating, an intermediate coating, the first base coating and the clear coating arranged next to each other in this order is 15-40% at wavelength of 360-700 nm. The mean light transmittance of the second base coating is 3% or less at wavelength of 440-560 nm, and 80-90% at wavelength of 650-700 nm.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a red multi-layer coating film and a method for forming a red multi-layer coating film.

In recent years, as a coating film for automobile bodies, a transparent colored clear coating film (second base coating film) containing a coloring pigment is laminated on a metallic base coating film (first base coating film) containing a bright pigment. A multi-layered coating film with excellent depth of color and high design properties is known, and is called a so-called “candy color” coating film. Candy color coating films are attracting attention as the appearance of automobile bodies due to their high designability.

For example, in Patent Document 1, the light reflectance of the metallic base coating film is 45 to 50% at a wavelength of 650 to 700 nm, and 20% or less at a wavelength of 410 to 440 nm and 510 to 590 nm. A method for forming a multilayer coating film having a transmittance of 50 to 70% at a wavelength of 400 to 700 nm, 88 to 92% at a wavelength of 650 to 700 nm, and 20 to 60% at a wavelength of 410 to 440 nm and 510 to 590 nm. disclosed.

JP 2014-042891 A

However, in recent years, there has been a demand for a multi-layer coating film having even higher designability in order to increase the added value of automobiles.

In addition, red is one of the main colors because red cars are produced in large numbers and red is used in a large number of paint colors for cars.

Accordingly, the present inventors conducted studies to improve the designability of reddish multi-layer coating films. In order to improve the design, the present inventors paid attention to the sense of brightness, saturation, and depth of color among the design.

First, the present inventors increased the average light reflectance of the first base coating film at a wavelength of 650 to 700 nm as described in Patent Document 1 in order to enhance the feeling of glitter. This is because the higher the average light reflectance, the higher the feeling of brightness. However, although increasing the average light reflectance of the first base coating increases the feeling of brightness, the metal unevenness of the red multi-layer coating becomes noticeable, and the design of the red multi-layer coating is the same as that of Patent Document 1. It did not increase as compared with the coating film. In the present specification, metal unevenness refers to non-uniformity in brightness in a multi-layer coating film.

Next, the present inventors increased the average light transmittance of the second base coating film at wavelengths of 410 to 440 nm and 510 to 590 nm as described in Patent Document 1 in order to increase the feeling of brightness while suppressing metal unevenness. . This is because even if the average light reflectance of the first base coating film is constant, the higher the average light transmittance of the second base coating film, the higher the feeling of brightness. However, although increasing the average light transmittance of the second base coating increases the feeling of brightness, the color unevenness of the red multi-layer coating becomes noticeable, and the design of the red multi-layer coating is inferior to that of Patent Document 1. It did not increase as compared with the layer coating film. In this specification, color unevenness refers to color unevenness in a red multi-layer coating film.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a red multi-layer coating film which is excellent in brilliance, chroma, and depth of color, and which is less in metal unevenness and color unevenness.

Another object of the present invention is to provide a method for forming a red multi-layer coating film which is excellent in brilliance, chroma, and depth of color, and which has little unevenness in metal and unevenness in color.

The red multi-layer coating film according to the present invention is a red multi-layer coating film comprising a first base coating film and a second base coating film adjacent in order,
The first base coating contains a coloring pigment and a bright pigment,
The second base coating contains a coloring pigment and substantially does not contain a bright pigment,
The coating film A comprising an electrodeposition coating film, an intermediate coating film, the first base coating film and a clear coating film adjacent in order has an average light reflectance of the clear coating film of 15 to 40 at a wavelength of 360 to 700 nm. % and
The average light transmittance of the second base coating is 3% or less at a wavelength of 440 to 560 nm and is 80 to 90% at a wavelength of 650 to 700 nm. As a result, the red multi-layer coating film is excellent in brilliance, chroma, and depth of color, and has little metal unevenness and color unevenness.

In one embodiment of the red-based multilayer coating film according to the present invention, the ratio of the total solid mass of the coloring pigment in the second base coating to the total solid mass of the second base coating is 4 to 8%.

In one embodiment of the reddish multilayer coating film according to the present invention, the dry film thickness of the second base coating film is 8 to 14 μm.

In one embodiment of the red-based multilayer coating film according to the present invention, the coloring pigments of the first base coating film and the second base coating film contain a red-based pigment.

A method for forming a reddish multilayer coating film according to the present invention comprises a first base coating composition for forming a first base coating film, and a second base coating composition for forming a second base coating film. A step of preparing a
A step B of applying the first base coating composition to an object to be coated to form an uncured first base coating film;
Step C of coating the second base coating composition on the uncured first base coating to form an uncured second base coating;
step D of curing the uncured first base coating and the uncured second base coating together to form the first base coating and the second base coating;
including
The first base paint composition contains a resin component, a color pigment and a bright pigment,
The second base paint composition contains a resin component and a color pigment, and substantially does not contain a bright pigment,
The coating film A comprising an electrodeposition coating film, an intermediate coating film, the first base coating film and a clear coating film adjacent in order has an average light reflectance of the clear coating film of 15 to 40 at a wavelength of 360 to 700 nm. % and
In the method for forming a red multi-layer coating film, the average light transmittance of the second base coating film is 3% or less at a wavelength of 440 to 560 nm and 80 to 90% at a wavelength of 650 to 700 nm. As a result, it is possible to form a red multi-layer coating film which is excellent in brilliance, chroma, and depth of color, and which has less unevenness in metal and unevenness in color.

In one embodiment of the method for forming a red multi-layer coating film according to the present invention, the total solid mass of the coloring pigment of the second base coating composition relative to the total solid mass of the second base coating composition The percentage is 4-8%.

In one embodiment of the method for forming a reddish multi-layer coating film according to the present invention, the dry film thickness of the second base coating film is 8 to 14 μm.

In one embodiment of the method for forming a red multi-layer coating film according to the present invention, the color pigments of the first base coating composition and the second base coating composition contain red pigments.

According to the present invention, it is possible to provide a red multi-layer coating film which is excellent in brilliance, chroma, and depth of color, and which is less in metal unevenness and color unevenness. Further, according to the present invention, it is possible to provide a method for forming a red multi-layer coating film which is excellent in brightness, chroma, and depth of color, and which has little metal unevenness and color unevenness.

FIG. 1 is a schematic diagram showing an example of the layer structure of the red multi-layer coating film according to the present invention. FIG. 2 is a schematic diagram showing an example of an automobile body having a reddish multi-layer coating film according to the present invention. FIG. 3 is a schematic diagram showing another example of an automobile body having a reddish multi-layer coating film according to the present invention. FIG. 4 is a schematic diagram showing another example of an automobile body having a reddish multi-layer coating film according to the present invention. FIG. 5 is a schematic diagram showing the layer structure of the coating film A. As shown in FIG.

Embodiments of the present invention will be described below. These descriptions are intended to be illustrative of the invention and are not intended to limit the invention in any way.

In the present invention, two or more embodiments can be arbitrarily combined.

In the present invention, paint and paint composition can be used interchangeably. In the present invention, the electrodeposition coating film and the undercoat coating film can be used interchangeably.

Numeric ranges are intended to include the upper and lower limits of the range unless otherwise indicated. For example, 15-40% means a range of 15% or more and 40% or less.

In this specification, the first base paint composition may be simply referred to as "first base paint". In this specification, the second base paint composition may be simply referred to as "second base paint". Further, in this specification, the first base paint and the second base paint may be collectively referred to as "base paint".

In this specification, the ratio (%) of the total solid mass of a certain pigment (coloring pigment or bright pigment) to the total solid mass in a certain paint composition (first base paint or second base paint) is referred to as " It is sometimes referred to as "pigment mass concentration" or "PWC".

In the present invention, the average particle size of the bright pigment refers to the median size of the volume-based particle size distribution measured by the laser diffraction scattering method using a Microtrac particle size distribution analyzer (trade name “MT3300”) manufactured by Nikkiso Co., Ltd.

In the present specification, a paint composition in which the dispersing medium with the highest content is water is referred to as an aqueous paint composition. In the present specification, a solvent-based coating composition is one in which the dispersing medium contained in the coating composition with the highest content is a solvent.

In this specification, the non-volatile content is sometimes referred to as "solid content".

Since the attached drawings are schematic diagrams with priority on facilitating understanding of the present invention, the scale of each coating film in the drawings is not accurate.

In the present invention, average light reflectance refers to the average value of light reflectance in the wavelength range of 360 to 700 nm. The average light reflectance in the wavelength region of 360 to 700 nm in the clear coating film of coating film A is measured by the method described in Examples.

In the present invention, average light transmittance refers to the average value of light transmittance in a predetermined wavelength range. The average light transmittance of the second base coating film is measured by the method described in Examples.

In the present invention, "red" refers to hues ranging from 10RP to 10R, ie, 10RP, 1R, 2R, 3R, 4R, 5R, 6R, 7R, 8R, 9R and 10R in the Munsell color system.

In the present invention, "uncured" refers to a state in which the curing reaction of the coating film has not been completed. In this specification, the term "preheating" refers to heating and drying the paint under conditions such as temperature and time that the applied paint does not harden.

(red multi-layer coating)
The red multi-layer coating film according to the present invention is a red multi-layer coating film comprising a first base coating film and a second base coating film adjacent in order,
The first base coating contains a coloring pigment and a bright pigment,
The second base coating contains a coloring pigment and substantially does not contain a bright pigment,
The coating film A comprising an electrodeposition coating film, an intermediate coating film, the first base coating film and a clear coating film adjacent in order has an average light reflectance of the clear coating film of 15 to 40 at a wavelength of 360 to 700 nm. % and
The average light transmittance of the second base coating is 3% or less at a wavelength of 440 to 560 nm and is 80 to 90% at a wavelength of 650 to 700 nm.

Hereinafter, the first base coating film and the second base coating film, which are essential elements of the reddish multi-layer coating film according to the present invention, will be described.

(First base coating film)
The first base coating film contains a color pigment and a luster pigment. The first base coating usually contains a resin component in addition to the coloring pigment and the luster pigment. The first base coating film is located closer to the object to be coated than the second base coating film, that is, closer to the body of the automobile. The first base coating film is formed from the first base coating composition described below.

(First base paint composition)
The first base coating composition forms the first base coating. The first base paint contains a resin component, a color pigment and a luster pigment. The resin component, color pigment and luster pigment of the first base paint will be described below.

- Resin component As the resin component, a resin component of a conventionally known base paint can be used. Examples of resin components include acrylic resins, polyester resins, alkyd resins, fluorine resins, epoxy resins, polyurethane resins, polyether resins, polyolefin resins, and the like. In addition, as the resin component, for example, coating film-forming resins such as acrylic emulsion resins, polyether polyols, and urethane emulsion resins described in Patent Document 1; may

You may use a resin component individually by 1 type or in combination of 2 or more types. The resin component of the first base coating composition may be the same as or different from the resin component of the second base coating composition described below.

The amount of the resin component in the first base paint may be adjusted as appropriate. ~80 parts by mass is preferred.

- Coloring pigment As the coloring pigment, conventionally known coloring pigments for base paints can be used. Examples of color pigments include organic pigments and inorganic pigments.

Examples of organic pigments include azochelate pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, Examples include dioxane-based pigments, quinacridone-based pigments, isoindolinone-based pigments, and metal complex pigments.

Examples of inorganic pigments include yellow iron oxide, nickel titanium yellow, red iron oxide, carbon black, and titanium dioxide.

Colored pigments may be of any color. Color pigments include, for example, gray, silver, black, red, yellow, green, and blue. In one embodiment, the colored pigment is one or more selected from the group consisting of black, red, gray and silver.

In one embodiment, the colored pigment of the first base paint comprises a red-based pigment. In another embodiment, the colored pigments of the first base paint and the second base paint include red-based pigments.

Commercially available colored pigments include, for example, Clariant's trade name "Hostaperm (registered trademark) Red P2GL-WD" (red), BASF's trade name "Paliogen (registered trademark) Red L3875" (red), Dainichiseika Kogyo Co., Ltd. trade name “Daipiro TM Red” (red), Columbia Carbon Co., Ltd. trade name “Carbon Black R-5000” (black), BASF trade name “Cinquasia Magenta RT-355-D” ” (reddish purple).

You may use a coloring pigment individually by 1 type or in combination of 2 or more types. The coloring pigment of the first base paint may be the same as or different from the coloring pigment of the second base paint, which will be described later.

The amount of color pigment in the first base paint may be adjusted as appropriate. The total solid weight of the color pigments in the first base paint is, for example, 0 to 20%, preferably 5 to 15%, relative to the total solid weight of the first base paint.

In one embodiment, the PWC of the colored pigment in the first base paint is 0.0% or more, 1.0% or more, 2.0% or more, 3.0% or more, 4.0% or more, 5.0% % or more, 5.5% or more, 6.0% or more, 6.5% or more, 7.0% or more, 7.5% or more, 8.0% or more, 8.5% or more, 9.0% or more , 9.5% or more, 10.0% or more, 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13 .5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, or 19.0% or more. In another embodiment, the PWC of the colored pigment in the first base paint is 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less; 0% or less, 14.5% or less, 14.0% or less, 13.5% or less, 13.0% or less, 12.5% or less, 12.0% or less, 11.5% or less, 11.0% 10.5% or less, 10.0% or less, 9.5% or less, 9.0% or less, 8.5% or less, 8.0% or less, 7.5% or less, 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, or 1.0% or less.

- Luminous Pigment As the luster pigment, a luster pigment such as a scale-like luster pigment for a conventionally known base paint can be used.

Luster pigments include, for example, metals such as aluminum, copper, zinc, iron, nickel, tin, and aluminum oxide; alloys thereof; luster pigments such as interference mica, white mica, graphite, glass flakes and alumina flakes; , alloys, interference mica, white mica, graphite, glass flakes or alumina flakes coated with metal oxides (e.g. titanium oxide, titanium dioxide, iron oxide) or metals (e.g. gold, silver) scale-like luster pigments is mentioned. In addition, for example, alumina flake pigment (a) described in JP-A-2016-221473; a scale-like luster pigment in which a metal substrate or a glass flake substrate is coated with a metal oxide or metal; a metal substrate or glass Scale-like luster pigments in which a color pigment is chemically adsorbed on the surface of a flake base material; aluminum pigments in which an aluminum oxide layer is formed on the surface of an aluminum base material; aluminum solid-solution plate-like iron oxide pigments; surfaces of interference mica, graphite or silica flakes scale-like luster pigments coated with titanium dioxide; plate-like iron oxide pigments; A preferred scale-like luster pigment is aluminum flake, which is a scale-like luster pigment in which a glass substrate is coated with a metal oxide.

In one embodiment, the glitter pigment is aluminum flake.

Effect pigments may be colorless, colored, or a combination thereof. Colored colors include, for example, gray, silver, black, red, yellow, green, blue, and the like. In one embodiment, the glitter pigment is one or more selected from the group consisting of gray and silver. In another embodiment, the luster pigment is one or more selected from the group consisting of gray, silver and black.

The average particle size of the luster pigment may be appropriately adjusted, and is, for example, 5 μm to 25 μm. In one embodiment, the average particle size of the bright pigment is 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μm or more, 17 μm. 18 μm or more, 19 μm or more, 20 μm or more, 21 μm or more, 22 μm or more, 23 μm or more, or 24 μm or more. In another embodiment, the average particle size of the bright pigment is 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, or 6 μm or less. In yet another embodiment, the glitter has an average particle size of 9-15 μm.

A commercially available product may be used as the luster pigment. Commercially available bright pigments include, for example, the Metashine (registered trademark) series such as ST1018 series, ST1025 series and GT1020 series manufactured by Nippon Sheet Glass; 76 series, TCR series, 54 series and WX series manufactured by Toyo Aluminum Co., Ltd.; WL series (trade name: "Alpaste (registered trademark)" series; Asahi Kasei Corp.: trade name: "Aluminum Paste": GX series; ECKART: trade name: "B001", etc.); trade name: "LUXAN" series; be done. Commercially available luster pigments include, in particular, the 76 series, TCR series, 54 series manufactured by Toyo Aluminum Co., Ltd. under the trade name of "Alpaste (registered trademark)" series; the GX series manufactured by Asahi Kasei under the trade name of "Aluminum Paste"; is preferred.

You may use a bright pigment individually by 1 type or in combination of 2 or more types.

The amount of bright pigment in the first base paint may be adjusted as appropriate. The total solid mass of the luster pigment in the first base paint is, for example, 0 to 25%, preferably 5 to 15%, relative to the total solid mass of the first base paint.

In one embodiment, the PWC of the bright pigment in the first base paint is 0.0% or more, 5.0% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0%. % or more, 14.0% or more, 15.0% or more, or 20.0% or more. In another embodiment, the PWC of the luster pigment in the first base paint is 25.0% or less, 20.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 0% or less, 11.0% or less, 10.0% or less, or 5.0% or less.

・Other components The first base paint contains resin components, color pigments and bright pigments, as well as curing agents, extender pigments, water, organic solvents, corrosion inhibitors, surface conditioners, thickeners, antioxidants, and ultraviolet rays. Known components of base paints such as inhibitors and antifoaming agents may also be included. Each of these other components may be used alone or in combination of two or more.

• Curing agent The first base paint may contain a curing agent. As the curing agent, conventionally known curing agents for base paints can be used. Examples of curing agents include amino resins and blocked isocyanates described in JP-A-2020-099888.

The amount of the curing agent in the first base paint may be adjusted as appropriate. When using the curing agent, for example, 10 to 60 parts per 100 parts by mass of the total solid content of the resin component and the curing agent in the first base paint. parts by mass, preferably 20 to 40 parts by mass.

The curing agent for the first base paint may be the same as or different from the curing agent for the second base paint, which will be described later.

The first base paint may be either a water-based paint composition or a solvent-based paint composition. In one embodiment, the first base paint and the second base paint are waterborne paint compositions.

The total amount of paint solids in the first base paint may be adjusted as appropriate, and is not particularly limited. For example, the total solid content of the paint is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, per 100 parts by weight of the first base paint.

Method for Preparing First Base Paint Composition The method for preparing the first base paint composition is not particularly limited as long as the above-described resin component, color pigment and luster pigment are included, and conventionally known methods can be used. For example, the first base paint can be prepared by kneading and dispersing the resin component, color pigment and luster pigment using a kneader or rolls.

The dry film thickness of the first base coating film may be appropriately adjusted. The dry film thickness of the first base coating film is, for example, 4 to 20 μm, preferably 6 to 12 μm. In one embodiment, the dry film thickness of the first base coating is 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm or more, 12 μm or more, or 15 μm or more. In another embodiment, the dry film thickness of the first base coating is 20 μm or less, 15 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less.

In the present invention, the average light reflectance of the first base coating, which is related to the brightness of the red multi-layer coating, is measured not only for the first base coating, but for the electrodeposition coating which is adjacent in order. , an intermediate coating film, a first base coating film and a clear coating film. FIG. 5 is a schematic diagram showing the layer structure of the coating film A. As shown in FIG. The coating film A is composed of four layers, an electrodeposition coating film 4, an intermediate coating film 5, a first base coating film 1 and a clear coating film 6, which are adjacent in order. In the present invention, the average light reflectance of the clear coating film of coating film A is 15 to 40% at a wavelength of 360 to 700 nm. A specific configuration of the coating film A is described in Examples.

In the present invention, the intermediate coating film, the first base coating film and the clear coating film of the coating film A are formed by wet-on-wet coating with 3 coats and 1 bake. That is, an intermediate coating is applied onto the electrodeposition coating to form an uncured intermediate coating. Next, a first base paint is applied onto the uncured intermediate coating film to form an uncured first base coating film. Next, a clear coating is applied onto the uncured first base coating to form an uncured clear coating. Then, the uncured intermediate coating film, the uncured first base coating film and the uncured clear coating film are cured together to form the intermediate coating film, the first base coating film and the clear coating film. A specific method for forming the coating film A is described in Examples.

In one embodiment, the average light reflectance of the coating film A at a wavelength of 360 to 700 nm is 15% or more, 18% or more, 20% or more, 21% or more, 22% or more, 23% or more, 24% or more, 25% 26% or more, 27% or more, 28% or more, 29% or more, 30% or more, or 35% or more. In another embodiment, the average light reflectance of Coating A at a wavelength of 360 to 700 nm is 40% or less, 35% or less, 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, 25% or less. % or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 18% or less, or 16% or less. In yet another embodiment, the average light reflectance of Coating A at wavelengths of 360-700 nm is 18-38%.

Coating film A is merely an evaluation coating film used for measuring and evaluating the average light reflectance of the first base coating film, which is related to the brightness of the red multi-layer coating film. The red multi-layer coating film of the present invention is not limited to the material, layer structure, film thickness, etc. of the coating film A.

(Second base coating film)
The second base coat contains color pigments. The second base coating usually contains a resin component in addition to the coloring pigment. The second base coating is positioned closer to the viewer than the first base coating. The second base coating film is formed from the second base coating composition described below.

The average light transmittance of the second base coating film is 3% or less at a wavelength of 440-560 nm and 80-90% at a wavelength of 650-700 nm.

When the average light transmittance of the second base coating film at a wavelength of 440 to 560 nm is 3% or less, color unevenness of the red multi-layer coating film is suppressed, and the design of the red multi-layer coating film is enhanced.

As a method for making the average light transmittance of the second base coating film 3% or less at a wavelength of 440 to 560 nm, for example, (1) setting the PT value described later to 45 or more; and (2) one type of pigment When the light transmittance of the second base coating film containing only the pigment (PWC: 10%, dry film thickness: 7 μm) is measured, a pigment that does not transmit light with a wavelength of 440 to 560 nm, such as a wavelength of 440 to 560 nm and selecting a pigment having an average transmittance of 1.5% or less for light rays.

Specific examples of the pigment used in method (2) include Clariant's trade name "Hostaperm (registered trademark) Red P2GL-WD" (red) and BASF's trade name "Paliogen (registered trademark) Red L3875" ( red), etc. In a preferred embodiment, a pigment having a transmittance of 1.5% or less for light with a wavelength of 440 to 560 nm is included in the coloring pigment in the second base coating in the range of 90 to 100% by weight or 95 to 100% by weight. Including in

Measurement of the light transmittance of the second base coating film containing only one type of pigment in the above method (2), PWC: 10%, dry film thickness: 7 μm, except for the “average light Transmittance measurement”.

In one embodiment, the average light transmittance of the second base coating at a wavelength of 440 to 560 nm is 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, 1.4%. 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, or 0.2% or less. In another embodiment, the average light transmittance of the second base coating at a wavelength of 440 to 560 nm is 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5 % or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, 1.0% or more, 1.1% or more, 1.2% or more, 1.3% or more , 1.4% or more, 1.5% or more, 2.0% or more, or 2.5% or more. In yet another embodiment, the average light transmittance of the second base coating at wavelengths of 440-560 nm is 0.4-2.9%.

When the average light transmittance of the second base coating film at a wavelength of 650 to 700 nm is 80% or more, the red color develops with high saturation, and the design of the red multi-layer coating film is enhanced. When the average light transmittance of the second base coating film at a wavelength of 650 to 700 nm is 90% or less, the depth of the red color is enhanced, and the design of the red multi-layer coating film is enhanced.

Methods for making the average light transmittance of the second base coating film 80 to 90% at a wavelength of 650 to 700 nm include, for example, (1) setting the PT value described later to 95 or less; and (2) using one type of pigment. When the light transmittance of the second base coating film (PWC: 10%, dry film thickness: 7 μm) containing only the pigment is measured, a pigment that easily transmits light with a wavelength of 650 nm or more, for example, For example, a pigment having a light transmittance of 75% or more is selected.

Specific examples of the pigment of method (2) with an average light transmittance of 80 to 90% include Clariant's trade name "Hostaperm (registered trademark) Red P2GL-WD" (red), BASF's product and the name "Paliogen (registered trademark) Red L3875" (red). In a preferred embodiment, a pigment having a transmittance of 75% or more for light with a wavelength of 650 nm is included in the second base coating in the range of 90 to 100% by mass or 95 to 100% by mass.

In one embodiment, the average light transmittance of the second base coating at a wavelength of 650 to 700 nm is 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more. In another embodiment, the average light transmittance of the second base coating at a wavelength of 650 to 700 nm is 90% or less, 89% or less, 88% or less, 87% or less, 86% or less, 85% or less, 84% or less. , 83% or less, 82% or less or 81% or less. In yet another embodiment, the average light transmittance of the second base coating at wavelengths of 650-700 nm is 81-87%.

(Second base paint composition)
The second base coating composition forms the second base coating. The second base paint contains a resin component and a color pigment, and does not substantially contain a luster pigment. The resin component and color pigment of the second base paint will be described below.

- Resin component As the resin component, a resin component of a conventionally known base paint can be used. Examples of the resin component are the same as those listed for the first base paint.

You may use a resin component individually by 1 type or in combination of 2 or more types.

The amount of the resin component in the second base paint may be adjusted as appropriate. ~80 parts by mass is preferred.

- Coloring pigment As the coloring pigment, conventionally known coloring pigments for base paints can be used. Examples of the coloring pigment are the same as the coloring pigments mentioned for the first base paint. You may use a coloring pigment individually by 1 type or in combination of 2 or more types.

In one embodiment, the colored pigment of the second base paint comprises a red-based pigment.

The amount of color pigment in the second base paint may be adjusted as appropriate. The total solid mass of the color pigments in the second base paint is, for example, 1.0 to 15.0%, preferably 4.0 to 8.0%, of the total solid mass of the second base paint. 0%.

In one embodiment, the PWC of the colored pigment in the second base paint is 1.0% or more, 2.0% or more, 3.0% or more, 4.0% or more, 4.5% or more, 5.0% % or more, 5.5% or more, 6.0% or more, 6.5% or more, 7.0% or more, 7.5% or more, 8.0% or more, 9.0% or more, 10.0% or more , 11.0% or more, 12.0% or more, 13.0% or more, or 14.0% or more. In another embodiment, the PWC of the colored pigment in the second base paint is 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less; 0% or less, 9.0% or less, 8.0% or less, 7.5% or less, 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% 4.5% or less, 4.0% or less, 3.0% or less, or 2.0% or less. In yet another embodiment, the PWC of the colored pigment in the second base paint is from 4.1% to 7.8%.

The second base paint is substantially free of luster pigments. In other words, the luster pigment is not intentionally added to the second base paint. If the second base paint contains a luster pigment, there may be problems such as a decrease in the transparency of the red multi-layer coating film, a lack of chroma, or a lack of depth of color.

・Other components In addition to resin components and color pigments, the second base paint includes curing agents, extender pigments, water, organic solvents, surface modifiers, thickeners, antioxidants, UV inhibitors, antifoaming agents, etc. known base paint components. Each of these other components may be used alone or in combination of two or more.

• Curing agent As the curing agent, conventionally known curing agents for base paints can be used. Examples of the curing agent are the same as those mentioned for the first base paint.

The amount of the curing agent in the second base paint may be adjusted as appropriate. When using the curing agent, for example, 10 to 60 parts per 100 parts by mass of the total solid content of the resin component and the curing agent in the second base paint. parts by mass, preferably 20 to 40 parts by mass.

The second base coating composition may be either a water-based coating composition or a solvent-based coating composition.

The total amount of paint solids in the second base paint may be adjusted as appropriate, and is not particularly limited. For example, the total solid content of the paint is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, per 100 parts by weight of the second base paint.

- Method for preparing the second base paint composition The method for preparing the second base paint composition is not particularly limited as long as the above-described resin component and color pigment are included, and conventionally known methods can be used. For example, the means described in the method for preparing the first base paint can be used.

In one embodiment of the red-based multilayer coating film according to the present invention, the ratio of the total solid mass of the coloring pigment in the second base coating to the total solid mass of the second base coating is 4 to 8%.

The dry film thickness of the second base coating film may be appropriately adjusted. The dry film thickness of the second base coating film is, for example, 4 to 20 μm, preferably 8 to 14 μm. In one embodiment, the dry film thickness of the second base coating is 4 μm or more, 5 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, or 15 μm or more. In another embodiment, the dry film thickness of the second base coating is 20 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, or 5 μm or less.

In the second base coating, the value obtained by multiplying the PWC (%) of the second base coating by the dry film thickness (μm) of the second base coating (hereinafter sometimes referred to as "PT value") is 45 ~ 95 (no units) is preferred. When the PT value is 45 or more, the second base coating film has an enhanced base-hiding property, and metal unevenness in the first base coating film containing the bright pigment is suppressed. In addition, when the PT value is 45 or more, the brightness of the red multi-layer coating film becomes appropriate, and the depth of color is enhanced. Further, when the PT value is 95 or less, the second base coating film has an appropriate base-hiding property, and the first base coating film has an enhanced brilliance.

In one embodiment, the PT value of the second base coating film is 45 or higher, 49 or higher, 50 or higher, 55 or higher, 59 or higher, 60 or higher, 65 or higher, 70 or higher, 75 or higher, 80 or higher, 85 or higher, or 90 or higher. is. In another embodiment, the PT value of the second base coating is 95 or less, 94 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, or 50 or less. . In yet another embodiment, the PT value of the second basecoat is 49-94.

In one embodiment, the red multi-layer coating film according to the present invention comprises a first base coating film and a second base coating film. In another embodiment, the red multi-layer coating film according to the present invention comprises a first base coating film, a second base coating film and a clear coating film.

FIG. 1 is a schematic diagram showing an example of the layer structure of the red multi-layer coating film according to the present invention. In FIG. 1, the red multi-layer coating consists of a first base coating 1 and a second base coating 2 which are adjacent in order.

FIG. 2 is a schematic diagram showing an example of an automobile body having a reddish multi-layer coating film according to the present invention. In FIG. 2, the vehicle body 3 has an electrodeposition coating film 4, an intermediate coating film 5, a first base coating film 1, a second base coating film 2, and a clear coating film 6 in order from the vehicle body 3 side. In this specification, the coating film consisting of five layers of the electrodeposition coating film 4, the intermediate coating film 5, the first base coating film 1, the second base coating film 2 and the clear coating film 6 is referred to as the coating film B. be.

FIG. 3 is a schematic diagram showing another example of an automobile body having a reddish multi-layer coating film according to the present invention. In FIG. 3, the vehicle body 3 has an electrodeposition coating film 4, a first base coating film 1, a second base coating film 2 and a clear coating film 6 adjacent in order from the vehicle body 3 side.

FIG. 4 is a schematic diagram showing another example of an automobile body having a reddish multi-layer coating film according to the present invention. In FIG. 4 , the vehicle body 3 has an electrodeposition coating film 4 , a first base coating film 1 and a second base coating film 2 adjacent in order from the vehicle body 3 side.

The electrodeposition coating film, intermediate coating film and clear coating film can be the electrodeposition coating film, intermediate coating film and clear coating film of conventionally known multi-layer coating films used for automobiles, respectively.

As the electrodeposition coating film, for example, the configuration of the electrodeposition coating film described in JP-A-2020-100732 can be employed. The dry film thickness of the electrodeposition coating film may be, for example, 15 to 40 μm. In one embodiment, the dry film thickness of the electrodeposition coating film is 15 μm or more, 20 μm or more, or 30 μm or more. In another embodiment, the dry film thickness of the electrocoated film is 40 μm or less, 30 μm or less, or 20 μm or less.

As the intermediate coating film, for example, the configuration of the intermediate coating film described in JP-A-2020-099888 can be employed. The dry film thickness of the intermediate coating film may be, for example, 10 to 100 μm. In one embodiment, the dry film thickness of the intermediate coating film is 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, or 90 μm or more. In another embodiment, the dry film thickness of the intermediate coating film is 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less.

As the clear coating film, for example, the structure of the clear coating film described in JP-A-2020-099888 can be employed. The dry film thickness of the clear coating film may be, for example, 10 to 80 μm. In one embodiment, the dry film thickness of the clear coating film is 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, or 70 μm or more. In another embodiment, the dry film thickness of the clear coating is 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less.

Applications of the red multi-layer coating film are not particularly limited, and examples thereof include vehicles such as automobiles. In a preferred embodiment, the application of the red multi-layer coating film of the present invention is for automotive applications.

(Method for forming red multi-layer coating film)

A method for forming a reddish multilayer coating film according to the present invention comprises a first base coating composition for forming a first base coating film, and a second base coating composition for forming a second base coating film. A step of preparing a
A step B of applying the first base coating composition to an object to be coated to form an uncured first base coating film;
Step C of coating the second base coating composition on the uncured first base coating to form an uncured second base coating;
step D of curing the uncured first base coating and the uncured second base coating together to form the first base coating and the second base coating;
including
The first base paint composition contains a resin component, a color pigment and a bright pigment,
The second base paint composition contains a resin component and a color pigment, and substantially does not contain a bright pigment,
The coating film A comprising an electrodeposition coating film, an intermediate coating film, the first base coating film and a clear coating film adjacent in order has an average light reflectance of the clear coating film of 15 to 40 at a wavelength of 360 to 700 nm. % and
In the method for forming a red multi-layer coating film, the average light transmittance of the second base coating film is 3% or less at a wavelength of 440 to 560 nm and 80 to 90% at a wavelength of 650 to 700 nm.

Hereinafter, each step A to D of the method for forming a reddish multi-layer coating film according to the present invention will be illustrated and explained.

・Process A
In step A, the above-described first base coating composition and second base coating composition are prepared. In step A, in addition to the first base coating composition and the second base coating composition, a clear coating for forming a clear coating film may be prepared. A known clear paint can be used as the clear paint.

In one embodiment of the method for forming a red multi-layer coating film according to the present invention, the total solid mass of the coloring pigment of the second base coating composition relative to the total solid mass of the second base coating composition The percentage is 4-8%.

In one embodiment of the method for forming a red multi-layer coating film according to the present invention, the color pigments of the first base coating composition and the second base coating composition contain red pigments.

・Process B
In step B, the first base coating composition is applied to the object to be coated to form an uncured first base coating film.

The method for applying the first base paint is not particularly limited, and conventionally known methods for applying a base paint for automobiles can be used. Examples of the method of applying the first base coating include spray coating and rotary atomization electrostatic coating.

The object to be coated with the first base coating composition in step B is, for example, an automobile body. The object to be coated may be, for example, an automobile body having an electrodeposition coating film, or an automobile body having an electrodeposition coating film and an intermediate coating film.

After applying the first base coating material to the object to be coated, the first base coating material may be preheated (also referred to as pre-drying) to form an uncured first base coating film.

Preheating conditions are, for example, 60 to 90° C. and 120 to 300 seconds, more preferably 80° C. and 180 seconds.

The film thickness of the uncured first base coating film is not particularly limited, and may be appropriately adjusted according to the desired dry film thickness.

・Process C
In step C, a second base coating is applied onto the uncured first base coating to form an uncured second base coating.

The method of applying the second base paint is not particularly limited, and a conventionally known method of applying a base paint can be used. Methods of applying the second base paint include, for example, spray painting and rotary atomization electrostatic painting. The method of applying the first base paint in step B and the method of applying the second base paint in step C may be the same or different.

After applying the second base coating, the second base coating may be preheated to form an uncured second base coating.

The film thickness of the uncured second base coating film is not particularly limited, and may be appropriately adjusted according to the desired dry film thickness.

・Process D
In step D, the uncured first basecoat and the uncured second basecoat are cured together to form a first basecoat and a second basecoat. Curing methods include, for example, heat curing. The heat curing conditions can be, for example, a temperature of 120 to 160° C. and a time of 10 to 30 minutes.

In step D, it is only necessary to cure the uncured first base coating and the uncured second base coating to form the first base coating and the uncured second base coating. In addition, an uncured clear coating formed on the uncured second base coating may be cured together.

In one embodiment of the method for forming a reddish multi-layer coating film according to the present invention, the dry film thickness of the second base coating film is 8 to 14 μm.

The method for forming a reddish multi-layer coating film according to the present invention may include, in addition to steps A to D, a step of forming a conventionally known automobile coating film. For example, a step of forming an electrodeposition coating film on an automobile body, a step of forming an intermediate coating film on the electrodeposition coating film, a step of coating a clear coating on an uncured second base coating film, Examples include a step of forming a clear coating film and a step of curing an uncured clear coating film to form a clear coating film.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but these Examples are intended to illustrate the present invention and do not limit the present invention in any way.

The details of the materials and equipment used to measure the average light reflectance are as follows.
Electrodeposition paint: cationic electrodeposition paint, trade name "Powernics 110" manufactured by Nippon Paint Automotive Coatings Co., Ltd.
Intermediate paint: Polyester/melamine resin-based intermediate paint, trade name “Aqualex AR-620 8105” manufactured by Nippon Paint Automotive Coatings Co., Ltd.
Steel plate: zinc phosphate treated SPCC-SD steel plate, dimensions 20 cm x 30 cm x 0.8 cm thick
Spectrophotometer: Hitachi's product name "U-3310", scan speed 300 nm / min, sampling interval set to 0.5 nm

The details of the materials and equipment used to measure the average light transmittance are as follows.
Polypropylene plate: Product name "Polypropylene" manufactured by TP Giken
Clear paint: trade name "Macflow O-1860 Clear" manufactured by Nippon Paint Automotive Coatings, acid epoxy curable acrylic resin paint Spectrophotometer: trade name "U-3310" manufactured by Hitachi, scan speed 300 nm /min, sampling interval set to 0.5 nm

The details of the apparatus used for measuring chroma are as follows.
Spectrophotometer: trade name "CM-512m3" manufactured by Konica Minolta

The details of the components of the base paint used in the examples are as follows.
Resin component 1: Acrylic resin manufactured by Nippon Paint Co., Ltd. described in Production Example 1 of paragraph [0059] of JP-A-2014-042891 Resin component 2: Production example 1 of paragraph [0059] of JP-A-2014-042891 Amino resin manufactured by Mitsui Chemicals, Inc., trade name "Uban (registered trademark) 128"
Bright pigment 1: trade name "WM-2025" manufactured by Toyo Aluminum Co., Ltd., silver color, average particle size 15 μm, indicated as "No. 1" in Table 1 Coloring pigment 1: trade name "Hostaperm (registered trademark)" manufactured by Clariant Red P2GL-WD", red, indicated as "No. 1" in Table 1 Coloring pigment 2: BASF's trade name "Paliogen (registered trademark) Red L3875", red, indicated as "No. 2" in Table 1 Coloring pigment 3: Dainichiseika Kogyo Co., Ltd. trade name "Daipiro TM Red", red, indicated as "No. 3" in Table 1 Coloring pigment 4: Columbia Carbon Co., Ltd. trade name "Carbon Black R-5000", black, front Color pigment 5: Trade name "Cinquasia Magenta RT-355-D" manufactured by BASF, reddish purple, indicated as "No. 5" in Table 1

(Examples 1-9 and Comparative Examples 1-9)
・Preparation of the first base paint composition In addition to the PWC (%) bright pigment and color pigment shown in Table 1, the following amount of resin component was blended and uniformly dispersed, and each example and comparative example A first base paint composition was obtained.
Resin component 1: 100 parts by mass (non-volatile content 60%)
Resin component 2: 66.7 parts by mass (non-volatile content 60%)

・Preparation of the second base paint composition In addition to the PWC (%) color pigment shown in Table 1, the same amount of resin component as the first base paint composition was blended and uniformly dispersed, and each example and A comparative second base coating composition was obtained.

Measurement of Average Light Reflectance An electrodeposition coating was applied to a steel plate so that the dry film thickness was 20 μm, and the coating was cured by heating at 160° C. for 30 minutes to obtain an electrodeposition coating film. Next, an intermediate coating was applied onto the electrodeposition coating film so that the dry film thickness was 20 μm to form an uncured intermediate coating film. After standing still for 3 minutes, the uncured intermediate coating film was preheated at 80° C. for 3 minutes. Next, the first base paint was applied onto the uncured intermediate coating film so that the dry film thickness was 10 μm to form an uncured first base coating film. After standing still for 3 minutes, the uncured first base coating film was preheated at 80° C. for 3 minutes. Next, a clear paint was applied onto the uncured first base coating film so that the dry film thickness was 30 μm to form an uncured clear coating film. Then, after standing still for 10 minutes, the uncured intermediate coating film, the uncured first base coating film and the uncured clear coating film were baked and cured together at 140°C for 30 minutes to obtain a coating film A. rice field. The intermediate coating, the first base coating and the clear coating were all coated with Metabel.

In the clear coating film of coating film A of each example and comparative example, using a spectrophotometer, the wavelength range of 300 to 700 nm was measured every 10 nm in wavelength scan mode, and the light reflection of coating film A at each wavelength was measured. asked for a rate. Then, the average light reflectance of the coating film A was obtained from the arithmetic mean (arithmetic mean) of the obtained light reflectance in the wavelength range of 360 to 700 nm. The results are also shown in Table 1.

Measurement of Average Light Transmittance The second base paint was spray-coated on a polypropylene plate so that the dry film thickness was about 12 μm, and cured by heating at 140° C. for 20 minutes to obtain a second base paint film. The second base coat was then peeled off from the polypropylene plate. For the peeled second base coating film, a spectrophotometer was used to measure the wavelength region of 300 to 700 nm in wavelength scan mode every 10 nm, and the light transmittance of the second base coating film at each wavelength was obtained. . Then, from the obtained arithmetic mean (arithmetic mean) of the light transmittance in the wavelength range of 440 to 560 nm and the arithmetic mean (arithmetic mean) of the wavelength range of 650 to 700 nm, the wavelength of the second base coating film from 440 to The average light transmittance was determined for each of the 560 nm region and the 650 to 700 nm wavelength region. The results are also shown in Table 1.

・Preparation of coating film B Coating film B consisting of an electrodeposition coating film, an intermediate coating film, a first base coating film, a second base coating film and a clear coating film, which are adjacent in order on a steel plate according to the following procedure. was made. The hue of coating film B was 5R.

The process up to the step of forming an uncured intermediate coating film, including preheating, was carried out in the same manner as for coating film A. Next, on the uncured intermediate coating film, the first base paint shown in Table 1 was applied with a metavel to a dry film thickness of 10 μm to form an uncured first base coating film. Then, after standing still for 2 minutes, the second base paint shown in Table 1 was applied on the uncured first base paint film with a metavel so that the dry film thickness was about 12 μm, and the uncured second base paint was applied. A coating was formed. After standing still for 3 minutes, the uncured second base coating was preheated at 80° C. for 3 minutes. Next, the same clear coating as coating film A was applied on the uncured second base coating film with a metavel to a dry film thickness of 35 μm to form an uncured clear coating film. Then, after standing still for 10 minutes, it was baked and hardened at 140° C. for 20 minutes to obtain a coating film B on a steel plate. Table 1 also shows the PT value of each second base coating film, that is, the value obtained by multiplying the PWC (%) of the second base coating film by the dry film thickness (μm) of the second base coating film.

Evaluation of Design Properties As the design properties of the coating films B obtained in Examples and Comparative Examples, brightness, chroma and depth were evaluated as follows.

- Brilliant feel The coating films B obtained in each of the examples and comparative examples were visually observed and evaluated according to the following evaluation criteria. Ratings A and B are acceptable. The results are also shown in Table 1.
Evaluation A: Feeling strong feeling of glitter Evaluation B: Evaluation feeling of slightly strong feeling of glitter C: Evaluation of feeling weak feeling of glitter D: Feeling no feeling of glitter

- Saturation The chroma C ^* value at 25° of the coating film B obtained in each example and comparative example was measured using a spectrophotometer. Here, the chroma at 25° is the chroma measured for the light reflected perpendicularly to the coating film B when the light is incident on the coating film B at an angle of 25°. The results are also shown in Table 1. A larger C value indicates better chroma.

- Feeling of depth of color The obtained coating films B of Examples and Comparative Examples were visually observed, and the depth of color was evaluated according to the following evaluation criteria. Ratings A and B are acceptable. The results are also shown in Table 1.
Evaluation A: Feeling a strong sense of depth of red Evaluation B: Evaluation of feeling a slightly strong sense of depth of red C: Evaluation of feeling a weak sense of depth of red D: Not feeling a sense of depth of red

- Evaluation of color unevenness The obtained coating film B of each example and comparative example was visually observed, and color unevenness was evaluated according to the following evaluation criteria. Ratings A and B are acceptable. The results are also shown in Table 1.
Evaluation A: The entire coating film has a uniform color, and there is no noticeable color unevenness. Evaluation B: Slight color unevenness is observed in a part of the coating film, but there is no practical problem. Evaluation C: Part of the coating film. Evaluation D: Remarkable color unevenness is seen in the entire coating film

- Evaluation of metal unevenness The obtained coating film B of each example and comparative example was visually observed, and color unevenness was evaluated according to the following evaluation criteria. Ratings A and B are acceptable. The results are also shown in Table 1.
Evaluation A: The entire coating film has a uniform feeling of brightness, and there is no noticeable metal unevenness. Evaluation D: Remarkable unevenness of the gloss is observed in a part of the film: Remarkable metal unevenness is observed in the entire coating film

As shown in Table 1, in Examples 1 to 9, it was possible to provide a red multi-layer coating film which was excellent in brilliance, chroma and color depth, and which had little metal unevenness and color unevenness.

According to the present invention, it is possible to provide a red multi-layer coating film which is excellent in brilliance, chroma, and depth of color, and which is less in metal unevenness and color unevenness. Further, according to the present invention, it is possible to provide a method for forming a red multi-layer coating film which is excellent in brightness, chroma, and depth of color, and which has little metal unevenness and color unevenness.

1: First base coating film 2: Second base coating film 3: Car body 4: Electrodeposition coating film 5: Intermediate coating film 6: Clear coating film

Claims (8)

A red multi-layer coating film comprising a first base coating film and a second base coating film adjacent in order,
The first base coating contains a coloring pigment and a bright pigment,
The second base coating contains a coloring pigment and substantially does not contain a bright pigment,
The coating film A comprising an electrodeposition coating film, an intermediate coating film, the first base coating film and a clear coating film adjacent in order has an average light reflectance of the clear coating film of 15 to 40 at a wavelength of 360 to 700 nm. % and
A red multi-layer coating film, wherein the second base coating film has an average light transmittance of 3% or less at a wavelength of 440 to 560 nm and 80 to 90% at a wavelength of 650 to 700 nm. The ratio of the total solid mass of the coloring pigment in the second base coating to the total solid mass of the second base coating is 4 to 8%, The red multi-layer coating according to claim 1. film. 3. The red multi-layer coating film according to claim 1, wherein the dry film thickness of the second base coating film is 8 to 14 μm. The red multi-layer coating film according to any one of claims 1 to 3, wherein the coloring pigments of the first base coating film and the second base coating film contain red pigments. Step A of preparing a first base coating composition for forming a first base coating and a second base coating composition for forming a second base coating;
A step B of applying the first base coating composition to an object to be coated to form an uncured first base coating film;
Step C of coating the second base coating composition on the uncured first base coating to form an uncured second base coating;
step D of curing the uncured first base coating and the uncured second base coating together to form the first base coating and the second base coating;
including
The first base paint composition contains a resin component, a color pigment and a bright pigment,
The second base paint composition contains a resin component and a color pigment, and substantially does not contain a bright pigment,
The coating film A comprising an electrodeposition coating film, an intermediate coating film, the first base coating film and a clear coating film adjacent in order has an average light reflectance of the clear coating film of 15 to 40 at a wavelength of 360 to 700 nm. % and
A method for forming a red multi-layer coating film, wherein the second base coating film has an average light transmittance of 3% or less at a wavelength of 440 to 560 nm and 80 to 90% at a wavelength of 650 to 700 nm. The ratio of the total solid mass of the coloring pigment of the second base coating composition to the total solid mass of the second base coating composition is 4 to 8%, The red complex according to claim 5. A method for forming a layer coating film. 7. The method for forming a red multi-layer coating film according to claim 5 or 6, wherein the dry film thickness of the second base coating film is 8 to 14 μm. The method for forming a red multi-layer coating film according to any one of claims 5 to 7, wherein the coloring pigment of the first base coating composition and the second base coating composition contains a red pigment.

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