JP2022126528A - Method for forming coating film on outer plate and inner plate of vehicle, and coating film of outer plate and inner plate of vehicle - Google Patents

Abstract

To provide a method for forming a coating film on an outer plate and an inner plate capable of reducing incongruity of hue of the coating film of the outer plate and the inner plate of a vehicle.SOLUTION: A method for forming a coating film on an outer plate and an inner plate of a vehicle includes a process (A) of preparing a coating material set which contains first base coating material and second base coating material, a process (B) of applying the first base coating material onto the outer plate of the vehicle to form the uncured first base coating film, a process (C) of applying the second base coating material onto the uncured first base coating material to form an uncured second base coating film, a process (D) of curing the uncured first and second base coating films to form the first and second base coating films and a process (E) of applying the second base coating material onto the inner plate to form base coating film (BI2). Therein, the inner plate contains only the base coating film (BI2) as base coating film, a discharge amount of the second base coating material on the process (E) is 150 to 320 cc/min and a moving speed of a spray gun is 1000 to 1300 mm/min.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a method of forming a coating on an automobile outer panel and an inner panel, and to a coating on an automobile outer panel and an inner panel.

A plurality of coating films are formed on the surface of an automobile. These plural coating films protect the vehicle body of the automobile and at the same time impart an excellent design property to the automobile.

Among the surfaces of automobiles, examples of the plurality of coating films on the outer panel on the outside of the vehicle body include, in order from the outer panel side, a primer coating film, an intermediate coating film, and a top coating film. Among these coating films, the one that greatly affects the design of automobiles is the top coating film located on the surface closest to the viewer. In some cases, the top coat consists of a base coat and a clear coat from the vehicle body surface side.

Furthermore, the base coating film may consist of a first base coating film and a second base coating film from the vehicle body surface side (see, for example, Patent Documents 1 and 2). Mainly, the first base coating film has a base-hiding property that makes the color of the base coating film (for example, the intermediate coating film) inconspicuous, and the second base coating film has design properties.

In recent years, consumers prefer automobiles with a sense of brightness, so the base coating film of the outer panel, especially the second base coating film, which is on the side of the viewer and mainly responsible for the design, has a scale-like appearance that creates a feeling of brightness. Bright pigments are often blended.

International Publication No. 2015-099150 JP 2020-099888 A

Among the surfaces of automobiles, the inner panel on the inner side of the vehicle body may have a different coating composition from the outer panel. For example, unlike the outer panel, the inner panel does not require high chipping resistance (preventing scratches caused by stone splashes), so there are cases where the intermediate coating is not used. Moreover, it may have only one of the first base coating film and the second base coating film.

Depending on the vehicle type, the base coating film of the outer plate consists of two layers, the first base coating film and the second base coating film, and the inner plate (for example, the inner plate of the door, the gas lid, the back side of the back door, the back side of the hood). In some cases, the base coating film of is composed of only the first base coating film. However, in that case, the base coating film of the outer plate consists of two layers, and the second base coating film, which is mainly responsible for the design, is on the observer side, while the base coating film of the inner plate has the ability to hide the substrate. Since it is only the first base coating film that mainly bears the

If there is a sense of incompatibility with the hue, a third paint is separately prepared for coating on the first base coating film of the inner plate in order to match the hue of the inner plate coating film to that of the outer plate coating film. I had to paint it. However, when the third paint is prepared, a total of three types of paints, the paint for the first base paint film, the paint for the second base paint film, and the third paint, are used to paint the outer plate and the inner plate. requires the step and cost of preparing the third paint and equipment such as a separate spray gun to apply the third paint.

In response to this, the present inventors considered using only the second base coating film instead of the first base coating film for the base coating film of the inner plate. In that case, it was thought that the hue of the second base coating film on the observer side of the two-layer base coating film of the outer plate and the hue of the second base coating film of the inner plate would approach, and the discomfort of the hue would be reduced. However, simply changing the color of the base coating film of the inner plate from the first base coating film to the second base coating film did not alleviate the discomfort of the hue.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for forming a coating film on an outer plate and an inner plate of an automobile, which can reduce the discomfort of the hue of the coating film on the outer plate and the inner plate of the automobile.

Another object of the present invention is to provide a coating film for an outer plate and an inner plate of an automobile, in which the hue of the coating film for the outer plate and the inner plate is less uncomfortable.

A method for forming a coating film according to the present invention is a method for forming a coating film on an outer panel and an inner panel of an automobile,
A step (A) of preparing a coating composition set for forming a multilayer coating film on the surface side of the outer plate,
The multilayer coating film includes a first base coating film and a second base coating film adjacent in order from the outer plate side,
The paint composition set includes a first base paint composition for forming the first base paint film and a second base paint composition for forming the second base paint film,
The first base paint composition contains a resin component, a first scale-like bright pigment, and a color pigment,
The second base paint composition contains a resin component, a second flake-like bright pigment, and a color pigment,
The total solid content (NV1) of the resin component, the first scale-like bright pigment and the coloring pigment in the first base coating composition relative to the total mass of the first base coating composition is 20 to 30%. ,
The amount of the first scale-like bright pigment is 5 to 15 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the first scale-like bright pigment and the color pigment of the first base coating composition. and
The total solid content (NV2) of the resin component, the second scale-like bright pigment and the coloring pigment in the second base coating composition relative to the total mass of the second base coating composition is 10 to 20%. ,
The amount of the second scale-like bright pigment is 14 to 40 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the second scale-like bright pigment and the color pigment of the second base coating composition. and
Step (A), wherein the NV2 is smaller than the NV1;
A step (B) of coating the surface side of the outer plate with the first base coating composition to form an uncured first base coating film;
a step (C) of coating the second base coating composition on the uncured first base coating to form an uncured second base coating;
a step (D) of curing the uncured first base coating and the uncured second base coating to form a first base coating and a second base coating;
A step (E) of applying the second base coating composition to the surface side of the inner plate using a spray gun to form a base coating film (BI2),
The inner plate contains only the base coating (BI2) as a base coating,
Step (E ), and a method of forming a coating on the exterior and interior panels of a motor vehicle. As a result, it is possible to reduce the sense of incongruity of the hue of the paint film of the outer plate and inner plate of the automobile.

In one embodiment of the method for forming a coating film on an outer plate and an inner plate of an automobile according to the present invention, the dry film thickness of the base coating film (BI2) is 5 to 11 μm.

In one embodiment of the method for forming a coating film on an outer plate and an inner plate of an automobile according to the present invention, the dry film thickness of the second base coating film is 3 to 5 μm.

In one embodiment of the method for forming a coating film on an outer plate and an inner plate of an automobile according to the present invention, the average particle size of the first scale-like bright pigment is 10 to 30 μm, and the average particle size of the second scale-like bright pigment The particle size is 10-30 μm.

In one embodiment of the method for forming a coating film on an outer panel and an inner panel of an automobile according to the present invention, the NV2 is 12 to 17%.

In one embodiment of the method for forming a coating film on an outer panel and an inner panel of an automobile according to the present invention, the amount of the second scale-like bright pigment is the resin component of the second base coating composition, the second scale-like It is 20 to 30 parts by mass with respect to 100 parts by mass of the total solid content of the bright pigment and the coloring pigment.

The coating film according to the present invention is a coating film for an outer plate and an inner plate of an automobile,
The outer plate coating film includes a multilayer coating film formed using the method for forming a coating film on an outer plate and an inner plate of an automobile according to any one of the above,
The multilayer coating film includes a first base coating film and a second base coating film adjacent in order from the outer plate side,
The coating film for the inner plate includes, as a base coating film, only a base coating film (BI2) formed using the method for forming a coating film for an outer plate and an inner plate of an automobile according to any of the above. It is the coating film of the plate and inner plate. As a result, the unnaturalness of the hue of the coating film of the outer plate and the inner plate is reduced, and the coating film of the outer plate and the inner plate has an excellent design property.

According to the present invention, it is possible to provide a method of forming a coating film on an outer plate and an inner plate of an automobile, which can reduce the discomfort of the hue of the coating film on the outer plate and the inner plate of the automobile. Further, according to the present invention, it is possible to provide a coating film for an outer plate and an inner plate of an automobile, in which the hue of the coating film for the outer plate and the inner plate is less uncomfortable.

FIG. 1 is a schematic diagram showing an example of the layer structure of a multi-layer coating film for an outer plate formed by the step (B) of the coating film forming method of the present invention. FIG. 2 is a schematic diagram showing an example of the layer structure of the multi-layer coating film of the outer plate formed by the step (C) of the coating film forming method of the present invention. FIG. 3 is a schematic diagram showing an example of the layer structure of the multi-layer coating film of the outer plate formed by the step (D) of the coating film forming method of the present invention. FIG. 4 is a schematic diagram showing an example of the layer structure of the coating film of the inner plate formed by the step (E) of the coating film forming method of the present invention. FIG. 5 is a schematic diagram showing an example of the layer structure of the coating film of the inner plate formed by the step (E) of the coating film forming method of the present invention.

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.

Numeric ranges are intended to include the upper and lower limits of the range unless otherwise indicated. For example, 20-30% means a range of 20% or more and 30% or less.

In this specification, the first base coating film, the second base coating film and the base coating film (BI2) are sometimes collectively referred to as "base coating film". Also, the paint for the base coating film is sometimes simply referred to as "base paint".

In the present specification, the amount (parts by mass) of the first scale-like bright pigment with respect to 100 parts by mass of the total solid content of the resin component of the first base coating composition, the first scale-like bright pigment and the color pigment is referred to as "pigment mass concentration or "PWC". In the present specification, the amount (parts by mass) of the second scale-like bright pigment with respect to 100 parts by mass of the total solid content of the resin component of the second base coating composition, the second scale-like bright pigment and the color pigment is referred to as "pigment mass concentration or "PWC".

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

In the present invention, a paint composition in which water is the largest content of the dispersion medium is called an aqueous paint composition. In the present invention, 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, symbols such as first, second, (A), (B), (C), (D), and (E) are merely symbols for distinguishing certain elements from other elements. The code itself does not limit position or order.

(Coating film forming method)
A method for forming a coating film according to the present invention is a method for forming a coating film on an outer panel and an inner panel of an automobile,
A step (A) of preparing a coating composition set for forming a multilayer coating film on the surface side of the outer plate,
The multilayer coating film includes a first base coating film and a second base coating film adjacent in order from the outer plate side,
The paint composition set includes a first base paint composition for forming the first base paint film and a second base paint composition for forming the second base paint film,
The first base paint composition contains a resin component, a first scale-like bright pigment, and a color pigment,
The second base paint composition contains a resin component, a second flake-like bright pigment, and a color pigment,
The total solid content (NV1) of the resin component, the first scale-like bright pigment and the coloring pigment in the first base coating composition relative to the total mass of the first base coating composition is 20 to 30%. ,
The amount of the first scale-like bright pigment is 5 to 15 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the first scale-like bright pigment and the color pigment of the first base coating composition. and
The total solid content (NV2) of the resin component, the second scale-like bright pigment and the coloring pigment in the second base coating composition relative to the total mass of the second base coating composition is 10 to 20%. ,
The amount of the second scale-like bright pigment is 14 to 40 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the second scale-like bright pigment and the color pigment of the second base coating composition. and
Step (A), wherein the NV2 is smaller than the NV1;
A step (B) of coating the surface side of the outer plate with the first base coating composition to form an uncured first base coating film;
a step (C) of coating the second base coating composition on the uncured first base coating to form an uncured second base coating;
a step (D) of curing the uncured first base coating and the uncured second base coating to form a first base coating and a second base coating;
A step (E) of applying the second base coating composition to the surface side of the inner plate using a spray gun to form a base coating film (BI2),
The inner plate contains only the base coating (BI2) as a base coating,
Step (E ), and a method of forming a coating on the exterior and interior panels of a motor vehicle.

FIG. 1 is a schematic diagram showing an example of the layer structure of a multi-layer coating film for an outer plate formed by the step (B) of the coating film forming method of the present invention. The outer panel 1 of FIG. 1 has an undercoat film 2 and an intermediate coating film 3 on its surface side, and an uncured first base coating film 14 is formed on the intermediate coating film 3 .

FIG. 2 is a schematic diagram showing an example of the layer structure of the multi-layer coating film of the outer plate formed by the step (C) of the coating film forming method of the present invention. The outer panel 1 of FIG. 2 has an uncured second base coating 15 formed on an uncured first base coating 14 .

FIG. 3 is a schematic diagram showing an example of the layer structure of the multi-layer coating film of the outer plate formed by the step (D) of the coating film forming method of the present invention. In the outer panel 1 of FIG. 3, the uncured first base coating film 14 and the uncured second base coating film 15 of FIG. 2 are cured to form the first base coating film 4 and the second base coating film 5. It is

4 and 5 are schematic diagrams showing an example of the layer structure of the inner plate coating film formed by the step (E) of the coating film forming method of the present invention. The inner plate 6 of FIG. 4 has the undercoat film 2 and the intermediate paint film 3 on its surface side, and the uncured base paint film (BI2) 17 is formed on the intermediate paint film 3 . In the inner plate 6 of FIG. 5, the uncured base coating film (BI2) 17 of FIG. 4 is cured to form a base coating film (BI2) 7 .

In one embodiment, the coating film of the outer plate is composed of a primer 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 from the outer plate side, and a multilayer The coating consists of a first base coating and a second base coating.

The steps (A) to (E), which are the essential steps of the method for forming a coating film on an outer panel and an inner panel of an automobile according to the present invention, will be described below.

・Process (A)
In step (A), a coating composition set for forming a multi-layer coating film on the surface side of the outer plate is prepared.

- Coating composition set The coating composition set includes 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.

- First Base Coating Composition The first base coating composition forms the first base coating film of the outer panel. The first base coating composition comprises a resin component, a first scale-like bright pigment, and a color pigment, and the resin component of the first base coating composition, the first scale The total solid content (NV1) of the bright pigment and the coloring pigment is 20 to 30%, and the amount of the first scale-like bright pigment is the resin component of the first base paint composition, the first scale-like bright pigment and the coloring It is 5 to 15 parts by mass with respect to 100 parts by mass of the total solid content of the pigment. The first base paint composition is not used for inner panels.

The resin component, the first scale-like luster pigment, and the color pigment, which are essential components of the first base paint composition, 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. Also, 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; water-dispersible resins described in Patent Document 2, and the like may be used.

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 coating composition is the total solid content (NV1 ) may be adjusted appropriately within a range satisfying 20 to 30%, for example, 85 to 85 to 85 to 100 parts by mass of the total solid content of the resin component of the first base paint composition, the first scale-like bright pigment and the color pigment 100 parts by mass, preferably 85 to 95 parts by mass.

- First scale-like bright pigment A conventionally known scale-like bright pigment can be used as the first scale-like bright pigment. Examples of scale-like luster pigments include 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; metals, 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) Bright pigments can be 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; Preferred scale-like luster pigments are scale-like luster pigments in which a glass substrate is coated with a metal oxide, glass flakes, and the like.

In one embodiment, the first scale-like bright pigment has a glass substrate coated with a metal oxide.

The first scale-like luster pigment may be colorless, colored, or a combination thereof. Chromatic colors include, for example, black, red, yellow, green, blue, purple, and the like.

The average particle size of the first scale-like bright pigment is, for example, 10 μm to 30 μm. In one embodiment, the average particle size of the first scale-like bright pigment is 10 μm or more, 15 μm or more, 20 μm or more, or 25 μm or more. In another embodiment, the average particle size of the first scale-like luster pigment is 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

In one embodiment of the method for forming a coating film on an outer plate and an inner plate of an automobile according to the present invention, the average particle size of the first scale-like bright pigment is 10 to 30 μm, and the average particle size of the second scale-like bright pigment The particle size is 10-30 μm.

A commercially available product may be used as the first scale-like bright pigment. Commercially available scale-like bright pigments include, for example, the Metashine (registered trademark) series manufactured by Nippon Sheet Glass Co., Ltd., and the alumina flake series manufactured by Merck.

You may use a 1st scale-like luster pigment individually by 1 type or in combination of 2 or more types. The first scale-like bright pigment may be the same as or different from the second scale-like bright pigment described later.

The amount of the first scale-like bright pigment in the first base coating composition is 5 to 15 parts by weight based on the total solid content of 100 parts by mass of the resin component, the first scale-like bright pigment and the color pigment of the first base coating composition. The amount of the second scale-like bright pigment in the second base paint composition described later is the total solid content of the resin component of the second base paint composition, the second scale-like bright pigment and the color pigment of 100 mass. 14 to 40 parts by mass per part. Even if the PWC of the second scaly bright pigment is 14 to 40 parts by mass, when the PWC of the first scaly bright pigment is less than 5 parts by mass, the concealment becomes low and the base scaly occurs, and the first scaly If the PWC of the bright pigment is more than 15 parts by mass, the appearance is poor.

In one embodiment, the PWC of the first scale-like bright pigment is 5 parts by mass or more, 6 parts by mass or more, 7 parts by mass or more, 8 parts by mass or more, 9 parts by mass or more, 10 parts by mass or more, 11 parts by mass or more, It is 12 parts by mass or more, 13 parts by mass or more, or 14 parts by mass or more. In another embodiment, the PWC of the first scale-like bright pigment is 15 parts by mass or less, 14 parts by mass or less, 13 parts by mass or less, 12 parts by mass or less, 11 parts by mass or less, 10 parts by mass or less, and 9 parts by mass or less. , 8 parts by mass or less, 7 parts by mass or less, or 6 parts by mass or less.

- Coloring pigments Coloring pigments have the function of imparting base-concealing properties and design properties to the base coating film.

The coloring pigment is not particularly limited, and known coloring pigments for base paints can be used. Coloring pigments include, for example, azochelate pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, dioxane organic coloring pigments such as quinacridone-based pigments, isoindolinone-based pigments, and metal complex pigments; and inorganic coloring pigments such as yellow lead, yellow iron oxide, red iron oxide, carbon black, and titanium oxide. Preferred colored pigments include carbon black.

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

The amount of the color pigment in the first base paint composition is the total solid content (NV1 ) may be adjusted appropriately within a range satisfying 20 to 30%, for example, 1 to 1 to 100 parts by mass of the total solid content of the resin component of the first base paint composition, the first scale-like bright pigment and the coloring pigment 5 parts by mass, preferably 2 to 4 parts by mass.

・Other components The first base paint composition contains, in addition to the resin component, the first scale-like bright pigment and the color pigment, an extender pigment, a curing agent, water, an organic solvent, a corrosion inhibitor, a surface conditioner, and a thickener. , anti-oxidants, anti-ultraviolet agents, anti-foaming agents, and other known base paint components. Each of these other components may be used alone or in combination of two or more.

Organic solvent Organic solvents include alcohols such as methanol, ethanol, 2-propanol and 1-butanol; ethyl acetate, butyl acetate, isobutyl acetate, ethyl propionate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate , esters such as propylene glycol monoethyl ether acetate; ethers such as diethyl ether, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dioxane, tetrahydrofuran (THF); ethylene glycol, diethylene glycol, propylene glycol, Glycols such as dipropylene glycol, 1,3-butylene glycol, pentamethylene glycol, 1,3-octylene glycol; formamide, N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO) , N-methylpyrrolidone (NMP) and other amides; acetone, methyl ethyl ketone (MEK), methyl propyl ketone, methyl isobutyl ketone, acetylacetone, cyclohexanone and other ketones; mineral spirits, kerosene and other aliphatic hydrocarbons; toluene, xylene , mesitylene, and dodecylbenzene; and halogen-based solvents such as chloroform and dichloromethylene. You may use an organic solvent individually by 1 type or in combination of 2 or more types.

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

The total solid content (NV1) of the resin component of the first base coating composition, the first scale-like bright pigment and the color pigment is 20 to 30% with respect to the total mass of the first base coating composition, and NV1 is described later. larger than NV2. When the NV1 is less than 20%, the coating workability evaluation shows that the fine particles are poorly formed during coating, and there are problems such as metal unevenness and sagging. There is a problem that the hue tends to fluctuate. In one embodiment, NV1 is 20% or greater, 21% or greater, 22% or greater, 23% or greater, 24% or greater, 25% or greater, 26% or greater, 27% or greater, 28% or greater, or 29% or greater. In another embodiment, NV1 is 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, or 21% or less .

Method for preparing the first base paint composition The method for preparing the first base paint composition includes the resin component, the first scale-like bright pigment and the color pigment described above, and if the predetermined range of NV1 and the predetermined range of PWC are satisfied is not particularly limited, and a conventionally known method can be used. For example, the first base paint composition can be prepared by kneading and dispersing the resin component, the first scale-like bright pigment and the color pigment using a kneader or rolls.

(Second base paint composition)
The second base coating composition forms the second base coating for the outer panel and the base coating for the inner panel (BI2). The second base paint composition contains a resin component, a second scale-like bright pigment, and a color pigment, and the resin component of the second base paint composition, the second scale The total solid content (NV2) of the bright pigment and the coloring pigment is 10 to 20%, and the amount of the second flake-like bright pigment is the resin component of the second base paint composition, the second flake-like bright pigment, and the coloring pigment. It is 14 to 40 parts by mass with respect to 100 parts by mass of the total solid content of the pigment.

The resin component, the second flake-like luster pigment, and the color pigment, which are essential components of the second base paint composition, 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 composition.

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 coating composition is the total solid content (NV2 ) may be adjusted appropriately within a range satisfying 10 to 20%, for example, 80 to 80 to 100 parts by mass of the total solid content of the resin component of the second base paint composition, the second scale-like bright pigment and the color pigment 90 parts by mass, preferably 82 to 88 parts by mass.

- Second scale-like bright pigment As the second scale-like bright pigment, a conventionally known scale-like bright pigment can be used. The scale-like bright pigment is the same as the first scale-like bright pigment mentioned in the first base paint composition.

The average particle diameter of the second flake-like bright pigment is, for example, 10 μm to 30 μm. In one embodiment, the average particle size of the second scale-like bright pigment is 10 μm or more, 15 μm or more, 20 μm or more, or 25 μm or more. In another embodiment, the average particle size of the second scale-like luster pigment is 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

You may use a 2nd scale-like luster pigment individually by 1 type or in combination of 2 or more types.

The amount of the second scale-like bright pigment in the second base coating composition is 14 to 40 parts by weight based on 100 parts by mass of the total solid content of the resin component, the second scale-like bright pigment and the color pigment in the second base coating composition. part by mass. Even if the PWC of the first scale-like bright pigment is 5 to 15 parts by mass, if the PWC of the second scale-like bright pigment is less than 14 parts by mass, the amount of the bright pigment is insufficient and gaps are visible, resulting in poor design. Therefore, when the PWC of the second flake-like bright pigment is more than 40 parts by mass, the amount of the bright pigment is too large and the bright pigment overlaps, resulting in a poor design.

In one embodiment, the PWC of the second scale-like bright pigment is 14 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, or 35 parts by weight or more. In another embodiment, the PWC of the second scale-like bright pigment is 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, or 20 parts by weight or less.

In one embodiment of the method for forming a coating film on an outer panel and an inner panel of an automobile according to the present invention, the amount of the second scale-like bright pigment is the resin component of the second base coating composition, the second scale-like It is 20 to 30 parts by mass with respect to 100 parts by mass of the total solid content of the bright pigment and the coloring pigment.

- 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 composition.

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

The amount of the color pigment in the second base paint composition is the total solid content (NV2 ) may be adjusted appropriately within a range satisfying 10 to 20%, for example, 10 to 10 to 100 parts by mass of the total solid content of the resin component of the second base paint composition, the second scale-like bright pigment and the color pigment 20 parts by mass, preferably 12 to 18 parts by mass.

・Other components The second base paint composition contains, in addition to the resin component, the second scale-like bright pigment and the color pigment, an extender pigment, a curing agent, water, an organic solvent, a corrosion inhibitor, a surface conditioner, and a thickener. , anti-oxidants, anti-ultraviolet agents, anti-foaming agents, and other known base paint components. Each of these other components may be used alone or in combination of two or more.

- Organic solvent Examples of the organic solvent are the same as the organic solvents mentioned in the first base paint composition.

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

The total solid content (NV2) of the resin component of the second base coating composition, the second scale-like bright pigment and the color pigment with respect to the total mass of the second base coating composition is 10 to 20%, and NV2 is NV1. less than If NV2 is less than 10%, a large discharge amount may be required to ensure a specified film thickness, and sagging may occur. If NV2 is more than 20%, the NV difference between NV1 and NV2 is small, so there is a possibility that the 2-base orientation will be defective and design defects such as low flip-flop (FF) properties will occur. In one embodiment, NV2 is 10% or greater, 11% or greater, 12% or greater, 13% or greater, 14% or greater, 15% or greater, 16% or greater, 17% or greater, 18% or greater, or 19% or greater. In another embodiment, NV2 is 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, or 11% or less .

In one embodiment of the method for forming a coating film on an outer panel and an inner panel of an automobile according to the present invention, the NV2 is 12 to 17%.

・Method for preparing the second base paint composition The method for preparing the second base paint composition includes the above-described resin component, the second scale-like bright pigment and the color pigment, and satisfies the predetermined range of NV2 and the predetermined range of PWC. is not particularly limited, and a conventionally known method can be used. For example, the second base coating composition can be prepared by kneading and dispersing the resin component, the second flake-like bright pigment and the color pigment using a kneader or rolls.

・Process (B)
In step (B), the first base coating composition is applied to the surface side of the outer panel to form an uncured first base coating film.

The layer structure of the surface side of the outer panel to be coated with the first base coating composition is not particularly limited, but usually, as shown in FIG. Therefore, the object of the exterior panel to which the first base coating composition is applied in step (B) is usually the intermediate coating film.

The primer coating film and the intermediate coating film are not particularly limited, and conventionally known primer coating films and intermediate coating films can be used.

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

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 composition is applied onto the uncured first base coating to form an uncured second base coating. For example, see FIG.

The method for applying the second base paint composition is not particularly limited, and conventionally known methods for applying base paints for outer panels of automobiles can be used. Examples of the method of applying the second base coating composition include spray coating and rotary atomization electrostatic coating. The method of applying the first base paint composition in step (B) and the method of applying the second base paint composition in step (C) may be the same or different.

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 base coating and the uncured second base coating are cured to form a first base coating and a second base coating. For example, see FIG.

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.

The dry film thickness of the first base coating film is, for example, 12 to 19 μm, preferably 13 to 17 μm.

The dry film thickness of the second base coating film is, for example, 4 to 6 μm, preferably 3 to 5 μm.

In one embodiment of the method for forming a coating film on an outer plate and an inner plate of an automobile according to the present invention, the dry film thickness of the second base coating film is 3 to 5 μm.

In the step (D), the uncured first base coating film and the uncured second base coating film are cured to form the first base coating film and the second base coating film. In addition to these two layers, an uncured clear coat formed on an uncured second base coat may be cured together.

・Process (E)
In step (E), the second base coating composition is applied to the surface side of the inner plate using a spray gun to form a base coating film (BI2), and the inner plate is coated with the base coating film as the base coating film. The second base coating composition containing only (BI2) has a discharge rate of 150 to 320 cc/min and a spray gun movement speed of 1000 to 1300 mm/min when the second base coating composition is applied. .

There are no particular restrictions on the layer structure on the surface side of the inner panel to which the second base coating composition is applied. For example, as shown in FIG. 4, the inner plate side may have the primer coating film and the intermediate coating film, or although not shown, the inner plate side may have the primer coating film. The primer coating film and intermediate coating film on the inner plate side are not particularly limited, and conventionally known primer coating film and intermediate coating film can be used. The undercoat coating film on the outer plate side and the undercoat coating film on the inner plate side may be the same or different. The intermediate coating film on the outer plate side and the intermediate coating film on the inner plate side may be the same or different.

As shown in FIG. 4, the surface side of the inner plate is coated with the second base coating composition using a spray gun to form an uncured base coating film (BI2).

The spray gun is not particularly limited as long as it can discharge the second base paint composition at a discharge amount within a predetermined range and the moving speed of the spray gun is within a predetermined range. A gun or the like can be used.

The discharge rate of the second base coating composition when applying the second base coating composition is 150 to 320 cc/min. If the discharge rate is less than 150 cc/min, there is a problem in coating work such as discharge failure, and if the discharge rate exceeds 320 cc/min, there is a problem in workability such as sagging or unevenness. In one embodiment, the discharge rate of the second base coating composition is 150 cc/min or more, 160 cc/min or more, 170 cc/min or more, 180 cc/min or more, 190 cc/min or more, 200 cc/min or more, 210 cc/min or more. , 220cc/min or more, 230cc/min or more, 240cc/min or more, 250cc/min or more, 260cc/min or more, 270cc/min or more, 280cc/min or more, 290cc/min or more, 300cc/min or more, or 310cc/min or more is. In another embodiment, the discharge rate of the second base coating composition is 320 cc/min or less, 310 cc/min or less, 300 cc/min or less, 290 cc/min or less, 280 cc/min or less, 270 cc/min or less, 260 cc/min. 250cc/min or less, 240cc/min or less, 230cc/min or less, 220cc/min or less, 210cc/min or less, 200cc/min or less, 190cc/min or less, 180cc/min or less, 170cc/min or less, or 160cc/min It is below.

The moving speed of the spray gun when applying the second base paint composition is 1000-1300 mm/min. If the moving speed is less than 1000 mm/min, it is not possible to reduce the discomfort of the hue of the paint film of the outer plate and inner plate of the automobile. In one embodiment, the travel speed of the spray gun when applying the second base coating composition is 1000 mm/min or more, 1100 mm/min or more, or 1200 mm/min or more. In another embodiment, the travel speed of the spray gun when applying the second base coating composition is 1300 mm/min or less, 1200 mm/min or less, or 1100 mm/min or less.

The film thickness of the uncured base coating film (BI2) is not particularly limited, and may be appropriately adjusted according to the desired dry film thickness.

A method for curing the uncured base coating film (BI2) includes, 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.

The dry film thickness of the base coating film (BI2) is, for example, 4 to 12 m, preferably 5 to 11 μm.

In one embodiment of the method for forming a coating film on an outer plate and an inner plate of an automobile according to the present invention, the dry film thickness of the base coating film (BI2) is 5 to 11 μm.

In step (E), the second base coating composition may be applied under predetermined conditions using a spray gun to form a base coating film (BI2), for example, on the uncured base coating film (BI2) The formed uncured clear coating may be cured together.

The order of steps (B), (C), (D) and (E) is not particularly limited except that step (C) is after step (B). For example, steps (E), (B), (C) and (D) may be ordered; steps (B), (C), (D) and (E) may be ordered; step (B) and (E) simultaneously, followed by steps (C) and (D).

In the method for forming a coating film on the outer plate and inner plate of an automobile of the present invention, in addition to the steps (A) to (E), for example, a clear coating material is applied on the uncured second base coating film. , a step of forming an uncured clear coating film, a step of curing the uncured clear coating film to form a clear coating film, applying a clear coating paint on the uncured base coating film (BI2), Other steps such as a step of forming an uncured clear coating film may be included.

(Coating films for outer and inner panels of automobiles)
The coating film according to the present invention is a coating film for an outer plate and an inner plate of an automobile,
The outer plate coating film includes a multilayer coating film formed using the method for forming a coating film on an outer plate and an inner plate of an automobile according to any one of the above,
The multilayer coating film includes a first base coating film and a second base coating film adjacent in order from the outer plate side,
The coating film for the inner plate includes, as a base coating film, only a base coating film (BI2) formed using the method for forming a coating film for an outer plate and an inner plate of an automobile according to any of the above. It is the coating film of the plate and inner plate.

The coating film of the outer plate includes a multi-layer coating film formed using the coating film forming method of the present invention. Also, the multilayer coating film includes a first base coating film and a second base coating film, which are adjacent in order from the outer plate side. In one embodiment, the coating film of the outer plate is composed of a primer 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 from the outer plate side, and a multilayer The coating consists of a first base coating and a second base coating.

The dry film thickness of the first base coating film is, for example, 12 to 19 μm, preferably 13 to 17 μm.

The dry film thickness of the second base coating film is, for example, 4 to 6 μm, preferably 3 to 5 μm.

The coating film of the inner panel includes only the base coating film (BI2) formed using the coating film forming method of the present invention as the base coating film. Therefore, the inner plate coating does not include the first base coating formed from the first base coating composition. Moreover, the coating film of the inner plate does not include a base coating film formed from a base coating other than the second base coating composition.

The dry film thickness of the base coating film (BI2) is, for example, 4 to 12 μm, preferably 5 to 11 μm.

The coating film of the inner plate may include only the base coating film (BI2) formed using the coating film forming method of the present invention as the base coating film, and the other layers are not particularly limited. The coating film of the inner plate may be composed of, for example, a primer coating film, an intermediate coating film, a base coating film (BI2) and a clear coating film, which are not shown in the drawings, and which are adjacent to each other in this order from the inner plate side; As shown in FIG. 5, from the inner plate side, it may be composed of a primer coating film, an intermediate coating film and a base coating film (BI2) adjacent in order; Adjacent in order, it may consist of a primer coat and a base coat (BI2); or it may consist of a primer coat, a base coat (BI2) and a clear coat.

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 each component of the coating composition used in the examples are as follows.
Resin component 1: acrylic emulsion resin, average particle size 150 nm, nonvolatile content 20%, solid content acid value 20 mgKOH/g, hydroxyl value 40 mgKOH/g, method of Production Example 6 in paragraph [0123] of JP 2014-147918 Resin component 2 prepared in: water-soluble acrylic resin, nonvolatile content 30.0%, solid content acid value 40 mgKOH / g, hydroxyl value 50 mgKOH / g, paragraph [0125] of JP 2014-147918 of Production Example 8 Resin component 3 prepared by method: trade name "Primepol PX-1000" manufactured by Sanyo Chemical Industries, Ltd., bifunctional polyether polyol, number average molecular weight 400, hydroxyl value 278 mgKOH/g, primary/secondary hydroxyl value ratio = 63/37, non-volatile content 100%
Resin component 4: Trade name "Neoletz R-9603" manufactured by Avecia, polycarbonate-based urethane emulsion resin, non-volatile content 33%
Tertiary amine (neutralizing agent): 10% by weight aqueous solution of dimethylethanolamine 06-0672N: Brilliant pigment, trade name "Alpaste (registered trademark) 06-0672" manufactured by Toyo Aluminum Co., Ltd., silver color, 17 μm
CP-315: Bright pigment, product name "CP Series" manufactured by Asahi Kasei Corporation, silver color, 15 μm
WL-0685: Luminous pigment, trade name "Alpaste" manufactured by Toyo Aluminum Co., Ltd., silver color, 18 μm
WL-Z-440: Luminescent pigment, trade name "Alpaste" manufactured by Toyo Aluminum Co., Ltd., silver color, 14 μm
R-5000: Coloring pigment (non-bright pigment), trade name "Carbon Black R-5000" manufactured by Columbia Carbon Co., Ltd., Black CR-97: Coloring pigment (non-bright pigment), trade name "Tipake" manufactured by Ishihara Sangyo Co., Ltd. , White G-314: Coloring pigment (non-bright pigment), trade name “Cyanine Blue G-314” manufactured by Sanyo Pigment Co., Ltd., Blue RL-NF: Coloring pigment (non-bright pigment), trade name “ Violet RL-NF", Violet Red 400RG: Coloring Pigment (Non-Bright Pigment), DIC's Trade Name "Quinacridone Pigment", Red Coloring Pigment (Non-Bright Pigment) TM RED 8270: Coloring Pigment (Non-Bright Pigment), Large Nissei Chemical Co., Ltd. trade name “Dipyroxide Pigment”, red clear paint: Nippon Paint Automotive Coatings trade name “Macflow O-1810 Clear”, acid-epoxy curable acrylic resin paint

Details of other materials and equipment used in the examples follow.
Steel plate: zinc phosphate treated SPCC-SD steel plate, dimensions 20 cm x 30 cm x 0.8 cm thick
Spectrophotometer: trade name "CM-512m3" manufactured by Konica Minolta
Standard light source box: Trade name “Biko Spectra Pro” manufactured by BYK

Preparation of the first base paint composition In addition to the resin component, scale-like bright pigment and color pigment of the formulation (parts by mass) shown in Table 1, the following amounts of curing agent, tertiary amine and corrosion inhibitor are blended. and uniformly dispersed to obtain a first base paint composition.
Curing agent: 15.2 parts by mass (15.2 parts by mass of nonvolatile matter)
Tertiary amine: 40 parts by mass (concentration 10% by mass)
Corrosion inhibitor: 0.2 parts by mass (0.1 parts by mass of nonvolatile matter)

・ Preparation of the second base paint composition In addition to the resin component (in terms of non-volatile content) of the formulation (parts by mass) shown in Table 2, the scale-like bright pigment and the coloring pigment, the same amount of curing agent as the first base paint composition , a tertiary amine and a corrosion inhibitor were blended and uniformly dispersed to obtain second base paint compositions 1-9.

表１中「ＰＷＣ」は、第１ベース塗料組成物の樹脂成分、第１鱗片状光輝顔料および着色顔料の全固形分１００質量部に対する第１鱗片状光輝顔料または着色顔料の量（質量部）を表す。

In Table 1, "PWC" is the amount of the first scale-like bright pigment or color pigment relative to 100 parts by mass of the total solid content of the resin component, first scale-like bright pigment, and color pigment of the first base coating composition (parts by mass). represents

表２中「ＰＷＣ」は、第２ベース塗料組成物の樹脂成分、第２鱗片状光輝顔料および着色顔料の全固形分１００質量部に対する第２鱗片状光輝顔料または着色顔料の量（質量部）を表す。

In Table 2, "PWC" is the amount of the second scale-like bright pigment or color pigment relative to the total solid content of 100 parts by mass of the resin component, the second scale-like bright pigment, and the color pigment of the second base coating composition (parts by mass). represents

・Preparation of the outer plate A zinc phosphate-treated steel plate, which is assumed to be the outer plate of an automobile, is coated with a cationic electrodeposition paint and an intermediate coating in order in the same manner as in Example 1 of Patent Document 1, and then the undercoat and intermediate coating. Nineteen outer panels with coating films formed thereon were prepared.

・Preparation of the inner plate A zinc phosphate-treated steel plate, which is assumed to be the inner plate of an automobile, is coated with a cationic electrodeposition paint and an intermediate coating in order in the same manner as in Example 1 of Patent Document 1, and then the undercoat and intermediate coating. Nineteen inner plates each having a coating film formed thereon were prepared.

(Examples 1-11 and Comparative Examples 1-8)
・Coating of the inner plate The second base paint composition with the number shown in Tables 3 and 4 was applied to the intermediate coating film of each inner plate using a spray gun, and the discharge amount and the movement speed of the spray gun were shown in Tables 3 and 4. Under the conditions of , coating was performed so as to have a dry film thickness shown in Tables 3 and 4 to form an uncured base coating film (BI2).

Coating of outer plates Next, the first base coating composition is applied to the intermediate coating film of each outer plate under standard robot coating conditions so that the dry film thickness is 12 μm, and the uncured first base coating composition A base coat was formed. Next, on the uncured first base coating film, the second base coating compositions having the numbers shown in Tables 3 and 4 were applied under standard robot coating conditions to a dry film thickness of 4 μm, and the uncured to form a second base coating film.

The inner and outer plates were then preheated at a temperature of 80°C for 3 minutes. Next, a clear coating was applied to the inner plate with a spray gun, and finally a clear paint was applied to the outer plate with a robot and baked at a temperature of 140° C. for 30 minutes to form a coating film.

(Evaluation of matching of hue between outer plate and inner plate)
A color difference ΔE45° at a light-receiving angle of 45° was measured using a spectrophotometer for the coating film of the outer plate and the coating film of the inner plate of each example and comparative example. Then, the matching of the hues of the outer plate and the inner plate was evaluated according to the following criteria. The evaluations A and B are acceptable because the hue is slightly uncomfortable, and the evaluations C and D are unacceptable because the hue is large. See paragraph [0044] of JP-A-2011-088132 for color difference ΔE.
Evaluation A: ΔE45° is less than 1.0 Evaluation B: ΔE45° is 1.0 or more and less than 1.5 Evaluation C: ΔE45° is 1.5 or more and less than 2.0 Evaluation D: ΔE45° is 2.0 or more

(Evaluation of transparency of inner plate coating film)
For the obtained coating film of the inner plate of each example and comparative example, using a standard light source box, light source: D65, the coating film of the inner plate was placed at an angle of 45 degrees from the horizontal, and the coating film of the inner plate and the observation A black and white check film was adhered to the undercoating under the condition of visual observation at a distance of about 50 cm from the human eye, and the transparency of the undercoat intermediate coating film was evaluated according to the following criteria.
Evaluation A: Pass evaluation B: Nearly pass evaluation C: Slightly transparent Evaluation D: Completely transparent

As shown in Table 3, it was possible to provide a method for forming a coating film on an outer panel and an inner panel of an automobile, which can reduce the discomfort of the hue of the coating on the outer panel and inner panel of an automobile. In addition, it was possible to provide a coating film for an outer plate and an inner plate of an automobile, in which the hue of the coating film for the outer plate and the inner plate is less uncomfortable.

According to the present invention, it is possible to provide a method of forming a coating film on an outer plate and an inner plate of an automobile, which can reduce the discomfort of the hue of the coating film on the outer plate and the inner plate of the automobile. Further, according to the present invention, it is possible to provide a coating film for an outer plate and an inner plate of an automobile in which the hue of the coating film for the outer plate and the inner plate is less uncomfortable.

1: outer plate 2: undercoat coating film 3: intermediate coating film 4: first base coating film 5: second base coating film 6: inner plate 7: base coating film (BI2)
14: Uncured first base coating film 15: Uncured second base coating film 17: Uncured base coating film (BI2)

Claims (7)

A method for forming a coating film on an outer panel and an inner panel of an automobile, comprising:
A step (A) of preparing a coating composition set for forming a multilayer coating film on the surface side of the outer plate,
The multilayer coating film includes a first base coating film and a second base coating film adjacent in order from the outer plate side,
The paint composition set includes a first base paint composition for forming the first base paint film and a second base paint composition for forming the second base paint film,
The first base paint composition contains a resin component, a first scale-like bright pigment, and a color pigment,
The second base paint composition contains a resin component, a second flake-like bright pigment, and a color pigment,
The total solid content (NV1) of the resin component, the first scale-like bright pigment and the coloring pigment in the first base coating composition relative to the total mass of the first base coating composition is 20 to 30%. ,
The amount of the first scale-like bright pigment is 5 to 15 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the first scale-like bright pigment and the color pigment of the first base coating composition. and
The total solid content (NV2) of the resin component, the second scale-like bright pigment and the coloring pigment in the second base coating composition relative to the total mass of the second base coating composition is 10 to 20%. ,
The amount of the second scale-like bright pigment is 14 to 40 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the second scale-like bright pigment and the color pigment of the second base coating composition. and
Step (A), wherein the NV2 is smaller than the NV1;
A step (B) of coating the surface side of the outer plate with the first base coating composition to form an uncured first base coating film;
a step (C) of coating the second base coating composition on the uncured first base coating to form an uncured second base coating;
a step (D) of curing the uncured first base coating and the uncured second base coating to form a first base coating and a second base coating;
A step (E) of applying the second base coating composition to the surface side of the inner plate using a spray gun to form a base coating film (BI2),
The inner plate contains only the base coating (BI2) as a base coating,
Step (E ). 2. The method for forming a coating film on an outer panel and an inner panel of an automobile according to claim 1, wherein the dry film thickness of the base coating film (BI2) is 5 to 11 μm. 3. The method for forming a coating film on an outer panel and an inner panel of an automobile according to claim 1, wherein the dry film thickness of the second base coating film is 3 to 5 μm. 4. The method according to any one of claims 1 to 3, wherein the first scale-like bright pigment has an average particle size of 10 to 30 µm, and the second scale-like bright pigment has an average particle size of 10 to 30 µm. and a method for forming a coating film on an outer panel and an inner panel of an automobile. The method for forming a coating film on an outer panel and an inner panel of an automobile according to any one of claims 1 to 4, wherein the NV2 is 12 to 17%. The amount of the second scale-like bright pigment is 20 to 30 parts by mass with respect to 100 parts by mass of the total solid content of the resin component, the second scale-like bright pigment and the coloring pigment of the second base coating composition. The method for forming a coating film on an outer panel and an inner panel of an automobile according to any one of claims 1 to 4, wherein A coating film for an outer panel and an inner panel of an automobile,
The outer plate coating film comprises a multi-layer coating film formed using the method for forming a coating film on an outer plate and an inner plate of an automobile according to any one of claims 1 to 6,
The multilayer coating film includes a first base coating film and a second base coating film adjacent in order from the outer plate side,
The coating film for the inner plate is a base coating film (BI2) formed by using the method for forming a coating film for an outer plate and an inner plate of an automobile according to any one of claims 1 to 6 as a base coating film. Automotive exterior and interior coatings, including chisels.

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