JP4942459B2 - Method for forming laminated coating film - Google Patents

Description

  The present invention relates to a method for forming a laminated coating film that can be formed on an automobile body or an automobile part.

  On the surface of a substrate such as an automobile, a plurality of coating films having various roles are formed to protect the substrate and at the same time give a beautiful appearance. The appearance of the coating film formed on the automobile is greatly related to the appearance value such as the luxury feeling of the automobile. Therefore, in the field of automobile painting, establishment of a coating composition and a coating method capable of forming a coating film having a coating film appearance corresponding to various needs is required.

  As such a top coat for automobile bodies, a coating using bright pigments such as aluminum flakes and mica is known. However, when a laminated coating film is formed using these glitter pigments, there is a problem that it is difficult to obtain a certain coating film appearance with good reproducibility. The reason for this is that when these bright pigments are used, the appearance of the coating film such as the color tone varies depending on slight changes in the film thickness of the coating film derived from the shape of the object to be coated. This is because it is difficult to obtain stable color development. That is, when coating a large and uneven article to be coated, there arises a problem that the coating film thickness varies depending on the portion to be coated, and the hue varies depending on the variation in the film thickness.

  Japanese Patent Laid-Open No. 2001-314807 (Patent Document 1) forms a first coating film by applying a first paint containing (1) a coloring component and / or a bright material to the surface of an object to be coated. (2) a step of forming a second coating film by applying a second coating material containing a coloring component on the first coating film without baking and curing the first coating film; A multilayer coating film forming method including a step of forming a clear coating film by applying a clear coating thereon without baking and curing the coating film is described. The multilayer coating film formed by this method includes the glittering material in the first coating film and the color pigment in the second coating film, however, the present invention is not included in the formation of the mica base coating film. And the process is different.

  Japanese Patent Laid-Open No. 2002-273332 (Patent Document 2) discloses (1) a step of forming a glittering base coating film having a concealed film thickness of 10 μm or less on a substrate, and (2) a step of forming a color clear base coating film. (3) A step of forming a clear top coating; a method of forming a glitter coating is sequentially described. The glitter coating film formed by this method is also different from the present invention in that it is composed of a glitter base coating film, a color clear base coating film, and a clear top coating film.

  Japanese Patent Application Laid-Open No. 2003-236465 (Patent Document 3) describes the formation of a mica coating film in which a color base coating film is formed and baked and cured, and then a base color coating film, a mica base coating film, and a clear coating film are sequentially formed. In the method, the hue exhibited by the color base coating film, the hue exhibited by the base color coating film, and the hue exhibited by the mica base coating film are similar colors, and the mica base coating material forming the mica base coating film is transparent. A high-design mica coating film forming method characterized by containing a pigment and a non-transparent pigment in a mass ratio of 3/1 to 20/1 is described. The coating film formed by this method is a point that a mica base coating film is formed using a mica base coating material containing a transparent pigment and a non-transparent pigment, and that a color clear coating film formation is not included during the painting process. This is different from the present invention.

  In Japanese Patent Application Laid-Open No. 11-276983 (Patent Document 4), a colored base coating film layer containing a color pigment is formed on an intermediate coating film of an object to be coated, and a hue is formed on the reflection color and absorption color thereon. Forming a mica base coating layer containing colored mica pigments having different colors, and further forming a clear coating layer on the mica base coating layer, wherein the hue of the colored base coating layer is changed to the mica base coating layer A method for forming a laminated coating film characterized by having a color similar to the absorption color of the colored mica pigment of the layer is described. This method differs from the present invention in that it is characterized by using colored mica pigments and does not include the formation of a color clear coating film during the coating process.

JP 2001-314807 A (Patent Document 1) JP 2002-273332 A (Patent Document 2) JP 2003-236465 A (Patent Document 3) Japanese Patent Laid-Open No. 11-276983 (Patent Document 4)

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a coating film appearance (coloring property) variation in a top coating film that can be formed on an automobile body or an automobile part. The object of the present invention is to provide a method for forming a laminated coating film having a small amount and a stable design.

The present invention
A method for forming a laminated coating film in which a metallic base coating film, a mica base coating film, and a color clear coating film are sequentially formed on an object having an intermediate coating film,
The hue exhibited by this metallic base coating film, the hue exhibited by this mica base coating film, and the hue exhibited by this color clear coating film are the same color or at least adjacent hues in the color arrangement of the hue ring of the Munsell color system. ,
In this mica base coating film, the 15 ° L * value of the coating film composed of the metallic base coating film and the mica base coating film has a variation range of −18 to −30% with respect to the 15 ° L * value of the metallic base coating film. It is a coating film formed so as to become,
The metallic base coating film, the mica base coating film, and the laminated coating composed of the color clear coating film have a 15 ° L * value of 20 to 60, and the metallic base coating composition for forming the metallic base coating film Contains a non-transparent scaly glitter pigment having an average particle size of 6 to 40 μm in an amount of 5 to 25% by mass of pigment mass concentration (PWC),
The mica base coating composition that forms this mica base coating film contains a transparent scaly glitter pigment in an amount of 0.25 to 15% by mass of a pigment mass concentration (PWC),
The color clear coating composition for forming the color clear coating film contains a color pigment in an amount of 0.01 to 10% by mass of a pigment mass concentration (PWC).
A method for forming a laminated coating film is provided, whereby the above object is achieved.

In the method for forming a multilayer coating film, the color clear coating film further has a 15 ° L * value of a multilayer coating film composed of a metallic base coating film, a mica base coating film, and a color clear coating film. The coating film is formed so that the fluctuation range is −16 to −30% with respect to the 15 ° L * value of the coating film made of the base coating film, and 15 ° L * of the obtained laminated coating film It is preferable that the fluctuation range is 0 to −47% with respect to the 15 ° L * value of the metallic base coating film.

  The present invention further provides a four-layer laminated coating film in which a top clear coating film is further formed using a top clear coating composition on the laminated coating film formed by the method for forming these laminated coating films. A method is also provided.

  The present invention further provides a multilayer coating film formed by these multilayer coating film forming methods.

  The laminated coating film according to the present invention has an advantage of exhibiting a stable design by having a mica base coating film and a color clear coating film on the metallic base coating film. The laminated coating of the present invention is also such that the hues of the metallic base coating, the mica base coating and the color clear coating are similar colors or at least adjacent hues in the color arrangement of the Munsell color system hue ring, and It has the characteristic that 15 degree L * value based on these coating films exists in a specific range. As a result, it is possible to provide a coating film having a sense of depth and excellent design properties in a state in which there is little variation in coating film appearance (color development). In other words, the present invention has found a means for providing a coating film having a sense of depth and excellent design properties in a state in which there is little variation in coating film appearance (color development).

Process up to the present invention

  In the coating of a substrate such as an automobile, for example, when a colored laminated coating film (including a base coating film and a color clear coating film) such as red is formed, the hue of the underlying base coating film is a coloring provided thereon. In some cases, a red metallic color of the same color as the color clear coating film formed may be used. The purpose of setting the hue of the base coating film in this way is to reduce the hue fluctuation of the laminated coating film when the thickness of the color clear coating film formed on the base coating film varies.

  However, if the hue of the base coating film and the hue of the multilayer coating film are too close for the purpose of reducing such hue fluctuations of the multilayer coating film, there is a disadvantage that the feeling of depth in the multilayer coating film is lost. The feeling of depth in this laminated coating film is greatly related to the design of the coating film appearance. A coating film having a sense of depth has a sense of quality and is excellent in design.

  An object of the present invention is to establish a method capable of preparing a laminated coating film having a sense of depth and excellent design properties in a state where there is little variation in coating film appearance (color development). The inventors of the present invention, when forming a laminated coating film composed of a metallic base coating film, a mica base coating film, and a color clear coating film, each having a hue of a similar color, is a so-called highlight brightness of 15 ° L *. It was found that the fluctuation of the value is greatly related to the appearance of the coating film obtained. Accordingly, it has also been found that the object of the present invention can be achieved by adjusting the 15 ° L * value of the coating film to a specific range. Hereinafter, the method of the present invention will be described sequentially.

Metallic base coating composition In the method for forming a laminated coating film of the present invention, a metallic base coating composition is used to form a metallic base coating film. As the metallic base coating composition, those containing a non-transparent scaly glittering pigment, a coloring pigment, a film-forming resin, a curing agent and the like are preferably used.

By including a non-transparent scale-like glitter pigment in the non-transparent scale-like glitter pigment metallic base coating composition, a metallic base coating film having high highlight brightness can be formed. In the non-transparent scaly glitter pigment, “non-transparency” means that the black-and-white concealment film thickness of the coating film obtained when the pigment concentration (PWC) in the solid content of the paint is 25% by mass is less than 30 μm. Means that. This black-and-white concealment film thickness can be measured using a concealment rate measuring paper (standard: JIS K5600) used for measuring the concealment force of the coating composition. The measurement method of the black-and-white concealment film thickness is as follows. Spray coating is performed on a black and white checkered pattern of 2 × 2 cm square included in the concealment rate measuring paper so that a dry film thickness gradient of 20 to 300 μm is formed, and then baking is performed to cure. Next, the limit coating film part where the black and white checkered pattern cannot be seen through is visually determined, the film thickness of the part is measured, and this film thickness is defined as the black and white masking film thickness.

  Specific examples of non-transparent scaly glittering pigments include aluminum pigments, colored aluminum pigments, copper pigments, zinc pigments, iron pigments, nickel pigments and tin pigments. Among these, aluminum pigments and colored aluminum pigments are preferably used. Here, the colored aluminum pigment is obtained by coating an aluminum pigment with an organic or inorganic colored pigment. The coating layer of colored pigment has a thickness of about 80 to about 600 nm. Examples of the color pigment coating include a wet method in which a color pigment and a polymer substance are dispersed in water and deposited on the surface of an aluminum pigment to form a colored layer.

  In the present invention, it is preferable to use those non-transparent scaly pigments having an average particle size of 6 to 40 μm in the longest direction, and more preferably an average particle size of 10 to 30 μm. . When the average particle diameter exceeds 40 μm, the tip of the scaly glitter pigment may protrude from the surface of the coating film, and the finished appearance of the resulting coating film may be deteriorated. On the other hand, when the average particle size is less than 6 μm, the underlying hiding property may be lowered. Moreover, as the non-transparent scaly glittering pigment, those having a thickness of 0.1 to 2 μm are preferably used.

In the present specification, the “average particle diameter” of the pigment is generally used to represent the particle size (whether the particle diameter is coarse or fine), and is a median diameter (D) measured by a laser light scattering method. ₅₀ ).

The non-transparent scaly glittering pigment is preferably contained in the metallic base coating composition in an amount of 5 to 25% by mass of pigment mass concentration (PWC), more preferably in an amount of 7 to 20% by mass. preferable. When the pigment mass concentration (PWC) is less than 5% by mass, the base concealability may be lowered in the metallic base coating film. On the other hand, when the pigment mass concentration (PWC) exceeds 25% by mass, the coating film appearance of the resulting laminated coating film may be inferior. The pigment mass concentration of the non-transparent scaly pigment is a calculation formula that also includes the amount of pigment other than the non-transparent scaly pigment described below,
PWC (mass%) = (total mass of non-transparent scale-like glitter pigment) / (total mass of non-transparent scale-like glitter pigment and other pigments and total resin solid content) × 100
Is calculated from The total resin means a film-forming resin and a curing agent.

  In the present invention, commercially available non-transparent scaly glitter pigments may be used, and examples of aluminum pigments include “Alpaste” series manufactured by Toyo Aluminum Co., Ltd. and “Alpaste” series manufactured by Asahi Kasei Co., Ltd. Examples of the colored aluminum pigment include “colored aluminum” series manufactured by Toyo Aluminum Co., Ltd., and “colored aluminum” series manufactured by Showa Aluminum Co., Ltd.

Examples of the color pigment that can be contained in the color pigment metallic base coating composition include various organic and inorganic color pigments. Examples of the color pigment include organic azo lake pigments, insoluble azo pigments, condensed azo pigments, diketopyrrolopyrrole pigments, benzimidazolone pigments, phthalocyanine pigments, indigo pigments, perinone pigments, and perylene pigments. Examples thereof include pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, inorganic chrome yellow, yellow iron oxide, bengara, carbon black, titanium dioxide and the like. Further, extender pigments such as calcium carbonate, barium sulfate, clay, aluminum powder, and talc can be added. Moreover, the metallic base coating film of a desired hue can be formed by using the said color pigment 1 type or in combination of 2 or more types.

When the metallic base coating composition contains a colored pigment, the content of the colored pigment contained in the metallic base coating composition is preferably a pigment mass concentration (PWC) of 5 to 40% by mass. By containing the color pigment in an amount in this range, the hue exhibited by the metallic base coating film, the hue exhibited by the mica base coating film, and the hue exhibited by the color clear coating film are in the color arrangement of the hue ring of the Munsell color system, A coating film having a similar color or at least an adjacent hue can be obtained. If it is less than the lower limit, the underlying hiding property may be lowered, and if it exceeds the upper limit, the appearance may be lowered. The pigment mass concentration (PWC) of the color pigment is preferably 7 to 35% by mass. The pigment mass concentration of the colored pigment is calculated using the above-mentioned non-transparent scaly glitter pigment,
PWC (mass%) = (total mass of colored pigment) / (total mass of colored pigment and other pigments and total resin solid content) × 100
Is calculated from

Examples of the film-forming resin contained in the film-forming resin and the curing agent metallic base coating composition include acrylic resins, polyester resins, alkyd resins, epoxy resins, polyurethane resins, polyether resins, and the like. An acrylic resin and / or a polyester resin are preferably used. These may be used alone or in combination of two or more. Examples of the curing agent include amino resins and (block) polyisocyanate compounds.

  Examples of the acrylic resin that is preferably used include a copolymer of an acrylic monomer and another ethylenically unsaturated monomer. Acrylic monomers that can be used for the copolymerization include methyl, ethyl, propyl, n-butyl, i-butyl, t-butyl, 2-ethylhexyl, lauryl, phenyl, benzyl, 2-hydroxy of acrylic acid or methacrylic acid. Examples include esterified products such as ethyl and 2-hydroxypropyl, ring-opening adducts of caprolactone of acrylic acid or 2-hydroxyethyl methacrylate, acrylamide, methacrylamide and N-methylolacrylamide. Other ethylenically unsaturated monomers copolymerizable with these include styrene, α-methylstyrene, itaconic acid, maleic acid, vinyl acetate and the like.

  Examples of the polyester resin preferably used include saturated polyester resins and unsaturated polyester resins, and examples thereof include condensates obtained by heat condensation of polybasic acids and polyhydric alcohols. Examples of the polybasic acid include saturated polybasic acids and unsaturated polybasic acids. Examples of the saturated polybasic acid include phthalic anhydride, terephthalic acid, succinic acid, and the like. Examples of the acid include maleic acid, maleic anhydride, fumaric acid and the like. Examples of the polyhydric alcohol include dihydric alcohol and trihydric alcohol. Examples of the dihydric alcohol include ethylene glycol and diethylene glycol. Examples of the trihydric alcohol include glycerin and trimethylolpropane. Etc.

  The ratio of the resin for forming the coating film and the curing agent is preferably 90 to 50% by mass of the resin for forming the coating film and 10 to 50% by mass of the curing agent in terms of solid content with respect to the total of both. It is more preferable that the forming resin is 85 to 60% by mass and the curing agent is 15 to 40% by mass. When the curing agent is less than 10% by mass (when the coating film forming resin exceeds 90% by mass), the crosslinking in the coating film may not be sufficient. On the other hand, when the crosslinking agent exceeds 50% by mass (when the coating film-forming resin is less than 50% by mass), the storage stability of the coating composition decreases and the curing rate increases, so May be worse.

In addition to the above components, other component metallic base coating compositions are anti-settling agents such as polyamide wax which is a lubricating dispersion of aliphatic amide or polyethylene wax which is a colloidal dispersion mainly composed of oxidized polyethylene, and a curing catalyst. , UV absorbers, antioxidants, leveling agents, surface conditioners such as silicon and organic polymers, sagging inhibitors, thickeners, antifoaming agents, lubricants, crosslinkable polymer particles (microgel), etc. are added as appropriate. be able to. These additives can improve the performance of the coating composition or the coating film by blending usually at a ratio of 15 parts by mass or less with respect to 100 parts by mass of the resin component (solid content basis).

Preparation of metallic base coating composition The metallic base coating composition is provided in a form in which the above-mentioned components are usually dissolved or dispersed in a solvent. Any solvent can be used as long as it dissolves or disperses the resin component, and an organic solvent and / or water can be used. Examples of the organic solvent include those usually used in the paint field. Examples thereof include hydrocarbons such as hexane, toluene and xylene, ketones such as acetone and methyl ether ketone, esters such as ethyl acetate, cellosolve acetate and butyl cellosolve, alcohols and the like. When the use of an organic solvent is regulated from the viewpoint of the environment, it is preferable to use water. In this case, an appropriate amount of a hydrophilic organic solvent may be contained.

  The method for preparing the metallic base coating composition is not particularly limited, and methods well known to those skilled in the art such as kneading and dispersing a compound such as a pigment using a mill, kneader, or roll can be used.

  The solid content of the metallic base coating composition is preferably 30 to 70% by mass during production, and preferably 20 to 55% by mass when the metallic base coating composition is applied.

Mica base coating composition A mica base coating film is formed using a mica base coating composition. As the mica-based coating composition, those containing a transparent scaly glitter pigment, a color pigment, a film-forming resin, a curing agent, and the like are preferably used.

Transparent scale-like glitter pigment Mica-based paint composition contains a transparent scale-like glitter pigment, so that the highlight brightness of the resulting mica-base coating film is high to some extent, and the highlight of the mica-base coating film A coating film having a brightness value lower than the highlight brightness value of the metallic base coating film can be formed.

  In the transparent scaly glitter pigment, “transparency” means that the black-and-white concealment film thickness of the coating film obtained when the pigment concentration (PWC) in the solid content of the paint is 25% is 100 μm or more. To do. Specific examples of the transparent scaly glitter pigment include mica flake pigment, metal oxide-coated mica flake pigment, alumina flake pigment, metal oxide-coated alumina flake pigment, metal oxide-coated silica flake pigment, and metal oxide-coated glass. Examples include flake pigments. Among these, mica flake pigment, metal oxide-coated mica pigment, alumina flake pigment, and metal oxide-coated alumina flake pigment are more preferably used.

  The mica flake pigment is a pigment composed of natural muscovite or synthetic mica. The metal oxide-coated mica pigment is a pigment obtained by coating the surface of natural muscovite or synthetic mica with a thin film of metal oxide such as titanium dioxide, iron oxide, or chromium, cobalt, tin, zirconium.

An alumina flake pigment is a pigment composed of aluminum oxide (A1 ₂ O ₃ ). The metal oxide-coated alumina flake pigment is obtained by coating the surface of aluminum oxide (A1 ₂ O ₃ ) with a metal oxide such as Fe ₂ O ₃ , TiO ₂ , SnO ₂ , or ZrO ₂ . Scattering by reflected light can be reduced by increasing the surface smoothness and sharpening the particle size distribution.

  The metal oxide-coated silica flake pigment is obtained by coating a substrate made of flaky silica (silicon dioxide) with a metal oxide different from silica. Examples of the metal oxide to be coated include iron oxide (iron monoxide, ferric trioxide, hematite) and titanium dioxide (anatase type or rutile type). The thickness of the metal oxide coating layer is preferably 50 to 200 nm, more preferably 60 to 180 nm.

  The metal oxide-coated glass flake pigment is a bright pigment in which titanium dioxide is coated on the surface of the glass flake. The thickness of the pigment is 0.1 to 5 μm, preferably 0.1 to 3 μm. If the thickness is less than 0.1 μm, the glitter pigment may be deformed or broken during preparation of the paint, and the paint composition may change with time. If it exceeds 5 μm, the appearance of the coating film may be deteriorated.

  Among the above pigments, a pigment coated with a metal oxide is sometimes referred to as an interference bright pigment. A pigment coated with these metal oxides can obtain a desired color by adjusting the type and amount (coating thickness) of the metal oxide to be coated.

  As the transparent scaly glittering pigment, it is preferable to use one having an average particle diameter in the longest direction of 10 to 30 μm and a thickness of 0.1 to 2 μm.

The transparent scaly glittering pigment is preferably included in the mica base coating composition in an amount of 0.25 to 15% by mass of pigment mass concentration (PWC), and is included in an amount of 0.5 to 10% by mass. Is more preferable. When the pigment mass concentration (PWC) is less than 0.25% by mass, a laminated coating film having excellent design properties may not be obtained. Moreover, when the pigment mass concentration (PWC) exceeds 15% by mass, the coating film appearance of the laminated coating film may be deteriorated. The pigment mass concentration of the transparent scaly glittering pigment is a calculation formula including other pigments described later,
PWC (mass%) = (total mass of transparent flaky glitter pigment) / (total mass of transparent flaky glitter pigment and other pigments and total resin solid content) × 100
Is calculated from

  A commercially available transparent scaly glittering pigment may be used. For example, as a metal oxide-coated mica pigment having a white interference color, “Silary T60-10 W3” (trade name) manufactured by Merck Japan Ltd., “Pearl Grace SME 90-9” (trade name) manufactured by Nippon Koken Co., Ltd., “Iriodin Ultra 7235 W2” (trade name) manufactured by Merck Japan as a metal oxide-coated mica pigment having a green interference color and “Iriodin Ultra” manufactured by Merck Japan as a metal oxide-coated mica pigment having a blue interference color 7225 W2 "(trade name)," Iriodin Ultra 7205 W2 "(trade name) manufactured by Merck Japan Co., Ltd., and the like as a metal oxide-coated mica pigment having an interference color of yellow. Furthermore, metal oxide-coated alumina flake pigments (alumina white, blue, red, green, gold) having interference light are also included.

As the color pigment, the color pigments mentioned in the description of the metallic base coating composition can be used. Then, by setting the pigment mass concentration (PWC) of the color pigment contained in the mica base coating composition to 0.5 to 15% by mass, the hue exhibited by the metallic base coating film, the hue exhibited by the mica base coating film, and the color clear It is possible to obtain a coating film in which the hue exhibited by the coating film is the same color or at least a hue adjacent to each other in the color arrangement of the Munsell color system hue ring.

Preparation of Film Forming Resin, Curing Agent and Mica Base Coating Composition Specifically, as the film forming resin and curing agent contained in the mica base coating composition, specifically, the description of the metallic base coating film described above The listed film-forming resins and curing agents can be used. It is more preferable to use the same type of film-forming resin and curing agent as those used in the metallic base coating composition. Furthermore, other components that can be included in the metallic base coating composition can be used as well. The preferred proportions of these components and the preparation of the mica base coating composition are the same as those of the metallic base coating composition.

  The paint form of the mica base paint used in the present invention may be any of an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion), and a non-water-dispersed type.

  The solid content of the mica-based coating composition is preferably 10 to 60% by mass at the time of production, and preferably 15 to 55% by mass at the time of coating.

Color Clear Coating Composition A color clear coating film is formed using a color clear coating composition. The color clear coating composition includes a color pigment, a film-forming resin, a curing agent, and the like.

  As the color pigment, the color pigments mentioned in the description of the metallic base coating composition can be used. Then, by setting the pigment mass concentration (PWC) of the color pigment contained in the color clear coating composition to 0.01 to 10% by mass, the hue exhibited by the metallic base coating film while maintaining the clear property, the mica base coating film A coating film in which the hue exhibited by the color clear and the hue exhibited by the color clear coating film have the same color or at least adjacent hues in the color arrangement of the Munsell color system hue ring can be obtained.

  The film-forming resin contained in the color clear coating composition is not particularly limited, and acrylic resin, polyester resin, epoxy resin, polyether resin, polyurethane resin that can be used in the metallic base coating composition. A film-forming resin such as can be used. These resins can be used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. From the viewpoint of transparency, a combination of an acrylic resin and / or a polyester resin and an amino resin is preferable. Moreover, when a color clear coating film is used as the uppermost coating film of a laminated coating film, an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system are preferable.

  The coating form of the color clear coating composition may be any of an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion), and a non-aqueous dispersion type.

  The solid content of the color clear coating composition is preferably 30 to 60% by mass, more preferably 35 to 55% by mass at the time of production. The solid content during coating of the color clear coating composition is preferably 20 to 55% by mass, and more preferably 30 to 55% by mass.

Top clear paint composition The top clear paint composition used in the present invention may be any of organic solvent type, aqueous type (water-soluble, water-dispersible, emulsion), non-aqueous dispersion type, and powder type. Examples include those containing a forming resin and a curing agent. If necessary, a curing catalyst, a surface preparation agent, and the like can be used. The film-forming resin is not particularly limited, and acrylic resin, polyester resin, epoxy resin, polyurethane resin, and the like can be used. These are used in combination with curing agents such as amino resins and / or (block) isocyanate resins. From the viewpoint of transparency or acid etching resistance, it is preferable to use a combination of an acrylic resin and / or a polyester resin and an amino resin, or an acrylic resin and / or a polyester resin having a carboxylic acid / epoxy curing system. Furthermore, the top clear paint can contain other additives as desired. Specifically, what was mentioned by description of the above-mentioned metallic base coating film can be used.

A schematic diagram of a multilayer coating film obtained by the method for forming a multilayer coating film forming method of the present invention of a multilayer coating film shown in FIG. The article 1 may have an electrodeposition coating 3 if desired. The laminated coating film of the present invention is formed by forming the metallic base coating film 7 on the intermediate coating film 5 and then sequentially forming the mica base coating film 9 and the color clear coating film 11. Furthermore, a top clear coating film 13 may be formed.

Coating object The coating object used for forming the laminated coating film of the present invention is not particularly limited, and examples thereof include metals, plastics, foams and the like. Of these objects to be coated, a metal substrate capable of cationic electrodeposition coating is particularly preferably used. The metal substrate is not particularly limited, and examples thereof include simple metals such as iron, copper, aluminum, tin, and zinc, and alloys and castings containing these simple metals. Specifically, passenger cars, trucks, etc. Automobile bodies and parts such as motorcycles and buses.

  When these metal substrates are used as the objects to be coated, it is particularly preferable that they are previously subjected to chemical conversion treatment with phosphate, chromate or the like. And it is preferable that the electrodeposition coating film is formed on the metal base material which such chemical conversion treatment was made. As the electrodeposition coating composition, both a cation type and an anion type can be used, but it is preferable to use a cationic type electrodeposition coating composition because a coating film having better anticorrosion properties can be formed. . As the cationic electrodeposition coating composition, a commonly used coating composition can be used.

Intermediate Coating Film The object to be coated used in the present invention has an intermediate coating film formed on an electrodeposition coating film as desired. The intermediate coating film has a function of concealing the underlying defects, ensuring surface smoothness after the top coating (improving appearance), and imparting physical properties of the coating film (impact resistance, chipping resistance, etc.). The intermediate coating film is formed using the intermediate coating composition. The intermediate coating composition contains a coating-forming resin, a curing agent, and the like, such as various organic and inorganic coloring pigments and extenders.

  As the color pigment used in the intermediate coating composition, for example, those described in the above-mentioned metallic base coating composition can be used. Typically, a dark gray, light gray or white intermediate coating composition containing carbon black and titanium dioxide as main pigments is used. A so-called color intermediate coating composition in which various color pigments are combined may be used.

  The film-forming resin used in the intermediate coating composition is not particularly limited, and for example, those described in the above-mentioned metallic base coating composition can be used. From the viewpoint of pigment dispersibility or workability, a combination of an alkyd resin and / or a polyester resin and an amino resin is preferable.

  The metallic base coating film may be formed in an uncured state after the intermediate coating composition is applied to an object on which an electrodeposition coating film is formed as desired. In addition, baking and curing may be performed before the formation of the metallic base coating film. When performing baking hardening, it can bake for 10 to 30 minutes at 100-180 degreeC of hardening temperature, Preferably it is 120-160 degreeC.

A metallic base coating film is formed by applying a metallic base coating composition to an object having an intermediate coating film. When the object to be coated is an automobile body, it is applied by multistage coating by air electrostatic spray coating, preferably by two stages, or by air electrostatic spray coating, commonly known as “μμ (micro micro) bell”, It is preferable to form the metallic base coating film by a coating method combined with a rotary atomizing electrostatic coater called “μ (micro) bell” or “metabell”. These coatings can further enhance the appearance and design of the coating film.

  Although the film thickness of the metallic base coating film in the present invention varies depending on the desired application, it is preferable to apply the coating so that the dry film thickness is 10 to 35 μm. If the upper limit is exceeded, sharpness may deteriorate, or defects such as unevenness or flow may occur during painting. If the lower limit is exceeded, the substrate may not be concealed and film breakage may occur.

  After the coating of the metallic base coating composition, the coating film may be baked and cured, or the next mica base coating film may be formed on the uncured metallic base coating film without baking and curing. In the case of baking and curing the metallic base coating film, baking is preferably performed at a curing temperature of 100 to 180 ° C, preferably 120 to 160 ° C for 10 to 30 minutes.

Mica base coating film On the metallic base coating film thus formed, a mica base coating film is formed using the mica base coating composition. The mica base coating film can be formed in the same manner as the metallic base coating film. In addition, when baking hardening is not performed after formation of a metallic base coating film, a mica base coating film will be formed by wet on wet.

  Here, wet-on-wet means that after the first coating composition (here, metallic base coating composition) is applied to form a coating film, the coating film is not baked and cured, and the second coating composition is formed thereon. It means that a coating film is formed by coating a product (here, a mica-based coating composition). In this case, before applying the second coating composition, the coating film obtained from the first coating composition may be set or preheated. Setting is generally performed by leaving the coating film at room temperature for 1 to 8 minutes. Moreover, preheating is generally performed by heating a coating film at 40-80 degreeC for 2 to 10 minutes.

  Although the film thickness of the mica base coating film varies depending on the desired application, it is preferable to apply the coating so that the dry film thickness is 10 to 35 μm. If the upper limit is exceeded, sharpness may deteriorate, or defects such as unevenness or flow may occur during painting. If the lower limit is exceeded, the substrate may not be concealed and film breakage may occur.

  In the method for forming a laminated coating film according to the present invention, the metallic base coating film and the mica base coating film thus obtained have the hue exhibited by the metallic base coating film and the hue exhibited by the mica base coating film in the hue ring of the Munsell color system. In the color arrangement, the colors are similar colors or at least adjacent hues.

  The Munsell color system is a type of system (color system) that expresses colors based on the three attributes of color. The Munsell color system is standardized as JIS Z 8721 (color display method using three attributes). Here, the three attributes mean three of hue, brightness, and saturation. Of the three attributes, “hue” represents the type of color. In this hue, there are five basic colors of red (R), yellow (Y), green (G), blue (B), purple (P), and yellow, red (YR), It is divided into a total of 10 colors including green (GY), blue-green (BG), blue-violet (PB), and red-purple (RP). These colors are further divided by 5 to express the color type with a total of 50 hues. A color circle obtained by arranging the colors divided into 50 hues in order. In this specification, “the same color or at least adjacent hues in the color arrangement of the Munsell color system hue ring” means that the same hue or adjacent colors are divided into 50 hues in the Munsell color system. It means the hue judged as the hue.

  In the formation of the multilayer coating film of the present invention, the hue exhibited by the metallic base coating film and the hue exhibited by the mica base coating film are the same colors or at least adjacent hues in the color arrangement of the hue ring of the Munsell color system. Thus, a laminated coating film having a sense of depth and hardly subject to fluctuations in the film thickness of each coating film can be obtained.

  Note that “the hue exhibited by the metallic base coating film and the hue exhibited by the mica base coating film are the same colors or at least adjacent hues in the color arrangement of the Munsell color system hue ring”, for example, the metallic base coating film Means that the hue of the mica-based coating film is classified into 2.5R to 7.5R when the hue is classified as “5R” in the Munsell color system.

  In the present invention, the hue exhibited by the metallic base coating film and the hue exhibited by the mica base coating film are the coating films obtained by individually coating and baking and curing the metallic base coating composition and the mica base coating composition, respectively. Use to measure hue. The coating film used for colorimetry can be prepared, for example, by coating and baking a coating composition on a black-and-white concealed test paper so that the dry film thickness is 15 μm. Here, the black-and-white concealment test paper is obtained by printing a black and white checkered pattern with an interval of 40 mm, and the brightness thereof is an L * value of 80 or more in the white portion and an L * value of 12 or less in the black portion. The color measurement of the hue of the Munsell color system in these coating films can be performed using a color difference meter of “Minolta spectrocolorimeter CM-2002” (trade name, manufactured by Minolta).

  In the method for forming a laminated coating film of the present invention, the mica base coating film has a metallic base coating film and a 15 ° L * value of the coating film composed of the mica base coating film with respect to the 15 ° L * value of the metallic base coating film. It is also characterized in that the coating film is formed so that the fluctuation range is -18 to -30%.

  Here, L * is determined according to JIS Z8729. L * is an index used to represent the color of the object to be measured according to the L * a * b * color system (CIE 1976). In this color system, L * represents lightness. The lightness L * means that the hue of the substance to be measured increases as the numerical value increases and the blackness increases as the numerical value decreases. The L * value can be measured using “CM512m-3” (Minolta's variable angle color difference meter).

  The 15 ° L * value means an L * value that is received by irradiating a light source from an angle of 15 ° when the light receiving portion in a position perpendicular to the coating film to be measured is 0 °. . FIG. 2 is a diagram for schematically explaining these light source irradiation angles.

  The state in which the 15 ° L * value of the coating film composed of the metallic base coating film and the mica base coating film has a fluctuation range of −18 to −30% with respect to the 15 ° L * value of the metallic base coating film refers to the metallic base The two-layer coating film composed of the coating film and the mica base coating film has a lower brightness than the case of the metallic base coating film alone. A mica base coating film in which the hue of the metallic base coating film and the hue of the mica base coating film are similar colors, and the brightness of the coating film composed of the metallic base coating film and the mica base coating film varies within the above range. By forming, it is possible to reduce a change in the appearance of the coating film due to a change in film thickness, and it is possible to form a laminated coating film with a sense of depth and excellent design.

  The 15 ° L * value of the coating film composed of the metallic base coating film and the mica base coating film has a fluctuation range of 0 to −18% (excluding −18%) with respect to the 15 ° L * value of the metallic base coating film. ), The sense of depth of the resulting laminated coating film is lowered and the design properties are inferior. Also, when the 15 ° L * value of the metallic base coating film and the mica base coating film is smaller than the fluctuation range of −30% relative to the 15 ° L * value of the metallic base coating film (absolute value of the fluctuation range). When it becomes large (for example, when it is -32%), a change in the color of the coating film is felt, and there is a possibility that a change in the appearance of the coating film may occur due to a change in the film thickness. When the 15 ° L * value of the coating film composed of the metallic base coating film and the mica base coating film exceeds the fluctuation range of 0 with respect to the 15 ° L * value of the metallic base coating film, Appearance will be inferior.

  The mica base coating film in which the 15 ° L * value of the coating film composed of the metallic base coating film and the mica base coating film has a variation range of −18 to −30% with respect to the 15 ° L * value of the metallic base coating film. As a forming method, a mica base coating composition having a pigment mass concentration (PWC) of a transparent scaly glittering pigment of 0.25 to 15% by mass is applied so that the dry film thickness is 6 to 15 μm. Examples thereof include a method for forming a film.

  After the application of the mica base coating composition, the coating film may be baked and cured, or the next color clear coating film may be formed without baking and curing. When the mica base coating film is baked and cured, it is preferably baked at a curing temperature of 100 to 180 ° C., preferably 120 to 160 ° C. for 10 to 30 minutes.

Color clear coating film A color clear coating film is formed on the coating film formed of the metallic base coating film and the mica base coating film by using the color clear coating composition. The color clear coating film can be formed in the same manner as the above metallic base coating film. In addition, when baking hardening is not performed after formation of a mica base coating film, a color clear coating film will be formed by wet on wet. In the case of applying wet-on-wet, the mica base coating film may be subjected to setting or preheating before applying the color clear coating composition. Preheating can be performed under the same conditions as in the case of the metallic base coating film described above.

  The film thickness of the color clear coating film varies depending on the desired application, but it is preferable to coat the film so that the dry film thickness is 10 to 60 μm. If the upper limit is exceeded, sharpness may deteriorate, or defects such as unevenness or flow may occur during painting. If the lower limit is exceeded, the substrate may not be concealed and film breakage may occur.

  Baking after coating of the color clear coating composition is preferably performed at a curing temperature of 100 to 180 ° C., preferably 120 to 160 ° C. for 10 to 30 minutes.

  In the method for forming a laminated coating film of the present invention, the hue exhibited by the color clear coating film is the hue exhibited by the metallic base coating film and the hue exhibited by the mica base coating film, and the color arrangement of the hue ring of the Munsell color system, Similar colors or at least adjacent hues. The color measurement of the hue of the coating film can be performed in the same manner as described above. When these coating films have such a hue, a laminated coating film having a sense of depth and hardly subject to variations in the film thickness of each coating film is obtained.

  In the method for forming a laminated coating film of the present invention, the color clear coating film has a 15 ° L * value of a coating film composed of a metallic base coating film, a mica base coating film, and a color clear coating film. It is also characterized in that the coating film is formed so that the fluctuation range is −16 to −30% with respect to the 15 ° L * value of the film.

  The 15 ° L * value of the coating composed of the metallic base coating, the mica base coating and the color clear coating varies from the range of −16 to − with respect to the 15 ° L * value of the metallic base coating and the mica base coating. The state of 30% means that a three-layer coating consisting of a metallic base coating, a mica base coating and a color clear coating is compared with a two-layer coating consisting of a metallic base coating and a mica base coating. The brightness is low. By forming a color clear coating film in which the hues of the metallic base coating film, mica base coating film and color clear coating film are similar colors, and the brightness varies within the above range, the film thickness varies. A change in the appearance of the coating film can be reduced, and a laminated coating film having a sense of depth and excellent design can be formed. The disadvantage when the fluctuation range of the 15 ° L * value is out of the range of −16 to −30% is the same as described above.

  The 15 ° L * value of the laminated coating composed of the metallic base coating, the mica base coating and the color clear coating has a variation range of −16 with respect to the 15 ° L * value of the metallic base coating and the mica base coating. As a method for forming a color clear coating film, which has a dry film thickness of 10 to 10%, a color clear coating composition having a pigment mass concentration (PWC) of 0.01 to 10% by weight is used. Examples thereof include a method of forming a coating film so as to be 60 μm.

  The 15 ° L * value of the laminated coating film composed of the metallic base coating film, the mica base coating film and the color clear coating film thus obtained has a fluctuation range of 0 to − with respect to the 15 ° L * value of the metallic base coating film. It is preferably 47%. When the fluctuation range is within this range, it is possible to obtain a coating film with little variation in coating film appearance. The fluctuation range is more preferably in the range of -37 to -47%.

  Moreover, it is preferable that the 15 degree L * value of the laminated coating film which consists of a metallic base coating film, a mica base coating film, and a color clear coating film is 20-60. When the 15 ° L * value of the multilayer coating film is 20 to 60, a multilayer coating film having a sense of depth and excellent design is obtained. When the 15 ° L * value of the laminated coating film is less than 20, only the coating color with a small amount of the glitter component can be designed, and the design properties of the laminated coating film may be lowered. When the 15 ° L * value of the laminated coating exceeds 60, the brightness difference between the metallic coating and the color clear coating is too large, and the hue difference due to the film thickness variation of the color clear coating increases. There is a fear.

Top clear coating film In the method for forming a laminated coating film of the present invention, a top clear coating film can be further formed on a laminated coating film comprising a metallic base coating film, a mica base coating film and a color clear coating film. . By forming the top clear coating film, the metallic base coating film, mica base coating film and color clear coating film can be protected.

  The top clear coating film can be formed using a top clear coating composition. As the top clear coating composition, those containing a film-forming resin and a curing agent are preferably used. As the film-forming resin and the curing agent, those that can be used in the color clear coating composition can be used. The top clear coating composition can be prepared in the same manner as the color clear coating composition.

  Specifically, the top clear coating composition is preferably applied by a rotary atomizing electrostatic coater such as the μμ bell or μbell described above.

  The dry film thickness of the top clear coating film formed from the top clear coating is generally preferably about 10 to 70 μm, more preferably about 20 to 50 μm. If the upper limit is exceeded, defects such as cracks or sagging may occur during painting, and if the lower limit is exceeded, the underlying irregularities may not be concealed.

  After forming the top clear coating film, a cured coating film having a high degree of crosslinking can be obtained by setting the curing temperature for curing the coating film to 100 to 180 ° C., preferably 120 to 160 ° C. If the upper limit is exceeded, the coating film may become hard and brittle, and if it is less than the lower limit, curing may not be sufficient. The curing time varies depending on the curing temperature, but it is suitably from 120 to 160 ° C. for 10 to 30 minutes. The top clear coating film is preferably applied wet-on-wet on the color clear coating film. The color clear coating film should be set and preheated before the top clear coating composition is applied. Can do. Preheating can be performed under the same conditions as those for the metallic base coating film.

  The film thickness of the laminated coating film formed in the present invention is often 30 to 300 μm, and preferably 50 to 250 μm. If the upper limit is exceeded, film properties such as cooling and cooling cycles may be reduced, and if the lower limit is not reached, the strength of the film itself may be reduced.

  The following examples further illustrate the present invention, but the present invention is not limited thereto. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Production Example 1 Production of Red Metallic Base Coating Composition Into a stainless steel container, 83.2 parts of acrylic resin (acid value 20 mgKOH / g, hydroxyl value 75, number average molecular weight 5000, solid content 60%) manufactured by Nippon Paint Co., Ltd. , 96.8 parts of pigment dispersion paste obtained by dispersing 13.6 parts of Perind Maroon 6436 (iron oxide red pigment manufactured by Miles Co., Ltd.) so as to have a particle size of 5 μm or less, and then weighing Uban 128 (Mitsui 44.7 parts of butylated melamine resin (trade name, solid content 60%) manufactured by Kagaku Co., Ltd., aluminum paste 7640 NS (aluminum pigment manufactured by Toyo Aluminum Co., Ltd., non-transparent scaly glitter pigment, product name, average particle size 18 μm) 9.7 parts and 15.3 parts of crosslinkable resin particles (acrylic viscosity imparting agent manufactured by Nippon Paint Co., Ltd., average particle size 55 nm, solid content 25%) It was stirred at tabletop stirrer to prepare a solvent-borne metallic base coating composition reddish. This was used after adjusting to the coating viscosity. The PWC of the non-transparent scaly glittering pigment contained in the metallic base coating composition was 23.3% by mass.

Production Example 2 Production of Red Mica Base Coating Composition Into a stainless steel container, 83.2 parts of acrylic resin (acid value 20 mg KOH / g, hydroxyl value 75, number average molecular weight 5000, solid content 60%) manufactured by Nippon Paint Co., Ltd. , Shinkasha Red RT-355 (Red Pigment made by Ciba Specialty Chemicals Co., Ltd.) 6.2 parts, Perind Maroon 6436 (Miles Co., Ltd. Iron Oxide Red Pigment) 0.4 parts so that each particle size is 5 μm or less. 90.6 parts of the pigment dispersion paste obtained by dispersing the pigment was weighed, then 44.7 parts of Uban 128 (Butylated melamine resin manufactured by Mitsui Chemicals, trade name, solid content 60%), Iriodine 7215WII (Merck) Mica pigment made, transparent scaly glitter pigment, trade name 0.8 parts and crosslinkable resin particles (acrylic viscosity imparting agent manufactured by Nippon Paint, average Diameter 55 nm, solid content 25%) 9.2 parts were weighed, and stirred at tabletop stirrer to prepare a solvent-mica base coating composition reddish. This was used after adjusting to the coating viscosity. The PWC of the transparent scaly glittering pigment contained in the mica base coating composition was 7.4% by mass.

Production Example 3 Manufacture of red color clear paint composition In a stainless steel container, Macflow O-1800 clear (acid / epoxy curable clear paint, trade name, manufactured by Nippon Paint Co., Ltd.), Perind Maroon 6436 (manufactured by Miles) A red solvent-type color clear coating composition obtained by dispersing a pigment of iron oxide (red pigment) so that the pigment concentration (PWC) is 0.7% by mass is prepared and adjusted to the coating viscosity. It was.

Production Example 4 Production of Top Clear Coating Composition Mac Flow O-1800 Clear (acid / epoxy curable clear coating, trade name, manufactured by Nippon Paint Co., Ltd.) was used after adjusting the coating viscosity.

Measurement of Munsell value of coating film formed from each coating composition Dried on black-and-white concealed test paper using metallic base coating composition, mica base coating composition and color clear coating composition obtained by the above production examples, respectively. The film was painted and baked to a film thickness of 15 μm. The obtained cured coating film was measured with a color difference meter of “Minolta spectrocolorimeter CM-2002” (trade name, manufactured by Minolta Co., Ltd.), and the color arrangement in the Munsell hue was measured. Here, the black-and-white concealment test paper is obtained by printing a black and white checkered pattern with an interval of 40 mm, and the brightness thereof is an L * value of 80 or more in the white portion and an L * value of 12 or less in the black portion. The measurement results are shown in Table 1.

Example 1
Cationic electrodeposition paint “Power Top U-50” (manufactured by Nippon Paint Co., Ltd.) and a dry film thickness of 20 μm on a zinc phosphate-treated SPCC-SD steel plate (Dal steel plate) with a thickness of 0.8 cm and 20 cm × 30 cm. Electrodeposition coating was performed and baked at 160 ° C. for 30 minutes. Next, on the obtained electrodeposition coating film, a gray intermediate coating “Orga TO-H-880-3 Gray” (manufactured by Nippon Paint Co., Ltd., polyester / melamine resin-based coating) is dried to a thickness of 30 μm. Then, spray coating was performed, and baking was performed at 140 ° C. for 20 minutes to prepare an object to be coated on which an intermediate coating film was formed.

On the obtained intermediate coating film, the metallic base coating composition of Production Example 1 was subjected to “Auto REA” (air electrostatic manufactured by Landsburg) in two stages at intervals of 2 minutes so that the dry film thickness was 15 μm. It was painted with a coating machine. After a 10 minute interval, it was baked at 140 ° C. for 20 minutes. Using “CM512m-3” (a variable angle colorimeter manufactured by Minolta Co., Ltd.), when the light receiving portion in a position perpendicular to the obtained metallic base coating film is set to 0 °, the light source is turned from an angle of 15 °. L * values measured by irradiation were measured. The measurement results are shown in Table 2.

  Subsequently, on the obtained metallic base coating film, the mica base coating composition of Production Example 2 was electrostatically coated in the same manner so that the dry film thickness was 9 μm. Next, after setting for 7 minutes, baking was performed at 140 ° C. for 20 minutes. The 15 ° L * value of the obtained coating film was measured in the same manner as described above. The measurement results are shown in Table 2.

  Next, on the obtained mica base coating film, the color clear coating composition of Production Example 3 was rotationally atomized electrostatically coated with a μμ bell so that the dry film thickness was 37 μm. An evaluation coating film was prepared by baking at 140 ° C. for 20 minutes. The 15 ° L * value of the obtained coating film was measured in the same manner as described above. The measurement results are shown in Table 2.

In Tables 2 to 4, “Variation 1” means the metallic base for the 15 ° L * value (15 ° L * (2)) of the coating consisting of the metallic base coating and the mica base coating. It is the fluctuation range for the 15 ° L * value (15 ° L * (1)) of the coating film, and is calculated from the following formula.
Fluctuation 1 = {(15 ° L * (2))-(15 ° L * (1))} / (15 ° L * (1)) x 100
“Variation 2” means the metallic base coating film for the 15 ° L * value (15 ° L * (3)) of the laminated coating consisting of metallic base coating, mica base coating and color clear coating. And a fluctuation range for a 15 ° L * value (15 ° L * (2)) of a coating film composed of a mica base coating film, and is calculated from the following formula.
Fluctuation range 2 ＝ {(15 ° L * (3))-(15 ° L * (2))} / (15 ° L * (2)) × 100
“Variation 3” means that the metallic base coating film has a 15 ° L * value (15 ° L * (3)) for a laminated coating composed of a metallic base coating, a mica base coating, and a color clear coating. This is the fluctuation range for the 15 ° L * value (15 ° L * (1)) and is calculated from the following equation.
Fluctuation 3 = {(15 ° L * (3))-(15 ° L * (1))} / (15 ° L * (1)) × 100

Appearance evaluation of laminated coating film The appearance of the laminated coating film thus obtained was evaluated by visual judgment. The evaluation criteria are as follows.
○: A coating film in which the depth is felt, and the entire coating film has a uniform color.
(Triangle | delta): The feeling of depth is a slightly weak coating film, or the hue change is felt by the fluctuation | variation of the film thickness of a coating film.
X: There is no feeling of depth and the hue is changing due to the film thickness variation of the coating film.

Examples 2-6 and Comparative Examples 1-7
The same procedure as in Example 1 was conducted except that the thicknesses of the metallic base coating film, mica base coating film and color clear coating film were changed to the film thicknesses shown in Tables 2 to 4. Evaluation and the like were performed in the same manner. The results are shown in Tables 2-4. In Examples 2 to 6 and Comparative Examples 1 to 7, the hue of each coating film was changed by substantially changing the coating film thickness of each coating film, and the hue change generated in each coating film layer Only evaluated.

  As shown in Tables 3 to 5, the laminated coating films obtained by the examples had a sense of depth and excellent design properties, and the hue variations of the laminated coating films due to film thickness variations were small. . On the other hand, in Comparative Examples 1, 4 and 5, since the change in the L * value was small, the obtained multilayer coating film had little sense of depth and was inferior in design. Further, in Comparative Examples 2, 3, 6 and 7, the change in L * value was large, and the obtained multilayer coating film felt a change in hue due to film thickness fluctuation.

  The laminated coating film according to the present invention has an advantage of exhibiting a stable design by having a mica base coating film on a metallic base coating film. The method for forming a laminated coating film according to the present invention is particularly suitable for industrial coating of an object having a large and complicated shape such as an automobile body.

It is typical sectional drawing of the laminated coating film prepared in the Example. It is a figure which illustrates roughly a light source irradiation angle.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Coating object, 3 ... Electrodeposition coating film, 5 ... Intermediate coating film, 7 ... Metallic base coating film, 9 ... Mica base coating film, 11 ... Color clear coating film, 13 ... Top clear coating film.

Claims (4)

A method for forming a laminated coating film in which a metallic base coating film, a mica base coating film, and a color clear coating film are sequentially formed on an object having an intermediate coating film,
The hue exhibited by the metallic base coating film, the hue exhibited by the mica base coating film, and the hue exhibited by the color clear coating film are the same colors or at least adjacent hues in the color arrangement of the hue ring of the Munsell color system. ,
The mica base coating film has a variation range of −18 to −30% for the 15 ° L * value of the metallic base coating film and the coating film composed of the mica base coating film with respect to the 15 ° L * value of the metallic base coating film. It is a coating film formed so as to become,
The metallic base coating composition, the mica base coating film, and the laminated coating composed of the color clear coating film have a 15 ° L * value of 20 to 60, and the metallic base coating composition that forms the metallic base coating film Contains a non-transparent scaly glitter pigment having an average particle size of 6 to 40 μm in an amount of 5 to 25% by mass of pigment mass concentration (PWC),
The mica base coating composition for forming the mica base coating film contains a transparent scaly glitter pigment in an amount of 0.25 to 15% by mass of a pigment mass concentration (PWC),
The color clear coating composition for forming the color clear coating film contains a color pigment in an amount of 0.01 to 10% by weight of pigment mass concentration (PWC).
A method for forming a laminated coating film. Further, the color clear coating film has a 15 ° L * value of a laminated coating film composed of a metallic base coating film, a mica base coating film, and a color clear coating film. The coating film is formed so that the fluctuation range is −16 to −30% with respect to the 15 ° L * value, and the 15 ° L * value of the obtained laminated coating film is the value of the metallic base coating film. The fluctuation range is 0 to −47% with respect to the 15 ° L * value.
The method for forming a laminated coating film according to claim 1.   4. Forming a multilayer coating film comprising four layers on the multilayer coating film formed by the method for forming a multilayer coating film according to claim 1 or 2, further forming a top clear coating film using a top clear coating composition. Method.   The laminated coating film formed by the formation method of the laminated coating film in any one of Claims 1-3.

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