Multi-layer coating film, and method for producing multi-layer coating film

Abstract

To provide a multi-layer coating film in which the hue changes depending on the observation angle or incident light angle, thereby making it possible to provide a unique, high-chroma blue design that is based on changes in hue, particularly for three-dimensionally shaped coated objects. By means of a multi-layer coating film having a first colored coating film and a second colored coating film, in that order, wherein the first colored coating film comprises a first coating film-forming resin and an aluminum flake pigment, the second colored coating film comprises a second coating film-forming resin and a blue pigment, the first colored coating and / or second colored coating film comprises an optically variable pigment, the hue angle h(45 / 0) is 205 to 295 degrees, the chroma C* (45 / 0) value is 30 to 60, the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30) and the hue angle h(45 / -30), as determined at an incident angle of 45 degrees and a receiving angle of -30 degrees, is 20 to 50 degrees, and the difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0) and the hue angle h(70 / 60), as determined at an incident angle of 70 degrees and a receiving angle of 60 degrees, is 5 to 55 degrees.

Description

241268 WO01 1 BASF Coatings GmbH[Document Name] SPECIFICATION[Title of the Invention] Multi-Layer Coating Film, and Method for Producing Multi-Layer Coating Film[Technical Field]

[0001] The present invention relates to a blue-colored multi-layer coating film and a method for forming a multi-layer coating film.[Background Art]

[0002] Greater diversity in consumer preferences has recently led to demand for coating films of varying color and design for the exteriors of industrial products such as automobiles. Multi-layer coating films in which a coating film that contains a coloring pigment has been laminated onto a coating film that contains a glitter pigment are an example of such coating films.

[0003] Patent Document 1, for example, proposes a method for forming a highly saturated, richer multi-layer coating film, with minimal color variation due to variations in film thickness and irregularities in color, from a first colored coating film that contains a glitter pigment and a color pigment, a second colored coating film that contains a color pigment, and a clear coating film.

[0004] Patent Document 2 also provides a multi-layer coating film that is richer and has bright, vivid highlights, consisting of: a metallic base coating film that contains an aluminum flake pigment, a surface conditioner, and a viscosity conditioner; and a transparent colored coating film that contains a blue pigment, which is formed on the metallic base coating film.

[0005] Patent Document 3 further discloses a coating composition that contains specific proportions of a glitter material that has an angle-dependent optically variable effect and a glitter material that does not have an angle-dependent optically variable effect, and the color of the resulting coating film changes from achromatic to chromatic when observation conditions are changed from face angle to grazing angle.241268 WO01 2 BASF Coatings GmbH[Prior Art Documents][Patent Documents]

[0006] [Patent Document 1] JP 6805401 B2[Patent Document 2] JP 7248670 B2[Patent Document 3] JP 4775460 B2[Summary of the Invention][Problem to be Solved by the Invention]

[0007] However, there is a trend toward greater diversity in consumer preferences for the design of industrial products such as automobiles.

[0008] Accordingly, an object of the present invention is to provide a multi-layer coating film, as well as a method for producing the film, in which the hue changes depending on the observation angle or incident light angle, thereby making it possible to provide a unique, high-chroma blue design that is based on changes in hue, particularly for three-dimensionally shaped coated objects.[Means for Solving the Problem]

[0009] As a result of extensive research by the inventors to solve the above-mentioned problem, the present invention was perfected upon the discovery that the above problem of the present invention is solved by: a multi-layer coating film comprising a first colored coating film, and a second colored coating film provided on the first colored coating film, said multi-layer coating film characterized in that the first colored coating film comprises a first coating film-forming resin and an aluminum flake pigment, the second colored coating layer comprises a second coating film-forming resin and a blue pigment, the first colored coating film and / or second colored coating film comprise an optically variable pigment, the hue angle h(45 / 0), as determined at an incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film, is 205 to 295 degrees, the chroma C* (45 / 0) value, as determined at an incident angle of 45 degrees and a receiving angle of 0 degrees, is 30 to 60, the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30), as determined at an incident angle of 45 degrees and a receiving angle of 30 degrees, and the hue angle h(45 / -30), as determined at an incident angle of 45 degrees and a receiving angle of -30 degrees, is 20 to 50 degrees, and the difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0), as determined at an incident angle of 10 degrees and a receiving angle of 0 degrees, and the hue angle h(70 / 60), as determined at an incident angle of 70 degrees and a receiving angle of 60 degrees, is 5 to 55 degrees.241268 WO01 3 BASF Coatings GmbH

[0010] In the multi-layer coating film of the present invention, the first coating film-forming resin and second coating film-forming resin furthermore are preferably each independently a thermosetting resin composed of, as a base resin, one or more selected from (meth)acrylic resins, polyester resins, polyurethane resins, and (meth)acrylic urethane resins.

[0011] In the multi-layer coating film of the present invention, the first colored coating film and / or second colored coating film furthermore preferably comprises an inorganic thickener.

[0012] In the multi-layer coating film of the present invention, the first colored coating film furthermore preferably comprises: a first coating film-forming resin containing (meth)acrylic urethane resin particles; and an inorganic thickener.

[0013] In the multi-layer coating film of the present invention, the first colored coating film furthermore preferably comprises a first coating film-forming resin containing (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having an aldehyde group and / or a ketone group as well as a compound having two or more hydrazide groups per molecule; and an inorganic thickener.

[0014] The multi-layer coating film of the present invention furthermore preferably furthermore has a clear coating layer on the second colored coating film.

[0015] The problem of the present invention is also solved by: a method for forming a multi-layer coating film, comprising: a step (1) in which a first colored coating composition is applied onto an object to be coated to form an uncured first colored coating film; a step (2) in which a second colored coating composition is applied onto the first colored coating film to form an uncured second colored coating film; and optionally, a step (3) in which a clear coating composition is applied onto the second colored coating film to form an uncured clear coating film, wherein the uncured first colored coating film in step (1), the uncured second colored coating film in step (2), and in cases where step (3) is carried out, the uncured clear coating film formed in step (3) are each cured by being heated, or the method furthermore comprises a step (4) in which the uncured first colored coating film, the uncured second colored coating film, and the optionally formed uncured clear coating film are cured by being heated simultaneously, said method for forming a multi-layer coating film being characterized in that the first colored coating composition comprises a first coating film-forming resin and an aluminum flake pigment,241268 WO01 4 BASF Coatings GmbHthe second colored coating composition comprises a second coating film-forming resin and a blue pigment, the first colored coating composition and / or second colored coating composition comprise an optically variable pigment, the hue angle h(45 / 0) of the resulting multi-layer coating film, as determined at an incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film, is 205 to 295 degrees, the chroma C* (45 / 0) value, as determined at an incident angle of 45 degrees and a receiving angle of 0 degrees, is 30 to 60, the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30), as determined at an incident angle of 45 degrees and a receiving angle of 30 degrees, and the hue angle h(45 / -30), as determined at an incident angle of 45 degrees and a receiving angle of -30 degrees, is 20 to 50 degrees, and the difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0), as determined at an incident angle of 10 degrees and a receiving angle of 0 degrees, and the hue angle h(70 / 60), as determined at an incident angle of 70 degrees and a receiving angle of 60 degrees, is 5 to 55 degrees.

[0016] In the method for producing a multi-layer coating film of the present invention, the first coating film-forming resin and second coating film-forming resin furthermore are preferably each independently a thermosetting resin composed of, as a base resin, one or more selected from (meth)acrylic resins, polyester resins, polyurethane resins, and (meth)acrylic urethane resins.

[0017] In the method for producing a multi-layer coating film of the present invention, the first colored coating film and / or second colored coating film furthermore preferably comprises an inorganic thickener.

[0018] In the method for producing a multi-layer coating film of the present invention, the first colored coating film furthermore preferably comprises: a first coating film-forming resin containing (meth)acrylic urethane resin particles; and an inorganic thickener.

[0019] In the method for producing multi-layer coating film of the present invention, the first colored coating composition furthermore preferably comprises a first coating filmforming resin containing (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having an aldehyde group and / or a ketone group as well as a compound having two or more hydrazide groups per molecule; and an inorganic thickener.241268 WO01 5 BASF Coatings GmbH[Effects of the Invention]

[0020] The present invention can provide a multi-layer coating film, as well as a method for producing the film, in which the hue changes depending on the observation angle or incident light angle, thereby making it possible to provide a unique, high-chroma blue design that is based on changes in hue, particularly for three-dimensionally shaped coated objects.[Brief Description of the Drawings]

[0021] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating a method for determining the hue angle h(45 / 0) and chroma C* (45 / 0) value of the multi-layer coating film of the present invention.[Figure 2] Figure 2 is a schematic diagram illustrating an outline of color flop, which is an optical property of the multi-layer coating film of the present invention.[Figure 3] Figure 3(a) is a schematic diagram illustrating a method for determining the hue angle h at an incident angle of 45 degrees and a receiving angle of 30 degrees relative to the normal of a multi-layer coating film (highlight conditions), and Figure 3(b) is a schematic diagram illustrating a method for determining the hue angle h at an incident angle of 45 degrees and a receiving angle of -30 degrees relative to the normal of a multi-layer (shade conditions).[Figure 4] Figures 4(a) and 4(b) are schematic diagrams illustrating an outline of changes in hue, which is an optical property of the multi-layer coating film of the present invention.[Figure 5] Figure 5(a) is a schematic diagram illustrating a method for determining the hue angle h at an incident angle of 10 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film (face angle conditions), and Figure 5(b) is a schematic diagram illustrating a method for determining the hue angle h at an incident angle of 70 degrees and a receiving angle of 60 degrees relative to the normal of the multi-layer coating film (grazing angle conditions).[Modes for Carrying Out the Invention]

[0022] The multi-layer coating film of the present invention comprises a first colored coating film and a second colored coating film provided on the first colored coating film.

[0023] In the multi-layer coating film of the present invention, the first colored coating film comprises a first coating film-forming resin and an aluminum flake pigment, the second colored coating film comprises a second coating film-forming resin and a blue pigment, and the first colored coating film and / or second colored coating film comprises an optically variable pigment.241268 WO01 6 BASF Coatings GmbH

[0024] The following are used in the method for forming a multi-layer coating film of the present invention: a first colored coating composition; a second colored coating composition; and, if necessary, a clear coating composition.

[0025] First, in step (1), a first colored coating composition is applied onto an object to be coated, forming an uncured first colored coating film. After the first colored coating composition has been applied, the coating may be heated over a period of 3 to 5 minutes at 70 to 80°C (flash-off), or may simply be allowed to stand at room temperature without being heated, to allow the solvent contained in the first colored film coating to volatilize off. If performed, flash-off is preferably carried out by selecting a temperature and time range using the above ranges as a guideline, so that the coating film is not completely cured.

[0026] Then, in step (2), a second colored coating composition is applied onto the first colored coating film obtained in step (1) to form an uncured second colored coating film. After the second colored coating composition has been applied, the coating may be heated over a period of 3 to 5 minutes at 70 to 80°C (flash-off), or may simply be allowed to stand at room temperature without being heated, to allow the solvent contained in the second colored film coating to volatilize off. If performed, flash-off is preferably carried out by selecting a temperature and time range using the above ranges as a guideline, so that the coating film is not completely cured.

[0027] Then, in step (3), as needed, a clear coating composition is applied onto the second colored coating film obtained in step (2) to form an uncured clear coating film. After being applied, the clear coating composition is commonly allowed to stand for 5 to 20 minutes at room temperature.

[0028] Lastly, in step (4), the uncured first colored coating film formed in step (1), the uncured second colored coating film formed in step (2), and, if necessary, the uncured clear coating film formed in step (3) are heated to simultaneously cure the three layers. In step (1), step (2) and step (3), the uncured first colored coating film, uncured second colored coating film, and uncured clear coating film can also be cured by being individually heated. Step (4) is not needed in such cases.

[0029] In the present invention, heating (baking) can be effected by known means; for example, a drying furnace such as an air-heating furnace, electrical furnace, or infrared induction heating furnace can be used. The baking temperature is not particularly limited, but is preferably 70 to 160°C, more preferably 75 to 155°C, and particularly preferably 80241268 WO01 7 BASF Coatings GmbHto 150°C. A baking temperature of 70 to 160°C can ensure that the curing reaction will progress adequately. The heating time is also not particularly limited, but is preferably 10 to 50 minutes, more preferably 15 to 45 minutes, and particularly preferably 20 to 40 minutes.

[0030] Optical features of the multi-layer coating film of the present invention and methods for determining such features are described below with reference to the drawings.

[0031] In the multi-layer coating film of the present invention, the hue angle h(45 / 0) is 205 to 295 degrees, and the chroma C* (45 / 0) value is 30 to 60. Ensuring that the above values are within these ranges will ensure that the multi-layer coating film is visually perceptible as being a vivid blue.

[0032] Here, the hue angle h and chroma C* value are values representing the hue angle and chroma, respectively, in the L*C*h color system. The L*C*h color system is a color system that was devised on the basis of the CIE LAB color system, which was established by the International Commission on Illumination (CIE) in 1976 and has also been adopted in JIS Z 8781-4:2013. The CIE LAB color system represents the chroma and hue of colors as coordinates (a * and b *) in the a*b* plane, whereas in the L*C*h color system, colors are represented in the a*b* plane by a chroma C* value, which is the distance from the point of origin, and a hue angle h, which moves counterclockwise from 0 degree on the a* axis (red).

[0033] The hue angle h(45 / 0) and chroma C* (45 / 0) value used in the present invention, which are determined at an incident angle of 45 degrees and a receiving angle of 0 degrees, can be determined using a colorimeter such as the multi-angle colorimeter BYKmac i (trade name, by BYK-Gardner).

[0034] In the present invention, the incident angle and receiving angle are both determined relative to the normal of the multi-layered coating film, where the receiving angle is positive on the specular reflected light side and is negative on the incident light side, relative to the normal of the multi-layer coating film. In Figure 1, the incident angle of incident light IL relative to the normal n of surface 1a on one side of the multi-layer coating film 1 is 45 degrees, and the specular reflected light RL is indicated by the dashed line. During everyday activities, an observer observes a coating film from various angles, but in the present invention, the hue angle h and chroma C* value are determined using a colorimeter (not shown), where the light receiving angle at 0 degrees241268 WO01 8 BASF Coatings GmbH(specifically, the location of the normal) is defined as the light receiving position P, as shown in Figure 1. The multilayer coating film 1 of the present invention preferably has a hue angle h(45 / 0), as determined in the above manner, of 205 to 295 degrees, and preferably 250 to 290 degrees, and the chroma C* (45 / 0) value should be 30 to 60, and preferably 35 to 50.

[0035] Figure 2 illustrates an outline of color flop, which is a change in hue exhibited by the multi-layer coating film of the invention.

[0036] In Figure 2, incident light IL and specular reflected light RL are indicated by dashed lines relative to the surface 1a on one side of a multi-layer coating film 1.

[0037] In Figure 2, the multi-layer coating film is observed by an observer P1 at a position between the specular reflected light RL and the normal n of the multi-layer coating film, and is observed by an observer P2 at a position between the incident light IL and the normal n of the multi-layer coating film 1. Here, the observation position or observation angle near the specular reflected light, as seen by observer P1, is called the highlight (position) or highlight angle (HL), and the observation position or observation angle that is away from the specular reflected light and is less affected by the glitter material, as seen by observer P2, is called the shade (position) or shade angle (SH). The above expression "near specular reflected light" means that the reception of specular reflected light itself is not an observation condition. This is because the glossiness of the coating film surface precludes the perception of color in specular reflected light.

[0038] In the visual observations depicted in Figure 2, the color produced by the reflection of glitter material included in the coating film, or optically variable color, is perceived as highlights (HL), whereas the color of the color pigment included in the coating film is mainly perceived as shade (SH).

[0039] When the position from which the observer observes the multi-layer coating film of the present invention continuously changes, the hue of the coated object is perceived as continuously changing.

[0040] In the present invention, color flop refers to this change in hue perceived by the observer as the position of the observer, where light lands from a given direction, changes relative to the multi-layer coating film.241268 WO01 9 BASF Coatings GmbH

[0041] In the present invention, this color flop is assessed based on the difference | h(45 / 30)-h(45 / -30) | between the hue angle h(45 / 30), as determined based on the exposure to light at an incident angle of 45 degrees and a receiving angle of 30 degrees, and the hue angle h(45 / -30), as determined based on the exposure to light at an incident angle of 45 degrees and a receiving angle of -30 degrees, relative to the normal n of the multi-layer coating film. In the multi-layer coating film of the present invention, | h (45 / 30)- h (45 / -30)| is 20 to 50 degrees and preferably 20 to 35 degrees.

[0042] The method for determining the above hue angle h(45 / 30) and hue angle h(45 / -30) is described with reference to Figures 3(a) and 3(b).

[0043] In Figures 3(a) and 3(b), the observation of light landing on the multi-layer coating film 1 of the present invention is depicted from a cross-sectional direction of the multilayer coating film 1.

[0044] Figure 3(a) shows a state in which incident light IL lands on the surface 1a on one side of the multi-layer coating film 1, at an incident angle of 45 degrees relative to the normal n of the surface 1a, and specular reflected light RL is reflected in the direction indicated by the dashed line. The light receiving position PL1 corresponds to a receiving angle of 30 degrees, and the reflected light at that position is measured by a colorimeter (not shown). The hue angle h under these measurement conditions is expressed as the hue angle h(45 / 30). Here, the observation position at the receiving angle of 30 degrees (15 degrees in the incident direction relative to the specular reflected light) corresponds to the highlight angle (HL) noted above. The incident and receiving conditions in this case are called highlight conditions.

[0045] In Figure 3(b), the position PL2, where the same incident light IL at an incident angle of 45 degrees as in Figure 3(a) is received, is -30 degrees, and the reflected light at that position is measured by a colorimeter (not shown). -30 degrees indicates a position that has shifted by 30 degrees in the incident light direction relative to the normal n, and the hue angle h under these measurement conditions is referred to as the hue angle h(45 / -30). Here, the observation position at a receiving angle of -30 degrees (75 degrees in the incident light direction relative to the specular reflected light) corresponds to the shade angle (SH) noted above. The incident and receiving conditions in this case are called shade conditions.

[0046] The above color flop-based change in hue will turn out well when the difference | h(45 / 30)-h(45 / -30)| between the hue angle h(45 / -30) under the highlight conditions241268 WO01 10 BASF Coatings GmbH(Figure 3(a)) and the hue angle h(45 / -30) under the shade conditions (Figure 3(b)) determined in this manner is in the range of 20 to 50 degrees.

[0047] The above hue angles h(45 / 30) and h(45 / -30) can be determined using a colorimeter such as the multi-angle colorimeter BYKmac i (trade name, by BYK-Gardner).

[0048] An outline of the change in hue, which is an optical property of the multi-layer coating film of the present invention, is described with reference to Figures 4(a) and 4(b).

[0049] In Figures 4(a) and 4(b), the incident light IL landing on surface 1a on one side of the multi-layer coating film 1 is indicated by a dashed line, but the incident light IL lands at different angles on surface 1a on one side of the multi-layer coating film 1 in Figures 4(a) and 4(b). The incident angle is smaller in Figure 4(a) and is greater in Figure 4(b).

[0050] Observation or measurement based on face angle refers to instances in which the incident angle is up to about 25 degrees greater than 0 degrees relative to the normal of the multi-layer coating film 1, and the receiving angle is near specular reflected light, as exemplified here in Figure 4(a), for example. Observation or measurement based on grazing angle refers to instances in which the incident angle is in the range from about 65 degrees to less than 90 degrees relative to the normal of the multi-layer coating film 1, and the receiving angle is near specular reflected light, as exemplified in Figure 4(b), for example. The expression "near specular reflected light" means, as noted above, that the reception of specular reflected light itself is not an observation condition. This is because the glossiness of the coating film surface precludes the perception of color in specular reflected light.

[0051] In both Figures 4(a) and 4(b), the observer P3 is near specular reflected light, and is engaged in observation at the position of the highlight angle (HL) described via Figure 2.

[0052] When the incident light angle changes, the hue of the multi-layer coating film of the present invention changes from the hue perceived at the face angle to the hue perceived at the grazing angle as a result of the color produced by the reflection of glitter material included in the coating film, or optically variable color. For example, a greenish-tinged blue (blue green) color, for example, is perceived at the face angle, and a reddish-tinged blue (purple) color, for example, is perceived at the grazing angle. Conversely, a reddish-tinged blue (purple) color, for example, may be perceived at the face angle, and a greenish-tinged blue (blue green) color, for example, may be perceived at the grazing241268 WO01 11 BASF Coatings GmbHangle. When the incident light angle changes continuously, the hue perceived by the observer also changes continuously, thus providing a unique design associated with changes in the hue of a coated object.

[0053] This change in the hue of the multi-layer coating film that is perceived by the observer in the highlight angle (HL) position as the incident angle of light falling on the multi-layer coating film changes is referred to as color shift in the present invention.

[0054] In the present invention, this color shift is assessed based on the difference | h(10 / 0)-h(70 / 60) | between the hue angle h(10 / 0), as determined based on the exposure to light at an incident angle of 10 degrees and a receiving angle of 0 degrees, and the hue angle h(70 / 60), as determined based on the exposure to light at an incident angle of 70 degrees and a receiving angle of 60 degrees. In the multi-layer coating film of the present invention, the |h(10 / 0)-h(70 / 60)| is 5 to 55 degrees, and is preferably 5 to 45 degrees.

[0055] The method for determining the above hue angle h(10 / 0) and hue angle h(70 / 60) is described with reference to Figures 5(a) and 5(b).

[0056] In Figures 5(a) and 5(b), the observation of light landing on the multi-layer coating film 1 of the present invention is depicted from a cross-sectional direction of the multilayer coating film 1.

[0057] Figure 5(a) shows a state in which incident light IL lands on the surface 1a on one side of the multi-layer coating film 1, at an incident angle of 10 degrees relative to the normal n of the surface 1a, and specular reflected light RL is reflected in the direction indicated by the dashed line. The light receiving position PL3 corresponds to the normal, specifically, a receiving angle of 0 degrees, and the reflected light at that position is measured by a colorimeter (not shown). The hue angle h under these measurement conditions is expressed as the hue angle h(10 / 0). The measurement conditions here correspond to the face angle noted above.

[0058] Figure 5(b) furthermore shows a state in which incident light IL lands at an incident angle of 70 degrees relative to the normal n on the surface 1a on one side of the multilayer coating film 1, and specular reflected light RL is reflected in the direction indicated by the dashed line. The light receiving position PL4 is a receiving angle of 60 degrees, and the reflected light at that position is measured by a colorimeter (not shown). The hue241268 WO01 12 BASF Coatings GmbHangle h under these measurement conditions is expressed as the hue angle h(70 / 60). The measurement conditions here correspond to the grazing angle noted above.

[0059] The above color shift-based change in hue will turn out well when the difference | h(10 / 0)-h(70 / -60)| between the hue angle h(10 / 0) under the face angle conditions and the hue angle h(70 / 60) under the grazing angle conditions determined in this manner is in the range of 5 to 45 degrees.

[0060] The above hue angles h(10 / 0) and h(70 / 60) can be measured using a colorimeter such as the variable angle Gonio-Spectrophotometric Color Measurement System GSP-2 (trade name, by Murakami Color Research Laboratory Co., Ltd.).

[0061] The hue angles h(45 / 0), h(45 / 30), h(45 / -30), h(10 / 0), and h(70 / 60), as well as the chroma C*(45 / 0) value can be adjusted to the desired values by adjusting, as appropriate, the types or amounts of the first coating film-forming resin, aluminum flake pigment, blue pigment, optically variable pigment, and thickener included in the first colored coating film, or of the second film-forming resin, blue pigment, optically variable pigment, and thickener included in the second colored coating film.

[0062] The multi-layer coating film of the present invention is described in detail below.[Object to be Coated]

[0063] The multi-layer coating film of the present invention can be formed on objects that are to be coated. Examples of coated objects on which the multi-layer coating composition of the present invention can be formed include, but are not particularly limited to, members consisting of metals such as iron, zinc, aluminum, and magnesium, members consisting of alloys of these metals, members upon which these metals have been plated or vapor-deposited, and members consisting of, for example, glass, plastic, and foamed articles of various materials. The coated objects used in the present invention are in particular preferably steel and plastic materials used to form automobile bodies. These members can be treated by, for example, degreasing treatments or surface treatments, as needed and appropriate.

[0064] Members on which an undercoat film has been formed can also be used as objects to be coated in the present invention. Undercoat films are applied in order to cover up the member surface or to make the member corrosion resistant, rust resistant, adhesive, or electrically conductive, for example, and can be formed by applying and curing or drying an undercoat coating. The undercoat coating is not particularly limited, and those that are241268 WO01 13 BASF Coatings GmbHwell known, such as electrostatic coatings, solvent-based primers, and water-based primers, can be used.

[0065] Members on which an intermediate coating film has been formed on the above undercoat film can also be used as objects to be coated in the present invention.Intermediate coating films are applied in order to ensure smoothness or resistance to chipping, for example, and can be formed by applying and curing or drying an intermediate coating. The intermediate coating is not particularly limited, and those that are well known, such as solvent-based or water-based intermediate coatings, can be used.[First colored coating film]

[0066] The first colored coating film used in the multi-layer coating film of the present invention is formed by a first colored coating composition comprising a first coating filmforming resin and an aluminum flake pigment.

[0067] The first colored coating composition of the present invention may be a thermosetting resin composition that contains, as the first coating film-forming resin, a thermosetting resin that is applied and then heated to form a coating film as a cross linking reaction progresses, and may be a thermoplastic resin composition that contains a thermoplastic resin as the first coating film-forming resin, where the solvent is volatilized off to form a coating film. The first coating film-forming resin can be used by being dissolved or dispersed in a solvent such as an organic solvent and / or water.

[0068] A thermosetting resin composition that contains a substrate resin and a curing agent, for example, can be used as the first coating film-forming resin in the first colored coating composition of the present invention. The curing agent solids content in the thermosetting resin composition (substrate resin + curing agent) is not particularly limited, but is preferably 0.1 to 50 parts by mass, more preferably 5 to 45 parts by mass, and particularly preferably 10 to 40 parts by mass, per 100 parts by mass total of the solids of the first coating film-forming resin. The first colored coating composition of the present invention, when it is a thermosetting resin composition, may be a one-component coating composition in which the substrate resin is mixed in advance with the curing agent, or may be a two-component coating composition in which the substrate resin is mixed with the curing agent immediately before coating.

[0069] Examples of substrate resins for the thermosetting resin composition in the first colored coating composition of the present invention include (meth)acrylic resins,241268 WO01 14 BASF Coatings GmbHpolyester resins, polyurethane resins, polyurea resins, (meth)acrylic urethane resins, polyurethane polyurea resins, polyolefin resins (including chlorinated and / or modified forms thereof), and epoxy resins, and in particular (meth)acrylic resins, polyester resins, polyurethane resins, and (meth)acrylic urethane resins. The substrate resin may furthermore be a partially cross linked particulate resin, or core / shell type resin particles in which the particles consist of an inside (core portion) and an outside (shell portion). Examples of particulate substrate resins include (meth)acrylic resin particles, polyurethane resin particles, polyurethane-polyurea resin particles, (meth)acrylic urethane resin particles, as well as core / shell type resins thereof. When a partially crosslinked particulate resin is used as the substrate resin, the crosslinked portion will be insoluble in organic solvents (gel component), and the degree of crosslinking can therefore be assessed by determining the gel fraction, which is a value indicating the proportion of the gel components of the substrate resin particle solids.

[0070] The first colored coating composition will in particular preferably include, as the substrate resin of the thermosetting resin composition, (meth)acrylic urethane resin particles, and the (meth)acrylic urethane resin particles will more preferably include a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups, and a compound having two or more hydrazide groups per molecule. When the first colored coating composition includes a thickener, particularly an inorganic thickener, in addition to the (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups as well as a compound having two or more hydrazide groups per molecule, the coating will have a greater viscosity as a result of the interaction between the components. More specifically, when the first colored coating composition is formulated with the above materials, the viscosity of the first colored coating composition will increase at a low shear rate, and the orientation of the aluminum flake pigment and / or the optically variable pigment will be disrupted less between the time that the first colored coating composition is applied onto the object to be coated and the time that it is thermally cured. This will thus result in better orientation of the aluminum flake pigment and / or the optically variable pigment in the resulting coating film. It will thus be possible to obtain a multi-layer coating film having both color flop (where the incident angle of the light is fixed, and the light receiving angle changes from the highlight region to the shade region) as well as color shift (where the incident angle of light changes from a face angle to a grazing angle in the observation conditions).

[0071] The method for producing (meth)acrylic urethane resins having aldehyde groups and / or ketone groups in the present invention is not particularly limited, and the usual methods noted in the known literature, for example, can be used. Examples include241268 WO01 15 BASF Coatings GmbHmethods in which (1) a urethane resin having radical polymerizable unsaturated bonds is produced, in the presence of which (2) a monomer having radical polymerizable unsaturated bonds and aldehyde groups and / or ketone groups, and (3) if necessary, other monomers having radical polymerizable unsaturated bonds is or are subjected to radical polymerization.

[0072] Examples of (2) monomers having radical polymerizable unsaturated bonds and aldehyde groups and / or ketone groups in the present invention include methyl vinyl ketone, (meth)acrolein, crotonaldehyde, and diacetone (meth)acrylamide.

[0073] Examples of (3) other monomers having radically polymerizable monomers include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and styrene.

[0074] When a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups is produced by a method in which (1) a urethane resin having radical polymerizable unsaturated bonds is produced, in the presence of which (2) a monomer having radical polymerizable unsaturated bonds and aldehyde groups and / or ketone groups, and (3) if necessary, other monomers having radical polymerizable unsaturated bonds is or are subjected to radical polymerization, the (1) urethane resin having radical polymerizable unsaturated bonds (solids) is preferably blended in an amount of 45 to 95 parts by mass, more preferably 55 to 90 parts by mass, and particularly preferably 65 to 85 parts by mass, as reaction components, per 100 parts by mass (solids) of the (meth)acrylic urethane resin having aldehyde groups and / or ketone groups that is produced.

[0075] During the production noted above, the (2) monomer component having radical polymerizable unsaturated bonds and aldehyde groups and / or ketone groups is preferably blended in an amount of 1 to 20 parts by mass, more preferably 1.5 to 15 parts by mass, and particularly preferably 2 to 10 parts by mass, per 100 parts by mass (solids) of the (meth)acrylic urethane resin having aldehyde groups and / or ketone groups that is produced.

[0076] In the present invention, examples of compounds having two or more hydrazide groups per molecule include bishydrazides of C2-12 dicarboxylic acids, such as bishydrazides of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid,241268 WO01 16 BASF Coatings GmbHpimelic acid, suberic acid, azelaic acid, sebacic acid, and phthalic acid isomers.Examples of polyfunctional hydrazides include hydrazides of nitrilotriacetic acid or ethylenediaminetetraacetic acid, for example.

[0077] The proportions in which the (meth)acrylic urethane resin having aldehyde groups and / or ketone groups is mixed in the (meth)acrylic urethane resin particles in the present invention are not particularly limited, but the molar ratio of (aldehyde groups+ketone groups):(hydrazide groups) is preferably 2:1 to 1:2, more preferably 1.5:1 to 1:1.5, and particularly preferably 1.2:1 to 1:1.2.

[0078] The substrate resin of the thermosetting resin composition used in the first colored coating composition of the present invention has one or more reactive functional groups for reacting with the curing agent. Examples of preferred reactive functional groups include hydroxyl groups and carboxyl groups. These substrate resins may be used alone or in combinations of two or more.

[0079] Examples of curing agents for the thermosetting resin composition in the first colored coating composition of the present invention include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, and polycarbodiimide compounds. Of these, polyisocyanate compounds and blocked polyisocyanate compounds are especially preferable. These curing agents may be used alone or in combinations of two or more.

[0080] In the present invention, amino resins are a generic term for resins obtained via the addition and condensation of formaldehyde with amino group-containing compounds. Examples of amino resins include melamine resins, urea resins, and guanamine resins, among which melamine resins are preferred.

[0081] Examples of melamine resins in the present invention include: partially or fully methylolated melamine resins obtained by reacting melamine with formaldehyde; partially or fully alkyl-etherified melamine resins obtained by partially or fully etherifying the methylol groups in a methylolated melamine resin with an alcohol component; imino group-containing melamine resins; and mixtures of two or more of said melamine resins. Further examples of alkyl-etherified melamine resins include methylated melamine resins, butylated melamine resins, and methyl / butyl mixed alkyl-etherified melamine resins.241268 WO01 17 BASF Coatings GmbH

[0082] Examples of polyisocyanate compounds in the present invention include: chain diisocyanates such as hexamethylene diisocyanate (HDI) and trimethyl hexamethylene diisocyanate; aromatic diisocyanates such as xylylene diisocyanate (XDI), tolylene diisocyanate (TDI), and 4,4-diphenylmethane diisocyanate (MDI); alicyclic diisocyanates such as isophorone diisocyanate, hydrogenated XDI, hydrogenated TDI, hydrogenated MDI, and diisocyanate dimers; as well as compounds consisting of uretdiones, allophanates, adducts, biurets, isocyanurates, and iminooxadiazinediones of the above, or other diisocyanate dimers, trimers, or higher diisocyanates. Aliphatic triisocyanate compounds such as 2-isocyanatoethyl-2,6-diisocyanatocaproate (LTI) and 1,8-diisocyanato-4-isocyanatomethyloctane may also be used. Furthermore, some of these isocyanate groups may be modified with amino group-containing silane coupling agents, for example.

[0083] Examples of blocked polyisocyanate compounds in the present invention include polyisocyanate compounds in which the isocyanate groups in the above-mentioned polyisocyanate compounds are blocked by alcohols such as butanol, oximes such as methyl ethyl ketoxime, lactams such as e-caprolactam, active methylenes such as malonic diesters and acetoacetic esters, pyrazoles such as 3,5-dimethylpyrazole, imidazoles such as imidazole and 2-ethylimidazole, and phenols such as m-cresol.

[0084] In the present invention, the polycarbodiimide compounds are preferably hydrophilic carbodiimide compounds. Hydrophilic carbodiimide compounds may be obtained, for example, when a polycarbodiimide compound having at least two isocyanate groups per molecule is reacted with a polyol having terminal hydroxyl groups, so as to result in an NCO / OH molar ratio greater than 1, and the resulting reaction product is reacted with a hydrophilizing agent having active hydrogen and a hydrophilic moiety.

[0085] Examples of thermoplastic resin compositions for the first colored coating composition of the present invention include thermoplastic resins having a molecular weight of 30,000 or more, such as acrylic resins, polyester resins, alkyd resins, urethane resins, polyolefin resins (including chlorinated and / or modified), and epoxy resins..

[0086] The aluminum flake pigment included in the first colored coating composition of the present invention is a flaked aluminum pigment having a metallic luster, that is produced by the wet ball mill method, for example. When the first colored coating composition is a water-based coating composition, the aluminum flake pigment is preferably treated to avoid reaction with water, and the surface is in particular preferably241268 WO01 18 BASF Coatings GmbHtreated with silica. Specific examples of aluminum flake pigments that have been surface treated with silica include the "EMERAL" Series (trade name, by Toyo Aluminum K.K.) and the "HYDROLAN" Series (trade name, by ECKART GmbH).

[0087] The aluminum flake pigment of the present invention can include colored aluminum flake pigments. Examples of colored aluminum flake pigments include aluminum flake pigment having a colored pigment chemically adsorbed on the surface and furthermore having a resin layer formed thereon, for example. Examples of color pigments used in colored aluminum flake pigments include white pigments, red pigments, orange pigments, yellow pigments, green pigments, blue pigments, purple pigments, and black pigments, and more specific examples include: inorganic pigments such as titanium oxide, iron oxide, and composite oxide pigments such as cobalt blue and titanium yellow; organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, azo metal chelate pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, threne pigments and indigo pigments; and carbon black. Of these, phthalocyanine-based or threne-based blue pigments are preferred as the color pigment used in the colored aluminum flake pigment in the present invention. A specific example of a preferred colored aluminum flake pigment is Friend Color EMR-D946BA (trade name, by Toyo Aluminum K.K.).

[0088] The aluminum flake pigment of the present invention can include vacuum metallized pigments. Vacuum metallized pigments are obtained via vapor deposition of an aluminum film on a base substrate, after which the base substrate is stripped off, and the deposited aluminum film is then broken down. Specific examples of vacuum metallized aluminum flake pigments include the "EMERAL SHINE" Series (trade name, by Toyo Aluminum K.K.) and the "HYDROSHINE" Series (trade name, by ECKART GmbH).

[0089] The average particle size (D50) of the aluminum flake pigment of the present invention is preferably 8 to 30 pm, more preferably 10 to 25 pm, and in particular preferably 12 to 20 pm.

[0090] As used in the present invention, the average particle size D50 is the particle size of 50% of the total volume of particles, from the smallest particle size to a given particle size, expressed as a percentage of the volume of all particles, in a cumulative particle size distribution determined by laser diffraction / scattering (static light scattering).Examples of devices for measuring particle size distribution by laser diffraction / scattering (static light scattering) include the Partica LA-960V2 series (trade name, manufactured241268 WO01 19 BASF Coatings GmbHby Horiba, Ltd.), SALD-2300 (trade name, manufactured by Shimadzu Corporation), and the MT3000II series (trade name, manufactured by MicrotracBel Corp.).

[0091] The content of the aluminum flake pigment in the first colored coating composition of the present invention is preferably 2.5 to 25 parts by mass, more preferably 3 to 20 parts by mass, and particularly preferably 3.5 to 15 parts by mass, per 100 parts by mass of the resin solids of the first coating film-forming resin included in the first colored coating composition. Ensuring that the content of the aluminum flake pigment is 2.5 to 25 parts by mass will make it possible to obtain a multi-layer coating film in which the blue hue changes significantly when the angle of incident light is fixed and the observation angle changes from the shade region to the highlight region. These aluminum flake pigments may be used alone or in combinations of two or more.

[0092] In the present invention, at least either one of the first color coating composition and the second color coating composition comprises an optically variable pigment.Optically variable pigments are pigments in which the surface of a transparent or semitransparent scaly substrate (of any of a variety of metal oxides) has been coated with a metal oxide having a refractive index that is different from that of the substrate; specific examples can include metal oxide-coated mica pigments, metal oxide-coated alumina flake pigments, metal oxide-coated glass flake pigments, and metal oxide-coated silica flake pigments. Of these, blue-colored metal oxide-coated mica pigments, blue-colored metal oxide-coated alumina flake pigments, and metal oxide-coated silica flake pigments are preferably used in the present invention. Specific examples of preferred optically variable pigments include blue-colored metal oxide-coated mica pigments such as IRIODIN 221 WNT, IRIODIN 225 WNT, IRIODIN 7225 WNT, PYRISMA T40-23 SW Blue, and PYRISMA T40-27 SW Indigo (trade names, by MERCK); blue-colored metal oxide coated alumina flake pigments such as XIRALLIC T60-23 WNT, Galaxy Blue, and XIRALLIC NXT T260-23 WNT, Tigris Blue (trade names, by MERCK); and metal oxidecoated silica flake pigments such as COLORSTREAM T20-01 WNT, Viola Fantasy, COLORSTREAM T20-02 WNT, Arctic Fire, COLORSTREAM T20-03 WNT, Tropic Sunrise, and COLORSTREAM T20-04 WNT, Lapis Sunlight (trade names, by MERCK).

[0093] The average particle size (D50) of the optically variable pigment of the present invention is preferably 6 to 25 pm, more preferably 8 to 22 pm, and particularly preferably 10 to 20 pm.

[0094] The content of the optically variable pigment in the colored coating composition of the present invention is preferably 2.5 to 20 parts by mass, more preferably 3.5 to 16241268 WO01 20 BASF Coatings GmbHparts by mass, and particularly preferably 4.5 to 14 parts by mass, per 100 parts by mass of the resin solids of the first coating film-forming resin or second coating film-forming resin included in the first colored coating composition or second colored coating composition. Ensuring that the content of the optically variable pigment is 2.5 to 20 parts by mass will make it possible to obtain a multi-layer coating film in which the hue changes when the incident angle of light changes from a face angle to a grazing angle in the observation conditions. These optically variable pigments may be used alone or in combinations of two or more.

[0095] The first colored coating composition may furthermore comprise a color pigment other than the aluminum flake pigment or optically variable pigment. Examples of color pigments that may be used in the first colored coating composition include white pigments, red pigments, orange pigments, yellow pigments, green pigments, blue pigments, purple pigments, and black pigments, and more specific examples include: inorganic pigments such as titanium oxide, iron oxide, and composite oxide pigments such as cobalt blue and titanium yellow; organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, azo metal chelate pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, threne pigments and indigo pigments; and carbon black. Of these, phthalocyanine-based or threne-based blue pigments are preferred as the color pigment used in the first colored coating composition of the present invention. These color pigments may be used alone or in combinations of two or more.

[0096] The first colored coating composition of the present invention preferably contains a thickener. Known thickeners can be used, examples of which include inorganic thickeners such as silica-based fine powders, mineral-based thickeners and barium sulfate atomized powders, and organic thickeners such as polyamide-based thickeners, micro-particulate organic resin thickeners, diurea-based thickeners, urethane associative thickeners, acrylic swellable polyacrylic acid-based thickeners, and cellulose-based thickeners.

[0097] Examples of mineral-based thickening agents include swellable lamellar silicates having a 2:1 type crystal structure, and more specifically, smectite group clay minerals such as natural or synthetic montmorillonite, saponite, hectorite, stevensite, beidellite, nontronite and bentonite.

[0098] The first colored coating composition of the present invention preferably contains an inorganic thickener, and in particular preferably a mineral-based thickener. When the241268 WO01 21 BASF Coatings GmbHcoating includes (meth)acrylic urethane resin particles, and in particular (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups as well as a compound having two or more hydrazide groups per molecule, the coating will have a greater viscosity as a result of the interaction with the inorganic thickener. In particular, the viscosity of the first colored coating composition will increase at a low shear rate, in the same manner as noted above, resulting in better orientation of the aluminum flake pigment and / or optically variable pigment. It will thus be possible to obtain a multi-layer coated film in which the blue hue changes significantly when the angle of incident light is fixed and the receiving angle changes from the highlight region to the shade region, and in which the hue furthermore changes when the incident angle of light changes from a face angle to a grazing angle in the observation conditions. Thickeners may be used alone or in combinations of two or more.

[0099] The following can furthermore be optionally blended, as needed, in the first colored coating composition of the present invention: solvents such as organic solvents and / or water; a variety of additives used in coatings, such as pigment dispersants, antisettling agents, curing catalysts, defoamers, antioxidants, and UV absorbers; and extender pigments. Examples of organic solvents include those routinely used to produce coating compositions, such as: aromatic hydrocarbons such as toluene, xylene, and aromatic naphtha; ketones such as acetone, methyl ethyl ketone, and methyl amyl ketone; esters such as ethyl acetate, butyl acetate, 2-butoxyethyl acetate, pentyl acetate, and ethyl ethoxy propionate; alcohols such as isopropanol, butanol, 2-butoxyethanol, and 2-ethylhexanol; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons; or mixtures thereof. In cases where polyisocyanate compounds (including ones that are blocked) are used as curing agents, the use of organic solvent alcohols or water should be avoided in order to ensure a smoother curing reaction.

[0100] The content of non-volatile components (first coating film-forming resin solids + aluminum flake pigment + other pigments + coating additive solids) that are used when the first colored coating composition of the present invention is applied is not particularly limited, but is preferably 10 to 60% by mass, more preferably 12 to 50% by mass, and particularly preferably 14 to 40% by mass.

[0101] The first colored coating composition of the present invention can be applied by methods such as electrostatic coating, air spraying, and airless spraying. The dry thickness of the first colored coating film is not particularly limited, but is preferably 3 to 30 pm, more preferably 4 to 25 pm, an in particular preferably 5 to 20 pm.241268 WO01 22 BASF Coatings GmbH[Second colored coating film]

[0102] The second colored coating film used in the multi-layer coating film of the present invention is formed by a second colored coating composition comprising a second coating film-forming resin and a blue pigment.

[0103] The second colored coating composition of the present invention may be a thermosetting resin composition that contains, as the second coating film-forming resin, a thermosetting resin that is applied and then heated to form a coating film as a crosslinking reaction progresses, and may be a thermoplastic resin composition that contains a thermoplastic resin as the second coating film-forming resin, where the solvent is volatilized off to form a coating film. The second coating film-forming resin can be used by being dissolved or dispersed in a solvent such as an organic solvent and / or water.

[0104] A thermosetting resin composition that contains a substrate resin and a curing agent, for example, can be used as the second coating film-forming resin in the second colored coating composition of the present invention. The curing agent solids content in the thermosetting resin composition (substrate resin + curing agent) is not particularly limited, but is preferably 0.1 to 50 parts by mass, more preferably 5 to 45 parts by mass, and particularly preferably 10 to 40 parts by mass, per 100 parts by mass total of the solids of the second coating film-forming resin. The second colored coating composition of the present invention, when it is a thermosetting resin composition, may be a one-component coating composition in which the substrate resin is mixed in advance with the curing agent, or may be a two-component coating composition in which the substrate resin is mixed with the curing agent immediately before coating.

[0105] Examples of the substrate resin of the thermosetting resin composition in the second colored coating composition of the present invention include the same resins given as examples of the substrate resin for the thermosetting resin in the first colored coating composition.

[0106] The second colored coating composition of the present invention may furthermore comprise an aluminum flake pigment and / or optically variable pigment. When the second colored coating composition of the present invention contains an aluminum flake pigment and / or an optically variable pigment, the second colored coating composition will in particular preferably include (meth)acrylic urethane resin particles, and will more preferably contain (meth)acrylic urethane resin particles that contain a (meth)acrylic241268 WO01 23 BASF Coatings GmbHurethane resin having aldehyde groups and / or ketone groups, as well as a compound having two or more hydrazide groups per molecule, in the same manner as the first colored coating composition. When the coating includes an inorganic thickener in addition to (meth)acrylic urethane resin particles, and in particular (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups as well as a compound having two or more hydrazide groups per molecule, the coating will have a greater viscosity as a result of the interaction between the components. In particular, the viscosity of the second colored coating composition will increase at a low shear rate, in the same manner as noted above in regard to the first colored coating composition, resulting in better orientation of the aluminum flake pigment and / or optically variable pigment. This will allow a multi-layer coating film that has both color flop and color shift properties to be obtained.

[0107] The substrate resin of the thermosetting resin composition used in the second colored coating composition of the present invention has one or more reactive functional groups for reacting with the curing agent. Examples of preferred reactive functional groups include hydroxyl groups, carboxyl groups, and epoxy groups. When the first colored coating composition and second colored coating composition of the present invention include thermosetting resins, the substrate resin of the second colored coating composition may be the same as or different from that used in the first colored coating composition. The substrate resin may be used alone or in combinations of two or more.

[0108] Examples of curing agents for the thermosetting resin composition in the second colored coating composition of the present invention are the same ones given as examples of curing agents for the thermosetting resin in the first colored coating composition. When the first colored coating composition and second colored coating composition of the present invention include thermosetting resins, the curing agent for the second colored coating composition may be the same as or different from that used in the first colored coating composition. The curing agent may be used alone or in combinations of two or more.

[0109] Examples of thermoplastic resins for the second colored coating composition of the present invention are the same ones given as examples of thermoplastic resins for the first colored coating composition. When the first colored coating composition and second colored coating composition of the present invention include thermoplastic resins, the thermoplastic resin of the second colored coating composition may be the same as or different from that used in the first colored coating composition.241268 WO01 24 BASF Coatings GmbH

[0110] The second colored coating composition of the present invention comprises a blue pigment. Forming a blue pigment-containing second colored coating film on the aluminum flake pigment-containing first colored coating film will allow a high-chroma blue multilayer coating film to be obtained. The blue pigment in the second coloring coating composition of the present invention is not particularly limited, provided that it is blue; examples include phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, threne pigments, and indigo-based blue pigments, among which phthalocyanine-based or threne-based blue pigments are preferred. Blue pigments may be used alone or in combinations of two or more.

[0111] The blue pigment content in the second colored coating composition of the present invention is preferably 0.02 to 15 parts by mass, more preferably 0.03 to 12 parts by mass, and particularly preferably 0.04 to 10 parts by mass, per 100 parts by mass of the total second coating film-forming resin solids included in the second colored coating composition.

[0112] When the second colored coating composition contains a colored aluminum flake pigment involving the use of a blue pigment, the content of the blue pigment used in the colored aluminum flake pigment is not included in the content of the blue pigment in the second colored coating composition.

[0113] In the present invention, as noted above, at least either one of the first colored coating composition and the second colored coating composition comprises an optically variable pigment. Examples of preferred optically variable pigments, the average particle size (D50) of the optically variable pigments, and the content of the optically variable pigments in the colored coating composition are also as described above. When the first colored coating composition and second colored coating composition both include optically variable pigments, the optically variable pigment of the second colored coating composition may be the same as or different from that used in the first colored coating composition. The optically variable pigments may be used alone or in combinations of two or more.

[0114] The second colored coating composition of the present invention may comprise an aluminum flake pigment. Examples of preferred aluminum flake pigments, the average particle size (D50) of the aluminum flake pigments, and the content of the aluminum pigments in the colored coating composition are also as described above. When the second colored coating composition includes an aluminum flake pigment, the aluminum flake pigment may be the same as or different from that used in the first colored coating241268 WO01 25 BASF Coatings GmbHcomposition. The aluminum flake pigments may be used alone or in combinations of two or more.

[0115] The second colored coating composition of the present invention may comprise another color pigment other than the blue pigment, optically variable pigment, or aluminum flake pigment. Examples of color pigments that may be used in the second colored coating composition include white pigments, red pigments, orange pigments, yellow pigments, green pigments, purple pigments, and black pigments, and more specific examples include: inorganic pigments such as titanium oxide, iron oxide, and composite oxide pigments such as cobalt blue and titanium yellow; organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, azo metal chelate pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, threne pigments and indigo pigments; and carbon black. These color pigments may be used alone or in combinations of two or more.

[0116] When the second colored coating composition of the present invention includes an aluminum flake pigment and / or an optically variable pigment, the second colored coating composition preferably contains a thickener in the same manner as the first colored coating composition. Examples of thickeners for the second colored coating composition of the present invention are the same ones given as examples of thickeners for the first colored coating composition.

[0117] The second colored coating composition of the present invention preferably contains an inorganic thickener, and particularly preferably a mineral-based thickener, in the same manner as the first colored coating composition. When the coating includes (meth)acrylic urethane resin particles, and in particular (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups as well as a compound having two or more hydrazide groups per molecule, the coating will have a greater viscosity as a result of the interaction with the inorganic thickener. In particular, the viscosity of the second colored coating composition will increase at a low shear rate, in the same manner as noted above in regard to the first colored coating composition, resulting in better orientation of the aluminum flake pigment and / or optically variable pigment. Improving the orientation of the aluminum flake pigment and / or optically variable pigment will allow a multi-layer coating film that has both color flop and color shift properties to be obtained. The thickener used in the second colored241268 WO01 26 BASF Coatings GmbHcoating composition may be the same as or different from that used in the first colored coating composition. Thickeners may be used alone or in combinations of two or more.

[0118] The following can furthermore be optionally blended, as needed, in the second colored coating composition of the present invention: solvents such as organic solvents and / or water; a variety of additives used in coatings, such as pigment dispersants, antisettling agents, curing catalysts, defoamers, antioxidants, and UV absorbers; and extender pigments. Examples of organic solvents include those routinely used to produce coating compositions, such as: aromatic hydrocarbons such as toluene, xylene, and aromatic naphtha; ketones such as acetone, methyl ethyl ketone, and methyl amyl ketone; esters such as ethyl acetate, butyl acetate, 2-butoxyethyl acetate, pentyl acetate, and ethyl ethoxy propionate; alcohols such as isopropanol, butanol, 2-butoxyethanol, and 2-ethylhexanol; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons; or mixtures thereof. In cases where polyisocyanate compounds (including ones that are blocked) are used as curing agents, the use of organic solvent alcohols or water should be avoided in order to ensure a smoother curing reaction.

[0119] The content of non-volatile components (second coating film-forming resin solids + blue pigment + other pigments + coating additive solids) that are used when the second colored coating composition of the present invention is applied is not particularly limited, but is preferably 10 to 60% by mass, more preferably 12 to 50% by mass, and particularly preferably 14 to 40% by mass.

[0120] The second colored coating composition of the present invention can be applied by methods such as electrostatic coating, air spraying, and airless spraying.

[0121] The dry thickness of the second colored coating film is not particularly limited, but is preferably 3 to 60 pm, more preferably 4 to 55 pm, an in particular preferably 5 to 50 pm.[Clear coating film]

[0122] The multi-layer coating film of the present invention may furthermore have a clear coating film on the second colored coating film. The clear coating film used in the present invention is formed by a clear coating composition comprising a coating film-forming resin (referred to as a clear coating film-forming resin).

[0123] The clear coating film-forming resin in the clear coating composition of the present invention may be a thermosetting resin composition that is applied and then heated to241268 WO01 27 BASF Coatings GmbHform a coating film as a cross linking reaction progresses. The clear coating film-forming resin can be used by being dissolved or dispersed in a solvent such as an organic solvent and / or water.

[0124] A thermosetting resin composition that contains a substrate resin and a curing agent, for example, can be used as the thermosetting resin composition for the clear coating composition of the present invention. The curing agent solids content in the thermosetting resin composition (substrate resin + curing agent) is not particularly limited, but is preferably 0.1 to 50 parts by mass, more preferably 5 to 45 parts by mass, and particularly preferably 10 to 40 parts by mass, per 100 parts by mass total of the solids of the clear coating film-forming resin. The clear coating composition of the present invention may be a one-component coating composition in which the substrate resin is mixed in advance with the curing agent, or may be a two-component coating composition in which the substrate resin is mixed with the curing agent immediately before coating.

[0125] Examples of the substrate resin for the clear coating composition of the present invention include (meth)acrylic resins, polyester resins, polyurethane resins, and (meth)acrylic urethane resins. The substrate resin also preferably has at least one functional group selected from the group selected from hydroxyl groups, carboxyl groups, and epoxy groups. These substrate resins may be used alone or in combinations of two or more.

[0126] Examples of curing agents for the clear coating composition of the present invention include amino resins, polyisocyanate compounds, and blocked polyisocyanate compounds.

[0127] Specific examples of amino resin, polyisocyanate compound, and blocked polyisocyanate compound curing agents for the clear coating composition of the present invention can be the same compounds as those given as examples of the curing agent for the thermosetting resin composition in the first colored coating composition. When either the first colored coating composition or second colored coating composition of the present invention is a thermosetting resin, the curing agent for the clear coating composition may be the same as or different from that used in either. These curing agents may be used alone or in combinations of two or more.

[0128] The following can furthermore be optionally blended, as needed, in the clear coating composition of the present invention: solvents such as organic solvents and / or241268 WO01 28 BASF Coatings GmbHwater; a variety of additives used in coatings, such as thickeners, pigment dispersants, anti-settling agents, curing catalysts, defoamers, antioxidants, and UV absorbers; extender pigments; and color pigments in amounts that will not compromise transparency. Examples of organic solvents include those routinely used to produce coating compositions, such as: aromatic hydrocarbons such as toluene, xylene, and aromatic naphtha; ketones such as acetone, methyl ethyl ketone, and methyl amyl ketone; esters such as ethyl acetate, butyl acetate, 2-butoxyethyl acetate, pentyl acetate, and ethyl ethoxy propionate; alcohols such as isopropanol, butanol, 2-butoxyethanol, and 2-ethylhexanol; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons; or mixtures thereof. In cases where polyisocyanate compounds (including ones that are blocked) are used as curing agents, the use of organic solvent alcohols or water should be avoided in order to ensure a smoother curing reaction.

[0129] The content of non-volatile components (clear coating film-forming resin solids + coating additive solids + pigment) that are used when the clear coating composition of the present invention is applied is not particularly limited, but is preferably 30 to 70% by mass, more preferably 35 to 68% by mass, and particularly preferably 40 to 66% by mass.

[0130] The clear coating composition of the present invention can be applied by methods such as electrostatic coating, air spraying, and airless spraying. The dry thickness of the clear coating film is not particularly limited, but it preferably 15 to 60 pm, more preferably 20 to 55 pm, an in particular preferably 25 to 50 pm.

[0131] The multilayer coating film and method for forming a multilayer coating film in the present invention are suitable for bodies, members, and parts of passenger cars, trucks, motorcycles, and buses, for example, and are particularly effective for use in metal automobile bodies and plastic automobile parts. The multi-layer coating and method for forming a multi-layer coating of the present invention are not limited to these technical fields and can be applied to vehicles other than automobiles, or building structures, and the like.[Examples]

[0132] The present invention is explained in greater detail below using examples, but is not limited to these examples. In the examples, "parts" means "parts by mass" and "%" relating to amounts blended or to content means "% by mass,” unless otherwise specified.241268 WO01 29 BASF Coatings GmbHProduction Example 1: Production of polyurethane resin dispersion Pll-1 for waterbased colored coating composition>1-(1) Production of polyester polyol solution PP-1

[0133] Into a flask equipped with a reflux condenser (with a separation tube for reaction water), a thermometer, a stirrer, and a nitrogen gas feed tube were charged 35.0 parts of the dimer acid PRIPOL 1017 (trade name, manufactured by Croda; based on a C36 dicarboxylic acid produced by dimerization of a C18 unsaturated fatty acid), 30.0 parts of isophthalic acid, 0.6 part of adipic acid, 33.6 parts of 1 ,6-hexanediol, and 0.8 part of trimethylolpropane; the raw material contents were dissolved by being heated to 120°C, and were then heated to 160°C while stirred. The contents were maintained at 160°C for 1 hour and were then heated to 230°C over a period of 5 hours. The resin acid value was periodically determined as the contents were maintained at 230°C, and when the resin acid value reached 4 mgKOH / g, the contents were cooled to 80°C. Lastly, 60.8 parts of methyl ethyl ketone were added, giving a polyester polyol solution PP-1. The polyester polyol solution PP-1 was characterized by a mass-average molecular weight of 7,200, an acid value of 4 mgKOH / g, a hydroxyl value of 62 mgKOH / g, and a resin solids content of 60% by mass.1-(2) Production of polyurethane resin dispersion Pll-1

[0134] Into a flask equipped with a thermometer, stirrer, and nitrogen gas feed tube were charged 110.0 parts of the polyester polyol solution PP-1 obtained in Production Example 1-(1), 4.5 parts of dimethylolpropionic acid, 2.0 parts of neopentyl glycol, and 20.3 parts of methyl ethyl ketone, and the contents were heated to 80°C while stirred. When the temperature had reached 80°C, 24.0 parts of isophorone diisocyanate was added, the temperature was maintained at 80°C, and when the isocyanate content reached 0.40 mmol / g, 3.2 parts of trimethylolpropane was added, and the temperature was maintained at 80°C. When the isocyanate content of the solution reached 0.03 mmol / g, 5.2 parts of 2-butoxyethanol was added; after the contents had cooled to 50°C, 3.3 parts of dimethylethanolamine was added to neutralize the acid groups, and 150.0 parts of deionized water was added. The contents were then heated to 100°C, and the methyl ethyl ketone was removed at reduced pressure, giving a polyurethane resin dispersion Pll-1. The polyurethane resin dispersion Pll-1 was characterized by a mass-average molecular weight of 71 ,000, an acid value of 21 mgKOH / g, a hydroxyl value of 21 mgKOH / g, and a resin solids content of 38% by mass.Production Example 2: Production of polyester resin solution PE-1 for water-based241268 WO01 30 BASF Coatings GmbHcolored coating composition>

[0135] Into a flask equipped with a reflux condenser (with a separation tube for reaction water), a thermometer, a stirrer, and a nitrogen gas feed tube were charged 15.0 parts of the above-mentioned dimer acid PRIPOL 1017 (trade name, manufactured by Croda), 30.0 parts of isophthalic anhydride, 3.1 parts of adipic acid, 31.5 parts of 1 ,6-hexanediol, and 10.3 parts of trimethylolpropane; the raw material contents were dissolved by being heated to 120°C, and were then heated to 160°C while stirred. The contents were maintained at 160°C for 1 hour, were then heated to 230°C over a period of 5 hours, were maintained at 230°C for 2 hours, and were then cooled to 180°C. 10 parts of trimellitic anhydride was then added, the acid value was periodically determined as the contents were maintained at 180°C, and when the resin acid value reached 25 mgKOH / g, the contents were cooled to at least 80°C. 25 parts of 2-butoxyethanol was added, 3.2 parts of dimethylethanolamine was added to neutralize the acid groups, and 34.1 parts of deionized water was added, giving a polyester resin solution PE-1. The polyester resin solution PE-1 was characterized by a mass-average molecular weight of 15,000, an acid value of 25 mgKOH / g, a hydroxyl value of 90 mgKOH / g, and a resin solids content of 60% by mass.<Production Example 3: Production of (meth)acrylic urethane resin dispersion All-1 for water-based colored coating composition>3-(1) Production of polyester polyol solution PP-2

[0136] Into a flask equipped with a reflux condenser (with a separation tube for reaction water), a thermometer, a stirrer, and a nitrogen gas feed tube were charged 49.9 parts of adipic acid, 18.5 parts of 1 ,6-hexanediol, and 31.6 parts of neopentyl glycol, and the contents were heated to 160°C while stirred in a nitrogen stream. The contents were maintained at 160°C for 1 hour and were then heated to 230°C over a period of 5 hours. The resin acid value was periodically determined as the contents were maintained at 230°C, and when the resin acid value reached 3.5 mgKOH / g, the contents were cooled to 80°C. Lastly, 21.9 parts of methyl ethyl ketone were added, giving a polyester polyol solution PP-2. The polyester polyol solution PP-2 was characterized by an acid value of 3.5 mgKOH / g, a hydroxyl value of 155 mgKOH / g, and a resin solids content of 80% by mass.3-(2) Production of (meth)acrylic urethane resin dispersion All-1

[0137] Into a flask equipped with dual dropping funnels, a reflux condenser, a thermometer, a stirrer, and a nitrogen gas feed tube were charged 420.0 parts of the polyester polyol solution PP-2 obtained in Production Example 3-(1), 31.0 parts of neopentyl glycol, 27.8 parts of trimethylolpropane monoallyl ether, 0.5 part of dibutyltin241268 WO01 31 BASF Coatings GmbHdilaurate, and 195.7 parts of methyl ethyl ketone, and the contents were stirred to homogeneity in a nitrogen stream.

[0138] 259.9 parts of isophorone diisocyanate were then added to the resulting solution. After the exothermic reaction had subsided, the reaction mixture was gradually heated to 80°C while stirred, and the contents continued to be stirred at that temperature until the isocyanate content of the solution reached 0.60 mmol / g. 66.7 parts of trimethylol propane were then added, and the contents were stirred at 80°C until free isocyanate groups in the solution were no longer detectable. 248.9 parts of methyl ethyl ketone were then added to the resulting polyurethane solution.

[0139] The temperature was then adjusted to 82°C, and a polymerizable monomer mixture consisting of 312.5 parts of n-butyl acrylate, 312.5 parts of methyl methacrylate, 74.7 parts of 2-hydroxypropyl methacrylate, and 58.4 parts of acrylic acid was added dropwise at a constant rate over a period of 3 hours using one of the dropping funnels. A polymerization initiator solution consisting of 22.8 parts of 2,2'-azobis(methylbutyronitrile) and 152.3 parts of methyl ethyl ketone was added dropwise at a constant rate over a period of 3.5 hours using the other dropping device at the same time that the other ingredients were added dropwise using the other dropping funnel.

[0140] After the dropwise addition of the monomer mixture and the polymerization initiator solution had been completed, the reaction mixture obtained was stirred for a further 2.5 hours, and 56.9 parts of dimethylethanolamine and 2242 parts of deionized water were added. The separation tube was then attached to the reflux condenser, and the solvent was removed at reduced pressure and a temperature of 45°C until the resin solids content of the dispersion reached 40% by mass, giving a (meth)acrylic urethane resin aqueous dispersion All-1. The resulting (meth)acrylic urethane resin dispersion liquid AU-1 had a mass average molecular weight of 41,000, an acid value of 32 mgKOH / g, and a hydroxyl value of 57 mgKOH / G.Production Example 4: Production of (meth)acrylic urethane resin particle dispersion AU-2 containing a (meth)acrylic urethane resin having aldehyde groups and / or ketone groups as well as a compound having two or more hydrazide groups per molecule for water-based colored coating composition>4-(1) Production of polyester polyol solution PP-3

[0141] Into a flask equipped with a reflux condenser (with a separation tube for reaction water), a thermometer, a stirrer, and a nitrogen gas feed tube were charged 109.7 parts of adipic acid, 128.5 parts of 1 ,6-hexanediol, and 26.5 parts of isophthalic acid, and the241268 WO01 32 BASF Coatings GmbHcontents were heated to 160°C while stirred in a nitrogen stream. The contents were maintained at 160°C for 1 hour and were then heated to 230°C over a period of 5 hours. The resin acid value was periodically determined as the contents were maintained at 230°C, and when the resin acid value reached 2.0 mgKOH / g, the contents were cooled to 80°C. Lastly, 25.8 parts of N-methyl-2-pyrrolidone were added, giving a polyester polyol solution PP-3. The polyester polyol solution PP-3 was characterized by an acid value of 2.0 mgKOH / g, a hydroxyl value of 88 mgKOH / g, and a resin solids content of 90% by mass.4-(2) Production of (meth)acrylic urethane resin particle dispersion All-2

[0142] Into a flask equipped with a dropping funnel, a reflux condenser, a thermometer, a stirrer, and a nitrogen gas feed tube were charged 257.8 parts of the polyester polyol solution PP-3 obtained in Production Example 4-(1), 23.0 parts of dimethylolpropionic acid, 10.9 parts of 1 ,6-hexanediol, and 82.8 parts of N-methyl-2-pyrrolidone, and the contents were stirred to homogeneity in a nitrogen stream.

[0143] The temperature was then adjusted to 90°C, 73.9 parts of isophorone diisocyanate were added over a period of 30 minutes, and the contents continued to be stirred for another hour at that temperature. 80.0 parts of methyl methacrylate and 0.2 part of 2,6-di-tert-butyl-4-methylphenol were then added to homogeneity. 41.3 parts of isophorone diisocyanate were then added over a period of 10 minutes at 90°C, and the contents were stirred until the isocyanate content of the solution reached 1.11% by mass. 25.3 parts of 2-hydroxyethyl methacrylate were then added, and the contents were stirred at 90°C until free isocyanate groups in the solution were no longer detectable.

[0144] 37.3 parts of methyl methacrylate, 16.0 parts of diacetone acrylamide, and 11.4 parts of dimethylethanolamine were then added, and 658.0 parts of 70°C hot water was added as the contents were vigorously stirred. The temperature was then adjusted to 80°C, 0.7 part of tert-butyl hydroperoxide (80% by mass in di-tert-butyl peroxide) was added, and the contents were stirred for 30 minutes. 1.3 parts of ascorbic acid dissolved in 130.0 parts of water was then added over a period of 90 minutes.

[0145] The contents were allowed to cool to room temperature, and 8.2 parts of adipic acid dihydrazide dissolved in 100 parts of water was then added while stirred, giving (meth)acrylic urethane resin particle dispersion All-2. The resulting (meth)acrylic urethane resin particle dispersion AU-2 was characterized by an acid value of 18 mgKOH / g, a hydroxyl value of 5 mgKOH / g, a resin solids content of 36% by mass, a pH of 7.5, and a gel fraction of 88%.241268 WO01 33 BASF Coatings GmbHProduction Example 5: Production of blue pigment paste WP-1 for water-based colored coating composition>

[0146] 100.0 parts of (meth)acrylic urethane resin dispersion All-1 (as dispersing resin), 40.0 parts of Heliogen Blue L 6900 (trade name, by Sun Chemical Colors & Effects; phthalocyanine-based blue pigment), and 60.0 parts of deionized water were mixed and then dispersed in a motor mill, giving a water-based blue pigment paste WP-1.Production Example 6: Production of blue pigment paste WP-2 for water-based colored coating composition>

[0147] A water-based blue pigment paste WP-2 was obtained using Lionol Blue ESP-05 (trade name, by TOYOCOLOR Co., Ltd.; phthalocyanine-based blue pigment) instead of the Heliogen Blue L 6900 used in Production Example 5.Production Example 7: Production of blue pigment paste WP-3 for water-based colored coating composition>

[0148] A water-based blue pigment paste WP-3 was obtained using Hostaperm Blue BT-729-D (trade name, by Heubach; phthalocyanine-based blue pigment) instead of the Heliogen Blue L 6900 used in Production Example 5.Production Example 8: Production of blue pigment paste WP-4 for water-based colored coating composition>

[0149] A water-based blue pigment paste WP-4 was obtained using Paliogen Blue L 6484 (trade name, by Sun Chemical Colors & Effects; threne-based blue pigment) instead of the Heliogen Blue L 6900 used in Production Example 5.Production Example 9: Production of purple pigment paste WP-5 for water-based colored coating composition>

[0150] A water-based blue pigment paste WP-5 was obtained using Heliogen Blue L 6600 F (trade name, by Sun Chemical Colors & Effects; phthalocyanine-based blue pigment) instead of the Heliogen Blue L 6900 used in Production Example 5.Production Example 10: Production of purple pigment paste WP-6 for water-based colored coating composition>

[0151] A water-based purple pigment paste WP-6 was obtained using Hostaperm Violet BL01 (trade name, by Heubach; dioxazine-based purple pigment) instead of the Heliogen Blue L 6900 used in Production Example 5.241268 WO01 34 BASF Coatings GmbHProduction Examples 11 through 18: Production of water-based first colored coating compositions WBBC1-1 through WBBC1-8>

[0152] The components listed in Table 1 were mixed in the order described, and were stirred for an additional 30 minutes. Dimethylethanolamine was then added to adjust the pH to 8.2. Deionized water was then added to adjust the viscosity to 100 mPa • s, as determined at a shear rate of 1000s-1and 20°C,using the rotary viscometer Rheomat RM180 (trade name, by METTLER TOLEDO) to obtain water-based first colored coating compositions WBBC1-1 through WBBC1-8.[Table 1]

[0153] Table 1241268 WO01 35 BASF Coatings GmbH241268 WO01 36 BASF Coatings GmbH

[0154] 1) Melamine resin solution: CYMEL 327 (trade name, by Allnex; resin solids content 90% by mass)2) Inorganic thickener: Mixture of 3 parts by mass of Laponite-RD (trade name, by BYK-Chemie; synthetic hectorite), 3 parts by mass of Pluriol P900 (trade name, by BASF; polypropylene glycol), and 94 parts by mass of deionized water3) Alkali swellable emulsion: Rheovis AS 1130 (trade name, by BASF)4) Water-based surface conditioner solution: SURFYNOL 104PA (trade name, by Evonik Industries AG; 50% by mass of active ingredient, acetylene glycol)5) Aluminum flake pigment paste 1: STAPA IL HYDROLAN2192 (trade name, by ECKART GmbH; average particle size (D50): 16 pm; non-volatile content: 60%)6) Aluminum flake pigment paste 2: EMERAL EMR-EX5620 (trade name, by Toyo Aluminum K.K.; average particle size (D50): 18 pm; non-volatile content: 60%)7) Aluminum flake pigment paste 3: EMERAL EMR-EX7671 (trade name, by Toyo Aluminum K.K.; average particle size (D50): 16 pm; non-volatile content: 52%)8) Optically variable pigment 1: XIRALLIC T60-23 WNT Galaxy Blue (trade name, by MERCK; average particle size (D50): 19 pm)241268 WO01 37 BASF Coatings GmbHProduction Examples 19 through 24: Production of water-based second colored coating compositions WBBC2-1 through WBBC2-6>

[0155] The components listed in Table 2 were mixed in the order described, and were stirred for an additional 30 minutes. Dimethylethanolamine was then added to adjust the pH to 8.2. Deionized water was then added to adjust the viscosity to 100 mPa • s, as determined at a shear rate of 1000s-1and 20°C, using the rotary viscometer Rheomat RM180 (trade name, by METTLER TOLEDO) to obtain water-based second colored coating compositions WBBC2-1 through WBBC2-6.[Table 2]

[0156] Table 2241268 WO01 38 BASF Coatings GmbH

[0157] 9) Optically variable pigment 2: IRIODIN 221 WNT (trade name, by MERCK; average particle size (D50): 12 pm)10) Optically variable pigment 3: Colorstream T20-01 WNT Viola Fantasy (trade name, MERCK; average particle size (D50): 20 pm)11) Optically variable pigment 4: Colorstream T20-02 WNT Arctic Fire (trade name, MERCK; average particle size (D50): 18 pm)Production Example 25: Production of (meth)acrylic resin solution AC-1 for solventbased colored coating composition>

[0158] To a flask equipped with dual dropping funnels, a reflux condenser, a thermometer, a stirrer, and a nitrogen feed tube was charged 33.9 parts of xylene, which was heated while stirred in a nitrogen stream and maintained at 140°C. A radical polymerizable monomer mixture consisting of 23.9 parts of 4-hydroxybutyl acrylate, 10.0 parts of styrene, 19.0 parts of isobutyl methacrylate, 6.2 parts of cyclohexyl methacrylate, and 0.9 parts of methacrylic acid was then added dropwise at a constant rate over a period of 2 hours using one of the dropping funnels at a temperature of 140°C. 5.0 parts of t-butyl peroxy-2-ethylhexanoate (polymerization initiator) was added dropwise at a constant rate over a period of 2 hours using the other dropping device at the same time as the other ingredients were added dropwise using the other dropping funnel. After the dropwise addition of the monomer mixture and the polymerization initiator had been completed, the contents were maintained for 1 hour at a temperature of 140°C, and the reaction temperature was then lowered to 110°C. 0.1 part of t-butyl peroxy-2-ethylhexanoate (polymerization initiator) was then dissolved in 1.0 part of xylene and added as additional catalyst, the temperature of 110°C was maintained for another 2241268 WO01 39 BASF Coatings GmbHhours, and the contents were then cooled, giving a (meth)acrylic resin solution AC-1. The (meth)acrylic resin solution AC-1 was characterized by a mass-average molecular weight of 7,000, an acid value of 9.8 mgKOH / g, a hydroxyl value of 155 mgKOH / g, a glass transition temperature of -10°C, and a resin solids content of 60%.Production Example 26: Production of blue pigment paste SP-1 for solvent-based colored coating composition>

[0159] 100.0 parts of (meth)acrylic resin solution AC-1 (as dispersing resin), 60.0 parts of Heliogen Blue L 6900 (trade name, by Sun Chemical Colors & Effects; phthalocyanine-based blue pigment), and 140.0 parts of xylene were mixed and then dispersed in a motor mill, giving a solvent-based blue pigment paste SP-1.Production Example 27: Production of solvent-based second colored coating composition SBCC2-1>

[0160] Of the raw materials listed in Table 3, the (meth)acrylic resin solution AC-1, blue pigment paste SP-1, and additive solutions (UV absorber solution, photostabilizer solution, and surface conditioner solution) were mixed and stirred to homogeneity. The polyisocyanate compound listed in Table 3 was then added to the mixtures, and the contents were again stirred to homogeneity. The resulting mixture was then diluted with Solvesso 100 (trade name, ExxonMobil) to a Ford #4 Cup viscosity of 25 seconds at 20°C, giving a solvent-based second colored coating composition SBCC2-1.[Table 3]

[0161] Table 3241268 WO01 40 BASF Coatings GmbH

[0162] 12) UV absorber solution: 20% by mass xylene solution of TINUVIN 900 (trade name, by BASF; benzotriazole-based UV absorber)13) Photostabilizer solution: 20% by mass xylene solution of TINUVIN 292 (trade name, by BASF; hindered amine-based photostabilizer)14) Solvent-based surface conditioner solution: 10% by mass xylene solution of BYK-300 (trade name, by BYK-Chemie Japan; silicon-based surface conditioner)15) Polyisocyanate compound: Desmodur N3300: trade name, by Sumika Covestro Urethane Co., Ltd.; hexamethylene diisocyanate (HDI) trimer; nonvolatile content: 100% by mass; NCO content: 21.8% by mass)[Methods for Determining Values of Resin Properties]

[0163] The values of resin properties in the present invention were determined by the following methods.1. Mass-average molecular weight

[0164] The mass-average molecular weight was determined, by means of gel permeation chromatography (GPC) at a temperature of 40°C and a flow rate of 1 mL / min using tetrahydrofuran (THF) as the eluent, as the value calculated on the basis of the massaverage molecular weight of polystyrene, from data obtained using a differential refractometer (refractive index detector). Here, the gel permeation chromatography (GPC) columns TSKgel G2000HXL, G3000HXL, G4000HXL, and G5000HXL (trade names, by Tosoh Corporation) were used in combination.2. Acid value

[0165] This was determined in accordance with JIS-K5601-2-1:1999.3. Hydroxyl group value

[0166] This was determined in accordance with JIS-K1557-1:2007.4. Resin solids content

[0167] The resin solids content was determined by weighing 1.0 g of a sample that had been heated to 130°C for 60 minutes.5. Gel fraction

[0168] 1.0 g of a sample was first heated to 130°C for 60 minutes and weighed. The heated sample was then immersed in excess tetrahydrofuran for 24 hours at 25°C to extract the dissolved components. The remaining insoluble components were then dried for 4 hours at 50°C and then weighed to determine the gel fraction.241268 WO01 41 BASF Coatings GmbH<Examples 1 through 5, and Comparative Examples 1 through 4>Preparation of Test Color Cards>

[0169] The commercially available cationic electrodeposition coating, CathoGuard No. 500 (trade name, by BASF Japan), was applied via electrodeposition to a dry film thickness of 20 pm on zinc phosphate-treated cold-rolled steel sheets (150 mm (length) x 75mm (width) x 0.8mm (thickness)) (also referred to as steel sheet) and cured by being heated for 30 minutes at 170°C. The water-based intermediate coating composition ProBloc N-3000 N3.5-3(W) (trade name, by BASF Japan) was then electrostatically applied to a dry film thickness of 20 pm, was allowed to stand for 5 minutes at room temperature, and was then heated to 140°C for 30 minutes, giving intermediate coated sheets.

[0170] In Examples 1 through 4 and Comparative Examples 1 and 3, the water-based first colored coating compositions WBBC1-1 through WBBC1-3, WBBC1-5, and WBBC1-7 listed in Table 1 were electrostatically applied to a dry film thickness of 7 pm on the intermediate coated sheets, and were allowed to stand for 3 minutes at room temperature.

[0171] Onto the above uncured water-based first colored coating films, the water-based second colored coating compositions WBBC2-1 through WBBC2-6 listed in Table 2 were then electrostatically applied to a dry film thickness of 7 pm, were allowed to stand for 5 minutes at room temperature, and were then pre-dried for 3 minutes at 80°C (flash-off). The solvent-based clear coating composition ProGloss HD-N(W) (trade name, by BASF Japan; 2-component acrylic-urethane coating) was then electrostatically applied to a dry film thickness of 35 pm, was allowed to stand for 10 minutes at room temperature, and was then heated to 140°C for 30 minutes, giving test color cards comprising multi-layer coatings formed on steel sheets.

[0172] In Example 5 and Comparative Example 2, the water-based first colored coating compositions WBBC1-4 and WBBC1-6 shown in Table 1 were electrostatically applied to a dry film thickness of 14 pm on the intermediate coated sheets, were allowed to stand for 5 minutes at room temperature, and were then pre-dried for 3 minutes at 80°C (flash-off). The solvent-based second colored coating composition SBCC2-1 listed in Table 3 was then electrostatically applied to a dry film thickness of 30 pm, was allowed to stand for 10 minutes at room temperature, and was then heated to 140°C for 30 minutes, giving test color cards comprising multi-layer coatings formed on steel sheets.241268 WO01 42 BASF Coatings GmbH

[0173] In Comparative Example 4, the water-based first colored coating composition WBBC1-8 listed in Table 1 was electrostatically applied to a dry film thickness of 14 pm on the intermediate coated sheet, was allowed to stand for 5 minutes at room temperature, and was then pre-dried for 3 minutes at 80°C (flash-off). The solvent-based clear coating composition ProGloss HD-N(W) (trade name, by BASF Japan); 2-component acrylic-urethane coating) was then electrostatically applied to a dry film thickness of 30 pm, was allowed to stand for 10 minutes at room temperature, and was then heated to 140°C for 30 minutes, giving a test color card comprising a multi-layer coating formed on a steel sheet.determination of hue angle h(45 / 0), chroma C*(45 / 0), hue angle difference |h(45 / 30)-h(45 / -30)|, and hue angle difference |h(10 / 0)-h(70 / 60)|>[Assessments]

[0174] Table 4 below shows the results of the assessments of Examples 1 through 5 and Comparative Examples 1 through 4.

[0175] The types of colored coating compositions that were used, as well as the combinations in which clear coating compositions were or were not used, are shown in Table 4 to make it easier to understand the layered structure of the test color cards of the examples and comparative examples.[Table 4]

[0176] Table 4241268 WO01 43 BASF Coatings GmbH

[0177] Solvent-based clear coat composition: O: Used Not useddetermination of hue angle h(45 / 0)>

[0178] This was determined at an incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film using the multi-angle colorimeter BYK-mac i (trade name, by BYK-Gardner).determination of chroma C*(45 / 0)>

[0179] This was determined at an incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film using the multi-angle colorimeter BYK-mac i (trade name, by BYK-Gardner).determination of hue angle difference |h(45 / 30)-h(45 / -30)|>

[0180] The multi-angle colorimeter BYK-mac i (trade name, by BYK-Gardner) was used to determine the hue angle h(45 / 30) at an incident angle of 45 degrees and a receiving angle of 30 degrees as well as the hue angle h(45 / -30) at an incident angle of 45 degrees241268 WO01 44 BASF Coatings GmbHand a receiving angle of -30 degrees relative to the normal of the multi-layer coating film, and the difference between the hue angle h(45 / 30) and hue angle h(45 / -30) was then determined.determination of hue angle difference |h(10 / 0)-h(70 / 60)|>

[0181] The variable angle Gonio-Spectrophotometric Color Measurement System GSP-2 (trade name, by Murakami Color Research Laboratory Co., Ltd.) was used to determine the hue angle h(10 / 0) at an incident angle of 10 degrees and a receiving angle of 0 degrees as well as the hue angle h(70 / 60) at an incident angle of 70 degrees and a receiving angle of 60 degrees relative to the normal of the multi-layer coating film using, and the difference between the hue angle h(10 / 0) and hue angle h(70 / 60) was then determined.<Visual Test>

[0182] The multi-layer coating films were visually tested via observation of color flop and color shift by a total of five individuals (two designers and three engineers) who had more than three years of experience in color development.

[0183] Color flop was observed using the byko-spectra effect (light source booth with variable-angle stage) (trade name, by BYK-Gardner). In this device, the angle of a stage exposed to incident light at an incident angle of 45 degrees relative to the normal line of multi-layer coating films can be changed, thus permitting observation over a broad receiving angle range of 60 to -65 degrees (the receiving angle is positive on the specular reflected light side and is negative on the incident light side, relative to the normal of multi-layer coating films). In this device, the receiving angle is displayed as the angle in the incident light direction relative to specular reflected light (the incident light direction is positive), thus resulting in a receiving angle range display of -15 to 110 degrees in this device.

[0184] As described with reference to Figure 2, color flop is observed through sequential observation at a highlight angle (HL), comprising an incident angle of 45 degrees and a receiving angle of 30 degrees (corresponding to 15 degrees in the display of the present device) relative to the normal n of the multi-layer coating film, and at a shade angle (SH), comprising an incident angle of 45 degrees and a receiving angle of -30 degrees (corresponding to 75 degrees in the display of the present device) relative to the normal n of the multilayer coating film.241268 WO01 45 BASF Coatings GmbH

[0185] As described with reference to Figures 4(a) and 4(b), color shift is observed via observation at a face angle (incident angle of about 10 degrees and receiving angle of about 0 degrees) and a grazing angle (incident angle of about 70 degrees and receiving angle of about 60 degrees). Artificial Sunlight Lighting XC-100CF (trade name, by SERIC Co., Ltd.) was used as the light source in the observation of color shift.The results of the observations were assessed based on the following criteria, where the numerical scores awarded by the most people were used as the scores for the assessment of the multi-layer coating films.

[0186] 4: Color flop and color shift both perceptible.

[0187] 3: Color flop perceptible but color shift not perceptible.

[0188] 2: Color flop not perceptible but color shift perceptible.

[0189] 1: Neither color flop nor color shift perceptible.

[0190] Inventions by the present inventors have been described in detail above based on embodiments, but the present invention is not limited to these embodiments, and it will be obvious that the invention can be modified in a variety of ways within the scope of the present invention.[Key to Symbols]

[0191] 1: Multi-layer coating film1a: Surfacen: NormalIL: Incident lightRL: Specular reflected lightP: Light receiving positionP1 , P2, P3: ObserversHL: Highlight (position) / highlight angleSH: Shade (position) / shade angle

Claims

241268 WO01 46 BASF Coatings GmbH[Document Name] CLAIMS

1. A multi-layer coating film comprising a first colored coating film, and a second colored coating film provided on the first colored coating film, said multi-layer coating film being characterized in thatthe first colored coating film comprises a first coating film-forming resin and an aluminum flake pigment,the second colored coating layer comprises a second coating film-forming resin and a blue pigment,the first colored coating film and / or second colored coating film comprises an optically variable pigment,the hue angle h(45 / 0), as determined at a light incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film, is 205 to 295 degrees,the chroma C* (45 / 0) value, as determined at an incident angle of 45 degrees and a receiving angle of 0 degrees, is 30 to 60,the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30), as determined at an incident angle of 45 degrees and a receiving angle of 30 degrees, and the hue angle h(45 / -30), as determined at an incident angle of 45 degrees and a receiving angle of -30 degrees, is 20 to 50 degrees, andthe difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0), as determined at an incident angle of 10 degrees and a receiving angle of 0 degrees, and the hue angle h(70 / 60), as determined at an incident angle of 70 degrees and a receiving angle of 60 degrees, is 5 to 55 degrees.

2. The multi-layer coating film according to Claim 1, wherein the first coating film-forming resin and second coating film-forming resin are each independently a thermosetting resin composed of, as a substrate resin, one or more selected from (meth)acrylic resins, polyester resins, polyurethane resins, and (meth)acrylic urethane resins.

3. The multi-layer coating film according to Claim 1 or 2, wherein the first colored coating film and / or second colored coating film furthermore comprises an inorganic thickener.241268 WO01 47 BASF Coatings GmbH

4. The multi-layer coating film according to Claim 1 or 2, wherein the first colored coating film comprises: a first coating film-forming resin containing (meth)acrylic urethane resin particles; and an inorganic thickener.

5. The multi-layer coating film according to Claim 1 or 2, wherein the first colored coating film comprises a first coating film-forming resin containing (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having an aldehyde group and / or a ketone group as well as a compound having two or more hydrazide groups per molecule; and an inorganic thickener.

6. The multi-layer coating film according to Claim 1 or 2, characterized by furthermore having a clear coating film on the second colored coating film.

7. A method for forming a multi-layer coating film, comprising:a step (1) in which a first colored coating composition is applied onto an object to be coated to form an uncured first colored coating film;a step (2) in which a second colored coating composition is applied onto the first colored coating film to form an uncured second colored coating film; andoptionally, a step (3) in which a clear coating composition is applied onto the second colored coating film to form an uncured clear coating film, whereinthe uncured first colored coating film in step (1), the uncured second colored coating film in step (2), and in cases where step (3) is carried out, the uncured clear coating film formed in step (3) are each cured by being heated, or the method further comprises a step (4) in which the uncured first colored coating film, the uncured second colored coating film, and the optionally formed uncured clear coating film are cured by being heated simultaneously, said method for forming a multi-layer coating film being characterized in thatthe first colored coating composition comprises a first coating film-forming resin and an aluminum flake pigment,the second colored coating composition comprises a second coating film-forming resin and a blue pigment,the first colored coating composition and / or second colored coating composition comprise an optically variable pigment,the hue angle h (45 / 0) of the resulting multi-layer coating film, as determined at an241268 WO01 48 BASF Coatings GmbHincident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multi-layer coating film, is 205 to 295 degrees,the chroma C* (45 / 0) value, as determined at an incident angle of 45 degrees and a receiving angle of 0 degrees, is 30 to 60,the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30), as determined at an incident angle of 45 degrees and a receiving angle of 30 degrees, and the hue angle h(45 / -30), as determined at an incident angle of 45 degrees and a receiving angle of -30 degrees, is 20 to 50 degrees, andthe difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0), as determined at an incident angle of 10 degrees and a receiving angle of 0 degrees, and the hue angle h(70 / 60), as determined at an incident angle of 70 degrees and a receiving angle of 60 degrees, is 5 to 55 degrees.

8. The method for forming a multi-layer coating film according to Claim 7, wherein the first coating film-forming resin and second coating film-forming resin are each independently a thermosetting resin composed of, as a substrate resin, one or more selected from (meth)acrylic resins, polyester resins, polyurethane resins, and (meth)acrylic urethane resins.

9. The method for forming a multi-layer coating film according to Claim 7 or 8, wherein the first colored coating film and / or second colored coating film furthermore comprises an inorganic thickener.

10. The method for forming a multi-layer coating film according to Claim 7 or 8, wherein the first colored coating composition comprises: a first coating film-forming resin containing (meth)acrylic urethane resin particles; and an inorganic thickener.

11. The method for forming a multi-layer coating film according to Claim 7 or 8, wherein the first colored coating composition comprises a first coating film-forming resin containing (meth)acrylic urethane resin particles that include a (meth)acrylic urethane resin having an aldehyde group and / or a ketone group as well as a compound having two or more hydrazide groups per molecule; and an inorganic thickener.

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