Multilayer coating film and method for forming a multilayer coating film

Abstract

The present invention provides a multi-layer coating film that, by changing its hue depending on the observation angle and the angle of incident light, can give a unique, highly saturated blue design to a three-dimensional object that has been coated, based on the change in hue. [Solution] A multilayer coating having a first colored coating and a second colored coating in this order, wherein the first colored coating contains a first coating-forming resin and an aluminum flake pigment, the second colored coating contains a second coating-forming resin and a blue pigment, the first colored coating and / or the second colored coating contains a light-interfering pigment, the hue angle h(45 / 0) is 205 to 295 degrees, and the saturation C*(45 / 0) is 30 to 6 A multi-layer coating film in which the h-angle is 0, the difference |h(45 / 30)-h(45 / -30)| between the h-angle h(45 / 30) and the h-angle h(45 / -30) measured 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 h-angle h(10 / 0) ​​and the h-angle h(70 / 60) measured at an incident angle of 70 degrees and a receiving angle of 60 degrees is 5 to 55 degrees.

Description

Technical Field

[0001] The present invention relates to a blue-based multilayer coating film and a method for forming the same.

Background Art

[0002] In recent years, due to the diversification of consumer preferences, there has been a demand for coating films having various colors and designs on the exterior of industrial products such as automobiles. As an example of such a coating film, a multilayer coating film in which a coating film containing a coloring pigment is laminated on a coating film containing a bright pigment can be cited.

[0003] For example, according to Patent Document 1, a method for forming a multilayer coating film having high chroma, excellent depth, and suppressed color variation due to color unevenness and film thickness variation is provided from a first colored coating film containing a bright pigment and a coloring pigment, a second colored coating film containing a coloring pigment, and a clear coating film.

[0004] Further, according to Patent Document 2, a multilayer coating film having excellent depth and high lightness and chroma in highlights is provided from a metallic base coating film containing an aluminum flake pigment, a surface conditioner, and a viscosity conditioner and a transparent colored coating film containing a blue pigment formed on the metallic base coating film.

[0005] Furthermore, Patent Document 3 describes a paint composition containing a bright material having an angle-dependent interference effect and a bright material having no angle-dependent interference effect at a specific ratio, and the color of the obtained coating film changes from achromatic to chromatic when the observation condition is changed from a face angle to a grazing angle.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

[0007] However, consumer preferences regarding the design of industrial products such as automobiles are becoming increasingly diverse.

[0008] Therefore, the object of the present invention is to provide a multilayer coating film that can give a unique, highly saturated blue design based on hue changes, particularly to three-dimensional coated objects, by changing the hue depending on the observation angle and the angle of incident light, and a method for manufacturing the same. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, the present invention provides a multilayer coating having a first colored coating and a second colored coating provided on the first colored coating, wherein the first colored coating contains a first coating-forming resin and an aluminum flake pigment, the second colored coating contains a second coating-forming resin and a blue pigment, the first colored coating and / or the second colored coating contains an optically coherent pigment, the hue angle h(45 / 0) measured with an incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multilayer coating is 205 to 295 degrees, and the chroma C*( We discovered that this problem can be solved by a multi-layer coating film characterized by the fact that the ratio of h(45 / 0) is 30 to 60, the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30) measured at an incident angle of 45 degrees and a receiving angle of 30 degrees and the hue angle h(45 / -30) measured 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) ​​measured at an incident angle of 10 degrees and a receiving angle of 0 degrees and the hue angle h(70 / 60) measured at an incident angle of 70 degrees and a receiving angle of 60 degrees is 5 to 55 degrees, and thus completed the present invention.

[0010] Furthermore, it is preferable that the multilayer coating of the present invention is composed of a thermosetting resin in which the first coating-forming resin and the second coating-forming resin are independently composed of one or more base resins selected from (meth)acrylic resin, polyester resin, polyurethane resin, and (meth)acrylic urethane resin.

[0011] Furthermore, it is preferable that the multilayer coating of the present invention contains an inorganic thickener in the first colored coating and / or the second colored coating.

[0012] Furthermore, it is preferable that the multilayer coating of the present invention comprises a first colored coating film containing a first coating film-forming resin containing (meth)acrylic urethane resin particles and an inorganic thickener.

[0013] Furthermore, the multilayer coating of the present invention preferably comprises a first colored coating film comprising a first coating film-forming resin containing (meth)acrylic urethane resin particles having an aldehyde group and / or ketone group and a compound having two or more hydrazide groups in one molecule, and an inorganic thickener.

[0014] Furthermore, it is preferable that the multilayer coating of the present invention further has a clear coating on the second colored coating.

[0015] Furthermore, the object of the present invention is the step (1) of applying a first colored coating composition to a workpiece to form an uncured first colored coating film, and the step (1) obtained The firstA multilayer coating method comprising: (2) painting a second color coating composition onto a colored coating film to form an uncured second color coating film; and optionally, (3) painting a clear coating composition onto the second color coating film to form an uncured clear coating film, wherein the method further comprises: (1) curing the uncured first color coating film by heating the uncured second color coating film by heating the uncured second color coating film by heating the uncured second color coating film by heating the uncured clear coating film by heating the uncured first color coating film by heating the uncured second color coating film by heating the uncured second color coating film by heating the uncured clear coating film by heating the uncured first color coating film by heating the uncured second color coating film and the optionally formed uncured clear coating film by heating the uncured first color coating film by heating the uncured second color coating film and the composition and (4) the uncured second color coating composition comprises a first coating film forming resin and an aluminum flake pigment, and the second color coating composition comprises a second coating film forming resin and a blue pigment, and the first color coating composition The product and / or the second colored coating composition contains an optically coherent pigment, and the resulting multilayer coating film has a hue angle h(45 / 0) of 205-295 degrees when measured at an incident angle of 45 degrees and a receiving angle of 0 degrees relative to the normal of the multilayer coating film, and a chrominance C*(45 / 0) of 30-60 when measured at an incident angle of 45 degrees and a receiving angle of 0 degrees, and a hue angle h(45 / 30) and a chrominance of -3 degrees when measured at an incident angle of 45 degrees and a receiving angle of 30 degrees. This problem can also be solved by a multi-layer coating method characterized in that the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / -30) measured at 0 degrees and |h(45 / 30)| is 20 to 50 degrees, and the difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0) ​​measured at an incident angle of 10 degrees and a receiving angle of 0 degrees and the hue angle h(70 / 60) measured at an incident angle of 70 degrees and a receiving angle of 60 degrees is 5 to 55 degrees.

[0016] Furthermore, in the multilayer coating film forming method of the present invention, it is preferable that the first coating film forming resin and the second coating film forming resin are thermosetting resins composed of one or more base resins selected from (meth)acrylic resin, polyester resin, polyurethane resin, and (meth)acrylic urethane resin, independently of each other.

[0017] Furthermore, the multilayer coating film formation method of the present invention is a first colored coating Composition and / or second color coating Composition However, it is preferable to include an inorganic thickener.

[0018] Furthermore, the method for forming a multilayer coating film of the present invention preferably comprises The first colored paint composition is a first coating film-forming resin containing (meth)acrylic urethane resin particles and an inorganic thickener.

[0019] Furthermore, the method for forming a multilayer coating film of the present invention preferably comprises a first coating film-forming resin containing (meth)acrylic urethane resin particles containing a (meth)acrylic urethane resin having an aldehyde group and / or a ketone group and a compound having two or more hydrazide groups in one molecule, and an inorganic thickener. [Advantages of the Invention]

[0020] According to the present invention, a multilayer coating film and a method for producing the same can be obtained, which can give a unique high-chroma blue design based on a hue change, particularly to a three-dimensional shaped object to be coated, due to the change in hue depending on the observation angle and the incident light angle. [Brief Description of the Drawings]

[0021] [Figure 1] FIG. 1 is a schematic cross-sectional view for explaining a method of measuring the hue angle h(45 / 0) and the chroma C*(45 / 0) of the multilayer coating film of the present invention. [Figure 2] FIG. 2 is a schematic view for explaining an outline of color flop, which is an optical characteristic of the multilayer coating film of the present invention. [Figure 3] FIG. 3(a) is a schematic view for explaining a method of measuring the hue angle h at an incident light angle of 45 degrees and a receiving light angle of 30 degrees (highlight condition) with respect to the normal line of the multilayer coating film, and FIG. 3(b) is a schematic view for explaining a method of measuring the hue angle h at an incident light angle of 45 degrees and a receiving light angle of -30 degrees (shade condition) with respect to the normal line of the multilayer coating film. [Figure 4] FIGS. 4(a) and 4(b) are schematic views for explaining an outline of color shift, which is an optical characteristic of the multilayer coating film of the present invention. [Figure 5]Figure 5(a) is a schematic diagram illustrating a method for measuring the hue angle h with an incident light angle of 10 degrees and a receiving light angle of 0 degrees (face angle condition) relative to the normal of a multi-layer coating film, and Figure 5(b) is a schematic diagram illustrating a method for measuring the hue angle h with an incident light angle of 70 degrees and a receiving light angle of 60 degrees (glazing angle condition) relative to the normal of a multi-layer coating film. [Modes for carrying out the invention]

[0022] The multilayer coating of the present invention comprises a first colored coating and a second colored coating provided on the first colored coating.

[0023] In the multilayer coating of the present invention, the first colored coating contains a first coating-forming resin and an aluminum flake pigment, the second colored coating contains a second coating-forming resin and a blue pigment, and furthermore, the first colored coating and / or the second colored coating contains a light-interfering pigment.

[0024] The multi-layer coating method of the present invention uses a first colored coating composition, a second colored coating composition, and, if necessary, a clear coating composition.

[0025] First, in step (1), the first colored paint composition is applied to the object to be coated, forming an uncured first colored coating film. After applying the first colored paint composition, heating (flash-off) may be performed at 70-80°C for 3-5 minutes to evaporate the solvent contained in the first colored coating film, or it may be left at room temperature without heating. If flash-off is performed, it is preferable to select the temperature and time range based on the above range so that the coating film does not completely harden.

[0026] Next, in step (2), the second colored paint composition is applied to the first colored coating obtained in step (1), forming an uncured second colored coating. After applying the second colored paint composition, heating (flash-off) may be performed at 70-80°C for 3-5 minutes to evaporate the solvent contained in the second colored coating, or it may be left at room temperature without heating. If flash-off is performed, it is preferable to select the temperature and time range based on the above range so that the coating does not completely harden.

[0027] Next, if necessary, as step (3), the clear coating composition is applied to the second colored coating obtained in step (2) to form an uncured clear coating. Generally, after applying the clear coating composition, it is left at room temperature for 5 to 20 minutes.

[0028] Finally, as step (4), the uncured first colored coating formed in step (1), the uncured second colored coating formed in step (2), and the uncured clear coating formed in step (3) as needed are heated to cure these three layers simultaneously. Alternatively, in steps (1), (2), and (3), the uncured first colored coating, the uncured second colored coating, and the uncured clear coating can be heated and cured individually. In this case, step (4) is not required.

[0029] In this invention, heating (baking) can be performed by known means, for example, drying furnaces such as hot air furnaces, electric furnaces, and infrared induction heating furnaces 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 80 to 150°C. By setting the baking temperature to 70 to 160°C, the curing reaction can be sufficiently advanced. 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] The optical characteristics of the multilayer coating film of the present invention, as well as the method for measuring them, will be described below with reference to the drawings.

[0031] The multi-layer coating of the present invention has a hue angle h(45 / 0) of 205 to 295 degrees and a saturation C*(45 / 0) in the range of 30 to 60. By keeping it within this range, the multi-layer coating can be visually recognized as a vivid blue color.

[0032] Here, the hue angle h and chroma C* are values ​​that represent the hue angle and chroma, respectively, in the L*C*h color system. The L*C*h color system is a color system devised based on the CIE LAB color system, which was defined by the International Commission on Illumination (CIE) in 1976 and adopted in JIS Z 8781-4:2013. While the CIE LAB color system represents the chroma and hue of a color using coordinates (a*,b*) on the a*b* plane, the L*C*h color system represents color using chroma C*, which is the distance from the origin on the a*b* plane, and the hue angle h, which is the angle obtained by moving counterclockwise from the axis in the a*red direction, with the a* axis being 0 degrees.

[0033] The hue angle h(45 / 0) and chroma C*(45 / 0) measured under the conditions of an incident angle of 45 degrees and a light-receiving angle of 0 degrees used in this invention can be measured using a colorimeter such as the multi-angle colorimeter BYKmac i (product name, manufactured by BYK-Gardner).

[0034] In this invention, both the angle of incidence and the angle of reception of light are angles measured with respect to the normal of the multilayer coating film, and the angle of reception is defined as positive on the specular reflection side and negative on the incident light side with respect to the normal of the multilayer coating film. In Figure 1, the angle of incidence of incident light IL with respect to the normal n of one surface 1a of the multilayer coating film 1 is set to 45 degrees, and the specular reflection RL is shown by a dashed line. In daily life, observers observe the coating film from various angles, but in this invention, as shown in Figure 1, the reception angle 0 degrees (i.e., the position of the normal n) is set as the reception position P, and the hue angle h and chroma C* are measured using a colorimeter (not shown). In this invention, it is preferable that the hue angle h(45 / 0) measured in this way is in the range of 205 to 295 degrees, preferably 250 to 290 degrees, and the chroma C*(45 / 0) is in the range of 30 to 60, preferably 35 to 50.

[0035] Figure 2 illustrates the outline of color flop, one of the hue changes exhibited by the multi-layer coating film of the present invention.

[0036] In Figure 2, the incident light IL and specular reflected light RL are shown as dashed lines for one surface 1a of the multilayer coating 1.

[0037] In Figure 2, observer P1 observes the multilayer coating at a position between the specularly reflected light RL and the normal n of the multilayer coating, while observer P2 observes the multilayer coating at a position between the incident light IL angle and the normal n of the multilayer coating 1. Here, the observation position or angle near the specularly reflected light shown by observer P1 is called the highlight (position) or highlight angle (HL), and the observation position or angle away from the specularly reflected light and less affected by the reflective material, as shown by observer P2, is called the shade (position) or shade angle (SH). Note that the above "near the specularly reflected light" means that receiving the specularly reflected light itself is not a condition for observation. This is because, with specularly reflected light, it is not possible to perceive color due to the gloss of the coating surface.

[0038] In visual observations as shown in Figure 2, highlights (HL) are primarily perceived as color due to reflection or interference colors from luminescent materials contained in the coating, while shades (SH) are primarily perceived as the color of the coloring pigments contained in the coating.

[0039] The multi-layer coating of the present invention is perceived as having a continuously changing hue when the observer's relative viewing position changes continuously.

[0040] In this invention, the phenomenon in which the hue perceived by the observer changes when the observation position changes relatively while light is incident on a multi-layer coating from a constant direction is called a color flop.

[0041] In this invention, the color flop was evaluated by the difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30) measured by light irradiation at an incident angle of 45 degrees and a receiving angle of 30 degrees relative to the normal n of the multilayer coating film, and the hue angle h(45 / -30) measured by light irradiation at an incident angle of 45 degrees and a receiving angle of -30 degrees. In the multilayer coating film of this invention, this |h(45 / 30)-h(45 / -30)| is between 20 and 50 degrees, and preferably between 20 and 35 degrees.

[0042] The measurement methods for the hue angles h(45 / 30) and h(45 / -30) described above will be explained using Figures 3(a) and 3(b).

[0043] Figures 3(a) and 3(b) show the multilayer coating film 1 of the present invention as observed from the cross-sectional direction of the multilayer coating film 1 after being irradiated with light.

[0044] Figure 3(a) shows the state in which one surface 1a of a multilayer coating film 1 is illuminated with incident light IL at an incident angle of 45 degrees relative to the normal n of surface 1a, and specular reflected light RL is reflected in the direction of the dashed line. The light receiving position PL1 corresponds to a light 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 hue angle h(45 / 30). Here, the observation position at a light receiving angle of 30 degrees (15 degrees in the direction of incident light relative to specular reflected light) corresponds to the highlight angle (HL) described above. The incident and receiving conditions in this case are called the highlight conditions.

[0045] Furthermore, in Figure 3(b), for incident light IL at an incident angle of 45 degrees, similar to Figure 3(a), the receiving position PL2 is set to a receiving angle of -30 degrees, and the reflected light at that position is measured by a colorimeter (not shown). Note that -30 degrees indicates a position shifted 30 degrees in the direction of incident light relative to the normal n, and the hue angle h under these measurement conditions is expressed as hue angle h(45 / -30). Here, the observation position at a receiving angle of -30 degrees (75 degrees in the direction of incident light relative to specularly reflected light) corresponds to the shade angle (SH) described above. The incident and receiving conditions in this case are called the shade conditions.

[0046] The difference |h(45 / 30)-h(45 / -30)| between the hue angle h(45 / 30) under highlight conditions (Figure 3(a)) and the hue angle h(45 / -30) under shade conditions (Figure 3(b)) is in the range of 20 to 50 degrees, in which case the hue change due to the color flop described above is well expressed.

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

[0048] Next, Figures 4(a) and 4(b) illustrate the color shift, another hue change exhibited by the multi-layer coating of the present invention.

[0049] In Figures 4(a) and 4(b), the incident light IL incident on one surface 1a of the multilayer coating 1 is shown by a dashed line. However, in Figures 4(a) and 4(b), the incident light is incident on one surface 1a of the multilayer coating 1 at different angles. Figure 4(a) shows the case where the angle of incidence is small, and Figure 4(b) shows the case where the angle of incidence is large.

[0050] Here, as illustrated in Figure 4(a), for example, when the angle of incidence from the normal n to the multilayer coating 1 is greater than 0 degrees and up to approximately 25 degrees, and the receiving angle is near specular reflection, this is called observation or measurement by face angle. Also, as illustrated in Figure 4(b), for example, when the angle of incidence from the normal n to the multilayer coating 1 is in the range of approximately 65 degrees to less than 90 degrees, and the receiving angle is near specular reflection, this is called observation or measurement by glazing angle. Note that "near specular reflection" means that, as described above, receiving specular reflection itself is not a condition for observation. This is because, with specular reflection, color cannot be perceived due to the gloss of the coating surface.

[0051] In both Figure 4(a) and Figure 4(b), observer P3 is located near the specular reflection and is observing at the position of the highlight angle (HL) as explained using Figure 2.

[0052] Furthermore, the multi-layer coating of the present invention changes from the hue perceived at the face angle to the hue perceived at the glazing angle when the angle of incident light changes, due to the color development or interference color caused by the reflection of the luminous material contained in the coating. For example, a greenish-blue (blue-green) may be perceived at the face angle, while a reddish-blue (purple) may be perceived at the glazing angle. Conversely, a reddish-blue (purple) may be perceived at the face angle, while a greenish-blue (blue-green) may be perceived at the glazing angle. When the angle of incident light changes continuously, the hue perceived by the observer also changes continuously, thus giving the coated object a unique design accompanied by hue changes.

[0053] In this invention, the change in the hue of a multi-layer coating as perceived by an observer at the highlight angle (HL) when the angle of incidence of light irradiating the multi-layer coating changes is referred to as color shift.

[0054] In this invention, this color shift was evaluated by the difference |h(10 / 0)-h(70 / 60)| between the hue angle h(10 / 0) ​​measured by light irradiation at an incident angle of 10 degrees and a receiving angle of 0 degrees, and the hue angle h(70 / 60) measured by light irradiation at an incident angle of 70 degrees and a receiving angle of 60 degrees. In the multilayer coating film of this invention, this |h(10 / 0)-h(70 / 60)| is set to 5 to 55 degrees, and 5 to 45 degree It is preferable.

[0055] The measurement methods for the hue angles h(10 / 0) ​​and h(70 / 60) described above will be explained using Figures 5(a) and 5(b).

[0056] Figures 5(a) and 5(b) show the multilayer coating film 1 of the present invention after being irradiated with light, as observed from the cross-sectional direction of the multilayer coating film 1.

[0057] Figure 5(a) shows the state in which one surface 1a of a multilayer coating film 1 is illuminated with incident light IL at an incident angle of 10 degrees relative to the normal n of surface 1a, and specular reflected light RL is reflected in the direction of the dashed line. The light receiving position PL3 is on the normal n, i.e., the light receiving angle is 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 denoted as hue angle h(10 / 0). Here, these measurement conditions correspond to the face angle described above.

[0058] Furthermore, Figure 5(b) shows the state in which one surface 1a of the multilayer coating 1 is illuminated with incident light IL at an incident angle of 70 degrees relative to its normal n, and specular reflected light RL is reflected in the direction of the dashed line. The light receiving position PL4 is set to a light receiving angle of 60 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 hue angle h(70 / 60). Here, these measurement conditions correspond to the glazing angle described above.

[0059] The difference between the hue angle h(10 / 0) ​​under the face angle condition and the hue angle h(70 / 60) under the glazing angle condition, as measured in this way, |h(10 / 0)-h(70 / 60)|, is between 5 and 45. degree Within this range, the hue change due to the aforementioned color shift is well expressed.

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

[0061] Here, the values ​​of hue angles h(45 / 0), h(45 / 30), h(45 / -30), h(10 / 0), h(70 / 60), and chroma C*(45 / 0) can be adjusted to preferred values ​​by appropriately adjusting the type and content of the first film-forming resin, aluminum flake pigment, blue pigment, light-interfering pigment, and thickener in the first colored coating film, or the second film-forming resin, blue pigment, light-interfering pigment, and thickener in the second colored coating film, as described later.

[0062] The details of the multi-layer coating film of the present invention will be further described below.

[0063] [Object to be coated] The multilayer coating of the present invention can be formed on a substrate. There are no particular limitations on the substrate to which the multilayer coating of the present invention can be applied. Examples include members made of metals such as iron, zinc, aluminum, and magnesium; members made of alloys of these metals; members that have been plated or vapor-deposited with these metals; and members made of glass, plastic, foams of various materials, etc. In particular, the substrates used in the present invention are preferably steel materials and plastic materials that constitute an automobile body. These members can be subjected to treatments such as degreasing and surface treatment as needed.

[0064] Furthermore, in the present invention, a substrate with a primer coating formed on it can also be used as the substrate. The primer coating is applied to conceal the surface of the substrate or to impart properties such as corrosion resistance, rust prevention, adhesion, and conductivity to the substrate, and can be formed by applying a primer and curing or drying it. This primer is not particularly limited, and known primers such as electrodeposition paints, solvent-based primers, and water-based primers can be used.

[0065] Furthermore, in the present invention, an intermediate coating film formed on the aforementioned undercoat film can also be used as the substrate. The intermediate coating film is applied to impart smoothness, chipping resistance, etc., and can be formed by applying the intermediate coating paint and curing or drying it. This intermediate coating paint is not particularly limited, and known paints such as solvent-based intermediate coating paints and water-based intermediate coating paints can be used.

[0066] [First colored coating film] The first colored coating used in the multilayer coating of the present invention is formed by a first colored coating composition containing a first coating-forming resin and an aluminum flake pigment.

[0067] The first colored paint composition of the present invention may be a thermosetting resin composition containing a thermosetting resin as a first film-forming resin, which forms a paint film by a crosslinking reaction that proceeds upon heating after application, or it may be a thermoplastic resin composition containing a thermoplastic resin as a first film-forming resin, which forms a paint film by the volatilization of the solvent. The first film-forming resin can be used by dissolving or dispersing it in an organic solvent and / or a solvent such as water.

[0068] As the first film-forming resin in the first colored paint composition of the present invention, for example, a thermosetting resin composition comprising a base resin and a curing agent can be used. There are no particular restrictions on the content of curing agent solids in this thermosetting resin composition (base resin + curing agent), but it 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 of the total amount of solids of the first film-forming resin. When the first colored paint composition of the present invention is a thermosetting resin composition, it may be a one-component paint composition in which the base resin and curing agent are mixed in advance, or it may be a two-component paint composition in which the base resin and curing agent are mixed immediately before painting.

[0069] Examples of the base resin of the thermosetting resin composition in the first colored coating composition of the present invention include (meth)acrylic resin, polyester resin, polyurethane resin, polyurea resin, (meth)acrylic urethane resin, polyurethane polyurea resin, polyolefin resin (including chlorinated and / or modified resins), epoxy resin, etc., with (meth)acrylic resin, polyester resin, polyurethane resin, and (meth)acrylic urethane resin being particularly noteworthy. Furthermore, the base resin may be a particulate resin in which a portion is crosslinked, or it may be a core / shell type resin particle consisting of an inner (core) part and an outer (shell) part. Examples of particulate base resins include (meth)acrylic resin particles, polyurethane resin particles, polyurethane-polyurea resin particles, (meth)acrylic urethane resin particles, and their core / shell type resin particles. When a particulate resin in which a portion of the base resin is crosslinked is used, the crosslinked portion becomes an insoluble portion (gel portion) in organic solvents, so the degree of crosslinking can be evaluated by measuring the gel fraction, which is a value indicating the proportion of the gel portion in the solid content of the base resin particles.

[0070] In the first colored paint composition, the thermosetting resin composition's base resin is particularly preferably to include (meth)acrylic urethane resin particles, and the (meth)acrylic urethane resin particles are more preferably to include a (meth)acrylic urethane resin having an aldehyde group and / or a ketone group, and a compound having two or more hydrazide groups in one molecule. When a thickener, particularly an inorganic thickener, is also included in the first colored paint composition containing (meth)acrylic urethane resin particles having an aldehyde group and / or a ketone group, the paint viscosity increases due to their interaction. Specifically, by constructing the first colored paint composition with the above materials, an increase in viscosity at low shear rates occurs in the first colored paint composition, and disruption of the orientation of the aluminum flake pigment and / or light-interfering pigment is suppressed from the time the first colored paint composition is applied to the substrate until it is heat-cured. As a result, the orientation of the aluminum flake pigment and / or optically coherent pigment in the resulting coating film is improved. This makes it possible to obtain a multilayer coating film that exhibits both color flop characteristics when the angle of incidence of light is kept constant and the receiving angle is changed from the highlight region to the shade region, and color shift characteristics when the angle of incidence of light is changed from the face angle to the glazing angle.

[0071] The method for producing the (meth)acrylic urethane resin having an aldehyde group and / or a ketone group in the present invention is not particularly limited, and conventional methods described in public documents can be used. For example, one method may involve (1) producing a urethane resin having a radically polymerizable unsaturated bond, and in its presence, (2) radically polymerizing a monomer having a radically polymerizable unsaturated bond and an aldehyde group and / or a ketone group, and optionally (3) other monomers having a radically polymerizable unsaturated bond.

[0072] Examples of monomers having a radically polymerizable unsaturated bond and an aldehyde group and / or a ketone group in the present invention include methyl vinyl ketone, (meth)acrolein, crotonaldehyde, and diacetone (meth)acrylamide.

[0073] (3) Other monomers having a radically polymerizable unsaturated bond in the present invention include, for example, (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, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, styrene, and the like.

[0074] In the present invention, when producing a (meth)acrylic urethane resin having an aldehyde group and / or ketone group by (1) producing a urethane resin having a radically polymerizable unsaturated bond, and then, in the presence of the urethane resin, (2) a monomer having a radically polymerizable unsaturated bond and an aldehyde group and / or ketone group, and optionally (3) other monomers having a radically polymerizable unsaturated bond, the amount of (1) urethane resin having a radically polymerizable unsaturated bond (solids) as a reaction component is preferably 45 to 95 parts by mass, more preferably 55 to 90 parts by mass, and particularly preferably 65 to 85 parts by mass, per 100 parts by mass (solids) of the (meth)acrylic urethane resin having an aldehyde group and / or ketone group produced.

[0075] Furthermore, in the above manufacturing process, the amount of monomer components having radical polymerizable unsaturated bonds and aldehyde and / or ketone groups is preferably 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 and / or ketone groups that is produced.

[0076] Examples of compounds having two or more hydrazide groups in one molecule in the present invention include bishydrazides of dicarboxylic acids having 2 to 12 carbon atoms, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and phthalic acid isomers. Furthermore, examples of polyfunctional hydrazides include nitrilotriacetic acid and ethylenediaminetetraacetic acid.

[0077] In the present invention, there are no particular restrictions on the mixing ratio of the (meth)acrylic urethane resin having aldehyde groups and / or ketone groups in the (meth)acrylic urethane resin particles and the compound having two or more hydrazide groups in one molecule. However, the molar ratio of (aldehyde group + ketone group):(hydrazide group) 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 base 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 a curing agent. Preferred reactive functional groups include, for example, hydroxyl groups and carboxyl groups. These base resins may be used individually or in combination 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. Among these, amino resins, blocked polyisocyanate compounds, and polycarbodiimide compounds are particularly preferred. These curing agents may be used individually or in combination of two or more.

[0080] In this invention, amino resins are a general term for resins obtained by adding formaldehyde to a compound containing an amino group and condensing the mixture. Examples of amino resins include melamine resin, urea resin, and guanamine resin, among which melamine resin is particularly preferred.

[0081] Examples of melamine resins in the present invention include partially or completely methylolated melamine resins obtained by reacting melamine with formaldehyde, partially or completely alkyl ether type melamine resins obtained by partially or completely etherifying the methylol groups of methylolated melamine resin with an alcohol component, imino group-containing melamine resins, and mixed melamine resins obtained by mixing two or more of these melamine resins. Furthermore, examples of alkyl ether type melamine resins include methylated melamine resins, butylated melamine resins, and methyl / butyl mixed alkyl ether type melamine resins.

[0082] Examples of polyisocyanate compounds in the present invention include linear aliphatic diisocyanates such as hexamethylene diisocyanate (HDI) and trimethylhexamethylene 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 dimer acid diisocyanate; and compounds comprising diisocyanate dimers, trimers, or more, such as uretdione, allophanate, adduct, biuret, isocyanurate, and iminooxadiazinedione compounds. Alternatively, aliphatic triisocyanate compounds such as 2-isocyanate ethyl-2,6-diisocyanate caproate (LTI) and 1,8-diisocyanato-4-isocyanatomethyloctane may be used. Furthermore, some of these isocyanate groups may be modified with an amino group-containing silane coupling agent or the like.

[0083] Examples of blocked polyisocyanate compounds in the present invention include those obtained by blocking the isocyanate group of the above-mentioned polyisocyanate compound with, for example, alcohols such as butanol, oximes such as methyl ethyl ketoxime, lactams such as ε-caprolactams, active methylene compounds such as malonic acid diesters and acetoacetate 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, hydrophilic carbodiimide compounds are preferred as polycarbodiimide compounds. Examples of hydrophilic carbodiimide compounds include those obtained by reacting a polycarbodiimide compound containing at least two isocyanate groups in one molecule with a polyol having hydroxyl groups at the molecular ends in a ratio such that the molar ratio of NCO / OH is greater than 1, and then reacting the resulting reaction product with an active hydrogen and a hydrophilizing agent having a hydrophilic portion.

[0085] The first colored coating of the present invention Fee group Examples of thermoplastic resins used in the finished product include acrylic resins, polyester resins, alkyd resins, urethane resins, polyolefin resins (including chlorinated and / or modified ones), epoxy resins, and other thermoplastic resins having a mass-average molecular weight of 30,000 or more.

[0086] The aluminum flake pigment contained in the first colored paint composition of the present invention is a flake-shaped aluminum pigment having a metallic luster, manufactured by a wet ball milling method or the like. When the first colored paint composition is an aqueous paint composition, it is preferable that the aluminum flake pigment is treated to suppress its reaction with water, and it is particularly preferable that its surface is silica-treated. Specific examples of aluminum flake pigments with a silica-treated surface include the "Emerald" series (product name, manufactured by Toyo Aluminum Co., Ltd.) and the "HYDROLAN" series (product name, manufactured by ECKART).

[0087] The aluminum flake pigment of the present invention may include colored aluminum flake pigments. Examples of colored aluminum flake pigments include those in which a coloring pigment is chemically adsorbed onto the surface of the aluminum flake pigment, and those in which a resin layer is further formed thereon. Examples of coloring 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. More specific examples include inorganic pigments such as titanium dioxide, iron oxide, cobalt blue, titanium yellow and other composite oxide pigments, azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolon pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, surene pigments, indigo pigments and other organic pigments, and carbon black. Among these, in the present invention, phthalocyanine-based or slene-based blue pigments are preferred as the coloring pigment used in the colored aluminum flake pigment. Specific examples of preferred colored aluminum flake pigments include Friend Color EMR-D946BA (product name, manufactured by Toyo Aluminum Co., Ltd.).

[0088] The aluminum flake pigment of the present invention may include vapor-deposited aluminum flake pigments. Vapor-deposited aluminum flake pigments are obtained by vapor-depositing an aluminum film onto a base substrate, peeling off the base substrate, and then pulverizing the vapor-deposited aluminum film. Specific examples of preferred vapor-deposited aluminum flake pigments include the "Emerald Shine" series (product name, manufactured by Toyo Aluminum Co., Ltd.) and the "HYDROSHINE" series (product name, manufactured by ECKART).

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

[0090] In this invention, the average particle size D50 is the particle size at which, in the volume-based particle size distribution measured by laser diffraction / scattering (static light scattering method), the total volume of particles from smallest to a certain particle size, expressed as a percentage of the total volume of particles, accounts for 50%. Examples of laser diffraction / scattering (static light scattering method) particle size distribution measuring devices include the Partica LA-960V2 series (product name, manufactured by Horiba, Ltd.), SALD-2300 (product name, manufactured by Shimadzu Corporation), and the MT3000II series (product name, manufactured by Microtrac-Bell Co., Ltd.).

[0091] In the present invention, the content of aluminum flake pigment in the first colored paint composition 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 film-forming resin contained in the first colored paint composition. By setting the content of aluminum flake pigment to 2.5 to 25 parts by mass, a multi-layer coating film can be obtained in which the hue changes significantly within the blue range when the observation angle is changed from the shade region to the highlight region while keeping the angle of incidence of light constant. These aluminum flake pigments may be used individually or in combination of two or more types.

[0092] In the present invention, at least one of the first colored paint composition and the second colored paint composition contains a light-coherent pigment. A light-coherent pigment is a pigment in which a metal oxide with a different refractive index than that of a transparent or translucent flaky substrate, such as various metal oxides, is coated on its surface. Specific examples 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. Among these, the present invention prefers to use blue-based metal oxide-coated mica pigments, blue-based metal oxide-coated alumina flake pigments, and metal oxide-coated silica flake pigments. Specific examples of preferred light-coherent pigments include blue 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, manufactured by MERCK); blue metal oxide coated alumina flake pigments such as XIRALLIC T60-23 WNT Galaxy Blue and XIRALLIC NXT T260-23 WNT Tigris Blue (trade names, manufactured by MERCK); and metal oxide coated 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, manufactured by MERCK).

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

[0094] In the present invention, the content of the light-coherent pigment in the colored paint composition is preferably 2.5 to 20 parts by mass, more preferably 3.5 to 16 parts by mass, and particularly preferably 4.5 to 14 parts by mass, per 100 parts by mass of the resin solids of the first or second film-forming resin contained in the first or second colored paint composition. By setting the content of the light-coherent pigment to 2.5 to 20 parts by mass, a multilayer coating film can be obtained that shows a change in hue even when the angle of incidence of light is changed from the face angle to the glazing angle under observation conditions. These light-coherent pigments may be used individually or in combination of two or more types.

[0095] Furthermore, the first colored paint composition ,a The first colored paint composition may contain coloring pigments other than luminium flake pigments and light-interfering pigments. Examples of coloring pigments used in the first colored paint composition include white pigments, red pigments, orange pigments, yellow pigments, green pigments, blue pigments, purple pigments, and black pigments. More specific examples include inorganic pigments such as titanium dioxide, iron oxide, cobalt blue, titanium yellow and other composite oxide pigments; organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolon pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, surene pigments, indigo pigments, and carbon black. Among these, phthalocyanine or surene blue pigments are preferred as coloring pigments used in the first colored paint composition of the present invention. These coloring pigments may be used individually or in combination of two or more.

[0096] The first colored coating composition of the present invention preferably contains a thickening agent. Known thickening agents can be used, for example, inorganic thickening agents such as silica-based fine powder, mineral-based thickening agents, and barium sulfate fine powder; organic thickening agents such as polyamide-based thickening agents, organic resin fine particle thickening agents, diurea-based thickening agents, urethane association-type thickening agents, acrylic swelling-type polyacrylic acid-based thickening agents, and cellulose-based thickening agents.

[0097] Examples of mineral-based thickeners include swelling layered silicates having a 2:1 crystal structure, and more specifically, natural or synthetic smectite group clay minerals such as montmorillonite, saponite, hectorite, stivunsite, bydelite, nontronite, and bentonite.

[0098] Colored paint composition of the present invention (1) teeth, It is preferable to include an inorganic thickener, and particularly preferable to include a mineral thickener. When the paint contains (meth)acrylic urethane resin particles, especially (meth)acrylic urethane resin particles containing an aldehyde group and / or ketone group and a compound having two or more hydrazide groups in one molecule, the inorganic thickener increases the viscosity of the paint through interaction. Specifically, as described above, an increase in viscosity occurs at low shear rates of the first colored paint composition, and as a result, the orientation of the aluminum flake pigment and / or light-coherent pigment is improved. This makes it possible to obtain a multi-layer coating film in which the hue changes significantly within the blue range when the angle of incidence of light is kept constant and the angle of reception is changed from the highlight region to the shade region, and further changes in hue are observed when the angle of incidence of light is changed from the face angle to the glazing angle. The thickener may be used alone or in combination of two or more types.

[0099] The first colored paint composition of the present invention may further contain, as needed, various paint additives such as organic solvents and / or water, pigment dispersants, anti-settling agents, curing catalysts, defoamers, antioxidants, and ultraviolet absorbers, as well as extender pigments. Examples of organic solvents include organic solvents commonly used in the manufacture of paint compositions, such as aromatic hydrocarbons like toluene, xylene, and aromatic naphtha; ketones like acetone, methyl ethyl ketone, and methyl amyl ketone; esters like ethyl acetate, butyl acetate, 2-butoxyethyl acetate, pentyl acetate, and ethyl ethoxypropionate; alcohols like isopropanol, butanol, 2-butoxyethanol, and 2-ethylhexanol; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons; or mixtures thereof. When a polyisocyanate compound (including blocked ones) is used as a curing agent, a smooth curing reaction can be achieved by limiting the use of alcohol and water as organic solvents.

[0100] The content of nonvolatile components (first film-forming resin solids + aluminum flake pigment + other pigments + paint additive solids) in the first colored paint composition of the present invention during application 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 film thickness of the first colored coating is not particularly limited, but is preferably 3 to 30 μm, more preferably 4 to 25 μm, and particularly preferably 5 to 20 μm.

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

[0103] The second colored paint composition of the present invention may be a thermosetting resin composition containing a thermosetting resin as a second film-forming resin, which forms a paint film by a crosslinking reaction that proceeds upon heating after application, or it may be a thermoplastic resin composition containing a thermoplastic resin as a second film-forming resin, which forms a paint film by the volatilization of the solvent. The second film-forming resin can be used by dissolving or dispersing it in an organic solvent and / or a solvent such as water.

[0104] As the second film-forming resin in the second colored paint composition of the present invention, for example, a thermosetting resin composition comprising a base resin and a curing agent can be used. There are no particular restrictions on the content of curing agent solids in this thermosetting resin composition (base resin + curing agent), but it 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, of the total amount of second film-forming resin solids per 100 parts by mass. When the second colored paint composition of the present invention is a thermosetting resin composition, it may be a one-component paint composition in which the base resin and curing agent are mixed in advance, or it may be a two-component paint composition in which the base resin and curing agent are mixed immediately before painting.

[0105] As the base resin of the thermosetting resin composition in the second colored coating composition of the present invention, for example, the same as those listed as examples of the base resin of the thermosetting resin in the first colored coating composition can be cited.

[0106] The second colored paint composition of the present invention may further contain aluminum flake pigment and / or light-coherent pigment. When the second colored paint composition of the present invention contains aluminum flake pigment and / or light-coherent pigment, the second colored paint composition particularly preferably contains (meth)acrylic urethane resin particles, similar to the first colored paint composition, and more preferably contains (meth)acrylic urethane resin particles comprising a (meth)acrylic urethane resin having an aldehyde group and / or ketone group and a compound having two or more hydrazide groups in one molecule. The (meth)acrylic urethane resin particles, particularly the (meth)acrylic urethane resin particles comprising a (meth)acrylic urethane resin having an aldehyde group and / or ketone group and a compound having two or more hydrazide groups in one molecule, increase the viscosity of the paint through their interaction when an inorganic thickener is included in the paint. Specifically, as described above with respect to the first colored paint composition, an increase in viscosity occurs in the second colored paint composition at low shear rates, resulting in improved orientation of the aluminum flake pigment and / or light-coherent pigment. This makes it possible to obtain a multi-layer coating that exhibits both color flop and color shift characteristics.

[0107] The base 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. Preferred reactive functional groups include, for example, hydroxyl groups, carboxyl groups, epoxy groups, etc. When the first colored coating composition and the second colored coating composition of the present invention contain a thermosetting resin, the base resin of the second colored coating composition may be the same as that of the first colored coating composition, or it may be different. The base resin may be used alone, or two or more may be used in combination.

[0108] As the curing agent for the thermosetting resin composition in the second colored paint composition of the present invention, for example, the same as those listed as examples of curing agents for the thermosetting resin in the first colored paint composition can be used. When the first colored paint composition and the second colored paint composition of the present invention contain a thermosetting resin, the curing agent for the second colored paint composition may be the same as that for the first colored paint composition, or it may be different. The curing agent may be used alone, or two or more may be used in combination.

[0109] As the thermoplastic resin in the second colored coating composition of the present invention, for example, the same as the thermoplastic resin given as an example in the first colored coating composition can be used. When the first colored coating composition and the second colored coating composition of the present invention contain a thermoplastic resin, the thermoplastic resin in the second colored coating composition may be the same as that in the first colored coating composition, or it may be different.

[0110] The second colored coating composition of the present invention contains a blue pigment. By forming a second colored coating film containing a blue pigment on a first colored coating film containing an aluminum flake pigment, a multi-layer coating film having a high-saturation blue color can be obtained. The blue pigment in the second colored coating composition of the present invention is not particularly limited as long as it is blue, but examples include phthalocyanine-based pigments, anthraquinone-based pigments, dioxazine-based pigments, surene-based pigments, indigo-based blue pigments, etc., and among these, phthalocyanine-based or surene-based blue pigments are preferred. The blue pigment may be used alone or in combination of two or more types.

[0111] The amount of blue pigment in the second colored paint 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, based on 100 parts by mass of the total amount of the second film-forming resin solids contained in the second colored paint composition.

[0112] Furthermore, if the second colored paint composition contains a colored aluminum flake pigment using a blue pigment, the amount of blue pigment used in the colored aluminum flake pigment shall not be included in the amount of blue pigment in the second colored paint composition.

[0113] In the present invention, as described above, at least one of the first colored paint composition and the second colored paint composition contains a light-coherent pigment. Examples of preferred light-coherent pigments, the average particle size (D50) of the light-coherent pigment, and the content of the light-coherent pigment in the colored paint composition are also as described above. When both the first colored paint composition and the second colored paint composition contain a light-coherent pigment, the light-coherent pigment in the second colored paint composition may be the same as that in the first colored paint composition, or it may be different. The light-coherent pigment may be used alone, or two or more may be used in combination.

[0114] The second colored paint composition of the present invention may contain an aluminum flake pigment. Examples of preferred aluminum flake pigments, the average particle size (D50) of the aluminum flake pigment, and the content of the aluminum flake pigment in the colored paint composition are as described above. When the second colored paint composition contains an aluminum flake pigment, the same aluminum flake pigment as in the first colored paint composition may be used, or a different one may be used. The aluminum flake pigment may be used alone, or in combination of two or more types.

[0115] The second colored paint composition of the present invention may contain colored pigments other than blue pigment, light-interfering pigment, and aluminum flake pigment. Examples of colored pigments used in the second colored paint composition include white pigment, red pigment, orange pigment, yellow pigment, green pigment, purple pigment, and black pigment. More specific examples include inorganic pigments such as titanium dioxide, iron oxide, cobalt blue, and titanium yellow composite oxide pigments; organic pigments such as azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, benzimidazolon pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, surene pigments, indigo pigments, and carbon black. These colored pigments may be used individually or in combination of two or more.

[0116] If the second colored paint composition of the present invention contains an aluminum flake pigment and / or a light-interfering pigment, it is preferable that the second colored paint composition, like the first colored paint composition, contains a thickening agent. Examples of thickening agents in the second colored paint composition of the present invention are the same as those given as examples of thickening agents in the first colored paint composition.

[0117] The second colored coating composition of the present invention, like the first colored coating composition, preferably contains an inorganic thickener, and particularly preferably contains a mineral thickener. When the coating contains (meth)acrylic urethane resin particles, particularly (meth)acrylic urethane resin particles containing an aldehyde group and / or ketone group and a compound having two or more hydrazide groups in one molecule, the inorganic thickener increases the viscosity of the coating through its interaction. Specifically, as described above with respect to the first colored coating composition, the viscosity of the second colored coating composition increases at low shear rates, and as a result, the orientation of the aluminum flake pigment and / or light-coherent pigment is improved. By improving the orientation of the aluminum flake pigment and / or light-coherent pigment, a multilayer coating film exhibiting both color flop and color shift properties can be obtained. The thickener of the second colored coating composition may be the same as that of the first colored coating composition, or it may be different. The thickener may be used alone, or two or more may be used in combination.

[0118] The second colored paint composition of the present invention may further contain, as needed, various paint additives such as organic solvents and / or water, pigment dispersants, anti-settling agents, curing catalysts, defoamers, antioxidants, and ultraviolet absorbers, as well as extender pigments. Examples of organic solvents include organic solvents commonly used in the manufacture of paint compositions, such as aromatic hydrocarbons like toluene, xylene, and aromatic naphtha; ketones like acetone, methyl ethyl ketone, and methyl amyl ketone; esters like ethyl acetate, butyl acetate, 2-butoxyethyl acetate, pentyl acetate, and ethyl ethoxypropionate; alcohols like isopropanol, butanol, 2-butoxyethanol, and 2-ethylhexanol; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons; or mixtures thereof. When a polyisocyanate compound (including blocked ones) is used as a curing agent, a smooth curing reaction can be achieved by limiting the use of alcohol and water as organic solvents.

[0119] The content of nonvolatile components (second film-forming resin solids + blue pigment + other pigments + paint additive solids) in the second colored paint composition of the present invention 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 paint composition of the present invention can be applied by methods such as electrostatic coating, air spraying, and airless spraying.

[0121] The dry film thickness of the second colored coating is not particularly limited, but is preferably 3 to 60 μm, more preferably 4 to 55 μm, and especially preferably 5 to 50 μm.

[0122] [Clear coating] The multilayer coating of the present invention may have a clear coating on the second colored coating. The clear coating used in the present invention is formed by a clear coating composition containing a coating-forming resin (also called a clear coating-forming resin).

[0123] As the clear coating film-forming resin for the clear coating composition of the present invention, a thermosetting resin composition is preferred, which forms a coating film by undergoing a crosslinking reaction upon heating after application. The clear coating film-forming resin can be used by dissolving or dispersing it in an organic solvent and / or a solvent such as water.

[0124] As the thermosetting resin composition in the clear coating composition of the present invention, for example, a thermosetting resin composition comprising a base resin and a curing agent can be used. There are no particular restrictions on the content of curing agent solids in this thermosetting resin composition (base resin + curing agent), but it 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 of the total amount of clear coating film forming resin solids. The clear coating composition of the present invention may be a one-component coating composition in which the base resin and curing agent are mixed in advance, or a two-component coating composition in which the base resin and curing agent are mixed immediately before painting.

[0125] Examples of base resins in the clear coating composition of the present invention include (meth)acrylic resin, polyester resin, polyurethane resin, and (meth)acrylic urethane resin. Furthermore, it is preferable that the base resin has one or more functional groups selected from hydroxyl groups, carboxyl groups, and epoxy groups. These base resins may be used individually or in combination of two or more.

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

[0127] Specific examples of the amino resin, polyisocyanate compound, and blocked polyisocyanate compound used as curing agents in the clear coating composition of the present invention include those listed in the examples of curing agents for the thermosetting resin composition in the first colored coating composition. If either the first colored coating composition or the second colored coating composition of the present invention is a thermosetting resin composition, the curing agent for the clear coating composition may be the same as those used therein, or it may be different. These curing agents may be used individually or in combination of two or more.

[0128] The clear coating composition of the present invention may further contain, as needed, various coating additives such as organic solvents and / or water, thickeners, pigment dispersants, anti-settling agents, curing catalysts, defoamers, antioxidants, and ultraviolet absorbers, as well as extender pigments and coloring pigments in amounts that do not impair transparency. Examples of organic solvents include organic solvents commonly used in the manufacture of coating compositions, such as aromatic hydrocarbons like toluene, xylene, and aromatic naphtha; ketones like acetone, methyl ethyl ketone, and methyl amyl ketone; esters like ethyl acetate, butyl acetate, 2-butoxyethyl acetate, pentyl acetate, and ethyl ethoxypropionate; alcohols like isopropanol, butanol, 2-butoxyethanol, and 2-ethylhexanol; ethers; aliphatic hydrocarbons including chlorinated hydrocarbons; or mixtures thereof. When a polyisocyanate compound (including blocked ones) is used as a curing agent, a smooth curing reaction can be achieved by limiting the use of alcohol and water as organic solvents.

[0129] The content of non-volatile components (clear film-forming resin solids + paint additive solids + pigments) in the clear coating composition of the present invention 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 film thickness of the clear coating is not particularly limited, but is preferably 15 to 60 μm, more preferably 20 to 55 μm, and particularly preferably 25 to 50 μm.

[0131] The multilayer coating film and method for forming a multilayer coating film of the present invention are applicable to the bodies, components, and parts of vehicles such as passenger cars, trucks, motorcycles, and buses, and are particularly effective for use on metal automobile bodies and plastic automobile parts. Furthermore, the multilayer coating film and method for forming a multilayer coating film of the present invention are not limited by the technical field and can be applied to vehicles other than automobiles, as well as buildings and the like. [Examples]

[0132] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, unless otherwise specified, "parts" means "parts by mass," and "%" in relation to blending amount and content means "mass%."

[0133] <Manufacturing Example 1: Manufacturing of Polyurethane Resin Dispersion PU-1 for Water-Based Colored Paint Compositions> 1-(1) Preparation of polyester polyol solution PP-1 In a flask equipped with a reflux condenser with a reaction water separation tube, a thermometer, a stirrer, and a nitrogen gas inlet tube, 35.0 parts of dimer acid PRIPOL1017 (trade name, Croda Corporation), whose main component is a C36 dicarboxylic acid produced by the dimerization of a C18 unsaturated fatty acid, 30.0 parts of isophthalic acid, 0.6 parts of adipic acid, 33.6 parts of 1,6-hexanediol, and 0.8 parts of trimethylolpropane were charged. The mixture was heated to 120°C to dissolve the raw materials, and then heated to 160°C while stirring. After being maintained at 160°C for 1 hour, the mixture was heated to 230°C over 5 hours. The resin acid value was measured periodically while maintaining the mixture at 230°C, and when the resin acid value reached 4 mg KOH / g, it was cooled to below 80°C. Finally, 60.8 parts of methyl ethyl ketone were added to obtain polyester polyol solution PP-1. The characteristic values ​​of the polyester polyol solution PP-1 were 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.

[0134] 1-(2) Production of polyurethane resin dispersion PU-1 In a flask equipped with a thermometer, a stirrer, and a nitrogen gas inlet tube, 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 were charged, and the mixture was heated to 80°C while stirring. At 80°C, 24.0 parts of isophorone diisocyanate were added, and the temperature was maintained at 80°C. When the isocyanate content of the solution reached 0.40 mmol / g, 3.2 parts of trimethylolpropane were added, and the temperature was maintained at 80°C. Next, when the isocyanate content of the solution reached 0.03 mmol / g, 5.2 parts of 2-butoxyethanol were added, the mixture was cooled to 50°C, and then 3.3 parts of dimethylethanolamine were added to neutralize the acidic groups, followed by the addition of 150.0 parts of deionized water. The mixture was then heated to 100°C, and the methyl ethyl ketone was removed under reduced pressure to obtain polyurethane resin dispersion PU-1. The characteristic values ​​of the polyurethane resin dispersion PU-1 were 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.

[0135] <Manufacturing Example 2: Manufacturing of Polyester Resin Solution PE-1 for Water-Based Colored Paint Composition> In a flask equipped with a reflux condenser with a reaction water separation tube, a thermometer, a stirrer, and a nitrogen gas inlet tube, 15.0 parts of the above-mentioned dimer acid PRIPOL1017 (trade name, manufactured by Croda), 30.0 parts of phthalic anhydride, 3.1 parts of adipic acid, 31.5 parts of 1,6-hexanediol, and 10.3 parts of trimethylolpropane were charged. The mixture was heated to 120°C to dissolve the raw materials, and then heated to 160°C while stirring. After holding at 160°C for 1 hour, the mixture was heated to 230°C over 5 hours, held at 230°C for 2 hours, and then cooled to 180°C. Next, 10 parts of trimellitic anhydride were added, and the resin acid value was measured periodically while maintaining the temperature at 180°C. When the resin acid value reached 25 mg KOH / g, the mixture was cooled to below 80°C. After adding 25 parts of 2-butoxyethanol, 3.2 parts of dimethylethanolamine were added to neutralize the acid group, and 34.1 parts of deionized water were added to obtain polyester resin solution PE-1. The characteristic values ​​of polyester resin solution PE-1 were 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.

[0136] <Manufacturing Example 3: Manufacturing of (meth)acrylic urethane resin dispersion AU-1 for water-based colored paint compositions> 3-(1) Preparation of polyester polyol solution PP-2 In a flask equipped with a reflux condenser with a reaction water separation tube, a thermometer, a stirrer, and a nitrogen gas inlet tube, 49.9 parts of adipic acid, 18.5 parts of 1,6-hexanediol, and 31.6 parts of neopentyl glycol were charged, and the mixture was heated to 160°C under a nitrogen stream while stirring. After holding at 160°C for 1 hour, the mixture was heated to 230°C over 5 hours. The resin acid value was measured periodically while maintaining the mixture at 230°C, and when the resin acid value reached 3.5 mg KOH / g, it was cooled to 80°C. Finally, 21.9 parts of methyl ethyl ketone were added to obtain polyester polyol solution PP-2. The characteristic values ​​of polyester polyol solution PP-2 were an acid value of 3.5 mg KOH / g, a hydroxyl value of 155 mg KOH / g, and a resin solid content of 80% by mass.

[0137] 3-(2) Preparation of (meth)acrylic urethane resin dispersion AU-1 In a flask equipped with two dropping devices, a reflux condenser, a thermometer, a stirrer, and a nitrogen gas inlet tube, 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 parts of dibutyltin dilaurate, and 195.7 parts of methyl ethyl ketone were charged, and the mixture was stirred under a nitrogen stream until homogenized.

[0138] Next, 259.9 parts of isophorone diisocyanate were added to the obtained solution. After the exothermic reaction subsided, the reaction mixture was gradually heated to 80°C while stirring, and stirring continued at this temperature until the amount of isocyanate in the solution reached 0.60 mmol / g. Then, 66.7 parts of trimethylolpropane were added, and the mixture was stirred at 80°C until no free isocyanate groups were detected in the solution. Subsequently, 248.9 parts of methyl ethyl ketone were added to the obtained polyurethane solution.

[0139] Next, the temperature was adjusted to 82°C, and a mixture of radical polymerizable monomers consisting of 312.5 parts n-butyl acrylate, 312.5 parts methyl methacrylate, 74.7 parts 2-hydroxypropyl methacrylate, and 58.4 parts acrylic acid was added dropwise at a constant rate over 3 hours using one dropping device. Simultaneously with the addition using the first dropping device, a polymerization initiator solution consisting of 22.8 parts 2,2'-azobis(methylbutyronitrile) and 152.3 parts methyl ethyl ketone was added dropwise at a constant rate over 3.5 hours using the other dropping device.

[0140] After the dropwise addition of the monomer mixture and polymerization initiator solution was complete, the resulting reaction mixture was stirred at 82°C for a further 2.5 hours, and 56.9 parts of dimethylethanolamine and 2242 parts of deionized water were added. Subsequently, a separation tube was attached to a reflux condenser, and desolvation was carried out under reduced pressure at 45°C until the resin solids content of the dispersion reached 40% by mass, to obtain (meth)acrylic urethane resin aqueous dispersion AU-1. The obtained (meth)acrylic urethane resin dispersion 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.

[0141] <Production Example 4: Production of (meth)acrylic urethane resin particle dispersion AU-2 containing an (meth)acrylic urethane resin having aldehyde groups and / or ketone groups for water-based colored paint compositions and a compound having two or more hydrazide groups per molecule> 4-(1) Preparation of polyester polyol solution PP-3 In a flask equipped with a reflux condenser with a reaction water separation tube, a thermometer, a stirrer, and a nitrogen gas inlet tube, 109.7 parts of adipic acid, 128.5 parts of 1,6-hexanediol, and 26.5 parts of isophthalic acid were charged, and the mixture was heated to 160°C under a nitrogen stream while stirring. After holding at 160°C for 1 hour, the mixture was heated to 230°C over 5 hours. The resin acid value was measured periodically while maintaining the mixture at 230°C, and when the resin acid value reached 2.0 mgKOH / g, it was cooled to 80°C. Finally, 25.8 parts of N-methyl-2-pyrrolidone were added to obtain polyester polyol solution PP-3. The characteristic values ​​of polyester polyol solution PP-3 were an acid value of 2.0 mgKOH / g, a hydroxyl value of 88 mgKOH / g, and a resin solid content of 90% by mass.

[0142] 4-(2) Preparation of (meth)acrylic urethane resin particle dispersion AU-2 In a flask equipped with a dropping device, reflux condenser, thermometer, stirrer, and nitrogen gas inlet tube, 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 were charged, and the mixture was stirred under a nitrogen stream until homogenized.

[0143] Next, the temperature was adjusted to 90°C, and 73.9 parts of isophorone diisocyanate were added over 30 minutes, followed by stirring at this temperature for 1 hour. Then, 80.0 parts of methyl methacrylate and 0.2 parts of 2,6-di-tert-butyl-4-methylphenol were added and homogenized. Subsequently, at 90°C, 41.3 parts of isophorone diisocyanate were added over 10 minutes, and stirring was continued until the isocyanate content of the solution reached 1.11% by mass. Then, 25.3 parts of 2-hydroxyethyl methacrylate were added, and the mixture was stirred at 90°C until no free isocyanate groups were detected in the solution.

[0144] Next, 37.3 parts of methyl methacrylate, 16.0 parts of diacetone acrylamide, and 11.4 parts of dimethylethanolamine were added, followed by the addition of 658.0 parts of 70°C warm water under vigorous stirring. Then, the temperature was adjusted to 80°C, and 0.7 parts of tert-butyl hydroperoxide (80% by mass of di-tert-butyl peroxide) were added and stirred for 30 minutes. After that, 1.3 parts of ascorbic acid dissolved in 130.0 parts of water were added over 90 minutes.

[0145] After cooling to room temperature, 8.2 parts of dihydrazide adipic acid dissolved in 100 parts of water were added under stirring to obtain (meth)acrylic urethane resin particle dispersion AU-2. The obtained (meth)acrylic urethane resin dispersion AU-2 had an acid value of 18 mg KOH / g, a hydroxyl value of 5 mg KOH / g, a resin solids content of 36% by mass, a pH of 7.5, and a gel fraction of 88%.

[0146] <Manufacturing Example 5: Manufacturing of Blue Pigment Paste WP-1 for Water-Based Colored Paint Composition> 100.0 parts of (meth)acrylic urethane resin dispersion AU-1, 40.0 parts of Heliogen Blue L 6900 (trade name, manufactured 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 to obtain aqueous blue pigment paste WP-1.

[0147] <Manufacturing Example 6: Manufacturing of Blue Pigment Paste WP-2 for Water-Based Colored Paint Compositions> In manufacturing example 5, Lionol Blue ESP-05 (product name, manufactured by Toyo Color Co., Ltd., phthalocyanine-based blue pigment) was used instead of Heliogen Blue L 6900 to obtain the aqueous blue pigment paste WP-2.

[0148] <Manufacturing Example 7: Manufacturing of Blue Pigment Paste WP-3 for Water-Based Colored Paint Compositions> In manufacturing example 5, Hostaperm Blue BT-729-D (trade name, manufactured by Heubach, phthalocyanine-based blue pigment) was used instead of Heliogen Blue L 6900 to obtain the aqueous blue pigment paste WP-3.

[0149] <Manufacturing Example 8: Manufacturing of Blue Pigment Paste WP-4 for Water-Based Colored Paint Composition> In manufacturing example 5, Paliogen Blue L 6484 (trade name, manufactured by Sun Chemical Colors & Effects, a vat-based blue pigment) was used instead of Heliogen Blue L 6900 to obtain the aqueous blue pigment paste WP-4.

[0150] <Production Example 9: For water-based colored paint compositions blue Manufacturing of pigment paste WP-5 > In manufacturing example 5, Heliogen Blue L 6600 F (trade name, manufactured by Sun Chemical Colors & Effects, phthalocyanine-based blue pigment) was used instead of Heliogen Blue L 6900 to obtain the aqueous blue pigment paste WP-5.

[0151] <Manufacturing Example 10: Manufacturing of WP-6 purple pigment paste for water-based colored paint compositions> In manufacturing example 5, Hostaperm Violet BL01 (trade name, manufactured by Heubach, dioxazine-based purple pigment) was used instead of Heliogen Blue L 6900 to obtain a water-based purple pigment paste WP-6.

[0152] <Manufacturing Examples 11-18: Manufacturing of Water-Based First Color Paint Compositions WBBC1-1 to WBBC1-8> The components listed in Table 1 were mixed in the order indicated and stirred for 30 minutes. Next, dimethylethanolamine was added to adjust the pH to 8.2. Then, deionized water was added, and the mixture was measured using a Rheomat RM180 rotational viscometer (trade name, manufactured by METTLER TOLEDO) at 20°C and a shear rate of 1000 s. -1 The viscosity measured was adjusted to 100 mPa·s to obtain the first water-based colored paint compositions WBBC1-1 to WBBC1-8.

[0153] [Table 1]

[0154] 1) Melamine resin solution: Cymel 327 (trade name, manufactured by Ornex, resin solids content 90% by mass) 2) Inorganic thickener: A mixture of 3 parts by mass of Laponite RD (trade name, manufactured by Bic Chemie, synthetic hectorite), 3 parts by mass of Pluriol P900 (trade name, manufactured by BASF, polypropylene glycol), and 94 parts by mass of deionized water. 3) Alkaline swelling emulsion: Rheovis AS 1130 (product name, manufactured by BASF) 4) Aqueous surface conditioning agent solution: Surfinol 104PA (trade name, manufactured by Evonik Industries, active ingredient 50% by mass, acetylene glycol) 5) Aluminum flake pigment paste 1: STAPA IL HYDROLAN 2192 (product name, manufactured by ECKART, average particle size (D50) 16 μm, non-volatile content 60%) 6) Aluminum flake pigment paste 2: Emeral EMR-EX5620 (product name, manufactured by Toyo Aluminum Co., Ltd., average particle size (D50) 18 μm, non-volatile content 60%) 7) Aluminum flake pigment paste 3: Emeral EMR-EX7671 (product name, manufactured by Toyo Aluminum Co., Ltd., average particle size (D50) 16 μm, non-volatile content 52%) 8) Optically coherent pigment 1: XIRALLIC T60-23 WNT Galaxy Blue (product name, manufactured by MERCK, average particle size (D50) 19 μm)

[0155] <Manufacturing Examples 19-24: Manufacturing of Water-Based Secondary Coloring Coating Compositions WBBC2-1-WBBC2-6> The components listed in Table 2 were mixed in the order indicated and stirred for 30 minutes. Next, dimethylethanolamine was added to adjust the pH to 8.2. Then, deionized water was added, and the mixture was measured using a Rheomat RM180 rotational viscometer (trade name, manufactured by METTLER TOLEDO) at 20°C and a shear rate of 1000 s. -1 The viscosity measured was adjusted to 100 mPa·s to obtain the water-based second colored paint compositions WBBC2-1 to WBBC2-6.

[0156] [Table 2]

[0157] 9) Optically coherent pigment 2: IRIODIN 221 WNT (trade name, manufactured by MERCK, average particle size (D50) 12 μm) 10) Optically coherent pigment 3: COLORSTREAM T20-01 WNT Viola Fantasy (product name, manufactured by MERCK, average particle size (D50) 20 μm) 11) Optical interference pigment 4: COLORSTREAM T20-02 WNT Arctic Fire (trade name, manufactured by MERCK, average particle size (D50) 18μm

[0158] <Manufacturing Example 25: Manufacturing of (meth)acrylic resin solution AC-1 for solvent-based colored paint compositions> 33.9 parts xylene was charged into a flask equipped with two dropping devices, a reflux condenser, a thermometer, a stirrer, and a nitrogen gas inlet tube, and heated under a nitrogen stream while stirring to maintain a temperature of 140°C. Next, at a temperature of 140°C, a mixture of radical polymerizable monomers consisting of 23.9 parts 4-hydroxybutyl acrylate, 10.0 parts styrene, 19.0 parts isobutyl methacrylate, 6.2 parts cyclohexyl methacrylate, and 0.9 parts methacrylic acid was added dropwise at a constant rate over 2 hours using one of the dropping devices. Simultaneously with the addition using the first dropping device, 5.0 parts of the polymerization initiator t-butyl peroxy-2-ethylhexanoate were added dropwise at a constant rate over 2 hours using the other dropping device. After the addition of the monomer mixture and polymerization initiator was complete, the temperature was maintained at 140°C for 1 hour, and then the reaction temperature was lowered to 110°C. Subsequently, 0.1 parts of t-butyl peroxy-2-ethylhexanoate were dissolved in 1.0 part of xylene and added as an additional catalyst as a polymerization initiator. After maintaining a temperature of 110°C for 2 hours, the mixture was cooled to obtain (meth)acrylic resin solution AC-1. The characteristic values ​​of (meth)acrylic resin solution AC-1 were a mass-average molecular weight of 7,000, an acid value of 9.8 mg KOH / g, a hydroxyl value of 155 mg KOH / g, a glass transition temperature of -10°C, and a resin solids content of 60%.

[0159] <Manufacturing Example 26: Manufacturing of blue pigment paste SP-1 for solvent-based colored paint compositions> As a dispersion resin, 100.0 parts of (meth)acrylic resin solution AC-1, 60.0 parts of Heliogen Blue L 6900 (trade name, manufactured by Sun Chemical Colors & Effects, phthalocyanine-based blue pigment), and 140.0 parts of xylene were mixed and then dispersed in a motor mill to obtain solvent-based blue pigment paste SP-1.

[0160] <Manufacturing Example 27: Manufacturing of Solvent-Based Second Coloring Coating Composition SBCC2-1> From the raw materials listed in Table 3, (meth)acrylic resin solution AC-1, blue pigment paste SP-1, and additive solutions (ultraviolet absorber solution, light stabilizer solution, and surface modifier solution) were mixed and stirred until homogeneous. Next, the polyisocyanate compounds listed in Table 3 were added to the mixture and stirred again until homogeneous. Then, the resulting mixture was diluted with Solvesso 100 (trade name, ExxonMobil) so that the viscosity of the Ford Cup #4 of the mixture was 25 seconds at 20°C to obtain the solvent-based second colored paint composition SBCC2-1.

[0161] [Table 3]

[0162] 12) UV absorber solution: 20% by mass xylene solution of Tinuvin 900 (trade name, manufactured by BASF, benzotriazole-based UV absorber) 13) Light stabilizer solution: 20% by mass xylene solution of Tinuvin 292 (trade name, manufactured by BASF, hindered amine light stabilizer) 14) Solvent-based surface modifier solution: 10% by mass xylene solution of BYK-300 (product name, manufactured by Bic Chemie Japan Co., Ltd., silicone-based surface modifier) 15) Polyisocyanate compound: Desmodulo N3300 (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., isocyanurate of hexamethylene diisocyanate (HDI), non-volatile content 100% by mass, NCO content 21.8% by mass)

[0163] [Method for measuring resin property values] In this invention, the resin property values ​​were measured by the following method.

[0164] 1.Mass average molecular weight The mass-average molecular weight was determined by gel permulation chromatography (GPC) using tetrahydrofuran (THF) as the eluent, under conditions of 40°C and a flow rate of 1 m / min, using a differential refractometer (Refractive Index detector). The data was then converted to a value based on the mass-average molecular weight of polystyrene. The GPC columns used were a combination of TSKgel G2000HXL, G3000HXL, G4000HXL, and G5000HXL (product names, manufactured by Tosoh Corporation).

[0165] 2. Acid value Measurements were taken in accordance with JIS-K5601-2-1:1999.

[0166] 3. Hydroxyl value Measurements were taken in accordance with JIS-K1557-1:2007.

[0167] 4. Resin solids The resin solid content was determined by measuring the mass of 1.0 g of the sample after heating it at 130°C for 60 minutes.

[0168] 5. Gel fraction First, 1.0 g of the sample was heated at 130°C for 60 minutes, and its mass was measured. Next, the heated sample was immersed in excess tetrahydrofuran at 25°C for 24 hours to extract the dissolved components. Subsequently, the gel fraction was determined by measuring the mass of the remaining insoluble components after drying at 50°C for 4 hours.

[0169] <Examples 1-5 and Comparative Examples 1-4> [Preparation of test coating plates] A zinc phosphate-treated cold-rolled steel sheet (150mm (length) x 75mm (width) x 0.8mm (thickness)) (also called a steel sheet) was electrodeposited with cationic electrodeposition paint Casoguard No. 500 (product name, manufactured by BASF Japan Ltd.) to a dry film thickness of 20 μm, and then heated at 170°C for 30 minutes to cure. Subsequently, a water-based intermediate coating composition ProBloc N-3000 N3.5-3(W) (product name, manufactured by BASF Japan Ltd.) was electrostatically applied to a dry film thickness of 20 μm, left at room temperature for 5 minutes, and then heated at 140°C for 30 minutes to create an intermediate coating sheet.

[0170] Next, for Examples 1-4, Comparative Example 1, and Comparative Example 3, the water-based first coloring paint compositions WBBC1-1 to WBBC1-3, WBBC1-5, and WBBC1-7 described in Table 1 were electrostatically coated onto the intermediate coating boards to a dry film thickness of 7 μm, and left at room temperature for 3 minutes.

[0171] Next, the water-based second color coating compositions WBBC2-1 to WBBC2-6 described in Table 2 were electrostatically applied onto the uncured water-based first color coating film to a dry film thickness of 7 μm, left at room temperature for 5 minutes, and then pre-dried (flash-off) at 80°C for 3 minutes. Subsequently, the solvent-based clear coating composition ProGloss HD-N(W) (trade name, manufactured by BASF Japan Ltd., two-component acrylic / urethane coating) was electrostatically applied to a dry film thickness of 35 μm, left at room temperature for 10 minutes, and then heated at 140°C for 30 minutes to obtain a test coated plate with a multi-layer coating film formed on the steel plate.

[0172] Furthermore, for Example 5 and Comparative Example 2, the water-based first coloring paint compositions WBBC1-4 and WBBC1-6 described in Table 1 were electrostatically coated onto the intermediate coating plate to a dry film thickness of 14 μm, left at room temperature for 5 minutes, and then pre-dried (flash-off) at 80°C for 3 minutes. Next, the solvent-based second coloring paint composition SBCC2-1 described in Table 3 was electrostatically coated to a dry film thickness of 30 μm, left at room temperature for 10 minutes, and then heated at 140°C for 30 minutes to obtain a test coated plate in which a multi-layer coating film was formed on the steel plate.

[0173] Furthermore, for Comparative Example 4, the water-based first coloring paint composition WBBC1-8 described in Table 1 was electrostatically coated onto the intermediate coating plate to a dry film thickness of 14 μm, left at room temperature for 5 minutes, and then pre-dried (flash-off) at 80°C for 3 minutes. Next, the solvent-based clear coating composition ProGloss HD-N(W) (trade name, manufactured by BASF Japan Ltd., two-component acrylic / urethane paint) was electrostatically coated to a dry film thickness of 30 μm, left at room temperature for 10 minutes, and then heated at 140°C for 30 minutes to obtain a test coated plate with a multi-layer coating formed on the steel plate.

[0174] <Measurement of hue angle h(45 / 0), saturation C*(45 / 0), hue angle difference |h(45 / 30)-h(45 / -30)|, and hue angle difference |h(10 / 0)-h(70 / 60)|> [evaluation] The following evaluations were performed on the test coated panels of Examples 1-5 and Comparative Examples 1-4, and the results are shown in Table 4.

[0175] Furthermore, in order to facilitate understanding of the layer structure of the test coatings for each example and comparative example, the type of colored coating composition used and whether or not a clear coating composition was used are listed in Table 4.

[0176] [Table 4]

[0177] Solvent-based clear coating composition: ○: Used ×: Not used

[0178] <Measurement of hue angle h(45 / 0)> Measurements were taken using a multi-angle colorimeter BYKmac i (product name, manufactured by BYK-Gardner) with a light incidence angle of 45 degrees and a light reception angle of 0 degrees relative to the normal of the multi-layer coating.

[0179] <Measurement of saturation C*(45 / 0)> Measurements were taken using a multi-angle colorimeter BYKmac i (product name, manufactured by BYK-Gardner) with a light incidence angle of 45 degrees and a light reception angle of 0 degrees relative to the normal of the multi-layer coating.

[0180] <Measurement of hue angle difference |h(45 / 30)-h(45 / -30)|> Using a multi-angle colorimeter BYKmac i (product name, manufactured by BYK-Gardner), the hue angle h(45 / 30) was measured at an incident angle of 45 degrees and a receiving angle of 30 degrees relative to the normal of the multi-layer coating film, and the hue angle h(45 / -30) was measured at an incident angle of 45 degrees and a receiving angle of -30 degrees. The difference between the hue angle h(45 / 30) and the hue angle h(45 / -30) was then calculated.

[0181] <Measurement of hue angle difference |h(10 / 0)-h(70 / 60)|> Using the Gonio Spectrophotometric Color Measurement System GSP-2 (product name, manufactured by Murakami Color Materials Research Institute Co., Ltd.), the hue angle h(10 / 0) ​​at an incident angle of 10 degrees and a receiving angle of 0 degrees relative to the normal of a multi-layer coating film, and the hue angle h(70 / ) at an incident angle of 70 degrees and a receiving angle of 60 degrees, were measured. 60 ) was measured, and the hue angle h(10 / 0) ​​and hue angle h(70 / 60 The difference between ) was calculated.

[0182] <Visual inspection> Visual inspection of the multi-layer coating was conducted by a total of five people: two designers and three engineers, each with more than three years of experience in color development. They observed color flop and color shift.

[0183] The color flop was observed using a BYK-Gardner BYK-Spectra Effect (product name), a light source booth with a variable-angle stage. This device allows for observation within a range of 60 to -65 degrees (where the incident light is irradiated at a 45-degree angle relative to the normal to the multi-layer coating), enabling observation within a range of 60 to -65 degrees relative to the normal to the multi-layer coating. Note that in this device, the receiving angle is displayed as the angle relative to the specularly reflected light (incident light direction is positive), so the receiving angle displayed on this device ranges from -15 to 110 degrees.

[0184] As explained using Figure 2, the observation of the color flop was performed sequentially at the highlight angle (HL), where the incident angle was 45 degrees relative to the normal n of the multilayer coating and the receiving angle was 30 degrees (corresponding to 15 degrees on the display of this device), and at the shade angle (SH), where the incident angle was 45 degrees relative to the normal n of the multilayer coating and the receiving angle was -30 degrees (corresponding to 75 degrees on the display of this device).

[0185] Furthermore, the color shift was observed using the face angle (incident angle approximately 10 degrees, receiving angle approximately 0 degrees) and glazing angle (incident angle approximately 70 degrees, receiving angle approximately 60 degrees), as explained using Figures 4(a) and 4(b). For the color shift observation, an artificial sun lamp XC-100CF (product name, manufactured by Seric Co., Ltd.) was used as the light source. The above observations were evaluated according to the following criteria, and the score given by the most people was used as the evaluation score for the multi-layer coating.

[0186] 4: Can recognize both color flops and color shifts.

[0187] 3: Color flops can be recognized, but color shifts cannot.

[0188] 2: Color flops cannot be recognized, but color shifts can.

[0189] 1: Unable to recognize both color flops and color shifts.

[0190] Although the present invention has been specifically described above based on embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence. [Explanation of Symbols]

[0191] 1. Multilayer coating 1a surface n normal vector IL incident light RL Specular reflection light P Light receiving position P1, P2, P3 Observers HL Highlight (Position) / Highlight Angle SH Shade (Position) / Shade Angle

Claims

1. It has a first colored coating film and a second colored coating film provided on the first colored coating film, The first colored coating film is formed from a first colored paint composition, and the second colored coating film is formed from a second colored paint composition, forming a multilayer coating film. 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 the second colored coating contains a light-interfering pigment, The content of aluminum flake pigment in the first colored paint composition is 3.5 to 15 parts by mass per 100 parts by mass of the resin solids of the first film-forming resin contained in the first colored paint composition. The content of the light-interfering pigment in at least one of the first colored paint composition and the second colored paint composition is 4.5 to 14 parts by mass per 100 parts by mass of the resin solids of the first film-forming resin contained in the first colored paint composition or the second film-forming resin contained in the second colored paint composition. The hue angle h(45 / 0), measured with a light incidence angle of 45 degrees and a light reception angle of 0 degrees relative to the normal of the multi-layer coating, is between 205 and 295 degrees. The chroma C* (45 / 0) measured at an incident angle of 45 degrees and a receiving angle of 0 degrees was between 30 and 60. The difference between the h(45 / 30) measured at an incident angle of 45 degrees and a receiving angle of 30 degrees and the h(45 / -30) measured at an incident angle of 45 degrees and a receiving angle of -30 degrees, |h(45 / 30) - h(45 / -30)| is between 20 and 50 degrees. A multi-layer coating characterized in that the difference |h(10 / 0) ​​- h(70 / 60)| between the hue angle h(10 / 0) ​​measured at an incident angle of 10 degrees and a receiving angle of 0 degrees and the hue angle h(70 / 60) measured at an incident angle of 70 degrees and a receiving angle of 60 degrees is between 5 and 55 degrees.

2. The multilayer coating according to claim 1, wherein the first coating-forming resin and the second coating-forming resin are thermosetting resins independently composed of one or more base resins selected from (meth)acrylic resin, polyester resin, polyurethane resin, and (meth)acrylic urethane resin.

3. The multilayer coating according to claim 1 or 2, wherein the first colored coating and / or the second colored coating further comprises an inorganic thickener.

4. The multilayer coating according to claim 1 or 2, wherein the first colored coating comprises a first coating-forming resin containing (meth)acrylic urethane resin particles and an inorganic thickener.

5. The multilayer coating according to claim 1 or 2, wherein the first colored coating comprises a first coating-forming resin containing (meth)acrylic urethane resin particles having an aldehyde group and / or ketone group and a compound having two or more hydrazide groups in one molecule, and an inorganic thickener.

6. The multilayer coating according to claim 1 or claim 2, further comprising a clear coating on the second colored coating.

7. Step (1) involves applying a first colored paint composition to the object to be coated to form an uncured first colored coating film, Step (2) involves applying a second colored paint composition onto the first colored coating to form an uncured second colored coating, The process optionally includes (3) a step of applying a clear coating composition onto the second colored coating to form an uncured clear coating, A method for forming a multilayer coating, further comprising: curing the uncured first colored coating in step (1), curing the uncured second colored coating in step (2), and curing the uncured clear coating in step (3) if step (3) is performed, by heating each of them, or curing the uncured first colored coating, the uncured second colored coating, and the optionally formed uncured clear coating by heating them simultaneously in step (4), The first colored paint composition comprises a first film-forming resin and an aluminum flake pigment. The second colored paint composition comprises a second film-forming resin and a blue pigment, The first colored paint composition and / or the second colored paint composition contains a light-interfering pigment, The content of aluminum flake pigment in the first colored paint composition is 3.5 to 15 parts by mass per 100 parts by mass of the resin solids of the first film-forming resin contained in the first colored paint composition. The content of the light-interfering pigment in at least one of the first colored paint composition and the second colored paint composition is 4.5 to 14 parts by mass per 100 parts by mass of the resin solids of the first film-forming resin contained in the first colored paint composition or the second film-forming resin contained in the second colored paint composition. The resulting multilayer coating film, when measured with an incident angle of 45 degrees and a reception angle of 0 degrees relative to the normal of the multilayer coating film, has a hue angle h(45 / 0) of 205 to 295 degrees. The chroma C* (45 / 0) measured at an incident angle of 45 degrees and a receiving angle of 0 degrees was between 30 and 60. The difference between the h(45 / 30) measured at an incident angle of 45 degrees and a receiving angle of 30 degrees and the h(45 / -30) measured at an incident angle of 45 degrees and a receiving angle of -30 degrees, |h(45 / 30) - h(45 / -30)| is between 20 and 50 degrees. A method for forming a multilayer coating film, characterized in that the difference between the h(10 / 0) ​​measured at an incident angle of 10 degrees and a receiving angle of 0 degrees and the h(70 / 60) measured at an incident angle of 70 degrees and a receiving angle of 60 degrees, |h(10 / 0) ​​- h(70 / 60)|, is between 5 and 55 degrees.

8. The multilayer coating method according to claim 7, wherein the first coating-forming resin and the second coating-forming resin are thermosetting resins composed of one or more base resins selected from (meth)acrylic resin, polyester resin, polyurethane resin, and (meth)acrylic urethane resin, independently of each other.

9. The method for forming a multilayer coating film according to claim 7 or 8, wherein the first colored coating composition and / or the second colored coating composition further comprises an inorganic thickener.

10. The method for forming a multilayer coating 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 multilayer coating method 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 having an aldehyde group and / or a ketone group and a compound having two or more hydrazide groups in one molecule, and an inorganic thickener.

Images