JP2011026543A - Paint composition and method of forming paint film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paint composition capable of forming a paint film showing particle feeling with high brightness and high color saturation at highlight (near the regular reflection) and no particle feeling with low brightness and low color saturation at shade (concave direction), and having a design of smoky texture with smooth brightness variation in between highlight and shade to various industrial products such as an exterior panel of a car body and having a heat shielding property, and a method of forming a paint film. <P>SOLUTION: This paint composition is one containing a coloring pigment reflecting and/or transmitting infrared rays and a scale-like bright pigment and whose paint film obtained by painting has a brightness of not greater than 10 in L*a*b* color system and whose brightness and color saturation varies from highlight to shade, and a method of forming a paint film is disclosed. A paint composition and a method of forming a paint film where the color pigment which reflects and/or transmits the infrared rays is perylene and/or a composite metal oxide are also disclosed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

In the present invention, the highlight (near the specular reflection light) has high brightness and high saturation, and there is no grain feeling in the shade (squash direction), and the saturation and lightness are low, and the brightness changes between the highlight and the shade. The present invention relates to a coating composition and a coating film forming method capable of forming a coating film having a mild smoky texture design and heat shielding properties.

For industrial products such as automobiles, a metallic paint color having a flip-flop feeling in which the brightness changes depending on the observation angle may be applied in order to increase the product power. Among them, metallic paint colors having high brightness at highlights and low brightness at shades are attracting attention as paint colors having a calm and high-class feeling.

  Patent Document 1 relates to a carbon black dispersion for coloring a metallic paint, a metallic paint composition, and a coating film forming method, and a metallic paint composition containing a carbon black dispersion containing a cellulose derivative and a carbon black pigment and a bright pigment. Is disclosed. Although the coating film obtained by applying the metallic paint composition disclosed in Patent Document 1 has a flip-flop feeling, it is a monotonous design whose brightness is greatly reduced from highlight to shade, There has been a problem that the temperature of the coated substrate is increased by the carbon black in the film absorbing infrared rays.

JP 2002-146243 A

The object of the present invention is that the highlight (in the vicinity of specular reflection light) has high brightness and high saturation and has a grain feeling, and the shade (in the direction of the shadow) has no grain feeling and has low saturation and brightness, and the brightness between the highlight and the shade. It is an object to provide a coating composition and a method of forming a coating film capable of forming a smoky textured design with a gentle change and a coating film having a heat shielding property.

The present invention
1. A coating composition containing a colored pigment that reflects and / or transmits infrared rays and a scaly glittering pigment, and a coating film obtained by coating has a brightness in an L * a * b * color system of 10 or less And a paint composition whose brightness and saturation change from highlight to shade,
2. The coating composition according to 1, wherein the color pigment that reflects and / or transmits infrared rays is perylene and / or a composite metal oxide,
3. 3. The coating composition according to item 1 or 2, wherein the scaly glitter pigment is an interference glitter pigment in which a metal oxide is coated on the surface of glass flakes or aluminum oxide.
4). It is related with the coating-film formation method which coats a top clear coating material further on the coating film obtained by apply | coating the coating composition of any one of 1-3 to a base material.

The coating composition of the present invention has high brightness and high saturation in the highlight (near the specular reflection light) and has a particle feeling, and there is no particle feeling in the shade (squash direction), and the saturation and brightness are low. Can be used to form a smoky textured design with a moderate change in brightness and a heat-shielding coating film, and is particularly useful in fields requiring a high-grade appearance such as automobile outer panels and home appliances. .

The coating composition of the present invention includes a color pigment that reflects and / or transmits infrared rays. In the present specification, a colored pigment that reflects and / or transmits infrared rays is a colorant in which only the colored pigment is applied to a cover rate test paper described in JIS K51014 Coverage Rate Test Paper Method in a wavelength range of 780 nm to 2500 nm. Means a pigment having a solar reflectance of 50% or more defined on JIS K5602 on a white substrate or a solar reflectance of 10% or more on a black substrate.

  Specific test methods in this specification will be described below. 15 parts by mass of the colored pigment is mixed per 100 parts by mass of a resin component comprising a hydroxyl group-containing acrylic resin (hydroxyl value 100, number average molecular weight 20000) and melamine resin, and the mixture is stirred and mixed, and diluted with an appropriate solvent. An organic solvent-type paint having a solid content of about 25% is prepared. Cover the opacity test paper horizontally on a flat glass plate, apply it on it using a doctor blade so that the cured coating thickness is 30 μm, and place it in a laboratory at room temperature of about 20 ° C. for 15 minutes. A spectrophotometer equipped with an integrating sphere ISR-3100 is used to measure the solar reflectance of the white base and black base portions of the coating film which has been allowed to stand and then heated and cured at 140 ° C. for 30 minutes using a hot air dryer. It is defined as the solar reflectance when UV-3100PC (both manufactured by Shimadzu Corporation) is used and the incident angle is 8 °.

  Specific examples of the colored pigment that reflects and / or transmits infrared rays include azo pigments, organic pigments such as aniline black and perylene black, composite oxide pigments, and the like.

  Examples of perylene pigments include perylene tetracarboxylic acid anhydrides disclosed in JP-A Nos. 2003-411144 and 2003-411145, and 2-methyl-2,4 disclosed in JP-A-2006-328238. A black pigment obtained by heating reaction of pentanediol and nitric acid, a diimide derivative of perylenetetracarboxylic acid, a black perylene pigment obtained by baking a diimide derivative of perylene diiminodicarboxylic acid, and JP2007-522297 Black pigments containing one or a mixture of two isomers of the isomers represented by formula 1a or 1b disclosed in US Pat.

Wherein R 1 and R 2 are independently of each other phenylene, naphthylene or pyridylene, which are mono- or polysubstituted by C 1 -C 12 -alkyl, C 1 -C 6 -alkoxy, hydroxyl, nitro and / or halogen, respectively. X is halogen and n is 0-4).

  Inorganic pigments include Cu-Fe-Mn, Cu-Cr, Cu-Cr-Mn, Cu-Cr-Mn-Ni, Cu-Cr-Fe, Co-Cr-Fe, and Mn-Bi. And composite oxide pigments such as Mn-Y and Mn-Y.

  In the present invention, the color pigment that reflects and / or transmits infrared rays can be used by selecting one or more kinds from the above depending on the color tone of the coating film obtained by coating.

  The amount of the color pigment that reflects and / or transmits infrared rays in the coating composition of the present invention is 100 parts by mass of the resin solid content in the coating composition from the viewpoint of the color tone and finish of the coating film obtained by coating. On the other hand, the total is preferably in the range of 1 to 20 parts by mass, more preferably in the range of 2 to 18 parts by mass, and particularly preferably in the range of 3 to 15 parts by mass.

  The coating composition of the present invention contains a scaly glittering pigment.

  The scaly glitter pigment is a surface of a scaly substrate such as mica, artificial mica, glass, iron oxide, aluminum oxide or various metals, and a metal oxide having a refractive index different from that of the substrate such as titanium dioxide or iron oxide. It means a coated optical interference pigment or a scale-like metal pigment such as aluminum, copper, nickel alloy, stainless steel.

  In the present invention, it is preferable to use the light-interfering pigment as the scaly glittering pigment from the viewpoint of brightness and particle feeling in the highlight of the coating film obtained by coating. In particular, it is particularly preferable to use a light interference pigment obtained by coating a glass flake or aluminum oxide with a metal oxide, which is a light interference pigment having a bright interference color and excellent particle feeling.

  When light interference pigment is used, L * C * h color of the interference color in highlights from the point that the change in saturation depending on the observation angle of the coating film obtained by painting is remarkable and a smoky design is expressed. The hue angle h in the system is preferably in the range of 60 ° to 270 °, more preferably in the range of 90 ° to 180 °. The L * C * h color system is a color system designed based on the L * a * b * color system specified by the International Commission on Illumination in 1976 and adopted in JIS Z 8729. H represents a hue angle, and is an angle moved counterclockwise with the red axis as 0 ° in the chromaticity diagram.

  Specifically, the hue angle of the interference color in the highlight of the light interference pigment is 45 ° on the coating film obtained by applying a paint containing only the light interference pigment as a colorant in the coating composition. It means a numerical value calculated based on the spectral reflectance obtained by irradiating light from an angle and measuring the color in the direction of 15 ° with respect to the regular reflection light.

  In this specification, the interference color in the highlight of a light interference pigment is a light interference pigment per 100 parts by mass of a resin component consisting of a hydroxyl group-containing acrylic resin (hydroxyl value 100, number average molecular weight 20000) and a melamine resin. An organic solvent-type paint having a solid content of about 25% obtained by adding a solvent and diluting to an appropriate viscosity for coating is added in advance to a black (N-2) coating film. The sprayed coating is coated with air spray to a film thickness of 18 μm as a cured coating film, left at room temperature for 15 minutes, and then the clear coating (Lugabe Kuku Clear, Kansai Paint) is applied to the uncured coating surface. (Product name, Acrylic resin / Amino resin type, Organic solvent type) is used as a cured coating film, air-sprayed to a thickness of 35 μm, and allowed to stand at room temperature for 15 minutes, after which a hot air dryer is used. Then, the coating film obtained by heating at 140 ° C. for 30 minutes and curing and drying was applied to specularly reflected light using MA-68II (trade name, multi-angle spectrophotometer) manufactured by X-Rite. The colorimetric value measured based on the spectral reflectance received at 15 ° is defined.

  In the coating composition of the present invention, the scale-like glitter pigment has an average particle size in the range of 5 to 25 μm. In view of the above, it is preferable that the particle diameter is in the range of 7 to 20 μm, particularly preferably in the range of 8 to 18 μm. It is preferable to use a thickness in the range of 0.05 to 0.5 μm. The particle diameter and thickness here mean numerical values obtained by observing the scaly glittering pigment with an optical microscope or an electron microscope.

  The content of the scaly glittering pigment in the coating composition of the present invention is the sum of the particle feeling in the highlight of the coating film obtained by coating, with respect to 100 parts by mass of the resin solid content in the coating composition. Is preferably in the range of 1 to 20 parts by mass, more preferably in the range of 2 to 18 parts by mass, and particularly preferably in the range of 3 to 15 parts by mass.

  The coating composition of the present invention may further contain a color pigment other than a color pigment that reflects and / or transmits infrared rays. In particular, when a light interference pigment is used as the scaly glitter pigment, a color pigment having the same color as the interference color in the highlight of the light interference pigment can be blended. By this combination, it is possible to increase the saturation of the highlight of the coating film formed by painting, and to produce an effect of making the interference color stand out.

  The color pigment in the present invention is not particularly limited, but specifically, a transparent iron oxide pigment, a composite metal oxide pigment such as titanium yellow, an azo pigment, a quinacridone pigment, a diketopyrrolopyrrole pigment. Perylene pigment, perinone pigment, benzimidazolone pigment, isoindoline pigment, isoindolinone pigment, metal chelate azo pigment, phthalocyanine pigment, indanthrone pigment, dioxane pigment, selenium pigment, indigo Arbitrary pigments and the like can be used alone or in combination.

  In the present invention, it is particularly preferable to use a transparent color pigment among the above-mentioned color pigments from the viewpoint of the depth and transparency of the coating film obtained by coating. Specifically, the transparent coloring pigment is blended so that the pigment amount is 20 parts by mass based on 100 parts by mass of the resin solid content in the paint, and the paint is smoothed so that the cured coating thickness is 30 μm. The coated film that was coated on a hard PTFE plate, cured, and peeled was measured with a spectrophotometer MPS-2450 (trade name, manufactured by Shimadzu Corporation), and the light transmittance in the visible light region (wavelength 400 nm to 700 nm) was 90% or more. The average primary particle diameter is 100 nm or less.

  In the present invention, the content of the color pigment in the coating composition is such that the resin solid content in the coating composition is 100 in terms of the effect of increasing the highlight saturation of the coating film obtained by coating and the finish. It is preferably within a range of 0.01 to 20 parts by mass, more preferably within a range of 0.1 to 10 parts by mass, and particularly preferably within a range of 0.5 to 3 parts by mass with respect to parts by mass. .

  The coating composition of the present invention can usually contain a resin component as a vehicle. Specifically, the resin component includes a base resin such as an acrylic resin, a polyester resin, an alkyd resin, or a urethane resin having a crosslinkable functional group such as a hydroxyl group, and a melamine resin, a urea resin, or a polyisocyanate as necessary. A combination of a crosslinking agent such as a compound (including a block body) is used, and these are used by being dissolved or dispersed in a solvent such as an organic solvent and / or water.

  Furthermore, various additives such as a solvent such as water or an organic solvent, a pigment dispersant, an antisettling agent, a curing catalyst, an antifoaming agent, an antioxidant, and an ultraviolet absorber are added to the coating composition of the present invention as necessary. An agent, extender, etc. can be appropriately blended.

  The coating composition of the present invention is prepared by mixing and dispersing the aforementioned components. The solid content at the time of painting is adjusted to 12 to 50% by mass, preferably 15 to 30% by mass based on the coating composition, and the viscosity at 20 ° C. is adjusted to 15 to 20 seconds / ford cup # 3. It is preferable to keep it.

  The coating composition of the present invention can be applied by a method such as electrostatic coating, air spray, airless spray, etc., and its film thickness should be in the range of 10 to 45 μm based on the cured coating film. From the viewpoint of the smoothness of the coating film. The coating film of the coating composition of the present invention can usually be crosslinked and cured at a temperature of about 70 to about 150 ° C.

  In the coating composition of the present specification, the lightness L * in the L * a * b * color system of the coating film obtained by painting is 10 or less. In the present specification, the lightness of the coating film obtained by applying the coating composition refers to diluting the coating composition to a viscosity suitable for coating on a coating plate on which a gray (N-6) coating film has been formed in advance. Then, it was air spray coated to a film thickness of 18 μm as a cured coating film, left at room temperature for 15 minutes, and then a clear paint (Lugabe Kukuriya, manufactured by Kansai Paint, product) Name, acrylic resin / amino resin type, organic solvent type) as a cured coating film, air sprayed to 35 μm, left at room temperature for 15 minutes, and then at 140 ° C. using a hot air dryer The coating film obtained by heating and drying for 30 minutes was received at 45 ° with respect to specular reflection light using MA-68II (trade name, multi-angle spectrophotometer) manufactured by X-Rite. Defined with numerical values calculated based on spectral reflectance And things.

  The coating film forming method of the present invention relates to a method of coating the coating composition on a substrate and curing and drying the coating composition.

  In the coating film forming method of the present invention, the base material is a metal such as iron, zinc or aluminum, an alloy containing these, a molded product plated or vapor-deposited with these metals, a building material such as concrete or slate, and And a molded product made of glass, plastic, foam or the like. Depending on these materials, it can be appropriately degreased or surface treated to form a substrate. Furthermore, an undercoat film or an intermediate coat film can be formed on the substrate to form a substrate, and these are particularly preferable.

  The undercoat film is formed to conceal the surface of the material or impart anticorrosion and rustproofness to the material, and can be obtained by applying an undercoat paint, drying and curing. it can. The type of the undercoat paint is not particularly limited, and examples thereof include an electrodeposition paint and a solvent-type primer.

  The intermediate coating film is formed to conceal the undercoat film or impart adhesion, chipping resistance, etc., and is a dry-cured undercoat film or an uncured undercoat film. It can be obtained by applying an intermediate coating on top, drying and curing. The type of intermediate coating is not particularly limited, and known ones can be used. For example, an organic solvent-based or water-based intermediate coating containing a thermosetting resin composition and a color pigment as essential components can be preferably used. .

  In the method for forming a coating film of the present invention, it is preferable to apply an intermediate coating material capable of forming an intermediate coating film having a high reflectivity from the viewpoint of reducing temperature rise due to solar radiation of the applied steel sheet or the like. Specifically, it is possible to form a coating film with high brightness, and a coating material having a carbon black pigment content of 0.5 parts by mass or less with respect to 100 parts by mass of resin solid content in the coating is preferable. Moreover, when mix | blending coloring pigments other than a white titanium oxide pigment with an intermediate coating, it is preferable to use the coloring pigment which reflects and / or permeate | transmits infrared rays.

  In the case where an undercoat film or an intermediate coat film is formed as a substrate, the undercoat film or the intermediate coat film can be heated, and the coating composition of the present invention can be applied after crosslinking and curing. Alternatively, the undercoating film and / or the intermediate coating film can be applied in an uncured state.

  In the coating film forming method of the present invention, a top clear coating film is formed by further coating one or more top clear coatings on the coating film obtained by coating the above coating composition on a substrate. Let

  The top clear coating in the method for forming a coating film of the present invention is a liquid that forms a colorless or colored transparent coating film comprising a resin component and a solvent as main components, and further blending with other coating additives as required. It is a paint.

  As the top clear paint in the method of the present invention, a conventionally known one can be used without limitation. For example, a liquid or powdery coating composition containing a base resin and a crosslinking agent can be applied. Examples of the base resin include acrylic resin, polyester resin, alkyd resin, fluororesin, urethane resin, and silicon-containing resin containing a crosslinkable functional group such as a hydroxyl group, a carboxyl group, a silanol group, and an epoxy group. It is done. As a crosslinking agent, a melamine resin capable of reacting with the functional group of the base resin, urea resin, polyisocyanate compound, block polyisocyanate compound, epoxy compound or resin, carboxyl group-containing compound or resin, acid anhydride, Examples thereof include alkoxysilane group-containing compounds or resins. Further, if necessary, additives such as a solvent such as water and an organic solvent, a curing catalyst, an antifoaming agent, an ultraviolet absorber, a rheology control agent, an antioxidant, and a surface conditioner can be appropriately blended.

  In the top clear coating, a color pigment or a dye can be blended in a timely manner within a range not impairing transparency. As the color pigments and dyes, conventionally known pigments and dyes for inks and paints can be used alone or in combination of two or more. The amount of addition may be determined as appropriate, but is 30 parts by mass or less, preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin solid content in the clear coating film.

  The top clear coating can be applied by methods such as electrostatic coating, air spray, airless spray, etc., and the film thickness is preferably in the range of 5 to 40 μm based on the cured coating film. The top clear coating itself can be crosslinked and cured at a temperature of about 70-150 ° C.

  The coating film forming method of the present invention is a so-called 2C2B process in which the coating composition of the present invention is applied, heated, dried and cured, and then the top clear coating is applied on the coated film, heated, and dried and cured. However, a multi-layer coating film can also be obtained by the so-called 2C1B process in which the top clear paint is applied in an uncured state after the coating composition is applied, and then heated to cure them simultaneously. .

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to only these examples. “Part” and “%” are based on mass.
Next, an Example is given and this invention is demonstrated more concretely.
(Production Example 1) Production of hydroxyl group-containing acrylic resin 50 parts of ethylene glycol monoethyl ether acetate was charged in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and dropping device, stirred and mixed, and the temperature was raised to 135 ° C. Warm up. Subsequently, the following monomer / polymerization initiator mixture was dropped into a reaction vessel maintained at the same temperature over 3 hours, and aging was performed for 1 hour after the completion of the dropping. Thereafter, a mixture of 10 parts of ethylene glycol monoethyl ether acetate and 0.6 parts of 2,2′-azobis (2-methylpropionitrile) was added dropwise over 1 hour 30 minutes maintained at the same temperature, and further 2 hours. Aged. Next, ethylene glycol monoethyl ether acetate was distilled off under reduced pressure to obtain a hydroxyl group-containing acrylic resin having a hydroxyl value of 54 mgKOH / g, a number average molecular weight of 20,000, and a resin solid content of 65% by mass. Here, the number average molecular weight means that measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.
Monomer / polymerization initiator mixture:
38 parts of methyl methacrylate, 17 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of hydroxyethyl methacrylate, 20 parts of lauryl methacrylate and 1 part of acrylic acid and 2,2′-azobis A mixture consisting of 2 parts of (2-methylpropionitrile).
(Measurement of interference color of scaly glitter pigment)
The interference color of the scaly glitter pigment used in Examples and Comparative Examples was measured in the following manner, and the results are shown in Table 1.

The interference color in the highlight of the scaly glittering pigment is a resin comprising 75 parts of the hydroxyl group-containing acrylic resin obtained in Production Example 1 and 25 parts of Uban 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals). For 100 parts (solid content) of the component, 15 parts of a scaly glittering pigment are blended, mixed by stirring, and a paint obtained by adding a solvent and diluting to an appropriate viscosity for coating is prepared in advance with a black (N-2 ) Is applied by air spray so that the film thickness becomes 18 μm as a cured coating film, and left at room temperature for 15 minutes, and then a clear paint (Lube-Club clear) is applied to the uncured coating surface. -Kansai Paint Co., Ltd., trade name, acrylic resin / amino resin type, organic solvent type) as a cured coating film, air sprayed to 35 μm and left at room temperature for 15 minutes, then hot air dryer The Using the coating film obtained by heating and drying at 140 ° C. for 30 minutes using MA-68II (trade name, multi-angle spectrophotometer) manufactured by X-Rite, The hue angle h in the L * C * h color system measured based on the spectral reflectance received at 15 °.
(Measurement of solar reflectance of colored pigments on white and black surfaces)
The solar reflectance of each of the color pigments used in Examples and Comparative Examples was measured in the following manner, and the results are shown in Table 1.

  15 parts by mass of the coloring pigment is mixed per 100 parts by mass of a resin component comprising a hydroxyl group-containing acrylic resin (hydroxyl value 100, number average molecular weight 20000) and melamine resin, and the mixture is stirred and mixed. An organic solvent-type paint having a solid content of about 25% is prepared. Cover the opacity test paper described in JIS K5101 4 Coverage Test Paper Method horizontally on a flat glass plate, and apply a doctor blade on it so that the cured coating thickness is 30 μm. The solar reflectance of the white base and black base portions of the coating that was left in a laboratory at room temperature of about 20 ° C. for 15 minutes, and then cured by heating at 140 ° C. for 30 minutes using a hot air dryer. Using a spectrophotometer UV-3100PC (both manufactured by Shimadzu Corporation) equipped with an integrating sphere ISR-3100, the reflectance defined in JIS K5602 was measured when the incident angle was 8 °.

Examples 1 to 7, Comparative Examples 1 and 2
Scale-like glitter per 100 parts (solid content) of a resin component comprising 75 parts of a hydroxyl group-containing acrylic resin obtained in Production Example 1 and 25 parts of Uban 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals, Inc.) Pigments and colored pigments were blended in the ratios shown in Table 2, mixed with stirring, diluted to an appropriate viscosity for coating, and organic solvent-type paints having a solid content of about 25% were prepared. Examples 1 to 7 and Comparative Examples The coating composition used for 1 and 2 was created.
(Creation of test plate)
Cationic electrodeposition paint “ELECRON 9400HB” (trade name: manufactured by Kansai Paint Co., Ltd., epoxy resin polyamine-based cation resin) on steel plate (JISG3141, size 150 × 75 × 0.8 mm) subjected to adjustment degreasing and zinc phosphate treatment of the base material (Using a block polyisocyanate compound as a curing agent) is electrodeposited so as to have a film thickness of 20 μm based on the cured coating film, and heated at 170 ° C. for 20 minutes to be crosslinked and cured to be electrodeposited. A membrane was obtained.

On the obtained electrodeposited surface, an intermediate coating “Lugabek intermediate coating white N-9” (trade name: manufactured by Kansai Paint Co., Ltd., polyester resin / melamine resin type, organic solvent type) is applied by air spray. Based on the cured coating film, it was applied to a film thickness of 30 μm, heated at 140 ° C. for 30 minutes to be crosslinked and cured, and a coated plate on which an intermediate coating film was formed was used as a substrate.
The coating composition prepared in Examples and Comparative Examples was applied to the base material prepared in the coating (1), using a REA gun, respectively, at 25 ° C. and 75% humidity as a cured coating film at 25 μm. Then, leave it at room temperature for 15 minutes, and then apply a clear paint (Lugabe Clear, manufactured by Kansai Paint, trade name, acrylic resin / amino resin, organic solvent type) to these uncured coating surfaces. ) Was coated as a cured coating film at 25-35 [mu] m under the conditions of a boot temperature of 25 [deg.] C. and a humidity of 75% using a mini-bell type rotary electrostatic coating machine. After coating, the sample was allowed to stand at room temperature for 15 minutes, and then heated in a hot-air circulating drying oven at 140 ° C. for 30 minutes to simultaneously dry and cure the multilayer coating film to obtain a test plate.
(3) Measurement of brightness The brightness of the coated plate prepared in (2) was measured. The measurement was performed using MA-68II (trade name, multi-angle spectrophotometer) manufactured by X-Rite, and L * a calculated based on the spectral reflectance received at 45 ° with respect to the regular reflection light. The lightness L * in the * b * color system is shown in Table 2.

(4) Evaluation of design properties by visual observation The prepared coated plate is illuminated with an artificial sun lamp (manufactured by Celic, color temperature 6500K), and observed at different angles with respect to the illumination of the test plate to highlight (near specular reflection light) The design properties of the shade and the shade were visually evaluated, and the results are shown in Table 2.
-Highlight particle feeling A: Excellent particle feeling.
○: Particle feeling
Δ: There is almost no particle feeling.
X: There is no particle feeling.
-Highlight saturation ◎: The interference color is strongly expressed and the saturation is excellent.
○: Interference color appears and there is a sense of saturation.
Δ: The interference color is weak and the saturation is low.
X: There is no feeling of saturation.
-Shade smoky feeling (Definition of a smoky feeling is a texture with low shade brightness and a moderate change in brightness between highlight and shade.)
A: Excellent smoky feeling.
○: There is a smoky feeling.
Δ: Little smoky feeling.
X: There is no smoky feeling.
(5) Evaluation of heat shielding properties A 70 mm square hole formed in the upper part of a corrugated cardboard box having a side of 40 cm was left in a laboratory at room temperature of about 20 ° C. for 30 minutes. A test plate used for design evaluation was cut into a size of 75 mm × 75 mm, and a coated plate with a thermocouple sensor fixed on the back with a cellophane tape,
It left still so that the said hole might be plugged up. HALOGEN LIGHT (LPL1500) was irradiated from a distance of 40 cm, and the coating plate temperature after 15 minutes was measured.

The coating composition and the coating film forming method of the present invention can be applied to various industrial products, particularly to the outer plate of an automobile body.

Claims (4)

A coating composition containing a colored pigment that reflects and / or transmits infrared rays and a scaly glittering pigment, and a coating film obtained by coating has a brightness in an L * a * b * color system of 10 or less A paint composition whose brightness and saturation change from highlight to shade. The coating composition according to claim 1, wherein the color pigment that reflects and / or transmits infrared rays is perylene and / or a composite metal oxide. The coating composition according to claim 1 or 2, wherein the scaly glittering pigment is a coherent glittering pigment having a glass flake or aluminum oxide surface coated with a metal oxide. The coating-film formation method which coats a top clear coating material further on the coating film obtained by apply | coating the coating composition of any one of 1-3 to a base material.