JP6380980B2 - Paint composition - Google Patents

Description

  The present invention relates to a coating composition having a high whiteness and a coating color having an appearance with an excellent denseness.

  The main purpose of painting is to protect the material and to give it an aesthetic appearance. In industrial products, the appearance, particularly “color” is particularly important in terms of enhancing its product power. The color of industrial products demanded by consumers is diverse, but in recent years, especially in the fields of automobile skins and home appliances, the pearl color, which changes slightly depending on the viewing angle, is a luxury. It has become very popular. In particular, white pearl color is attracting attention as a color that combines cleanliness and luxury.

  The pearl-colored coating is usually coated with a metallic base paint containing a scaly glitter pigment that determines the texture of the pearl color on the paint film by the color base paint that determines the hue and lightness of the multilayer coating film. It can be obtained by applying a top clear coating that protects the coating to form a multilayer coating.

  Among pearl paint colors, glitter pigments using alumina flakes as scaly substrates are used to express a strong glitter feeling when viewed in a state close to perpendicular to the coated plate (highlight). There is a case. The glitter pigment that uses alumina flakes as the scale-like substrate is a highlight and gives a strong glitter feeling, but the glitter pigment used in the top coating has a slightly larger particle size, In some cases, the sense of denseness was insufficient.

  Therefore, bright pigments having a relatively small particle size have been used for pearl coating colors that require a fine feeling. However, generally, the glitter pigment having a small particle size has a problem that the glitter feeling of highlight is weaker than the glitter pigment using alumina flake as the scale-like substrate.

  In addition, a bright pigment that uses natural mica as a general base material as a bright pigment having a small particle diameter emits a yellow complementary color to the interference color when viewed obliquely from above (shade) with respect to the coated plate. In order to bring a yellowish impression to the coating film, there was a problem that the high-quality feeling of the coating color was impaired.

  Patent Document 1 discloses a white pearl coating film forming method for sequentially forming a white color base coating film, a mica base coating film, and a clear coating film on a substrate on which an undercoat coating film and an intermediate coating film are formed, The mica base coating film contains a specific amount of reduced titanium-coated interference mica pigment with respect to the total mass of the reduced titanium-coated interference mica pigment and the metal oxide-coated pigment. A method is disclosed.

  However, the coating film obtained by the above-mentioned white pearl coating film forming method has a yellowish shade and lacks the whiteness of highlight.

  Patent Document 2 contains a specific amount of a luster pigment (A) having a particle diameter of 5 to 14 μm in which titanium oxide is coated on an alumina flake base material with respect to 100 parts by mass of the vehicle-forming resin composition, and further contains alumina flakes. A coating composition comprising a glitter pigment (B) having a particle size of 15 to 25 μm and coated with titanium oxide on a substrate, wherein the mass ratio of the glitter pigments (A) and (B) is specific. A metallic paint composition is disclosed that is characterized by

  However, the coating film obtained by the metallic coating composition lacks highlight whiteness.

JP 2006-326538 A JP 2007-70424 A

  An object of the present invention is to provide a coating composition, a multilayer coating film forming method, and a coated article that can provide a coating film with high whiteness of highlights, less shade yellowness, and excellent appearance with a dense feeling. That is.

The present invention is a coating composition comprising a titanium oxide-coated synthetic mica (A) and a vehicle-forming resin (B), the titanium oxide-coated synthetic mica (A) based on 100 parts by mass of the vehicle-forming resin (B), Containing 5-20 parts by weight,
The titanium oxide-coated synthetic mica (A) is a glittering pigment that satisfies the following conditions.

A coating composition comprising only 10 parts by mass of titanium oxide-coated synthetic mica (A) as a colorant based on 100 parts by mass of the vehicle-forming resin (B) is used as a lightness L * in the L * a * b * color system. Apply 15 to 88 on the surface of the metal plate so that the thickness of the cured coating film is 10 μm,
Furthermore, a multilayer coating film obtained by applying and curing a clear coating on the film so that the film thickness of the clear coating film upon curing is 35 μm,
When measured with a multi-angle spectrophotometer (trade name “MA-68II”, manufactured by Videojet X-Rite Co., Ltd.)
Highlight L value (L * 25 value) is 92-100,
HG value is 5-40,
FF (flip-flop) value is 0.5-0.9,
Highlight a value (a * 25 value) is -1.5 to -0.5,
The b value (b * 75 value) of the shade is 3.5 to 6.5.
It is.

  The coating composition of the present invention provides a coating film with high whiteness of highlights, less shade yellow, and excellent appearance, and particularly high-grade appearances such as automobile outer panels and home appliances. It is useful in the field that is required.

The coating composition of the present invention contains titanium oxide-coated synthetic mica (A) and vehicle-forming resin (B), and the titanium oxide-coated synthetic mica (A) is blended in an amount of 100 parts by mass of vehicle-forming resin (B). As a standard, it is 5-20 mass parts, Preferably it is 8-18 mass parts.
Titanium oxide coated synthetic mica (A)
The titanium oxide-coated synthetic mica (A) is obtained by coating the surface of a synthetic mica flake with titanium oxide.

Synthetic mica is a phyllosilicate obtained by mixing compounds containing potassium, sodium, magnesium, aluminum, silicon, fluorine, etc. at a certain ratio, melting, crystallizing, cooling, and mechanically grinding the mixture. It is a mineral. Examples of such are as follows.
KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ potassium phlogopite,
KMg ₂ 1/2 (Si ₄ O ₁₀ ) F ₂ potassium tetrasilicon mica,
KMg ₂ Li (Si ₄ O ₁₀ ) F ₂ potassium teniolite,
_{NaMg 3 (AlSi 3 O 10)} F 2 Sodium phlogopite,
NaMg ₂ Li (Si ₄ O ₁₀ ) F ₂ sodium teniolite,
NaMg ₂ 1/2 (Si ₄ O ₁₀ ) F ₂ sodium tetrasilicon mica,
_{Na1 / 3Mg 2 2 / 3Li1 /} 3 (Si 4 O 10) F 2 Sodium hectorite.

  Synthetic mica has less impurities and is relatively uniform in size and thickness when compared with natural mica.

  The titanium oxide-coated synthetic mica (A) is obtained by coating the surface of the synthetic mica flakes with titanium oxide, and controlling the coating amount of titanium oxide to form a powder having a desired interference color.

  The titanium oxide-coated synthetic mica (A) may be subjected to surface treatment for further improving dispersibility, water resistance, chemical resistance, weather resistance and the like after being coated with titanium oxide.

In this specification, the titanium oxide-coated synthetic mica (A) is characterized by the colorimetric value of the coating film obtained from the paint using the titanium oxide-coated synthetic mica (A). That is, the titanium oxide-coated synthetic mica (A) is a bright pigment whose colorimetric values when forming a coating film under the following conditions are in the following numerical ranges.
Coating composition for characterizing titanium oxide-coated synthetic mica (A) Coating composition comprising only 10 parts by mass of titanium oxide-coated synthetic mica (A) as a colorant, based on 100 parts by mass of vehicle-forming resin (B) The product is applied to the surface of the metal plate having a lightness L * 15 of 88 in the L * a * b * color system so that the film thickness of the cured coating film is 10 μm.
Furthermore, a clear paint is applied thereon and cured so that the film thickness of the clear coating film upon curing is 35 μm.

The lightness L * 15 is an L * value at a light receiving angle of 15 degrees measured according to the method of JIS Z 8729 (2004) using a multi-angle spectrophotometer (trade name “MA-68II”). .
Coating Colorimetric Method and Colorimetric Values for Characterizing Titanium Oxide-Coated Synthetic Mica (A) The coating obtained as described above is a multi-angle spectrophotometer (trade name “MA-68II”, Videojet X Measured by Wright)
Highlight L value (L * 25 value) is 92-100, preferably 94-99,
HG value is 5-40, preferably 10-35,
FF (flip-flop) value is 0.5 to 0.9, preferably 0.6 to 0.8,
The a value (a * 25 value) of the highlight is -1.5 to -0.5, preferably -1.3 to -0.8,
The b value (b * 75 value) of the shade is 3.5 to 6.5, preferably 4.0 to 6.0,
It is.

  The coating composition of the present invention can provide a coating film having a high whiteness of highlights, a little shade of shade, and an excellent appearance.

  The whiteness of the highlight was measured using a multi-angle spectrophotometer (trade name “MA-68II”) according to the method of JIS Z 8729 (2004). * A * b * Represented by “L * 25 value” in the color system. Specifically, measurement light was irradiated from an angle of 45 ° with respect to an axis perpendicular to the measurement target surface, and L * was measured for light received at an angle of 25 ° from the regular reflection angle in the direction of the measurement light. The larger the L * 25 value, the higher the brightness of the obtained coating film, and the better the whiteness.

  The whiteness of the highlight can also be quantified by the redness of the highlight. The redness of the highlight is measured using a multi-angle spectrophotometer (trade name “MA-68II”) according to the method of JIS Z 8729 (2004). * A * b * Also expressed by “a * 25 value” in the color system. It means that the smaller the a * 25 value, the less redness and the better the resulting coating film is white.

  Shade yellowness is represented by “b * 75 value” in the L * a * b * color system measured with a multi-angle spectrophotometer (trade name “MA-68II”). It means that the smaller the b * 75 value is, the less yellowish the color is and the better the resulting coating film is.

  The fineness is expressed by an “HG value” measured with a multi-angle spectrophotometer (trade name “MA-68II”). The HG value is one of the measures of micro glitter when the coating surface is observed microscopically, and is an index representing the particle feeling at highlights. The HG value is calculated as follows. First, the surface of the coating film was photographed with a CCD camera at a light incident angle of 15 degrees / light receiving angle of 0 degrees, and the obtained digital image data (two-dimensional luminance distribution data) was subjected to a two-dimensional Fourier transform process. A spectral image is obtained. Next, from this power spectrum image, measurement parameters obtained by extracting only the spatial frequency region corresponding to the particle sensation further take a numerical value of 0 to 100, and there is a linear relationship with the particle sensation. The value converted so as to be maintained is the HG value. The HG value is a value where 0 is a value where the glittering pigment has no particle feeling, and 100 is a value where the glittering pigment has the largest particle feeling.

The flip-flop value (FF value) represents a change in brightness depending on the observation angle of the coating surface, and is calculated based on the Y value (referred to as “Y15”) calculated based on the spectral reflectance at a light receiving angle of 15 degrees and a light receiving angle of 45 degrees. It is a value calculated by the following calculation formula (1) from the Y value calculated based on the spectral reflectance (this is referred to as “Y45”). Here, the Y value is a Y value in the XYZ color system defined in JIS Z 8701 (2004).
FF value = [2 × (Y15−Y45)] / (Y15 + Y45) (1)
The titanium oxide-coated synthetic mica (A) preferably has the following volume average particle diameter and thickness from the viewpoint of the brightness, brightness, and denseness of the resulting coating film.

In laser diffraction particle size distribution measurement of titanium oxide-coated synthetic mica (A),
The volume average particle diameter D90 is 10 to 20 μm, preferably 12 to 18 μm, and
The volume average particle diameter D50 is 5 to 15 μm, preferably 6 to 12 μm, and
The thickness is 0.2 to 0.5 μm, preferably 0.2 to 0.4 μm.

Here, the thickness of the titanium oxide-coated synthetic mica (A) is an average value obtained by measuring the thickness of 100 randomly selected titanium oxide-coated synthetic mica, which is seen when the cross section of the coating film is observed with an electron microscope. Say.
Vehicle forming resin (B)
The vehicle-forming resin (B) used in the coating composition of the present invention is preferably a thermosetting resin. Specifically, for example, an acrylic resin, a polyester resin, or an alkyd having a crosslinkable functional group such as a hydroxyl group. Examples include those in which a base resin such as resin or urethane resin and a crosslinking agent such as melamine resin, urea resin, or polyisocyanate compound (including a block body) are used in combination, such as an organic solvent and / or a solvent such as water. It can be used by dissolving or dispersing.
Scale-like interference pigment (C)
The coating composition of the present invention can further contain a scaly interference glittering pigment (C) other than (A) from the lightness, glitter, and shadow of the resulting coating film.

  The scaly interference bright pigment (C) is different from the titanium oxide-coated synthetic mica (A).

  The scaly interference bright pigment (C) is a pigment in which titanium oxide is coated on a scaly substrate selected from natural mica, synthetic mica, glass flakes, alumina flakes, and silica flakes. The scale-like substrate is preferably synthetic mica from the viewpoint of the brightness, brightness, and denseness of the resulting coating film.

  When the scaly interference bright pigment (C) is used in the coating composition of the present invention, the scaly interference bright pigment (C) is used from the viewpoints of brightness, brightness, and denseness of the resulting coating film. The amount of the synthetic mica occupied is preferably 50% or more, preferably 60% or more, based on the total amount of the scaly interference bright pigment (C).

  The scaly interference bright pigment (C) controls the coloration of the interference color by the amount of titanium oxide coated on the scaly substrate, that is, the thickness of the titanium oxide layer formed on the scaly substrate surface. It is something that can be done. When it is desired to obtain a white pearl paint film, it is particularly preferable to add an interference pearl pigment that expresses a blue interference color.

  The scaly interference glitter pigment (C) preferably has the following volume average particle diameter and thickness from the viewpoint of the brightness, glitter, and denseness of the resulting coating film.

The particle size of the scaly interference bright pigment (C) is determined by the laser diffraction particle size distribution measurement.
The volume average particle diameter D90 is 30-50 μm, preferably 35-45 μm, and
The volume average particle diameter D50 is 15 to 25 μm, preferably 16 to 23 μm.

  The thickness of the scaly interference bright pigment (C) is 0.2 to 0.6 μm, preferably 0.3 to 0.5 μm.

  The scaly interference bright pigment (C) used as necessary in the coating composition of the present invention is different from the titanium oxide-coated synthetic mica (A).

The scaly interference bright pigment (C) is a bright pigment whose colorimetric values when forming a coating film under the following conditions are in the following numerical ranges.
Coating film forming conditions for characterizing scaly interference bright pigment (C) Based on 100 parts by weight of vehicle forming resin (B), only 10 parts by weight of scaly interference bright pigment (C) is included as a colorant. Is applied to the surface of a metal plate having a lightness L * 15 of 88 in the L * a * b * color system such that the thickness of the cured coating film is 10 μm,
Furthermore, a clear paint is applied thereon and cured so that the film thickness of the clear coating film upon curing is 35 μm.
Coating film colorimetry method and colorimetric values for characterizing scaly interference bright pigment (C) The coating film obtained as described above was measured with a multi-angle spectrophotometer (trade name “MA-68II”). The L value of the highlight (L * 25 value) is 88-100, preferably 90-99,
HG value of 5 to 75, preferably 10 to 70,
FF (flip-flop) value is 0.50 to 0.98, preferably 0.60 to 0.95,
Highlight a value (a * 25 value) is −1.8 to −0.5, preferably −1.5 to −0.8,
The b value (b * 75 value) of the shade is 3.5 to 7.5, preferably 4.0 to 6.5,
It is.

  When the coating composition of the present invention contains the scaly interference bright pigment (C), the blending amount of the scaly interference bright pigment (C) is the brightness, brightness, and denseness of the resulting coating film. From the viewpoints of the above, it is preferable to contain 1 to 15 parts by mass, preferably 1 to 10 parts by mass based on 100 parts by mass of the scaly interference bright pigment (C) vehicle-forming resin (B). In the coating composition, the blending ratio of (A) and (C) is (A) / (C) = 99.9 / 0 from the viewpoint of the brightness, brightness, and denseness of the resulting coating film. .1 to 50/50, preferably 90/10 to 60/40.

  The coating composition of the present invention may contain other colored pigments in addition to the titanium oxide-coated synthetic mica (A) and the scaly interference bright pigment (C). As the color pigment, conventionally known pigments for ink and paint can be used alone or in combination of two or more. Specific examples of the color pigment include metal oxide pigments such as titanium oxide and iron oxide, composite metal oxide pigments such as titanium yellow, carbon black, azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, and perylene pigments. Pigments, perinone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, indanthrone pigments, dioxane pigments, indigo pigments, etc. it can.

  When the color pigment is used, the blending amount is 50 parts by mass with respect to 100 parts by mass of the vehicle-forming resin (B) in the coating composition from the viewpoint of coloring power and finished appearance of the obtained coating film. It is preferable that the content is 0.1 to 20 parts by mass.

Furthermore, in the coating composition of the present invention, if necessary, a solvent such as water or an organic solvent, a rheology control agent, a pigment dispersant, an anti-settling agent, a curing catalyst, an antifoaming agent, an antioxidant, an ultraviolet absorber. Various additives such as extender, extender pigments and the like can be appropriately blended.
Multi-layer coating film forming method The method of the present invention is a multi-layer coating film forming method in which a top clear coating material is further applied onto a coating film obtained by applying the above-mentioned coating composition to an object to be coated.

In the method of the present invention, the objects to be coated include metals such as iron, zinc and aluminum, alloys of these metals, molded products plated with these metals, and glass, plastics and foams. A material such as a molded product by the body can be listed. These materials may be subjected to degreasing treatment or surface treatment.

  The coating object may further be a coating film forming material on which an undercoat film or an intermediate coat film is formed.

  The above-mentioned undercoat film is used to conceal the surface of the material, impart anticorrosion and rustproofness to the material, and further improve the adhesion between the intermediate coat film and topcoat film described later and the material. It is formed and can be obtained by applying and curing an undercoat. The undercoat paint type is not particularly limited, and examples thereof include an electrodeposition paint and a primer.

  The intermediate coating film is formed to conceal the surface of the material or the undercoating film, or to impart adhesion or chipping resistance. It can be obtained by applying and curing a paint. The type of the 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 can be preferably used.

  In the method of the present invention, in the case of using an undercoat and / or an intermediate coat formed as an object to be coated, the undercoat and / or the intermediate coat is heated, and after crosslinking and curing, The coating composition of the present invention can be applied, and the coating composition of the present invention can be applied in a state where the undercoat film and / or the intermediate coating film is uncured. Including cases.

  When it is desired to obtain a white pearl color coating film, the intermediate coating film preferably has a high brightness.

  In the method of the present invention, as the object to be coated, a product in which a color base coating film is further formed on an undercoating film and / or an intermediate coating film can be used. Color base paint is a paint that has the function of hiding the color of the base material, improving the smoothness of the multilayer coating film, and determining the color tone of the multilayer coating film. May be painted. The color base coating film may be uncured or a cured coating film.

  The color base paint contains a color pigment and a vehicle-forming resin composition. As the color pigment, conventionally known pigments for ink and paint can be used alone or in combination of two or more. Specific examples of the color pigment include metal oxide pigments such as titanium oxide and iron oxide, composite metal oxide pigments such as titanium yellow, carbon black, azo pigments, quinacridone pigments, diketopyrrolopyrrole pigments, and perylene pigments. Pigments, perinone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, indanthrone pigments, dioxane pigments, indigo pigments, etc. it can.

  In particular, when it is desired to obtain a white pearl color coating film in the present invention, the color pigment preferably contains titanium oxide.

  When it is desired to obtain a white pearl color coating film, the amount of the color pigment is 10 to 10 parts by mass with respect to 100 parts by mass of the vehicle-forming resin composition of the color base paint from the viewpoint of coloring power and finished appearance of the obtained coating film. 150 parts by mass, preferably 30 to 120 parts by mass.

  When it is desired to obtain a coating film other than the white pearl color, the blending amount of the color pigment is 70 with respect to 100 parts by mass of the vehicle-forming resin composition of the color base paint from the viewpoint of coloring power and finished appearance of the obtained coating film. The amount is preferably at most 1 part by mass, particularly preferably 1-50 parts by mass.

  The vehicle-forming resin composition is preferably a thermosetting resin composition. Specifically, for example, 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 combination of a crosslinking agent such as a melamine resin, a urea resin, or a polyisocyanate compound (including a block body), and these should be used by dissolving or dispersing in a solvent such as an organic solvent and / or water. Can do.

  Furthermore, the color base coating material may be various solvents such as a solvent such as water or an organic solvent, a rheology control agent, a pigment dispersant, an anti-settling agent, a curing catalyst, an antifoaming agent, an antioxidant, and an ultraviolet absorber as necessary. Additives, extender pigments and the like can be appropriately blended.

  In the present invention, the color base paint can be applied by a method such as electrostatic coating, air spraying, airless spraying, and the film thickness is 5 to 40 μm based on the cured coating film from the viewpoint of the smoothness of the coating film. It is preferable to be within the range.

  The coating composition of the present invention can be applied to a coating film obtained by applying and curing a color base paint, and the above-described coating composition of the present invention can be applied to an uncured coating film without heating and curing the color base coating composition. Objects can be painted. The color base paint film itself can be cured and dried at a temperature of about 70 to about 150 ° C.

  The coating composition of the present invention can be suitably used particularly when it is desired to obtain a white pearl color coating film.

In such a case, it is preferable to use an object to be coated having the following (1) or (2).
(1) On the electrodeposition coating film, an intermediate coating material having a lightness L * 15 of 55 to 90 in the L * a * b * color system and a lightness L * 15 in the L * a * b * color system Is a coating film obtained by sequentially applying white color base paints having a 80-95.
(2) A coating obtained by applying a white color base paint having a lightness L * 15 of 70 to 95 in the L * a * b * color system on an electrodeposition coating.

  In the method of the present invention, the coating composition of the present invention is applied to the aforementioned object to be coated.

  In the method of the present invention, the coating composition of the present invention comprises, in particular, a titanium oxide-coated synthetic mica (A) and a bright pigment such as a scaly interference bright pigment (C) used as necessary on the coating surface. In order to arrange them in parallel, it is preferable to form a coating film by painting on a plurality of stages. The method of painting in multiple stages is a method of forming a coating film that is originally formed by a single painting in multiple stages (stages), which takes a setting time between each stage. means. In the case of painting at a plurality of stages, the number of times is not particularly limited, but is preferably twice from the viewpoint of the efficiency of the painting operation and the finish of the coating film to be formed.

  In the method of the present invention, the coating composition of the present invention can be applied by a method such as electrostatic coating, air spraying, airless spraying, and the film thickness is cured from the viewpoint of smoothness of the coating film and glitter. It is preferable to be in the range of 5 to 40 μm based on the coating film.

Top clear paint In the method of the present invention, the top clear paint is applied onto the coating film obtained by applying the coating composition of the present invention. The coating film obtained by applying the coating composition of the present invention may be a heat-cured coating film or may be uncured.

  The coating film itself of the coating composition of the present invention can be cured and dried at a temperature of about 70 to about 150 ° C.

  In the method of the present invention, a top clear coating can be formed by further coating one or more top clear coatings on the coating obtained by applying the coating composition of the present invention.

  As the top clear coating material of the present invention, conventionally known ones 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. As a crosslinking agent, melamine resin, urea resin, polyisocyanate compound, block polyisocyanate compound, epoxy compound or resin, carboxyl group-containing compound or resin, acid anhydride, alkoxysilane group-containing, which can react with the functional group of the base resin Examples thereof include compounds or resins. Moreover, additives, such as solvents, such as water and an organic solvent, a curing catalyst, an antifoamer, and a ultraviolet absorber, can be suitably mix | blended as needed.

  In the top clear paint in the present invention, a color pigment can be appropriately blended within a range not impairing transparency. As the color pigment, one or a combination of two or more conventionally known pigments for ink and paint can be blended. The addition amount may be appropriately determined, but is 30 parts by weight or less, preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the vehicle-forming resin composition in the clear coating composition.

  The top clear coating in the present invention can be applied by a method such as electrostatic coating, air spray, or airless spray, and the film thickness is preferably in the range of 5 to 40 μm based on the cured coating film.

  In the present invention, when the top clear paint is applied without heating and curing the paint film of the color base paint and / or the paint composition of the present invention, the top clear paint is applied and then these paint films are heated simultaneously. Can be cured. The top clear coating film itself can be crosslinked and cured at a temperature of about 70 to about 150 ° C.

When the multi-layer coating film obtained as described above is a white pearl color,
Highlight L value (L * 25 value) is 92-98, preferably 93-97,
HG value of 5 to 55, preferably 10 to 50,
FF (flip-flop) value is 0.5 to 0.9, preferably 0.6 to 0.9,
The a value (a * 25 value) of the highlight is -1.5 to -0.5, preferably -1.3 to -0.8,
The b value (b * 75 value) of the shade is 3.5 to 7.0, preferably 4.0 to 6.5.
It is desirable that
Each of the above parameters is a value obtained using a multi-angle spectrophotometer (trade name “MA-68II”).

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
Coating film forming conditions and coating colorimetric values for characterizing the titanium oxide-coated synthetic mica (A) and scaly interference bright pigment (C) used in Examples and Comparative Examples Hydroxyl-containing acrylic resin (hydroxyl value 100, Each titanium oxide-coated synthetic mica (A) or scaly interference bright pigment (C) is 10 parts per 100 parts by mass of a vehicle-forming resin composition comprising 75 parts of a number average molecular weight 20000) and 25 parts of melamine resin. The mixture was mixed and stirred to prepare an organic solvent type paint.

  Next, the metallic base paint obtained as described above is applied to the article 1 obtained in Production Example 1 described later using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.), and the booth temperature. A cured coating film was applied to a thickness of 10 μm under the conditions of 20 ° C., humidity 75%, discharge pressure 2.5 kgf / cm 2 and gun distance 20 cm. Then, it was allowed to stand at room temperature for 15 minutes, and then the top clear paint “Magiclon 7100” was applied to these uncured coating surfaces using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.) at a booth temperature of 20 ° C. The coating was applied to a thickness of 35 μm as a cured coating film under the conditions of a humidity of 75%, a discharge pressure of 2.5 kgf / cm 2, and a gun distance of 20 cm. After coating, it 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 dry and cure the multilayer coating film at the same time to obtain a coating film. About the obtained coating film, the color was measured by the method as described in the "evaluation test" mentioned later. The obtained colorimetric values are shown in Table 1.

Preparation of paint Examples 1-3 and Comparative Examples 1-6
Table 2 shows the glittering material and, if necessary, the colored pigment as a solid content per 100 parts by mass of the vehicle-forming resin composition comprising 75 parts of a hydroxyl group-containing acrylic resin (hydroxyl value 100, number average molecular weight 20000) and 25 parts of melamine resin. The organic solvent-type paint was prepared by mixing at a ratio and stirring to prepare a metallic base paint for use in each of Examples and Comparative Examples.

Preparation of coating object Production Example 1 (Coating object 1)
Cationic electrodeposition paint "Electron 9400HB" (trade name: manufactured by Kansai Paint Co., Ltd., amine-modified epoxy resin-based cationic resin on hardened steel sheet (JISG3141, size 400 x 300 x 0.8 mm) subjected to degreasing and zinc phosphate treatment And a block polyisocyanate compound) were 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 obtain an electrodeposition coating film.

An intermediate coating “Lugabake” (trade name: manufactured by Kansai Paint Co., Ltd., polyester resin / melamine resin organic solvent type paint, lightness L * 15 value; 60) is cured by air spray on the obtained electrodeposited surface. Based on the film, it was applied to a film thickness of 30 μm, and heated at 140 ° C. for 30 minutes to be crosslinked and cured to form an intermediate coating film. On the resulting intermediate coating film, a color base paint “Magiclon 5600” (trade name: Kansai Paint Co., Ltd., acrylic / melamine solvent paint, brightness L * 15 value; 88) is diluted with an organic solvent to obtain a solid content of 25 It adjusted to the mass%, and it applied on the conditions of booth temperature 20 degreeC and humidity 75% using the mini bell type rotary electrostatic coating machine. After coating, the mixture was allowed to stand at room temperature for 15 minutes, and then heated in a hot-air circulating drying furnace at 140 ° C. for 30 minutes to obtain a cured coating film having a thickness of 30 μm.
Production Example 2 (Subject 2)
Cationic electrodeposition paint "Electron 9400HB" (trade name: manufactured by Kansai Paint Co., Ltd., amine-modified epoxy resin-based cationic resin on hardened steel sheet (JISG3141, size 400 x 300 x 0.8 mm) subjected to degreasing and zinc phosphate treatment And a block polyisocyanate compound) were 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 obtain an electrodeposition coating film.

A color base paint “Majicron 5600” (trade name: Kansai Paint Co., Ltd., acrylic / melamine solvent paint, lightness L * 15 value; 88) is diluted with an organic solvent on the obtained electrodeposition coating surface to obtain a solid content of 25 It adjusted to the mass%, and it applied on the conditions of booth temperature 20 degreeC and humidity 75% using the mini bell type rotary electrostatic coating machine. After coating, the mixture was allowed to stand at room temperature for 15 minutes, and then heated in a hot-air circulating drying furnace at 140 ° C. for 30 minutes to obtain a cured coating film having a thickness of 30 μm.
Preparation of test plate On the object to be coated 1, the metallic base paint prepared as described above is diluted with an organic solvent to adjust the solid content to 25% by mass, and a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.) is used. Using this, a cured coating film was applied to a thickness of 10 μm under the conditions of a booth temperature of 20 ° C., a humidity of 75%, a discharge pressure of 2.5 kgf / cm 2, and a gun distance of 20 cm. After that, it was allowed to stand at room temperature for 15 minutes, and then a top clear paint “Magiclon 7100” (trade name: Kansai Paint Co., Ltd., acrylic / melamine solvent paint) was applied to these uncured coating surfaces with a small spray gun (Anest Iwata) Using W-101), a coating film having a booth temperature of 20 ° C. and a humidity of 75% was applied to a thickness of 25 to 35 μm. 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.

Using a small spray gun (W-101, manufactured by Anest Iwata Co., Ltd.), the booth temperature 20 ° C., humidity 75%, discharge pressure 2.5 kgf / Under the conditions of cm 2 and gun distance of 20 cm, the cured coating film was manually sprayed so as to be 10 μm.
Then, it was allowed to stand at room temperature for 15 minutes, and then the top clear paint “Magiclon 7100” was applied to these uncured coating surfaces using a small spray gun (W-101 manufactured by Anest Iwata Co., Ltd.) Under the conditions of a humidity of 75%, a discharge pressure of 2.5 kgf / cm 2, and a gun distance of 20 cm, the cured coating film was manually sprayed to a thickness of 35 μm. 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.
Evaluation Test Each of the test plates obtained above was subjected to color measurement with MA-68II (trade name, multi-angle spectrophotometer, manufactured by VideoJet X-Rite Co., Ltd.), and each color measurement value, specifically, high The light L value (L * 25 value), HG value, FF (flip-flop) value, highlight a value (a * 25 value), and shade b value (b * 75 value) were obtained. Table 2 shows the results.

  The first comparative example has a higher flip-flop value (FF value) than the first embodiment. That is, since the change in lightness depending on the observation angle of the paint surface is too large, it is not the intended paint color of the present invention. Also, the HG value is high. That is, it is not the coating color that is the target of the present invention even in the point of being inferior in the denseness.

  In Comparative Example 2, the L * 25 value is high and the a * 25 value is low compared to the Example. That is, since the highlight has a strong green tint and inferior in brightness, it is not the coating color targeted by the present invention.

  Comparative Example 3 has a high b * 75 value compared to the Example. That is, the shade of the shade is strong and the brightness is inferior, so that the coating color targeted by the present invention is not achieved.

  The comparative example 4 has a low L * 25 value as compared with the example. That is, since it is inferior in the brightness of highlight, it is not the coating color aimed at by the present invention. Moreover, a * 25 value is low. That is, since the highlight has a strong green tint and inferior in brightness, it is not the coating color targeted by the present invention.

  In Comparative Example 5, the HG value is high and the L * 25 value is low compared to the Example. That is, since it is inferior to the fineness and brightness of the highlight, it is not the coating color targeted by the present invention.

  Comparative Example 6 has a higher HG value than the Examples. That is, since it is inferior in a dense feeling, it does not become the coating color targeted by the present invention.

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 (2)

On the electrodeposition coating,
An intermediate coating having a lightness L * 15 value of 55 to 93 in the L * a * b * color system;
To an article having a coating film obtained by sequentially applying a color base paint having a lightness L * 15 value of 80 to 95 in the L * a * b * color system,
A coating composition comprising a titanium oxide-coated synthetic mica (A) and a vehicle-forming resin (B),
5 to 20 parts by mass of titanium oxide-coated synthetic mica (A) based on 100 parts by mass of the vehicle-forming resin (B),
Titanium oxide coated synthetic mica (A) is, Ri satisfy the following condition bright pigment der,
A coating composition comprising only 10 parts by mass of titanium oxide-coated synthetic mica (A) as a colorant based on 100 parts by mass of the vehicle-forming resin (B) is used as a lightness L * in the L * a * b * color system. Apply 15 to 88 on the surface of the metal plate so that the thickness of the cured coating film is 10 μm,
Furthermore, a multilayer coating film obtained by applying and curing a clear coating on the film so that the film thickness of the clear coating film upon curing is 35 μm,
When measured with a multi-angle spectrophotometer, the highlight L value (L * 25 value) is 92-100,
HG value is 5-40,
FF (flip-flop) value is 0.5-0.9,
Highlight a value (a * 25 value) is -1.5 to -0.5,
The b value (b * 75 value) of the shade is 3.5 to 6.5.
A method for forming a multilayer coating film, wherein a top clear coating material is further applied onto a coating film obtained by applying the coating composition.   A coated article obtained by the method for forming a multilayer coating film according to claim 1.