JP2011251252A - Method for forming multilayer coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a multilayer coating film having a gold hue, exhibiting a bright feeling, and having both high chroma and high luminance.SOLUTION: The method for forming a multilayer coating film includes forming a luster base coating film containing a colored aluminum pigment (A), an aluminum pigment (B) and a colored pigment (C) on a material to be coated on; and further forming a clear coating film to form a multilayer coating film of which the hue (H) in the Munsell color system is 7.5YR to 5Y, wherein the colored aluminum pigment (A) is a scaly luster pigment having an average particle diameter of 5 to 25 μm obtained by coating 100 pts.mass of an aluminum flake as a base material while 10 to 25 pts.mass of a coating component containing at least iron oxide is coated by a vapor-deposition method; and the colored pigment (C) is a colored pigment containing, in the case where the hue exhibited by the colored aluminum pigment (A) is taken as the basis (0-position) of the Munsell color hue ring of 100, and a hue is indicated in +50 clockwise and -50 counterclockwise, at least two types of a colored pigment (c1) exhibiting a hue in the range of -3 to -15 and a colored pigment (c2) exhibiting a hue in the range of +3 to +15.

Description

  The present invention relates to a method for forming a multilayer coating film, which can be applied to painting of an automobile body or the like, has both high saturation and brightness, and has a glitter feeling.

  A plurality of coating films having various roles are sequentially formed on the surface of an object such as an automobile body to protect the object to be coated and at the same time impart a beautiful appearance and an excellent design. As a method of forming a multilayer coating film, a method of forming an undercoating film such as an electrodeposition coating film on an object having excellent conductivity, and sequentially forming an intermediate coating film and an overcoating film thereon Is common. Among these coating films, the top coating film composed of a base coating film and a clear coating film particularly greatly affects the appearance and design of the coating film. In particular, in automobiles, the appearance and design of a top coating film comprising a base coating film and a clear coating film formed on a vehicle body are extremely important.

  In addition, recently, consumers tend to prefer a brilliant paint color rather than a so-called solid color. This glittering effect has an effect of enhancing a design having a complicated shape such as an automobile. In particular, there is an effect of strongly emphasizing the press line of the fender part and the door part, which is well lit by light and greatly affects the appearance impression. Such an effect is due to the glitter pigment contained in the glitter coating film. In such an intricately shaped part of an automobile, the reflection angle of light changes in a complicated manner, so the role of glitter in the coating film is very important. In recent years, consumers' preference for coatings has increased, not only that there is a sense of glitter, but the color of the coating itself is vivid, that is, both brightness and saturation are high, and there is also a sense of glitter. Vivid designs are being sought.

  JP-A No. 2002-121488 (Patent Document 1) discloses a coating composition containing a colored aluminum pigment and an auxiliary colored pigment as a colored pigment component, and the colored aluminum pigment and the auxiliary colored pigment have a Munsell display. The paint composition is characterized in that the hues of the ten hue rings are similar colors, the Munsell display saturation difference is 5 or less, and the brightness difference is 3 or less (Claim 1). It is described that by using this coating composition, even when used outdoors for a long period of time, no color jump is observed and a highly saturated coating film can be obtained. On the other hand, the hue of the coating film obtained by this coating composition is the so-called red color of Munsell display hue (H) 2.5R to 10R (Claim 5), and the hue of the multilayer coating film (gold) in the present invention. Is different.

  Japanese Patent Application Laid-Open No. 2001-232282 (Patent Document 2) discloses a color clear coating containing a color pigment after forming a glitter pigment having colorability and a glitter base coating film containing the color pigment on a substrate. A method for forming a glitter coating film for forming a film is described. In this method, the hue of the colored pigment in the glitter base coating, the hue of the glitter pigment, and the hue of the colored pigment in the color clear coating satisfy the specific conditions, It is described that the saturation of the composite coating film with the color clear coating film is improved. As described above, in this method, a color clear coating film having a limited hue range is used, and the method is different from the present invention.

JP 2002-121488 A JP 2001-232282 A

  An object of the present invention is to provide a multilayer coating film having a so-called gold (gold) hue, which has both high saturation and brightness, and has a glittering feeling.

The present invention
A luster-based coating film containing a colored aluminum pigment (A), an aluminum pigment (B), and a coloring pigment (C) is formed on an object to be coated, and further a clear coating film is formed. (H) is a multilayer coating film forming method for forming a multilayer coating film having 7.5YR to 5Y,
The colored aluminum pigment (A) was obtained by coating 10 to 25 parts by mass of a coating component containing at least iron oxide by vapor deposition with respect to 100 parts by mass of aluminum flakes as a base material. A scaly glittering pigment of 25 μm,
The colored pigment (C) has a hue of −3 to −3 of the hue represented by counterclockwise −50 and clockwise +50 when the hue of the colored aluminum pigment (A) is the reference (0 position) of the Munsell hue ring 100. A coloring pigment (c1) having a hue range of -15 and a coloring pigment containing at least two types of coloring pigments (c2) having a hue range of +3 to +15;
Multilayer coating film forming method,
This solves the above problem.

  The pigment concentration (PWC) of the colored aluminum pigment (A) in the glittering base coating composition for forming the glittering base coating film is 1 to 10% by mass, and the colored aluminum pigment (A) and the aluminum The mass ratio of the pigment (B) is preferably (A) / (B) = 1/5 to 10/5.

  The mass ratio of the colored pigment (c1) and the colored pigment (c2) in the glittering base coating composition for forming the glittering base coating film is (c1) / (c2) = 9/1 to 3/7. Is preferred.

  In the colored aluminum pigment (A), the ratio of iron oxide in the coating component covering the aluminum flakes is preferably 90 to 100% by mass, and the thickness of the coating component is preferably 10 to 30 nm.

  The present invention also provides a multilayer coating film obtained by the above multilayer coating film forming method.

  The multilayer coating film obtained by the multilayer coating film forming method of the present invention is a coating film having a so-called golden (gold) hue that has a glitter feeling and a hue (H) of 7.5YR to 5Y. And even if this multilayer coating film is a coating film with a glittering feeling, it has the characteristics that a color is bright because of high brightness, and a color is vivid because of high saturation. In the present invention, a specific colored aluminum pigment (A), an aluminum pigment (B), and a colored pigment (C) are included, and this colored pigment (C) is specific to the hue produced by the colored aluminum pigment (A). A glittering base coating composition is used which is a color pigment containing at least the color pigment (c1) and the color pigment (c2) having a hue in a range. As a result, a coating film having a golden hue, high saturation and brightness, and a glittering feeling can be obtained.

It is a figure which shows the Munsell color system of the Munsell color system. (Quoted from the website of DIC Color Design Co., Ltd.) It is a schematic explanatory drawing which shows the measurement position of the lightness (L *) and saturation (C *) in an Example and a comparative example. It is a graph which shows the numerical value of the brightness (15L *) of the highlight part of the multilayer coating film obtained by the Example and the comparative example, and the saturation (15C *) of a highlight part.

  In the present invention, the hues of the colored aluminum pigment (A), the colored pigment (c1), the colored pigment (c2), and the multilayer coating film are represented by the Munsell color system. The Munsell color system is well known to those skilled in the art as “a method of displaying colors by three attributes” (JIS Z 8721), and is the three attributes of color, hue (H), brightness, and saturation. Sort the colors by.

  In the Munsell color system, the hue (H) is indicated by a combination of a Munsell hue ring symbol (R, Y, G, B and P) and a number (such as 5 and 10). In the Munsell color wheel, “R” indicates red, “Y” indicates yellow, “G” indicates green, “B” indicates blue, and “P” indicates purple. The intermediate hues “YR” indicate yellow red, “GY” indicates green yellow, “BG” indicates blue green, “PB” indicates purple blue, and “RP” indicates Shows red purple. The above 10 colors become the 10 hues of the Munsell hue circle. Then, these 10 hues are each equally divided into 10 to obtain a Munsell hue ring 100 hue ring (Munsell hue ring 100). FIG. 1 is a schematic explanatory diagram for explaining the Munsell hue ring 100. In the present invention, the hue (H) of the Munsell color system can be measured by, for example, a multi-angle spectrophotometer “MA-68 II” manufactured by X-Lite.

  The method for forming a multilayer coating film of the present invention is a method of sequentially forming a glittering base coating film and a clear coating film on an object on which an undercoat coating film and an intermediate coating film are formed. Hereinafter, the glitter base coating composition used for forming the glitter base coating film and the clear coating composition used for forming the clear coating film will be sequentially described.

Glittering base coating composition In the method of the present invention, the glittering base coating film is a coating film formed on an object to be coated, and has a golden hue, and has both saturation and brightness. The coating film is high and has a glittering feeling. Such a glittering base coating film includes a colored aluminum pigment (A), an aluminum pigment (B), and a colored pigment (C), and the colored pigment (C) has a hue exhibited by the colored aluminum pigment (A). On the other hand, it is formed by using a glittering base coating composition which is a color pigment containing at least the color pigment (c1) and the color pigment (c2) having a specific range of hues. In addition to the pigments (A) to (C), this glittering base coating composition contains a film-forming resin, and optionally a curing agent and other components.

Colored aluminum pigment (A)
The glittering base coating composition used in the method of the present invention contains a colored aluminum pigment (A). This colored aluminum pigment (A) is a pigment based on aluminum flakes. The colored aluminum pigment (A) is a pigment obtained by coating 10 to 25 parts by mass of a coating component containing at least iron oxide with respect to 100 parts by mass of aluminum flakes as a base material. The colored aluminum pigment (A) is a scaly glittering pigment having an average particle diameter of 5 to 25 μm. When this colored aluminum pigment (A) has the above-described configuration, it becomes a bright pigment in which the hue of gold (gold) is visually recognized.

It is preferable that the average thickness of the aluminum flakes that are the base material constituting the colored aluminum pigment (A) is 100 to 600 nm.
In addition, average thickness (it is set as t) is the value computed by the following formula using the water surface diffusion area WCA (m < ² > / g) per 1g of aluminum metal components obtained by measurement.
t = 0.4 / WCA
The above-described method for calculating the average thickness is described in, for example, Aluminum Paint and Powder, J. MoI. D. Edwards & R. I. Wray, 3rd edition, Reinhold Publishing Corp. New York (1955), pages 16-22. The water surface diffusion area can be determined according to JIS K 5906: 1998 after a certain preliminary treatment.

  The coating component that coats the aluminum flakes as a substrate is provided that iron oxide is contained at least. This coating component includes, in addition to iron oxide, oxides of metals such as titanium, chromium, molybdenum, zirconium or aluminum, hydrates and salts thereof, and silicon dioxide, phosphates and the like. Also good. The ratio of iron oxide in the coating component is preferably 90% by mass or more, and more preferably 95 to 100% by mass. As described above, when the coating component contains iron oxide in a high content, a golden hue with high saturation is exhibited.

  The said coating | coated component is coat | covered on the aluminum flake which is a base material by a vapor deposition method. Examples of the coating method include chemical vapor deposition (CVD), in which aluminum flakes are fluidized in the gas phase, and iron carbonyl (pentacarbonyl iron, etc.) is vapor-deposited (deposited) thereon by oxidation. It is done.

  The said coating component can be coat | covered with the quantity of 10-25 mass parts with respect to 100 mass parts of aluminum flakes by coat | covering the said coating component on the aluminum flake which is a base material by a vapor deposition method. The amount of the coating component is more preferably 15 to 20 parts by mass. When the amount of the coating component is less than 10 parts by mass, the saturation of the hue exhibited by the colored aluminum pigment (A) decreases. On the other hand, when the amount of the coating component exceeds 25 parts by mass, the displayed hue turns red, making it difficult to obtain the hue (7.5YR to 5Y) of the multilayer coating film intended in the present invention.

  In this way, the coating component is coated on the aluminum flakes by vapor deposition, so that the thickness of the coating component is preferably adjusted to a very thin thickness of about 10 to 30 nm, more preferably 15 to 25 nm. Can do. Thereby, the obtained colored aluminum pigment (A) exhibits both the light interference effect by the coating component layer containing iron oxide and the light reflection effect of the aluminum flakes as the base material, and has high saturation. A hue of gold (gold), more specifically, a Munsell hue circle (100 hues) of 7.5YR to 5Y (H) will be exhibited. The thickness of the coating component can be measured using an electron microscope such as a transmission electron microscope.

In the present invention, a scaly glittering pigment having an average particle diameter of 5 to 25 μm is used as the colored aluminum pigment (A). When the average particle size is less than 5 μm, the brightness feeling is lowered, and the brightness of the highlight portion of the obtained coating film is lowered. Moreover, when average particle diameter exceeds 25 micrometers, there exists a possibility that the smoothness of the coating film obtained may fall and an external appearance defect may be caused. Note the average particle diameter in the present specification, to measure the particle size distribution by a laser diffraction method, showing a median value (D _50).

  The colored aluminum pigment (A) is preferably contained in the glittering base coating composition in an amount that provides a pigment concentration (PWC) of 1 to 10% by mass. If the amount of the colored aluminum pigment (A) is less than 1% by mass, the color developability may be lowered, and if it exceeds 10% by mass, the finished appearance may be lowered. This pigment concentration (PWC) represents the mass of the colored aluminum pigment (A) as a percentage (mass%) with respect to the mass of the total solid content of the glittering base coating composition. The total solid content of the glittering base coating composition includes the colored aluminum pigment (A), the aluminum pigment (B), the coloring pigment (C), the resin solid content of the glittering base coating composition, and other as required. All pigments and other components (solid content) are included.

A commercially available product may be used as the colored aluminum pigment (A). Examples of commercially available products that can be preferably used include PASF Chrome Gold L2025 (D ₅₀ = 16 μm), Palio Chrome Gold L2000 (D ₅₀ = 20 μm), and Palio Chrome Gold L2020 (D ₅₀ = 16 μm) manufactured by BASF. It is done.

Aluminum pigment (B)
In the glittering base coating composition used in the method of the present invention, the aluminum pigment (B) is used in combination with the colored aluminum pigment (A). The aluminum pigment (B) preferably has, for example, an average particle diameter (D ₅₀ ) of 2 to ₅₀ μm and a thickness of 0.1 to 5 μm. Those having an average particle diameter in the range of 10 to 35 μm are excellent in glitter and are more preferably used. The average particle size of the aluminum pigment (B) is a median value (D ₅₀ ) measured by a particle size distribution by a laser diffraction method.

  As the aluminum pigment (B), an aluminum pigment coated with an organic film or an inorganic film may be used. Examples of organic coatings include monomeric or polymer (oligomer) fatty acids such as dimer acid, organic phosphates, phosphate ester compounds, organic phosphonic acid compounds (esters), aminosilane compounds, and organic silicate compounds such as silane coupling agents. Examples of inorganic coatings include borate, phosphate, phosphite, silicate, molybdate, vanadate, chromium oxide, zirconium oxide, and aluminum oxide. . However, the coating component containing iron oxide that constitutes the colored aluminum pigment (A) is not included in the inorganic coating referred to here. In the aluminum pigment coated with such an organic film or inorganic film, the surface of the metal pigment is stabilized by the coating. And, by using an aluminium pigment coated with such an organic film or inorganic film, it is possible to suppress the generation of hydrogen gas in the paint when the glittering base paint composition is an aqueous base paint. There is.

  A commercially available pigment may be used as the aluminum pigment (B). Examples thereof include aluminum pigment pastes “MH-8801” and “MH-9901” manufactured by Asahi Kasei Kogyo Co., Ltd. and “Alpaste 60-600” manufactured by Toyo Aluminum Co., Ltd.

  The aluminum pigment (B) preferably has a pigment concentration (PWC) of 1 to 10% by mass. The colored aluminum pigment (A) and the aluminum pigment (B) are preferably contained in a mass ratio of 1/5 to 10/5. By including the aluminum pigment (B) in the above ratio, there is an advantage that the brightness in both the highlight portion and the shade portion can be set high and concealability can be imparted.

Color pigment (C)
In the present invention, the color pigment (C) contained in the glittering base coating composition contains at least two kinds of color pigments, that is, the color pigment (c1) and the color pigment (c2). And these coloring pigments (c1) and coloring pigments (c2) are counterclockwise −50 and clockwise +50 when the hue of the colored aluminum pigment (A) is the reference (0 position) of the Munsell hue ring 100. The color pigment (c1) having a hue range of −3 to −15 and the color pigment (c2) having a hue range of +3 to +15 in the displayed hue.

  The colored aluminum pigment (A) used in the present invention develops the Munsell hue ring (100 hue) 7.5YR to 5Y hue (H) by having the above structure. In addition to the colored aluminum pigment (A) and the aluminum pigment (B), when the hue of the colored aluminum pigment (A) is used as the reference (0 position) of the Munsell hue ring 100, the counterclockwise rotation Two types of color pigments (c1): a color pigment (c1) having a hue range of −3 to −15, and a color pigment (c2) having a hue range of +3 to +15 in hues represented by −50 and clockwise +50 By using (c2) and (c2), it becomes possible to form a multilayer coating film having high chroma and high brightness.

  When the hue range of the color pigment (c1) exceeds -3 and is in the range of -2 to 0, and the hue range of the color pigment (c2) is less than +3 and is in the range of 0 to +2, the colored aluminum pigment When the hue range of (A) and the hue ranges of the color pigments (c1) and (c2) are approximated, there is a possibility that hue adjustment in the case of forming a coating film may not be possible. There is a possibility that the stability of the paint may be reduced due to the increase of the pigment. Further, when the hue range of the color pigment (c1) is smaller than −15 and −16 to −50 and the hue range of the color pigment (c2) is larger than +15 and +16 to +50, the colored aluminum pigment When the hue range of (A) and the hue ranges of the colored pigments (c1) and (c2) are greatly different, the saturation and brightness of the resulting multilayer coating film may be lowered. Color pigments (c1) and (c2) are obtained by selecting two arbitrary pigments and setting them as c1 and c2.

  As such colored pigments (c1) and (c2), organic colored pigments and inorganic colored pigments can be used. Examples of organic colored pigments include azo pigments (for example, azo chelate pigments, insoluble azo pigments, condensed azo pigments), quinacridone pigments, benzimidazolone pigments, diketopyrrolopyrrole pigments, and isoindole. Examples thereof include linone pigments, perinone pigments, perylene pigments, dioxane pigments, quinophthalone pigments, dioxazine pigments, and metal complex organic pigments. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of inorganic coloring pigments include chrome lead, zinc white, cadmium red, molybdenum red, chromium yellow, chromium oxide, yellow iron oxide, and bengara. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The mass ratio of the colored pigment (c1) and the colored pigment (c2) is preferably (c1) / (c2) = 9/1 to 3/7, and (c1) / (c2) = 7/1 to More preferably, it is 3/5. When the mass ratio of the color pigments (c1) and (c2) deviates from the above range, the saturation and brightness of the resulting multilayer coating film may be lowered.

  In the present invention, the glittering base coating composition contains the colored aluminum pigment (A), the aluminum pigment (B), and the colored pigment (C) containing at least the colored pigments (c1) and (c2). As a result, the resulting multi-layer coating film has both high saturation and brightness, and has a glittering feeling. In general, a large amount of colored pigment is used to form a vivid coating film with high saturation. However, when a large amount of color pigment is used, the saturation increases while the brightness decreases, resulting in a dark color although the color is dark and vivid. On the other hand, for example, by selecting a color pigment so that a yellow to orange hue is exhibited, and adding an aluminum pigment, which is a general glitter pigment, to this, it exhibits a golden color (gold), It is thought that a certain coating film is obtained. However, such a coating film is colored by a combination of hue coloring by a coloring pigment and glittering coloring by a glittering pigment, so that the highlight portion is discolored and whitened and the shade portion is darkened. There is a problem that the degree becomes low. On the other hand, a glittering base coating composition containing the colored aluminum pigment (A), the aluminum pigment (B), and the colored pigment (C) containing the specific colored pigments (c1) and (c2) is used. As a result, a multi-layer coating film having a glittering feeling and high chroma and brightness was obtained.

  In the method of the present invention, the glittering base coating composition containing the colored aluminum pigment (A), the aluminum pigment (B), and the colored pigment (C) containing the colored pigments (c1) and (c2) is further used. Thus, there is an advantage that a multilayer coating film having a hue (H) in the range of 7YR to 5Y can be obtained regardless of whether the background is white or black. This is because the colored aluminum pigment (A) itself used in the present invention exhibits a reflection effect by the layer of the coating component containing iron oxide.

  In the present invention, if necessary, in addition to the colored aluminum pigment (A), the aluminum pigment (B) and the colored pigment (C), other bright pigments, organic colored pigments, and inorganic colored pigments. In addition, pigments such as extender pigments may be appropriately blended in the glittering base coating composition.

Other bright pigments include, for example, natural or synthetic alumina (Al ₂ O ₃ ) flakes, natural or synthetic silica (SiO ₂ ) flakes, natural or synthetic mica flakes or glass flakes, for example Examples thereof include those coated with oxides of metals such as titanium, iron, chromium, cobalt, tin and zirconium, metal titanium flakes, stainless steel flakes, glass flakes and mica flakes. These may be used alone or in combination of two or more.

  Examples of extender pigments include calcium carbonate, barium sulfate, clay, and talc. These may be used alone or in combination of two or more.

  However, in the case of using these other pigments, it is a condition that it is an amount that does not adversely affect the hue exhibited by the colored aluminum pigment (A), the aluminum pigment (B) and the colored pigment (C) in the present invention. .

  In the glittering base coating composition, the total pigment concentration (PWC) is 5 to 50% by mass, preferably 5 to 30% by mass. If it is less than 5% by mass, the base concealability in the case of a coating film may be reduced, and if it exceeds 50% by mass, the finished appearance may be reduced.

Examples of the film-forming resin contained in the film-forming resin and the curing agent glittering base coating composition include acrylic resin, polyester resin, alkyd resin, epoxy resin, polyurethane resin, and polyether resin. In particular, acrylic resins and polyester resins are preferably used. These can be used in combination of two or more. In addition, the film-forming resin includes a curable type and a lacquer type, but a curable type is usually used. In the case of a curable type, it is used after being mixed with a curing agent (or crosslinking agent) such as an amino resin and / or a blocked isocyanate compound, an amine, a polyamide, or a polyvalent carboxylic acid, and heated or at room temperature. The curing reaction can proceed. It is also possible to use a film-forming resin of a type having no curability in combination with a type having curability.

Examples of the acrylic resin acrylic resin include a copolymer of an acrylic monomer, or a copolymer of an acrylic monomer and another ethylenically unsaturated monomer. Acrylic monomers that can be used for the copolymerization include methyl, ethyl, propyl, n-butyl, i-butyl, t-butyl, 2-ethylhexyl, lauryl, phenyl of acrylic acid, methacrylic acid, acrylic acid or methacrylic acid. , Benzyl, 2-hydroxyethyl, 2-hydroxypropyl esterified products, acrylic acid or 2-hydroxyethyl methacrylate caprolactone ring-opening adduct, acrylamide, methacrylamide and N-methylolacrylamide. Examples of other ethylenically unsaturated monomers copolymerizable with these include styrene, α-methylstyrene (or dimer), itaconic acid, maleic acid, vinyl acetate and the like. Moreover, it is preferable to make an acrylic resin into an aqueous emulsion by a method known to those skilled in the art, for example, according to the method disclosed in JP-A-2007-39615.

As the polyester resin polyester resin, saturated and polyester resins and unsaturated polyester resins. For example, condensate obtained a polybasic acid and a polyhydric alcohol heated condensation and the like. Examples of the polybasic acid include saturated polybasic acids and unsaturated polybasic acids. Examples of the saturated polybasic acid include phthalic anhydride, terephthalic acid, succinic acid, and the like. Examples of the acid include maleic acid, maleic anhydride, fumaric acid and the like. Examples of the polyhydric alcohol include dihydric alcohol and trihydric alcohol. Examples of the dihydric alcohol include ethylene glycol and diethylene glycol. Examples of the trihydric alcohol include glycerin and trimethylolpropane. Etc.

Alkyd resin Alkyd resin reacts with the above polybasic acids and polyhydric alcohols and other modifiers such as fats and oils and fats (soybean oil, linseed oil, coconut oil, stearic acid, etc.) and natural resins (rosin, amber, etc.). The alkyd resin obtained by making it use can be used.

Examples of the epoxy resin epoxy resin include resins obtained by reaction of bisphenol and epichlorohydrin. Examples of bisphenol include bisphenol A and F. Examples of the bisphenol type epoxy resin include Epicoat 828, Epicoat 1001, Epicoat 1004, Epicoat 1007, Epicoat 1009 (all manufactured by Shell Chemical Co., Ltd.), etc., and these can be chained using an appropriate chain extender. Extended ones can also be used.

Examples of the polyurethane resin include a resin having a urethane bond obtained from various polyol components such as acrylic, polyester, polyether, and polycarbonate and a polyisocyanate compound. Examples of the polyisocyanate compound include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and mixtures thereof (TDI), diphenylmethane-4,4 ′. Diisocyanate (4,4′-MDI), diphenylmethane-2,4′-diisocyanate (2,4′-MDI), and mixtures thereof (MDI), naphthalene-1,5-diisocyanate (NDI), 3,3 ′ -Dimethyl-4,4'-biphenylene diisocyanate (TODI), xylylene diisocyanate (XDI), dicyclohexylmethane diisocyanate (hydrogenated HDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), hydrogenated xylylene diene Isocyanate (HXDI) It can be mentioned.

Polyether resin Polyether resin is a polymer or copolymer having an ether bond, such as polyoxyethylene polyether, polyoxypropylene polyether, polyoxybutylene polyether, bisphenol A or bisphenol F. A polyether resin having at least two hydroxyl groups per molecule, such as a polyether derived from an aromatic polyhydroxy compound, or the polyether resin and succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, Examples thereof include a carboxyl group-containing polyether resin obtained by reacting a polyvalent carboxylic acid such as terephthalic acid or trimellitic acid or a reactive derivative such as an acid anhydride thereof.

  As a ratio of the coating film-forming resin and the curing agent, the coating film-forming resin is preferably 90 to 50% by mass and the curing agent is 10 to 50% by mass in terms of solid content. It is 85-60 mass%, and it is more preferable that a hardening | curing agent is 15-40 mass%. When the curing agent is less than 10% by mass (when the coating film-forming resin exceeds 90% by mass), crosslinking in the coating film may not be sufficient. On the other hand, when the curing agent exceeds 50% by mass (when the coating film-forming resin is less than 50% by mass), the storage stability of the coating composition is decreased and the curing rate is increased, so that the coating film appearance may be decreased. There is.

In addition to the above-mentioned components, the glittering base coating composition that can be used in the present invention, such as other components , includes a colloidal dispersion mainly composed of a polyamide wax which is a lubricating dispersion of an aliphatic amide or polyethylene oxide. Anti-settling agents such as polyethylene wax, curing catalysts, UV absorbers, antioxidants, leveling agents, surface conditioners such as silicone and organic polymers, anti-sagging agents, thickeners, antifoaming agents, lubricants, organic amides Crosslinked resin particles and the like can be added as appropriate. These additives are generally blended at a ratio of 15 parts by mass or less with respect to 100 parts by mass (solid content basis) of the total amount of the film-forming resin and the curing agent, thereby improving the performance of the paint or coating film. Can be improved.

  The glittering base coating composition of the present invention is provided in a form in which the above-mentioned components are usually dissolved or dispersed in a solvent. Any solvent can be used as long as it dissolves or disperses the film-forming resin and the curing agent, and an organic solvent and / or water can be used. Examples of the organic solvent include those usually used in the paint field. Examples thereof include hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ether ketone, esters such as ethyl acetate, cellosolve acetate and butylcellosolve, alcohols and the like. From the viewpoint of the environment, it is preferable to use water when the use of an organic solvent is regulated. In this case, an appropriate amount of a hydrophilic organic solvent may be blended.

  In a particularly preferred embodiment, the glittering base coating composition that can be used in the present invention is a film-dispersing resin containing an acrylic resin emulsion, and a reaction product obtained by reacting an acrylic resin with a hydrophobic melamine resin is dispersed in water. It may contain the hardening | curing agent containing the hydrophobic melamine resin aqueous dispersion with a particle size of 20-140 nm obtained by doing, By this, the coating film which has the outstanding coloring property can be obtained. Further, in the method for forming a multilayer coating film in automobile coating, when the above glittering base coating composition is used as a water-based coating, it is possible to obtain a coating film having excellent recoat adhesion, chipping property, and water adhesion resistance. . Therefore, the above glittering base coating composition can be suitably used as an aqueous glittering base coating composition.

Clear coating composition In the method of the present invention, the clear coating film is formed using a clear coating composition. The clear coating composition that can be used in the method of the present invention is not particularly limited, and a clear coating composition generally used for top coating can be used, for example, acrylic resin, polyester resin, fluorine It is possible to use at least one thermosetting resin selected from resins, epoxy resins, polyurethane resins, polyether resins, modified resins thereof, and the like, and those containing the curing agent as necessary.

  If necessary, the clear coating composition is a colored pigment, an extender pigment, a modifier, an ultraviolet absorber, a leveling agent, as long as the transparency is not impaired or the design of the base is not hindered. Additives such as a dispersant and an antifoaming agent can be blended. In addition, the clear coating composition containing a carboxyl group-containing polymer and an epoxy group-containing polymer described in JP-B-8-19315 is provided with the above-described glittering base coating layer in terms of acid rain countermeasures and the W / W method. From the standpoint of not disturbing the orientation of the glitter pigment and the color pigment when formed. In addition, the clear coating composition can take various forms such as a solvent type, an aqueous type, and a powder type. As the solvent-based paint or water-based paint, a one-component paint may be used, or a two-component paint such as a two-component urethane resin paint may be used.

  Preferred examples of the solvent-based clear coating composition include a combination of an acrylic resin and / or a polyester resin with an amino resin and / or an isocyanate, or a carboxylic acid / epoxy curing system from the viewpoint of transparency or acid etching resistance. Examples thereof include acrylic resins and / or polyester resins.

  Examples of the water-based clear coating composition include a resin obtained by neutralizing a film-forming resin contained in the solvent-based clear coating composition described above as an example of the solvent-type clear coating composition with a base to make it water-based. Things can be mentioned. This neutralization can be carried out by adding tertiary amines such as dimethylethanolamine and triethylamine before or after polymerization.

  Furthermore, it is preferable that a viscosity control agent is added to the clear coating composition in order to ensure coating workability. As the viscosity control agent, those generally showing thixotropy can be used. For example, a conventionally well-known thing can be used as such a thing. Moreover, a curing catalyst, a surface conditioner, etc. can be included if necessary.

  In addition, as a clear coating composition used in the above-mentioned multilayer coating film forming method, Ford Cup No. 20 at 20 ° C. is used from the viewpoint of the influence on the environment due to the content of the organic solvent. 4 is a solvent-type clear coating composition or a water-based clear coating composition, or a powder-type clear, in which the solid content of the clear coating composition when diluted to a viscosity of 20 to 50 seconds is 50% by mass or more A coating composition is preferred.

Multilayer coating film forming method The method of the present invention is a multilayer coating film forming method in which a glittering base coating film and a clear coating film are sequentially formed on an object to be coated.

The object to be coated used in the method for forming a multilayer coating film of the present invention is not particularly limited, and metals such as iron, aluminum, magnesium, copper, tin, zinc or alloys thereof, and Molded articles; inorganic materials such as glass, cement, concrete; polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, polyester resin And plastic materials such as polystyrene resin and ABS resin, various plastic materials such as FRP, and molded articles or foams thereof; natural or synthetic materials such as wood and fiber materials (paper, cloth, etc.). In order to effectively express the vivid design obtained by the present invention, the object to be coated has a curved surface, for example, a car body and parts (car body, door, etc.) such as a passenger car, a truck, a motorcycle, and a bus. It is preferable that it has. Specific examples of the plastic molded product include automobile parts such as a spoiler, a bumper, a mirror cover, a grill, and a door knob. Further, these plastic molded articles are preferably those washed with steam or neutral detergent with trichloroethane. Furthermore, primer coating for enabling electrostatic coating may be applied.

  In the method for forming a multilayer coating film according to the present invention, when the object to be coated is an automobile body or its parts, the conductive object to be coated is previously subjected to degreasing treatment or chemical conversion treatment (such as phosphate or zirconium salt). After the chemical conversion treatment, etc., it is preferable to apply a base coating such as electrodeposition coating or intermediate coating to the object to be coated.

  Electrodeposition coating is performed for the purpose of imparting rust prevention by forming an electrodeposition coating film on a conductive object such as a steel plate. The electrodeposition coating composition capable of forming such an electrodeposition coating film is not particularly limited, and cationic electrodeposition coating compositions and anionic electrodeposition coating compositions well known to those skilled in the art are included. Either can be used. From the viewpoint of rust prevention, a cationic electrodeposition coating composition is preferable, and an epoxy cationic electrodeposition coating composition is particularly preferable.

  In the present invention, when the object to be coated is an automobile body or a steel plate, pretreatment up to degreasing, water washing, chemical film formation, water washing, pure water washing and drying is performed by a conventionally known method before the electrodeposition coating film is formed. Is preferred. As the electrodeposition coating film forming method, an appropriate method may be arbitrarily selected from conventionally known methods. Further, the electrodeposition coating film forming conditions, the bake curing conditions, the thickness of the electrodeposition coating film, and the like can be appropriately determined according to the type of the object to be coated and the type of the electrodeposition coating composition to be used. .

  In the intermediate coating, an intermediate coating layer is formed on the electrodeposition coating formed as necessary to improve performance such as undercoating, chipping resistance, and adhesion to the top coating layer. It is done for the purpose. The intermediate coating layer also functions as a base for smoothing the final glittering multilayer coating film to obtain a coating film having a good appearance. The intermediate coating layer further serves as a binder between the electrodeposition coating layer and the top coating layer, and is required to have weather resistance against deterioration of the coating due to ultraviolet rays, water, etc. reaching through the coating surface.

  There are no particular limitations on the intermediate coating composition that can form the intermediate coating layer. In addition to solvent-based coatings well known to those skilled in the art, aqueous coatings, powder coatings, high solid coatings, etc. Can also be used. Specifically, epoxy ester / melamine resins, alkyd / melamine resins or oil-free polyester / melamine resin paints, intermediate paints combining acrylic resins and / or polyester resins with amino resins and / or isocyanate curing agents It can be used by appropriately selecting from conventionally known intermediate coating compositions such as compositions.

  As the method for forming the intermediate coating film layer, an appropriate method can be arbitrarily selected from conventionally known methods. Further, in the present invention, a gray-based intermediate coating composition comprising carbon black and titanium dioxide as main pigments, a combination of set gray and various colored pigments that match the lightness and hue of the top coat layer, so-called A color intermediate coating composition can be used. These color intermediate coating compositions can develop a composite color of the intermediate coating layer and the top coating layer, and can further enhance the design. Further, flat pigments such as aluminum powder and mica powder may be added to these intermediate coating compositions. Further, the intermediate coating composition may contain additives that can be usually added to the coating, for example, a surface conditioner, an antioxidant, an antifoaming agent, and the like. The dry film thickness of the intermediate coating layer is preferably 20 to 100 μm, more preferably 30 to 50 μm.

  The intermediate coating film layer can be used in an uncured state after being coated on an object or an electrodeposition coating film, or can be used in a cured state. In the case of curing the intermediate coating film, a cured film having a high degree of crosslinking can be obtained by setting the curing temperature to 100 to 180 ° C, preferably 120 to 160 ° C. If the upper limit is exceeded, the coating film becomes hard and brittle, and if it is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature, but it is suitably from 120 to 160 ° C. for 10 to 30 minutes.

Application of glitter base coating composition and clear coating composition In the method of the present invention, the glitter base coating composition and the clear coating composition are applied on the substrate to be coated in this order by wet-on-wet. It is preferable to form the coating film by a 2-coat 1-bake method in which these coating films are simultaneously cured. Further, the present invention can also be applied to a 2-coat 2-bake coating method in which the glittering base coating composition is applied and cured on the object to be coated, and then the clear coating composition is applied and cured.

  The method for applying the glittering base coating composition is, for example, a method of applying a multi-stage coating by air electrostatic spray coating, preferably a two-stage coating, in order to enhance the design when, for example, an automobile body is coated. It is a coating method that combines air electrostatic spray coating with a rotary atomizing electrostatic coating machine called “μμ (micro micro) bell”, “μ (micro) bell” or “metabell”. It is preferable.

  The dry film thickness of the glitter base coating film formed by application of the glitter base coating composition varies depending on the desired application, but in many cases, the lower limit is preferably 5 μm and the upper limit is 30 μm. If it is less than 5 μm, the underlying layer cannot be concealed and there is a risk of film breakage. If it exceeds 30 μm, there is a risk of problems such as flow during painting.

  In the case of forming a multilayer coating film by the above-mentioned two-coat one-bake, after applying the glittering base coating composition, the process proceeds to a step of applying the clear coating composition without heating and curing. In this case, if necessary, before applying the clear coating composition, a solvent such as moisture by heating at a temperature lower than the temperature used in the heat curing (baking) treatment, for example, at 40 to 100 ° C. for 1 to 10 minutes. You may perform the preheating process which volatilizes.

  As the coating method of the clear coating composition, a method of coating by the above-described rotary atomizing electrostatic coating machine is preferable, similarly to the glittering base coating composition. In general, the dry film thickness of the clear coating film formed from the clear coating composition is preferably 20 μm at the lower limit and 70 μm at the upper limit. If it is less than 20 μm, there is a possibility that the concavity and convexity of the foundation is insufficiently concealed. If it exceeds 70 μm, there is a risk that problems such as cracking or sagging may occur during painting. The lower limit is more preferably 25 μm, and the upper limit is more preferably 60 μm.

  In the 2-coat 1-bake method, after applying the glittering base coating composition and the clear coating composition, these uncured coating films are cured. The curing temperature is preferably a lower limit of 100 ° C. and an upper limit of 180 ° C. If it is less than 100 ° C, curing may be insufficient. If it exceeds 180 ° C, the coating film may become hard and brittle. The lower limit is more preferably 120 ° C. and the upper limit is more preferably 160 ° C. in that a cured coating film having a high degree of crosslinking can be obtained. Although hardening time changes with hardening temperature, in the case of 120-160 degreeC, 10-30 minutes are preferable.

  When a multi-layer coating film is formed by two coats and two bake, after applying the glittering base coating composition, for example, it is cured by heating at 120 to 160 ° C. for 10 to 30 minutes, and then the clear coating composition is applied. After coating in the same manner as described above, it is preferable to cure by heating at 120 to 160 ° C. for 10 to 30 minutes, for example.

  The film thickness of the multilayer coating film formed by the method for forming a multilayer coating film of the present invention is preferably a lower limit of 30 μm and an upper limit of 300 μm. If it is less than 30 μm, the strength of the film itself may be reduced, and if it exceeds 300 μm, film physical properties such as a cooling / heating cycle may be reduced. The lower limit is more preferably 50 μm, and the upper limit is more preferably 250 μm.

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

Production Example 1 Preparation of Acrylic Resin Emulsion (Em-1) 135.4 parts of ion exchange water, Aqualon HS-10 (polyoxyethylene alkylpropenyl phenyl ether sulfate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.1 The temperature was raised to 80 ° C. with mixing and stirring in a nitrogen stream. Next, 35.73 parts of methyl acrylate, 8.57 parts of butyl methacrylate, 5.7 parts of 2-hydroxyethyl methacrylate, 20 parts of styrene, 0.5 part of Aqualon HS-10, Adeka Soap NE-20 ( α- [1-[(allyloxy) methyl] -2-nonylphenoxy] ethyl) -ω-hydroxyoxyethylene (manufactured by Asahi Denka Co., Ltd., 80% aqueous solution) 0.5 part and ion-exchanged water 49.7 parts A first-stage ethylenically unsaturated monomer mixture and an initiator solution consisting of 0.21 part of ammonium persulfate and 8.6 parts of ion-exchanged water were dropped into the reaction vessel in parallel over 2 hours. After completion of the dropping, aging was performed at the same temperature for 1 hour.

  Furthermore, 25.3 parts of butyl methacrylate, 2.4 parts of 2-hydroxyethyl methacrylate, 2.3 parts of methacrylic acid, 0.1 part of Aqualon HS-10 and 24.7 parts of ion-exchanged water were added to this reaction vessel. A second stage ethylenically unsaturated monomer mixture and an initiator solution consisting of 0.08 parts ammonium persulfate and 7.4 parts ion-exchanged water were added dropwise in parallel over 0.5 hours at 80 ° C. . After completion of the dropping, aging was performed at the same temperature for 2 hours.

  Next, after cooling to 40 ° C. and filtering with a 400 mesh filter, 2.14 parts of ion-exchanged water and 0.24 part of dimethylaminoethanol were added to adjust the pH to 6.5, an average particle diameter of 80 nm, and a non-volatile content of 30% An acrylic resin emulsion (Em-1) having a solid content acid value of 15 mgKOH / g and a hydroxyl value of 35 mgKOH / g was obtained.

Production Example 2: Preparation of water-soluble acrylic resin 23.89 parts of dipropylene glycol methyl ether and 16.11 parts of propylene glycol methyl ether were added to a reaction vessel, and the mixture was heated to 105 ° C. with mixing and stirring in a nitrogen stream. Next, 13.1 parts of methyl methacrylate, 68.4 parts of ethyl acrylate, 11.6 parts of 2-hydroxyethyl methacrylate, 6.9 parts of methacrylic acid, 10.0 parts of dipropylene glycol methyl ether and t-butyl An initiator solution consisting of 1 part of peroxy 2-ethylhexanoate was dropped into the reaction vessel in parallel over 3 hours. After completion of the dropping, aging was performed at the same temperature for 0.5 hours.

  Next, an initiator solution consisting of 5.0 parts of dipropylene glycol methyl ether and 0.3 part of t-butylperoxy 2-ethylhexanoate was dropped into the reaction vessel over 0.5 hours. After completion of the dropping, aging was performed at the same temperature for 2 hours.

  Further, using a solvent removal apparatus, 16.11 parts of the solvent was distilled off at 110 ° C. under reduced pressure (70 torr), and then 204 parts of ion-exchanged water and 7.1 parts of dimethylethanolamine were added to obtain a water-soluble acrylic resin. It was. The obtained acrylic resin solution had a non-volatile content of 30%, a solid content acid value of 40 mgKOH / g, and a hydroxyl value of 50 mgKOH / g.

Production Example 3: Preparation of Hydrophobic Melamine Resin Water Dispersion (MFD-1 ) 50 parts of MFDG (methylpropylene diglycol, manufactured by Nippon Emulsifier Co., Ltd.) was added to the reaction vessel, and the temperature was raised to 130 ° C. while stirring in a nitrogen stream. Warm up. Next, an ethylenic polymer consisting of 14.77 parts of acrylic acid, 32.48 parts of 2-hydroxyethyl methacrylate, 47.75 parts of butyl acrylate, and 5 parts of MSD-100 (α-methylstyrene dimer, Mitsui Chemicals). A saturated monomer mixture and an initiator solution consisting of 13 parts of Kayaester O (tert-butyl peroctanoate, manufactured by Kayaku Akzo) and 10 parts of MFDG were dropped into the reaction vessel in parallel over 3 hours. After the completion of dropping, an initiator solution consisting of 0.5 parts of Kayaester O and 5 parts of MFDG was added dropwise over 0.5 hours. After completion of the dropping, aging was performed at the same temperature for 1 hour. Subsequently, it was cooled to 50 ° C. to obtain an acrylic resin (Ac1) having a nonvolatile content of 60%, a solid content acid value of 110 mgKOH / g, a hydroxyl value of 140 mgKOH / g, and a number average molecular weight (Mn) = 3000.

  178.5 parts of the obtained acrylic resin (Ac1) was mixed with 800 parts of Uban 20SB (fully butylated melamine resin, Nippon Cytec Co., Ltd., non-volatile content 75%, Sp = 9.6), and 4 at 80 ° C. Stir for hours. Thereafter, 18.3 parts of dimethylethanolamine was added and dispersed uniformly. After cooling to 40 ° C., 1003.2 parts of ion-exchanged water was added dropwise over 1 hour, whereby a hydrophobic melamine resin aqueous dispersion (MFD-1) was added. ) The particle size of the resin particles in this aqueous dispersion was 80 nm.

Example 1
Preparation of glitter base coating composition 153.3 parts of acrylic resin emulsion (Em-1) of Production Example 1 as a coating film-forming resin, 5 parts of a 10% by weight dimethylethanolamine aqueous solution, water-soluble acrylic resin of Production Example 2 16.7 parts, Primepole PX-1000 (manufactured by Sanyo Chemical Industries, Ltd., bifunctional polyether polyol, number average molecular weight 1000, hydroxyl value 278 mg KOH / g, water tolerance infinity), hydrophobic melamine of Production Example 3 Resin water dispersion (MFD-1) 100 parts, and as a colored aluminum pigment (A), 5 parts by BASF, Paliochrome Gold L2025,
As an aluminum pigment (B), Asahi Kasei Kogyo Co., Ltd., an aluminum pigment paste “MH-8801” having a solid content mass of 5 parts,
7 parts of SICOTRANS RED L2818 (iron oxide red) manufactured by BASF Corporation as the color pigment (c1)
As a coloring pigment (c2), 1 part of BAXFAST YELLOW Y5688 (azo chelate yellow pigment) manufactured by LANXESS,
Was formulated. Furthermore, 30 parts of ethylene glycol monohexyl ether was mixed and stirred, adjusted to pH = 8.5 by adding a 10% by mass dimethylaminoethanol aqueous solution, and uniformly dispersed to obtain an aqueous glittering base coating composition. The resulting aqueous glittering base coating composition has a coating viscosity of 20 ° C. Ion-exchanged water was added and diluted so as to be 60 seconds in a 4 Ford cup to obtain a glittering base coating composition.
In addition, the pariochrome gold L2025 which is a colored aluminum pigment (A) was obtained by coating 17.5 parts by mass of iron oxide by vapor deposition with respect to 100 parts by mass of aluminum flakes which are base materials. It was a scaly glittering pigment having a size of 16 μm. Moreover, the thickness of the iron oxide layer which is a coating component was 20 nm. The hue based on the Munsell hue ring of the colored aluminum pigment (A) was 10 YR.
Further, when the hue of the colored aluminum pigment (A) is the reference (0 position) of the Munsell hue ring 100, the hue of the colored pigment (c1) displayed as counterclockwise −50 and clockwise +50 is −4.1. The hue of the color pigment (c2) was 3.5.

Formation of multilayer coating Dull steel plate (length 300 mm, width 100 mm and thickness 0.8 mm) was subjected to chemical conversion treatment using a zinc phosphate treating agent ("Surfdyne SD2000", manufactured by Nippon Paint Co., Ltd.), and then cation An electrodeposition paint (“Powernics PN 310”, manufactured by Nippon Paint Co., Ltd.) was electrodeposited so that the dry film thickness was 25 μm. Next, after baking at 160 ° C. for 30 minutes, as an intermediate coating material, a polyester / melamine gray intermediate coating material (“Olga P-30”, manufactured by Nippon Paint Co., Ltd.) ethyl acetate / solvesso 100 / butyl diglycol acetate = 1 / 1/1 (mass ratio), Ford Cup No. 4 was adjusted so that the viscosity was 30 seconds, and the intermediate coating was performed using a rotary electrostatic coating machine, and baked and dried at 140 ° C. for 30 minutes. The intermediate coating film with an average dry film thickness of 30 μm A layer was formed.

Further, the glittering base coating composition was spray-coated on the intermediate coating layer so that the average dry film thickness was 15 μm. The coating was performed using an electrostatic coating machine (“Auto REA”, manufactured by ABB Industry) at an atomization pressure of 2.0 kg / cm ² . The booth atmosphere during painting was maintained at a temperature of 25 ° C. and a humidity of 75%. After painting, set for 3 minutes, preheat at 80 ° C. for 5 minutes, and then wet-on-wet on top of the acrylic / melamine resin-based clear coating composition (acid epoxy curable acrylic resin-based clear coating composition, “Mac Flow O -1810 "(manufactured by Nippon Paint Co., Ltd.) was spray-coated to a dry film thickness of 35 μm, set at room temperature for 7 minutes, baked at 140 ° C. for 30 minutes, and then double-layered by 2 coats 1 bake (2C1B) A coating film was formed.

Examples 2-8 and Comparative Examples 1-5
A glittering base coating composition was prepared in the same manner as in Example 1 except that the colored aluminum pigment (A), the aluminum pigment (B) and the colored pigment (C) were changed to those shown in Table 1 or 2. Next, a multilayer coating film was formed in the same manner as in Example 1 using the resulting glittering base coating composition.
In Tables 1 and 2, the “hue range” of the colored pigment (C) is the counterclockwise −50 when the hue of the colored aluminum pigment (A) is the reference (0 position) of the Munsell hue ring 100 and This means the hue displayed as clockwise +50.

  The following evaluation was performed using the multilayer coating film obtained by the said Example and comparative example.

Hue evaluation of multilayer coating film The hue (H) in the Munsell color system (JIS Z 8721) of the multilayer coating film obtained in the examples and comparative examples is expressed by a multi-angle spectrophotometer "MA-" manufactured by X-Lite. 68 II ". The results are shown in the table below.

Measurement of Lightness (L *) and Saturation (C *) of Multilayer Coating Film For the multilayer coating films obtained in Examples and Comparative Examples, the lightness (L *) and saturation (C *) are as follows. It was measured. The results are shown in the table below.

Lightness (L *)
A multi-angle spectrophotometer manufactured by X-Lite Co., Ltd. was used to illuminate the obtained multilayer coating film with a light source at an angle of 45 ° from the vertical position and received light at an angle of 15 ° from the regular reflection position. It measured using "MA-68 II". The lightness (L *) at a light receiving angle of 15 degrees was determined by calculating the average value of the measured values thus obtained. In the following table, it is indicated as “15L *”.

Saturation (C *)
A multi-angle spectrophotometer manufactured by X-Lite Co., Ltd. was used to irradiate the obtained multilayer coating film with a light source at an angle of 45 ° from the vertical position and receive light at an angle of 15 ° from the regular reflection position. It measured using "MA-68 II". The saturation (C *) at the light receiving angle of 15 degrees was determined by calculating the average value of the measured values thus obtained. In the following table, it is indicated as “15C *”.

FIG. 2 is a schematic explanatory diagram showing measurement positions of the lightness (L *) and saturation (C *).

  The above L * and C * are parameters in the L * C * h color system, and can be obtained according to JIS Z8729. This L * C * h color system is a color system defined by the International Lighting Commission, and is described in Section 4.2 of CIE Publication 15.2 (1986). In the L * C * h color system, L * represents lightness, C * represents saturation, and h represents hue angle. The lightness L * means that the hue of the substance to be measured increases as the numerical value increases and the blackness increases as the numerical value decreases. The saturation C * indicates that the larger the value, the brighter the color of the object to be measured. On the other hand, when the value of C * is small, it indicates that it is close to an achromatic color having no color.

  As shown in Tables 1 and 2 above, in the examples, the glittering properties including the colored aluminum pigment (A), the aluminum pigment (B), and the colored pigment (C) including both the colored pigments (c1) and (c2). The multilayer coating film obtained using the base coating composition has a lightness (L *) of 100 or more (especially 102 or more) and a saturation (C *) of 85 or more, and has high lightness and saturation. It was confirmed that Moreover, all of the hue (H) of these multilayer coating films were in the range of 7.5YR to 5Y, and it was recognized that the hue of gold (gold) was exhibited visually.

  Comparative Example 1 is an experimental example using a coating composition that does not contain the colored aluminum pigment (A). In this experimental example, the brightness (15L *) of the highlight portion was as high as 101 due to the inclusion of the aluminum pigment (B), but the saturation (15C *) of the highlight portion was as low as less than 85.

  Comparative Example 2 is an experimental example using a coating composition that does not contain the colored aluminum pigment (A) and does not contain the colored pigment corresponding to the colored pigment (c2) in the present invention. Also in this experimental example, the lightness (15L *) of the highlight part is as high as 101.3 due to the inclusion of the aluminum pigment (B), but the saturation (15C *) of the highlight part is less than 85. It was low. Moreover, the hue (H) of the obtained multilayer coating film was 5YR, and it became an orangeish coating film.

  Comparative Example 3 is an experimental example using a coating composition containing only the colored pigment (c1) as the colored pigment (C) although the colored aluminum pigment (A) and the aluminum pigment (B) are included. Also in this experimental example, the lightness (15L *) of the highlight portion was as high as 101.5, but the saturation (15C *) of the highlight portion was as low as less than 85. Moreover, the hue (H) of the obtained multilayer coating film was 5YR, and it became an orangeish coating film. Note that it can be confirmed from Comparative Example 3 that it is necessary to use a pigment containing both the color pigments (c1) and (c2) as the color pigment (C).

  Comparative Example 4 contains a colored aluminum pigment (A), an aluminum pigment (B), and a colored pigment (c2), but includes a colored pigment whose hue range of the pigment corresponding to the colored pigment (c1) is lower than −15. It is an experimental example using a coating composition. In this experimental example, both the lightness (15L *) of the highlight portion and the saturation (15C *) of the highlight portion are greatly reduced.

  Comparative Example 5 includes a colored aluminum pigment (A), an aluminum pigment (B), and a colored pigment (c1), but includes a colored pigment having a hue range of the pigment corresponding to the colored pigment (c2) greater than +15 It is an experimental example using a composition. Also in this experimental example, both the lightness (15L *) of the highlight portion and the saturation (15C *) of the highlight portion are greatly reduced.

  FIG. 3 is a graph showing numerical values of the lightness (15L *) of the highlight portion and the saturation (15C *) of the highlight portion of the multilayer coating films obtained by the above examples and comparative examples.

  The multi-layer coating film obtained by the multi-layer coating film forming method of the present invention has a feature that it has a golden (gold) hue, a glittering feeling, and high chroma and brightness. By applying the method of the present invention to the coating of automobile bodies and parts, there is an advantage that a vivid coating film can be formed and a unique design can be imparted.

Claims (5)

A luster-based coating film containing a colored aluminum pigment (A), an aluminum pigment (B), and a coloring pigment (C) is formed on an object to be coated, and further a clear coating film is formed. (H) is a multilayer coating film forming method for forming a multilayer coating film having 7.5YR to 5Y,
The colored aluminum pigment (A) has an average particle size of 5 to 5 obtained by coating 10 to 25 parts by mass of a coating component containing at least iron oxide with respect to 100 parts by mass of aluminum flakes as a base material. A scaly glittering pigment of 25 μm,
The colored pigment (C) has a hue represented by −3 to −3 of the hue represented by counterclockwise −50 and clockwise +50 when the hue of the colored aluminum pigment (A) is the reference (0 position) of the Munsell hue ring 100. A coloring pigment (c1) having a hue range of -15 and a coloring pigment containing at least two types of coloring pigments (c2) having a hue range of +3 to +15;
A method for forming a multilayer coating film.   The pigment concentration (PWC) of the colored aluminum pigment (A) in the glittering base coating composition forming the glittering base coating film is 1 to 10% by mass, and the colored aluminum pigment (A) and the aluminum The method for forming a multilayer coating film according to claim 1, wherein the mass ratio of the pigment (B) is (A) / (B) = 1/5 to 10/5.   The mass ratio of the colored pigment (c1) and the colored pigment (c2) in the glittering base coating composition that forms the glittering base coating film is (c1) / (c2) = 9/1 to 3/7. The method for forming a multilayer coating film according to claim 1 or 2.   The colored aluminum pigment (A) has a ratio of iron oxide in a coating component covering aluminum flakes of 90 to 100% by mass, and a thickness of the coating component is 10 to 30 nm. The multilayer coating film formation method in any one.   The multilayer coating film obtained by the multilayer coating-film formation method in any one of Claims 1-4.

Images