JP3386222B2 - Design film formation method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a design coating film useful for industrial coating of automobiles and parts thereof, bicycles, home electric appliances and the like. The present invention relates to a method for forming a multi-layer coating film having high chroma, no turbidity, and excellent esthetic properties giving a pearlescent luster that reproduces the color of a colored base. 2. Description of the Related Art Conventionally, silver and interference mica titanium having a thin film of titanium dioxide coated on the surface of flaky mica have been used as a paint component for imparting a pearlescent luster to a coating film. The coating film is formed by a three-coat multi-layer coating method in which a paint containing the mica pigment is applied on a colored undercoat film and a clear coat is formed. [0003] As a coating technique of a paint containing this kind of silver and interference mica titanium, for example, a particle size of 5 to 5 is used.
Lacquer coating method using pearlescent pigment (Japanese Patent Application Laid-Open No. 58-166964), in which a lacquer containing 25 μm titanium dioxide-coated mica pigment is applied, and then a clear lacquer is applied. A coating method in which a transparent pearl coating containing mica coated with a metal oxide mainly composed of titanium dioxide of 6 to 13% (resin solid content ratio) on a color base is applied, and a top clear coat is applied (Japanese Patent Application Laid-Open No. No. 61-37423), when a low concealment paint containing a titanized mica pigment is overcoated on a colored undercoat film, a titanized mica pigment whose pigment interference color is the same as the hue of the colored undercoat film is used. A paint finishing method to be used (JP-A-59-160571) and the like have been proposed. As a base material of these titanium dioxide-coated mica pigments, flaky natural muscovite having a smooth surface is selectively used in order to obtain excellent glitter. However, trace amounts as a natural muscovite impurity iron, are included mud, etc., of a pale yellow or slightly yellowish brown oxidized when by calcining titanium hydroxide which these components are coated is converted to TiO ₂ Cause the phenomenon to be exhibited. When such a phenomenon occurs, pure whiteness peculiar to muscovite is disturbed, and the shade portion gives a sense of bottom turbidity. In order to solve such a problem, a pearl-like luster composition comprising a titanium dioxide-coated barium sulfate pigment in which the coated substrate is a highly transparent flaky barium sulfate single crystal and a method for producing the same have been proposed by the present applicant. (Japanese Patent Publication No. 47-24930). The above flaky barium sulfate pigment coated with titanium dioxide is excellent in transparency as compared with the mica pigment coated with titanium dioxide, and is a pure single crystal, which causes coloring. Contains no impurities. Therefore, although the problem of hue at the time of using the above-mentioned titanium dioxide-coated mica pigment is solved, there is a problem that luster is poor. The present inventors have conducted intensive studies to solve the above-mentioned drawbacks inherent in the titanium dioxide-coated mica pigment and the titanium dioxide-coated flaky barium sulfate pigment. As a result, these titanium dioxide-coated mica pigments and Titanium-coated flaky barium sulfate pigment is formulated into a paint by mixing it in a specific range of the amount ratio, and this is applied to a colored undercoating surface having a certain lightness and saturation, and then a clear coating film is formed on the upper surface. It was confirmed that the components complemented each other's disadvantages and developed a pearlescent luster that indicates the hue of the colored base. The present invention has been developed on the basis of the above findings, and has as its object to provide an excellent pearlescent luster that reproduces the color tone of a colored base without having a high saturation and no turbidity in a shade portion. And to provide a method for forming a design coating film. Means for Solving the Problems [0009] The method for forming a design coating film according to the present invention for achieving the above object includes the following (1) to (3).
The film forming process is sequentially performed. (1) The brightness in the Munsell display system is 3 or more and the saturation is 2
Above colored underlayer coating film forming step (2) Titanium dioxide-coated flaky barium sulfate pigment (P1) and titanium dioxide-coated mica pigment (P2) in weight ratio (P1 / P2) in the range of 95/5 to 50/50. A) a bright layer coating film containing 3 to 10 parts by weight per 100 parts by weight of resin solid content of a bright pigment having a composition comprising: (3) a clear film forming step; The object to be coated includes metals including iron, aluminum, copper or alloys thereof, glass, cement, inorganic materials such as concrete, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyamide, poly Acrylic, polyester, ethylene-polyvinyl alcohol copolymer, vinyl chloride, vinylidene chloride, polycarbonate, polyurethane and other resin molded products and various FRP Plastic material, wood, fiber material is appropriate. It is optional to apply an appropriate undercoat or precoat treatment to these substrates in advance. The coating can be applied directly to the object to be coated. For example, in the case of coating an automobile, an undercoating such as an electrodeposition paint is usually applied after a surface chemical conversion treatment, and the coating is cured after the coating is cured. Form. As a coating method, an atomization type coating or a roll coater type coating is used. In particular, an air spray coating, an electrostatic coating or the like by the atomization type coating method is suitably used. First, a colored base coat generally called a color intermediate coat is formed on an object to be coated. As the pigment used for the color intermediate coating, various types of organic and inorganic coloring pigments and extenders commonly used for coatings can be used.
As the color pigment, for example, an organic azo lake pigment,
Inorganic graphite such as insoluble azo pigment, condensed azo pigment, phthalocyanine pigment, indigo pigment, perinone pigment, perylene pigment, dioxazine pigment, quinacridone pigment, isoindolinone pigment, metal complex pigment, etc. ,
Calcium carbonate, barium sulfate, clay, talc and the like are used as extenders such as yellow iron oxide, red iron oxide, carbon black and titanium dioxide. Examples of the resin serving as a vehicle for forming a coating film include a system in which a basic resin such as an acrylic resin, a polyester resin, or an alkyd resin is mixed with a crosslinking agent such as an amino resin or (block) polyisocyanate. In addition, a two-component polyurethane resin or silicone resin that can be cured by drying at room temperature is also used. The dry film thickness of the colored undercoat film to be formed is in the range of 25 to 50 μm, preferably 30 to 40 μm. The colored undercoating film formed in this step is controlled such that the hue of the coating film is 3 or more in Munsell display system and 2 or more in saturation by controlling the mixing ratio of the coloring pigment and the vehicle resin. Adjust to When the lightness is less than 3, a blurred feeling or uneven color is generated, and when the saturation is less than 2, the sense of bottom turbidity increases. It is not possible to express a pearlescent brightness that can be effectively reproduced. Particularly preferred hue of the colored undercoat film is Munsell display system having a lightness of 6 or more and a chroma of 4
That is all. On the surface of the colored undercoat film, a paint containing a glitter pigment obtained by mixing a flaky barium sulfate pigment coated with titanium dioxide and a mica pigment coated with titanium dioxide is applied by dry-on-wet to form a glitter layer coating film. Depending on the process, it is also possible to use wet-on-wet. The titanium dioxide-coated flaky barium sulfate pigment (P1) constituting the glittering paint has a coating composition in which titanium dioxide is coated as a thin layer on the surface of a flaky barium sulfate single crystal powder. It can be prepared as follows. Sulfate concentration of 0.5 to 0.001 mol /
l of soluble sulfate solution having a barium salt concentration of 0.5 to 0.1.
001 mol / l of a soluble barium salt solution was added, and the mixture was allowed to react under a condition of an acidic pH range from room temperature to the boiling point to obtain a solution having a size of 5%.
A single crystal of flaky barium sulfate having a thickness of about 100 μm and a thickness of about 0.05 to 1 μm is produced. For example, p
H3, 10 l of a 0.01 mol solution of ammonium sulfate heated to 40 DEG C. and 5.5 l of a 0.02 mol solution of barium chloride heated at 40 DEG C. were reacted to give a long diameter of 5-100 .mu.m. A slightly deformed rhombic crystal of barium sulfate having a flaky aspect with a minor axis of 5 to 30 μm is formed. Preferably, the major axis is 10 to 40 μm and the minor axis is 5 to 30 μm. The obtained flaky barium sulfate is washed with water, classified, suspended in pure water, and added with titanyl sulfate, titanium tetrachloride or another water-soluble titanium compound or complex compound, and hydrolyzed by heat or alkali. Titanium hydroxide adhered to the surface of the flaky barium sulfate by this hydrolysis is subjected to a baking treatment after washing with water, so that a thin layer is coated as titanium dioxide. In this step, a metal oxide such as tin or zirconium may be added as long as coloring is not hindered. In this way, a titanium dioxide-coated flaky barium sulfate pigment having pearl luster and interference and having pearl luster is obtained. On the other hand, as the mica pigment coated with titanium dioxide (P2), a mica fine powder coated with a thin layer of titanium dioxide to give a pearly luster is used, and is used in combination with the above-mentioned flaky barium sulfate pigment coated with titanium dioxide. Mixed. The compounding ratio of the titanium dioxide-coated flaky barium sulfate pigment (P1) and the titanium dioxide-coated mica pigment (P2) is the weight ratio (P1 /
P2) is set in the range of 95/5 to 50/50. If the blending ratio of the titanium dioxide-coated mica pigment falls below the above range, the glitter will decrease, and if it exceeds the range, the sense of bottom turbidity will increase and the hue of the colored undercoat film will become cloudy. More preferred weight ratio (P1 / P2) is 80/20 to 50/50.
Range. A brilliant pigment having a composition obtained by mixing a flaky barium sulfate pigment coated with titanium dioxide and a mica pigment coated with titanium dioxide is mixed with a vehicle component to prepare a brilliant paint.
As the vehicle resin, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a silicon resin, and a fluororesin is used by mixing with a crosslinking agent such as an amino resin or a (block) polyisocyanate. Not only one kind but also two or more kinds can be used in combination. In addition, a two-component polyurethane resin or silicone resin that can be cured by drying at room temperature is also used. The amount of the glitter pigment added to the vehicle resin is 3 to 10 parts by weight, preferably 4 to 8 parts by weight, per 100 parts by weight of the resin solids. When the addition amount is less than 3 parts by weight, the interference color and the brilliant feeling are reduced, and when the added amount is more than 10 parts by weight, the brilliant feeling is too strong to be blurred or the reproduction of the colored base color is reduced. The thickness of the bright layer coating film to be formed is preferably in the range of 10 to 30 μm as a dry film thickness. [0020] Crosslinked polymer fine particles consisting of fine resin particles may be added to the above-mentioned brilliant paint, and this addition effectively functions to control the viscosity and improve the appearance of the coating film.
The crosslinked polymer fine particles are, for example, suspension polymerization or emulsion polymerization of an ethylenically unsaturated monomer and a crosslinkable comonomer in an aqueous medium, and the resulting fine resin particle dispersion is solvent-exchanged, azeotropic. Non-aqueous organic solvents in which monomers dissolve but polymers do not dissolve like low SP organic solvents such as fatty acid hydrocarbons or high SP organic solvents such as esters, ketones, alcohols, etc. In which an ethylenically unsaturated monomer and a crosslinkable copolymer are copolymerized to disperse the obtained fine resin particles (copolymer) (referred to as NAD method or precipitation method) It is manufactured by In addition, JP-A-58-1
A method using a water-soluble resin having a zwitterionic group described in 29066 may be adopted. The added crosslinked polymer fine particles preferably have an average particle size in the range of 0.01 to 10 μm. For example, AZS797 and AZS597 manufactured by Nippon Paint Co., Ltd.
Are preferably used. The compounding amount is 100 resin solids.
The amount is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight with respect to parts by weight. In addition, various additives commonly used in conventional coating compositions can be arbitrarily added to the glittering coating. Examples of additives include anti-settling agents such as oxidized polyethylene wax and polyamide wax, curing catalysts such as dodecylbenzene sulfonic acid, benzotriazole-based ultraviolet absorbers, benzophenol-based antioxidants, silicone and organic polymers. Surface conditioners, anti-sagging agents, thickeners and the like. These components can generally improve the performance of paints and coatings in amounts of 5 parts by weight or less based on 100 parts by weight of the resin for forming a coating. The top coat is generally of an organic solvent type, but is not limited thereto, and can be formed in various forms such as a non-aqueous dispersion type, an aqueous solution type and an aqueous dispersion type. The solid content at the time of production is preferably 30 to 70% by weight. At the time of coating, it is diluted with a solvent such as an organic solvent or water to a coating-suitable viscosity and used.
~ 50% by weight is preferred. Next, a clear coating is applied to the surface of the bright coating film by a wet-on-wet method to form a clear coating film. As the clear paint, a commonly used transparent resin similar to the vehicle resin used for the glitter paint is used. The bright coating film and the clear coating film are simultaneously cured by a two-coat one-bake method to form a composite coating film. The preferred dry film thickness of the clear coating film to be formed is 30 to 60 μm.
m. According to the method for forming a design coating film of the present invention, a coating containing a glittering pigment component is applied to the surface of a colored undercoating film having a certain hue or more to form a glittering coating film, and further, a clear coating film is formed. It consists of the step of forming a coating film, but the purpose is to use a glittering pigment component composed of flaky barium sulfate coated with titanium dioxide and a mica pigment coated with titanium dioxide, particularly blended as a glittering pigment in a specific ratio range. There are major components that have the effect of That is, the refractive index of barium sulfate, which is the base material of the bright pigment, is 1.64, which is close to the refractive index of mica, which is the other base material, of 1.54 to 1.59. For this reason, flaky barium sulfate pigment coated with titanium dioxide,
The pigment has high transparency inside the coating film, and since the base material is single crystal and contains no impurities, the pigment itself is not turbid. On the other hand, the mica pigment coated with titanium dioxide functions to complement the phenomenon of weakening of the glitter caused by the flaky barium sulfate pigment coated with titanium dioxide. The function of complementing the pigment components is to provide a titanium dioxide-coated flaky barium sulfate (P1) and a titanium dioxide-coated mica pigment (P2) in a weight ratio (P1 / P2) of 95/5 to 50/50.
Effective when set to a range of 50, with no reduction in lightness and saturation of the colored base coating film, with no turbidity, blurring, uneven color, etc. It develops a pearlescent luster that clearly reproduces the hue of the base. Therefore, it is possible to always form a glittering coating film having excellent design properties. EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples. The titanium dioxide-coated thin film barium sulfate pigment (P1) and titanium dioxide-coated mica pigment (P
2) and the film-forming resin were the following commercially available products. In addition,
The designation of the components in Tables 1 to 7 is in accordance with the symbol shown before each component. The amount was shown in parts by weight of the solid content. Flaky barium sulfate pigment coated with titanium dioxide
(P1); (P1a) Nippon Koken Kogyo Co., Ltd., “Genestar 710
1 "(silver color) (P1b) Nippon Koken Kogyo Co., Ltd.," Genestar 720
1 "(interference gold) Mica pigment coated with titanium dioxide (P2); (P2a)" Iriodin 103WII "manufactured by Merck Japan
(Silver color) (P2b) “Iriodin 205WII” manufactured by Merck Japan
(Interference Gold) Mica pigment coated with iron oxide (P3: for comparative example); (P3) “NP Lassett WII” film-forming resin manufactured by Merck Japan; acrylic resin is styrene / methyl methacrylate /
Ethyl acrylate / hydroxyethyl methacrylate / methacrylic acid copolymer, number average molecular weight 2000
0, hydroxyl value 45, acid value 15, solid content 50%. Melamine resin manufactured by Mitsui Toatsu Chemicals, "Uban 20SE"
(Solid content 60%). Examples 1 to 16 and Comparative Examples 1 to 17 A 0.8 mm-thick dull steel plate base material chemically treated with zinc phosphate was coated with a cationic electrodeposition paint [Nippon Paint Co., Ltd., “Power Top U- 50 "] was applied so that the dry coating film became 25 µm, and baked at 160 ° C for 30 minutes. A polyester / melamine resin intermediate coating [Nippon Paint Co., Ltd., “Olga S-90 Sealer”]
Blue, yellow, green, red, blue green,
Was spray-coated with air so that the dry coating film had a thickness of 40 μm, and baked at 140 ° C. for 30 minutes to prepare a test plate. The hue of each of the formed colored undercoat films was measured together with the Munsell color chart (displayed in the upper margin of Tables 1 to 7). Flaky barium sulfate pigment coated with titanium dioxide
(P1) and titanium dioxide-coated mica pigment (P2) in a predetermined weight ratio (P
1 / P2), the blending amount of the brilliant pigment with respect to 100 parts by weight of the resin solid content was blended in the ratio shown in the content of each table, and this was mixed with the paint forming resin [acrylic resin / melamine resin = 80/20 (solid )) To prepare a glittering paint. The viscosity of this glitter paint is adjusted with a solvent (toluene / xylene / ethyl acetate / butyl acetate = 70/15/10/5) in a Ford cup # 4 at 20 ° C. for 12 to 15 seconds. Is 15
The test piece was coated on the colored undercoat film surface so as to have a thickness of μm.
Coating is performed by an electrostatic coating machine [Auto manufactured by Randsburg Gema, Auto
REA] at an atomization pressure of 2.8 kg / cm ² , and the booth atmosphere during coating was maintained at a temperature of 25 ° C. and a humidity of 75%. After setting for 3 minutes after painting,
An acrylic / melamine resin-based clear coating (“Super Rack 0-100”, manufactured by Nippon Paint Co., Ltd.) was applied by wet-on-wet so that the dry film thickness was about 35 μm. Then, after setting at room temperature for about 10 minutes, baking was performed at 140 ° C. for 30 minutes. The coating film thus formed was subjected to CIE according to the following criteria.
(L ^* , a ^* , b ^* ) optical measurement of hue in display system,
In addition, the feeling of bottom turbidity, the feeling of white blur, the feeling of glitter, and the unevenness of color by visual observation were evaluated. The results are shown for each intermediate coating hue of the colored base coat, the type, blending ratio (P1 / P2) of titanium dioxide-coated flaky barium sulfate pigment (P1) and titanium dioxide-coated mica pigment (P2) of glittering paint, and Tables 1 to 7 in comparison with the content (parts by weight) of the brilliant pigment based on 100 parts by weight of the solid content
It was shown to. Tables 6 and 7 are examples in which the brightness or the saturation of the colored underlayer coating film falls outside the required range of the present invention. Measurement of hue in CIE (L ^* , a ^* , b ^* ) display system; goniospectrocolorimeter [G
The CMS-3 type, D65 light source, 2 degree field of view] is used to illuminate the light source at an angle of 45 ° from the perpendicular to the coating-formed measurement sample as shown in FIG. 15 ° (light receiving point H in the highlight direction) and 11
Light was received simultaneously at an angle of 0 ° (light receiving point S in the shade direction). The color was measured using a lightness-chroma L ^* a ^* b ^* color system, and lightness (L ^* ) and chroma (C ^* ) were measured. C ^* was calculated by ^{{(a *) 2 + (} b *) 2} 1/2. ΔL ^* in the table
And ΔC ^* are the differences from the colored base coat. Criteria for Evaluation by Visual Evaluation; The criteria for evaluation by visual observation were as follows. Bottom turbidity: ◎ None 殆 ど Almost none □ Somewhat △ Yes × Strong white blur: ◎ Nothing ○ Almost no □ Somewhat □ Somewhat △ Yes × Strong glitter: ◎ Very strong ○ Strong □ Somewhat weak △ Weak × No Color shading: ◎ Very strong ○ Strong □ Slightly weak △ Weak × None [Table 1] Table Note: S part shows shade part, H part shows highlight part (the same applies hereinafter). [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7] From the results shown in Tables 1 to 7, it can be seen from the results that the design coating films according to the examples formed according to the present invention have relatively ΔL ^* and ΔC.
The width of ^* is small, the feeling of turbidity and blurring is small, and excellent brightness without color unevenness is maintained. On the other hand, the comparative example group which does not satisfy the requirements of the present invention is inferior in at least one of performances of bottom turbidity, white blur, brilliantness and color unevenness, and shows the color sensation of a colored base such as the coating film of the example. It was not possible to develop a pearlescent luster that clearly reproduced. The preferred embodiments of the present invention are as follows. (1) A design coating film forming method in which a glittering coating film and a clear coating film are formed by a wet-on-wet method after baking and curing the colored underlayer coating film. (2) The weight ratio of titanium dioxide-coated flaky barium sulfate (P1) and titanium dioxide-coated mica pigment (P2) in the glittering coating film (P1 / P
2) A method for forming a decorative coating film, wherein is 80/20 to 50/50. (3) A method for forming a decorative coating film in which the glitter pigment in the glitter layer coating film is 4 to 8 parts by weight per 100 parts by weight of the resin solid content. (4) The lightness of the colored underlayer coating film in the Munsell display system is 6
As described above, a method for forming a decorative coating film having a saturation of 4 or more. (5) The particle size of the titanium dioxide-coated flaky barium sulfate pigment (P1) in the bright layer coating film is 5 to 100 μm in major axis and 5 to 3 in minor axis.
0 μm. (6) The dried film thickness of the colored underlayer coating film / bright layer coating film / clear coating film is 25 to 50 μm / 10 to 30 μm / 30 to 60 μm.
m. (7) Crosslinking wherein the resin of the bright layer coating film is at least one thermosetting resin selected from acrylic resin, polyester resin, alkyd resin, silicone resin, and fluororesin, and amino resin and / or (block) polyisocyanate. A method for forming a decorative coating film, which is a combination of agents. (8) A method for forming a decorative coating film in which a colored underlayer coating film is subjected to a chemical conversion treatment and then formed on the electrodeposited coating film layer which has been electrodeposited. As described above, according to the design coating film forming method according to the present invention, a titanium oxide-coated flaky barium sulfate pigment coated with a specific blending ratio is coated on the colored underlayer coating film surface having a fixed hue. A pearlescent luster that reproduces the color sensation of a colored base without turbidity or color unevenness by sequentially performing the process of forming a luminous coating containing mica pigment coated with titanium dioxide and titanium dioxide, and a clear coating. It is possible to obtain a layer coating film.
Therefore, it is extremely useful for the purpose of forming a high-quality multilayer coating film on various substrates to be coated, such as the exterior surface coating of an automobile body requiring excellent design properties.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a hue measuring method in an example.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yanagita Higashi 6-1, Ichibancho, Tachikawa-shi, Tokyo Nippon Koken Kogyo Co., Ltd. (72) Inventor Kazuhiro Kimura 6, Ichibancho, Tachikawa-shi, Tokyo No. 1 in Nihon Koken Kogyo Co., Ltd. (56) References JP-A-5-163447 (JP, A) JP-A-5-169019 (JP, A) JP-A-61-123673 (JP, A) JP-A-5-311098 (JP, A) JP-A-58-21455 (JP, A) JP-A-3-32784 (JP, A) JP-A-59-215857 (JP, A) JP-A-63-205177 (JP, A) JP, A) JP-A-63-232882 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 5/06 B05D 1/38 B05D 7/24 301 B05D 7/24 303

Claims (1)

(57) [Claims] [Claim 1] A method for forming a design coating film, which comprises sequentially performing the following coating film forming steps (1) to (3). (1) The brightness in the Munsell display system is 3 or more and the saturation is 2
Above colored underlayer coating film forming step (2) Titanium dioxide-coated flaky barium sulfate pigment (P1) and titanium dioxide-coated mica pigment (P2) in weight ratio (P1 / P2) in the range of 95/5 to 50/50. And (3) a clear coating film-forming step in which a glitter pigment having a composition of 3 to 10 parts by weight per 100 parts by weight of resin solid content is contained.