JP2011231194A - Coating composition and method for forming coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition capable of forming a coating film capable of being applied to various kinds of industrial products, especially an outer panel of an automobile, having high lightness at highlight (near a normal reflection light), having color change generated from the highlight toward face (middle of highlight and shade) and having small lightness change from the highlight to the shade (oblique direction), and a method for forming a coating film.SOLUTION: The coating composition contains a multi-color brilliant pigment, a scale-like aluminum pigment and an oxidized titanium pigment, and in the coating composition, the multi-color brilliant pigment is selected from a scale-like light-interfering pigment of a multi-layer structure and a scale-like silica pigment covered with a cholesteric liquid crystal polymer and a metal oxide. In the method for forming the coating film, a substrate is coated with the coating composition and is further coated with clear coating.

Description

The present invention has high brightness in highlights (near specularly reflected light), a hue change from highlight to face (between highlight and shade), and brightness change from highlight to shade (diagonal direction) Relates to a coating composition capable of forming a small coating film and a coating film forming method.

In exterior colors of industrial products such as automobiles, metallic colors whose color appearance changes depending on the viewing angle dominate. So far, in the metallic color, a large color change from a highlight (near regular reflection light) to a shade (oblique direction) and whiteness (high brightness) of the highlight have been pursued. On the other hand, there is a strong demand for complex textures such as gentle brightness changes and subtle hue changes with respect to the viewing angle. Until now, several methods for obtaining a paint color whose hue changes depending on the observation angle have been proposed.

  In Patent Document 1, as a method for forming a metallic coating film having excellent depth and metallic feeling, metallic paint containing flake-like aluminum powder and titanium oxide powder having a particle size (diameter) of 0.01 to 0.08 μm. A method for forming a metallic coating film in which a clear coating is applied is described. However, the method of Patent Document 1 has a problem that the hue change from highlight to shade is insufficient.

  Patent Document 2 discloses an aluminum-containing coating film containing an aluminum pigment on a substrate as a metallic multi-layer coating film having a high transparency and an opal-like glitter that allows gold coloration to be recognized depending on the viewing angle. A multilayer coating comprising a titanium-containing coating comprising finely divided titanium dioxide and a clear coating is described. However, the method of Patent Document 2 also has a problem that the hue change from the highlight to the shade is insufficient, and the number of processes increases because it is a three-coat film.

  Patent Document 3 discloses a base containing a silver-plated glass flake pigment, an aluminum flake pigment having an average particle size of 15 μm or less, and a titanium dioxide pigment as a method for forming a coating film having a different design from the glitter or metallic feeling. A method for forming a clear coating on a coating is described. However, the method of Patent Document 3 has a problem that a hue change from highlight to face does not occur.

JP-A-6-254484 JP 2009-183884 A JP 2009-291713 A

The object of the present invention is high brightness in highlights (near specular reflection light), hue change from highlight to face (middle of highlight and shade), and from highlight to shade (oblique direction). It is to provide a coating composition and a coating film forming method capable of forming a coating film having a small change in brightness.

The present invention
1. A coating composition comprising a multicolor glitter pigment, scaly aluminum pigment and titanium oxide pigment,
2. 2. The coating composition according to item 1, wherein the multi-colored glitter pigment is selected from a scaly light interference pigment having a multilayer structure, a cholesteric liquid crystal polymer, and a scaly silica pigment coated with a metal oxide,
3. The coating composition according to item 2 or 3, wherein the average particle size of the scaly aluminum pigment is in the range of 5 to 40 µm,
4). The coating composition according to any one of items 1 to 4, wherein the titanium oxide pigment has an average particle size of 10 to 400 nm,
5). The coating composition according to any one of 1 to 4, wherein a part or all of the titanium oxide pigment is a fine particle titanium oxide pigment having an average particle size of 20 to 80 nm,
6). It is related with the coating-film formation method which coats the coating composition described in any one of 1-5 with a base material, and also coats a clear coating material.

According to the present invention, the highlight (in the vicinity of specular reflection light) has high brightness, a hue change occurs from the highlight to the face (between the highlight and the shade), and from the highlight to the shade (in an oblique direction). It is possible to obtain a coating composition and a coating film forming method capable of forming a coating film having a small change in brightness.

The coating composition of the present invention contains a multicolor glitter pigment for the purpose of changing the color of a coating film obtained by painting from highlight to face. Examples of the multicolor glitter pigment include a multi-layered scaly light interference pigment, a metal oxide-coated scaly silica pigment, and a cholesteric liquid crystal polymer.

  Multi-layered scaly interference pigments have a wavelength that is determined for a specific incident / reflecting direction because the wavelength range of the reflected light is determined by the refractive index of the materials that make up the multi-layered structure and the thickness of each layer. Since only the light is strongly reflected, a structural color whose color changes depending on the observation angle can be expressed.

  Examples of the multi-layered scale-like light interference pigment include mica, artificial mica, glass, silica, iron oxide, aluminum oxide, aluminum, aluminum, aluminum, aluminum, etc. , Iron oxide, zinc sulfide, magnesium fluoride, aluminum fluoride, sodium fluoride, silicon oxide, aluminum oxide, thorium fluoride, chromium, etc. Examples thereof include pigments formed and pigments obtained by laminating three or more layers of films having different refractive indexes.

  A metal oxide-coated scale-like silica pigment is obtained by coating scale-like silica, which is a base material having a smooth surface and a uniform thickness, with a metal oxide having a refractive index different from that of the base material. Since the thickness of the layer is uniform, when blended with a coating composition, the coating film obtained by coating changes color depending on the observation angle.

  A cholesteric liquid crystal polymer is prepared by, for example, arranging a three-dimensional cross-linkable polymer such as a polyorganosiloxane having a methacryloyloxy group or an acryloyloxy group in the side chain and a liquid crystal substance into a parallel layer and then spiraling the molecules. In order to make a structure, the layers are stacked in layers so that the molecular orientation is slightly different depending on the electric field or magnetic field, the molecules oriented by the polymerization reaction are fixed, the thin film layer is three-dimensionally cross-linked, then separated from the substrate, What was obtained by grind | pulverizing to a desired particle size can be mentioned.

  Since the cholesteric liquid crystal polymer has a helical structure, the wavelength range of light reflected is determined by the pitch width of the helical structure and the refractive index of the liquid crystal, and the reflected light of a specific range of wavelengths has a pitch corresponding to the light wavelength. The light component is split into a spiral structure and becomes a reflection component and a transmission component according to the direction of rotation of the spiral. Since the spiral pitch varies depending on the observation angle, a structural color that changes color appears.

  In the present invention, it is particularly preferable to use a metal oxide-coated scaly silica pigment as the multicolor glitter pigment because the coating film obtained by coating is excellent in weather resistance and is easily available.

  In the present invention, the multicolor glitter pigment preferably has a longitudinal average particle diameter (D50) in the range of 1 to 50 μm, preferably in the range of 3 to 30 μm, from the viewpoint of the finish of the coating film. It is more preferable to use those within the range, and it is particularly preferable to use those within the range of 5 to 25 μm. Moreover, it is preferable to use the thing within the range of 0.01 micrometer-10 micrometers, and it is especially preferable to use the thing within the range of 0.1 micrometer-5 micrometers.

  The content of the multi-color glitter pigment is based on 100 parts by mass of the solid content of the resin composition in the coating composition from the viewpoint of expressing an appropriate hue change from the highlight of the coating film obtained by coating to the face. It is preferably within the range of 0.01 to 50 parts by mass, more preferably within the range of 0.05 to 40 parts by mass, and particularly preferably within the range of 0.1 to 20 parts by mass.

  The coating composition of the present invention contains a scaly aluminum pigment for the purpose of increasing the brightness in highlights.

  The scaly aluminum pigment is generally produced by grinding and grinding aluminum in a ball mill or attritor mill using a grinding aid in the presence of a grinding fluid. As the grinding aid, aliphatic amines, aliphatic amides and aliphatic alcohols are used in addition to higher fatty acids such as oleic acid, stearic acid, isostearic acid, lauric acid, palmitic acid and myristic acid. Aliphatic hydrocarbons such as mineral spirits are used as the grinding fluid.

  The scaly aluminum pigment can be roughly classified into a leafing type and a non-leafing type depending on the type of grinding aid. The leafing type is arranged (leafing) on the surface of the coating film obtained by painting when blended into the paint composition, resulting in a strong metallic finish, heat reflection, and rust prevention. Therefore, it is often used for various building materials such as tanks, ducts, piping, and roof roofing. In the coating composition of the present invention, it is preferable to use a non-leafing type scaly aluminum pigment from the viewpoint of the whiteness of the highlight of the coating film obtained by coating.

  The scale-like aluminum pigment preferably has an average particle size in the range of 5 to 40 μm from the viewpoint of the finish of the coated film and the brightness of the highlight, more preferably the particle size. The diameter is in the range of 7 to 30 μm, particularly preferably in the range of 8 to 25 μm. It is preferable to use a thickness in the range of 0.05 to 0.5 μm. The particle size and thickness here means a numerical value obtained by observing the scaly aluminum pigment with an optical microscope or an electron microscope, or a numerical value measured with a particle size distribution measuring apparatus using a laser such as a laser diffraction method. To do.

  Further, the content of the scaly aluminum pigment is preferably in the range of 1 to 25 parts by mass in total with respect to 100 parts by mass of the resin solid content in the paint from the viewpoint of the finish of the coating film obtained by coating. More preferably, it is in the range of 3 to 20 parts by mass, particularly preferably in the range of 5 to 18 parts by mass.

  The coating composition of the present invention contains a titanium oxide pigment for the purpose of suppressing a change in brightness from the face (middle of highlight and shade) to the shade (oblique direction) of the coating film obtained by painting. The titanium oxide pigment has an average particle size in the range of 10 nm to 400 nm in terms of the effect of suppressing the change in brightness from the face (middle of highlight and shade) to the shade (diagonal direction) of the coating film obtained by painting. It is preferable to use those. Here, the average particle diameter of the titanium oxide pigment is an average particle diameter measured by observation with an electron microscope.

  Although it does not specifically limit as a titanium oxide pigment, The thing etc. which are manufactured by the normal sulfuric acid method and a chlorine method can be mentioned. Furthermore, from the point of improving weather resistance, it may be surface-treated with oxides or hydroxides such as silica, alumina, zirconia, etc., or represented by organosilicon compounds such as polydimethylsiloxane or stearic acid. Higher fatty acid or isopropyl triisostearoyl titanate and surface treated with an organic titanium compound represented by isopropyl triisostearoyl titanate.

  In the coating composition of the present invention, part or all of the titanium oxide pigment is a fine particle titanium oxide pigment having an average particle diameter of 20 to 80 nm, from the point of improving the saturation of the coating film obtained by coating. preferable. The fine-particle titanium oxide pigment is a pigment that has a high transparency due to its small particle diameter and causes a subtle change in hue depending on the observation angle due to the effect of scattering light.

  In the coating composition of the present invention, the content of the titanium oxide pigment has the effect of suppressing a change in brightness from the face (middle of highlight and shade) to the shade (diagonal direction) of the coating film obtained by painting. From within a range of 0.01 to 50 parts by weight, more preferably 0.05 to 30 parts by weight, and particularly preferably 0.1 to 25 parts by weight as solids with respect to 100 parts by weight of resin solids in the coating composition. Within the range of parts by mass.

  The coating composition of the present invention can also contain a coloring pigment other than the titanium oxide pigment for the purpose of adjusting the hue of the coating film obtained by coating. The coloring pigment is not particularly limited, and specifically, inorganic pigments such as transparent iron oxide pigments and composite oxide pigments such as titanium yellow, azo pigments, quinacridone pigments, diketopyrrolopyrrole. Pigments, perylene pigments, perinone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, metal chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, selenium pigments, Any organic pigments such as indigo pigments can be used alone or in combination.

  When the color pigment is blended in the coating composition of the present invention, the content thereof is based on 100 parts by mass of the resin solid content in the coating from the viewpoint of the saturation in the highlight of the coating film obtained by coating and the brightness of the shade. It is preferably in the range of 0.01 to 30 parts by mass, more preferably 0.05 to 25 parts by mass, and particularly preferably 0.5 to 20 parts by mass.

The coating composition of the present invention can usually contain a resin component as a vehicle.
Specifically, as the resin component, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, or a urethane resin having a crosslinkable functional group such as a hydroxyl group, a melamine resin, a urea resin, a polyisocyanate compound (block body). Are used in combination with a crosslinking agent such as an organic solvent and / or a solvent such as water.

Furthermore, in the coating composition of the present invention, if necessary, a solvent such as water or an organic solvent, a pigment dispersant, an anti-settling agent, a curing catalyst, an antifoaming agent, an antioxidant, an ultraviolet absorber, a surface conditioner Various additives such as rheology control agents, extender pigments and the like can be appropriately blended.

The coating composition of the present invention is prepared by mixing and dispersing the aforementioned components. The solid content at the time of coating is 12 to 60% by mass, preferably 15 to 50%, based on the coating composition.
It is preferable to adjust to mass%.

  In the method for forming a coating film of the present invention, the coating composition as described above is applied to a substrate, and a clear coating is applied to the obtained coating film.

  Base materials include metals such as iron, zinc, aluminum and magnesium, alloys containing these, molded products plated or vapor-deposited with these metals, and molded products made of glass, plastic, foam, etc. Can be mentioned. Depending on these materials, it can be appropriately degreased or surface treated to form a substrate. Furthermore, an undercoating film or an intermediate coating film can be formed on the substrate to form a substrate, and these coated substrates are particularly preferable.

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

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

In particular, when an undercoat film or an intermediate coat film is formed as a substrate, the undercoat film or the intermediate coat film can be heated, and the coating material for the next step described later can be applied after crosslinking and curing. Alternatively, the coating composition of the present invention can be applied in a state where the undercoat film and / or the intermediate coat film is uncured.

  The coating composition of the present invention can be applied by a method such as electrostatic coating, air spraying, airless spraying, and the film thickness is within the range of 5 to 30 μm based on the cured coating film. From the viewpoint of smoothness. Usually, it can be heated and dried and cured after being applied to a predetermined film thickness, but a clear paint described later can be applied in an uncured state. The coating film itself of the coating composition of the present invention can be crosslinked and cured usually at a temperature of about 50 to about 150 ° C. in the case of a baking dry type, and in the case of a normal temperature drying type or a forced drying type, It can be cross-linked and cured at a temperature from dry to about 80 ° C.

The clear coating in the method of the present invention is a coating to be applied to the uncured or cured coating surface of the above-described coating composition. The clear coating is mainly composed of a resin component and a solvent, and, if necessary, other coating additives. Is a liquid paint that forms a colorless or colored transparent coating film.

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

In the clear paint in the method of the present invention, a color pigment can be blended in a timely manner as long as transparency is not impaired. As the color pigment, one or a combination of two or more conventionally known pigments for ink and paint can be blended. The amount of addition may be determined as appropriate, but is 30 as a solid content with respect to 100 parts by mass of the resin solid content in the clear coating film.
It is within a range of not more than mass parts, preferably 0.01 to 15 mass parts, particularly preferably 0.01 to 10 mass parts.

The clear coating in the present invention can be applied by a method such as electrostatic coating, air spraying, airless spraying, and the film thickness is preferably in the range of 15 to 70 μm based on the cured coating film. The clear coating film itself can be crosslinked and cured usually at a temperature of about 50 to about 150 ° C. in the case of a baking drying type, and in the case of a room temperature drying type or a forced drying type, it is room temperature drying to about 80. Crosslinking and curing can be performed at a temperature of ° C.

In the coating film forming method of the present invention, after coating the coating composition of the present invention as described above, heating,
After drying and curing, the clear coating may be applied onto the coating film and heated to dry and cure. However, after the coating composition is applied, the clear coating is applied in an uncured state. Then, it is possible to obtain a multilayer coating film in the process of heating and drying and curing these simultaneously.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to only these examples. “Part” and “%” are based on mass.
Next, an Example is given and this invention is demonstrated more concretely.
Examples 1-7, Comparative Examples 1-6
(Production Example 1) Production of hydroxyl group-containing acrylic resin 50 parts of ethylene glycol monoethyl ether acetate was charged in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser and dropping device, stirred and mixed, and the temperature was raised to 135 ° C. Warm up. Subsequently, the following monomer / polymerization initiator mixture was dropped into a reaction vessel maintained at the same temperature over 3 hours, and aging was performed for 1 hour after the completion of the dropping. Thereafter, a mixture of 10 parts of ethylene glycol monoethyl ether acetate and 0.6 parts of 2,2′-azobis (2-methylpropionitrile) was added dropwise over 1 hour 30 minutes maintained at the same temperature, and further 2 hours. Aged. Next, ethylene glycol monoethyl ether acetate was distilled off under reduced pressure to obtain a hydroxyl group-containing acrylic resin having a hydroxyl value of 54 mgKOH / g, a number average molecular weight of 20,000, and a resin solid content of 65%. Here, the number average molecular weight means that measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.
Monomer / polymerization initiator mixture:
38 parts of methyl methacrylate, 17 parts of ethyl acrylate, 17 parts of n-butyl acrylate, 7 parts of hydroxyethyl methacrylate, 20 parts of lauryl methacrylate and 1 part of acrylic acid and 2,2′-azobis (2-methylpropionitrile) A mixture of 2 parts.

(Preparation of coating composition)
Per 100 parts of resin component (solid content) consisting of 75 parts of a hydroxyl group-containing acrylic resin obtained in Production Example 1 and 25 parts of Uban 28-60 (trade name, butyl etherified melamine resin, manufactured by Mitsui Chemicals, Inc.) Color pigments are blended in the ratios shown in Table 1, mixed with stirring, diluted to an appropriate viscosity for coating, and an organic solvent-type paint having a solid content of about 25% is prepared. The paint composition used in Examples and Comparative Examples A product was prepared.

(Creation of test plate)
Cationic electrodeposition paint “ELECRON 9400HB” (trade name: manufactured by Kansai Paint Co., Ltd., epoxy resin polyamine-based cation resin) on steel plate (JISG3141, size 400 × 300 × 0.8 mm) subjected to adjustment degreasing and zinc phosphate treatment (Using a block polyisocyanate compound as a curing agent) is electrodeposited to a film thickness of 20 μm based on the cured coating, and heated at 170 ° C. for 20 minutes for crosslinking to obtain an electrodeposition coating. It was.

On the surface of the electrodeposited coating, an intermediate coating “Lugabek Intermediate Coating Gray” (trade name: manufactured by Kansai Paint Co., Ltd., polyester resin / melamine resin type, organic solvent type) is applied by air spray. Based on the film, it was applied to a film thickness of 30 μm, heated at 140 ° C. for 30 minutes to be crosslinked and cured, and a coated plate on which an intermediate coating film was formed was used as a base material.
Coating The coating composition prepared in Examples 1 to 7 and Comparative Examples 1 to 6 was applied to the substrate using an air spray so that the cured coating film had a thickness of 20 μm. After coating, the room temperature was about 20 ° C. Leave it in the laboratory for about 15 minutes, and then use a clear paint (Lugabe Kukurya, manufactured by Kansai Paint, trade name, acrylic resin / amino resin type, organic solvent type) as a cured coating film to be 30 μm. Painted on. After coating, the sample was allowed to stand at room temperature for 15 minutes, and then heated in a hot-air circulating drying oven at 140 ° C. for 30 minutes to simultaneously dry and cure the multilayer coating film to obtain a test plate.
(Evaluation)
The design properties of the test plate were evaluated in the following manner, and the results are shown in Table 1.
The prepared coated plate is illuminated with an artificial sunlamp (Ceric, color temperature 6500K), and observed at a different angle with respect to the illumination of the test plate. From the highlight (near the specular reflection light) to the shade (oblique direction) Lightness change and hue change were evaluated visually according to the following criteria. The evaluation was conducted by a total of 5 designers and 3 engineers engaged in color development for 3 years or more, and the average score was adopted.
Lightness change:
3: High brightness at highlight and lightness gradually changes from highlight to shade.
2: The brightness changes sharply from highlight to shade with high brightness.
1: Low brightness at highlight, and brightness does not change from highlight to shade.
Hue change:
3: The hue changes greatly from the highlight to the face.
2: Slight hue change from highlight to face.
1: There is almost no hue change from highlight to face.

The coating film forming method of the present invention can be applied to various industrial products, particularly automobile outer plates.

Claims (6)

A coating composition comprising a multicolor glitter pigment, a scaly aluminum pigment, and a titanium oxide pigment. 2. The coating composition according to claim 1, wherein the multi-color glitter pigment is selected from a scaly light interference pigment having a multilayer structure, a cholesteric liquid crystal polymer, and a scaly silica pigment coated with a metal oxide. The coating composition according to claim 1 or 2, wherein the scaly aluminum pigment has an average particle diameter in the range of 5 to 40 µm. The coating composition according to any one of claims 1 to 3, wherein the titanium oxide pigment has an average particle size of 10 to 400 nm. The coating composition according to any one of claims 1 to 4, wherein a part or all of the titanium oxide pigment is a fine particle titanium oxide pigment having an average particle diameter of 20 to 80 nm. A coating film forming method in which a coating composition according to any one of claims 1 to 5 is applied to a substrate, and further a clear coating is applied.