JPH101625A - Coating composition, coating film forming method and painted object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition, a coating film forming method, and a coated product which have a strong glittering shine in a highlight portion and an excellent solid coating color in a face or a shade portion. SOLUTION: To 100 parts by weight of solid content of resin for forming a coating film,
(1) Average particle diameter (D ₅₀₎ 18～30Myuemu, the particles having an average thickness of 0.
5 to 1.5 μm, the gradient n in the rosin-Rammler diagram is
2.5 or more aluminum flake pigment A, (2) the average diameter of the particles is
Pigment B having a BET specific surface area of not less than 0.1 μm and a BET specific surface area of not more than 30 m ² / g, (3)
BET specific surface area of 30 m ² / g with an average particle diameter of less than 0.1 μm
(4) (A / B) is 2/8 to 5/5,
And (5) a coating composition comprising 10 to 60 parts by weight of a pigment component in which (A + B) / (A + B + C) is blended in a weight ratio of 0.5 or more. A coating film forming method for forming a clear coating film after applying the coating composition, and a coating product coated by the coating composition and the coating film forming method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial coating for automobiles, bicycles, home electric appliances and parts thereof, for example, which has a high glitter in a highlight portion,
A coating composition capable of forming a colored solid metallic coating film with little turbidity in the face and shade portion, a coating film forming method using the coating composition, and the coating composition or the coating film forming method The present invention relates to a coated article formed by using the method.

A two-coat solid-like coating composition having a solid feeling by increasing the hiding power by reducing the amount of a pigment added to a coating film is disclosed in JP-A-2-132171.
The publication discloses rutile type titanium dioxide (A) and at least 8
0% by weight contains a total of at least 60% by weight of flaky aluminum powder (B) having a particle diameter of 1 to 32 μm, and the ratio of (A) / (B) is 99/1 to 90/10
(Weight ratio) of the pigment composition having a resin solid content of 10
A coating composition containing 10 to 200 parts by weight to 0 part by weight is disclosed. However, in general, when an aluminum pigment is used, the coating color becomes turbid due to the gray color peculiar to aluminum metal, and the saturation is reduced. Also,
When titanium dioxide is used in combination, the refractive index of titanium dioxide is high, so that the diffuse reflection becomes strong, and there is a problem that the excellent glittering feeling of aluminum tends to be reduced.

[0003] In the highlight part, a metallic feeling is provided.
In the shade part, as a 2 coat 1 bake pearl finish coating with a solid feeling, the base coat for pearl finish uses a pigment component consisting of titanium white pigment, metallic pigment and mica powder as an essential component, and further uses a coloring pigment as necessary A pearl finish coating method (Japanese Patent Laid-Open No. 5-212345) which is a liquid paint prepared as described above has been proposed. This coating method uses titanium dioxide, aluminum pigments and mica pigments in combination to compensate for the glitter and gray turbidity of aluminum pigments, and achieves pearl and solid tones utilizing the high diffuse reflectance of titanium dioxide. To form a coating film having However, there is a drawback that there is no turbidity as a hue due to the effect of turbidizing the color of the aluminum pigment, and it is difficult to obtain a highly saturated color.

[0004]

As described above, the coating film using the aluminum pigment and titanium dioxide in combination has a problem that the turbidity and the brightness of the coating color are reduced, and the present inventors have solved these problems. As a result of repeated research for the purpose of solving,
Particle size distribution of aluminum pigment, average diameter and BET of color pigment particles that reduce the glitter of aluminum pigment
It has been found that the specific surface area has a significant effect, and that by setting the compounding ratio in a specific range, a solid metallic coating film having a metallic feeling and a solid feeling, with less saturation and turbidity can be obtained. Was.

The present invention has been completed on the basis of these findings. The object of the present invention is to provide an excellent brilliant glitter in a highlight portion and an opaque but vivid color of a solid paint color in a face or a shade portion. A coating composition capable of forming a solid metallic coating film with low turbidity, a method for forming a coating film using the coating composition, and a coating material formed by the coating composition and the coating film forming method. It is in.

[0006]

In order to achieve the above object, a coating composition according to the present invention comprises a resin 100 for forming a coating film.
The following (1) to (5) pigment components 10 to 60
It is characterized in that it contains parts by weight. (1) Aluminum flake pigment A having an average particle diameter (D ₅₀ ) of 18 to 30 μm, an average particle thickness of 0.5 to 1.5 μm, and a gradient n in a rosin-Rammler diagram of 2.5 or more, (2) particles Has an average diameter of 0.1 μm or more and a BET specific surface area of 30 m ^2.
/ G or less, Pigment C having an average particle diameter of less than 0.1 μm and a BET specific surface area of more than 30 m ² / g, (4)
Weight ratio of aluminum flake pigment A to pigment B [A / B]
Is 2/8 to 5/5, and (5) the weight ratio of the aluminum flake pigment A to the pigment B and the pigment C [(A + B) / (A + B +
C)] is 0.5 or more.

The pigment B is preferably a coloring pigment other than titanium dioxide, and the mixing ratio of the aluminum flake pigment A, the pigment B and the pigment C is [(A + B) / (A
+ B + C)] is preferably 0.5 or more and 0.95 or less.

The method for forming a coating film of the present invention forms a clear coating film after applying the coating composition, and the coated product is coated by the coating composition and the coating film forming method. It is assumed that.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Among the paint components constituting the paint composition of the present invention, resins generally used for paints are used as a vehicle-forming resin for forming a coating film.
Examples of these resins include an acrylic resin, a polyester resin, an alkyd resin, a fluororesin, and the like, which are usually used after being mixed with a crosslinking agent such as an amino resin or a blocked polyisocyanate compound. Further, these resins are not limited to one kind, and 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.

[0010] Other additives to the resin for forming a coating film include, for example, a curing catalyst such as dodecylbenzenesulfonic acid,
Benzotriazole-based UV absorbers, benzophenol-based antioxidants, surface conditioners such as silicone and organic polymers, anti-sagging agents, thickeners, anti-settling agents, and cross-linkable polymer particles (microgels) are appropriate. Used for 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.

As the pigment component constituting the coating composition of the present invention, those having the following particle properties are selectively used. Aluminum flake pigment A: Among the pigment components, aluminum flake pigment A serving as a brilliant material has an average particle diameter (D ₅₀ ) of 18 to 30 μm, an average particle thickness of 0.5 to 1.5 μm,
Those having a particle property with a gradient n of 2.5 or more in a rosin-Rammler diagram are selectively used. This particle property is compared with the conventionally used aluminum flake pigment,
It is characterized in that it has a narrow particle size distribution width, shows a highly uniform particle size distribution, and has properties of being thick and having excellent smoothness.

The properties of these particles are determined by the following measuring methods. The average particle size (D ₅₀ ) indicates a 50% value of the particle size distribution measured by a laser diffraction type particle size distribution analyzer. The average particle thickness (μm) is [4
000 / water surface area (cm ² / g)], and the measurement method is described in, for example, “Aluminum Handbook” (9th edition, published on April 15, 1972, Japan Light Metal Association; Asakura Shoten) ) P. 1243. Also, the Rosin-Rammler diagram is [R
= 100exp (-bD ⁿ )] (where R is the cumulative weight% from the maximum particle size to the particle size D, D is the particle size, and b and n are constants). And the gradient n means the n value of the rosin-Rammler formula represented by a straight line connecting the cumulative weight% from the maximum particle size to the particle size D in the particle size diagram. A specific measurement method is to obtain a particle size distribution using a laser diffraction type particle size distribution measuring device, plot the obtained cumulative distribution for each particle size on a rosin-Rammler diagram, and translate the straight line in parallel to an extreme point ( Calculate n by extrapolating from Pol P).

Average particle size (D ₅₀ ) of aluminum flake pigment
If the average particle size is less than 18 μm, the particles become too fine and the glitter does not sufficiently appear. Conversely, if the average particle size exceeds 30 μm, the particles become large, and the particles are protruded from the coating film surface due to disorder in the orientation and overlapping of the particles. Will occur. When the average particle thickness is in the range of 0.5 to 1.5 μm, it is relatively thicker than conventional aluminum flake pigments, hardly deformed, and has excellent surface smoothness. When the average thickness of the particles is less than 0.5 μm, the glitter cannot be enhanced.On the other hand, when the average thickness of the particles exceeds 1.5 μm, the aluminum flake pigment cannot be improved. Projection occurs due to poor orientation, resulting in poor coating film appearance. Also, the gradient n of the rosin-Rammler diagram
The particle properties of 2.5 or more are characterized by a narrow particle size distribution of the aluminum flake pigment, and the uniform particle size suppresses irregular reflection based on fine particles to enhance glitter and reduce coarse particles. , Good coating appearance. When the gradient n is less than 2.5, the particle size distribution is broadened, and the fine-grain-side particles enhance the gray-white characteristic of aluminum flakes, giving a reduction in glitter and a sense of turbidity and a reduction in depth. Become. The gradient n in the rosin-Rammler diagram is preferably in the range of 2.7 to 3.5.

The aluminum flake pigment having the above-mentioned particle properties is obtained by, for example, grinding atomized aluminum spherical powder whose particle size has been previously selected by primary classification or the like, by grinding a grinding aid, an aliphatic or aromatic hydrocarbon solvent. It can be obtained by performing wet pulverization treatment with a pulverizer in the presence of a medium and the like, sieving and classifying under a wet state, and then performing solid-liquid separation with a filter press or the like. The particle shape has a macroscopically circular or rounded flat shape, and has a very small number of uneven fracture surfaces existing at the flake ends.

Pigment B: As the pigment B, the average particle diameter of the pigment particles is 0.1 μm or more, and the BET specific surface area is 30 m ² / g.
The following particle-like color pigments are used. This color pigment has high opacity, and when used in combination with a brilliant pigment such as a metallic pigment or a mica pigment, the reflection and absorption on the surface of the color pigment is increased and the transmission and scattering of light is reduced. And the metallic feeling is reduced. The present invention reduces the glitter of aluminum by using, as pigment B, a color pigment having a particle property having an average particle diameter of 0.1 μm or more and a BET specific surface area of 30 m ² / g or less. An opacity can be imparted. Preferably, the average diameter of the particles is 0.2 to
Those having a 0.4 μm BET specific surface area of 12 to 30 m ² / g are used. The measurement of the average particle diameter is a particle diameter determined by a counting method using an electron microscope.

In this case, the mixing ratio of the aluminum flake pigment A and the pigment B having a high luminance feeling is such that [A / B] is 2 by weight ratio.
By setting the ratio to / 8 to 5/5, a coating composition having an opacity of metallic feeling and solid feeling and capable of forming a coating film excellent in solid metallic feeling with little decrease in brightness or turbidity. Things. When the weight ratio [A / B] is less than 2/8, the opacity of the coloring pigment causes the glitter to decrease even when a highly glittering aluminum flake pigment is used. This is because the flop feeling peculiar to metallic becomes stronger.

Pigment C: The pigment C has an average particle diameter of less than 0.1 μm and a BET specific surface area of 30 m ² / g.
Transparent pigments having a particle property of more than 1 are used.
This coloring pigment has high transparency, and when used in combination with a brilliant pigment such as a metallic pigment or a mica pigment, the reflection and absorption on the surface of the coloring pigment decreases, and the transmission and scattering of light increases.
The amount of light reaching the glittering pigment increases, and a metallic feeling is strongly exhibited. The present invention suppresses the decrease in glitter by using together a pigment C having a small average particle diameter and a large BET specific surface area.

These pigment components are weight ratio of aluminum flake pigment A, pigment B and pigment C, [(A + B) / (A
+ B + C)] is 0.5 or more. If the weight ratio is less than 0.5, the metallic feeling is increased and the flop feeling peculiar to the metallic is enhanced. Preferably, the value is set in the range of 0.5 or more and 0.95 or less.

As described above, the coating composition of the present invention comprises particles of aluminum flake pigment A as a glittering material, opaque pigment B as a color pigment, and transparent pigment C,
In addition, by setting the blending weight ratio in a specific range, it is possible to form a solid metallic coating film having both glitter and opacity, that is, having little turbidity as a hue and having high saturation. .

The coating composition for forming a brilliant coating film having the above-mentioned composition is generally of the organic solvent type, but is not limited thereto, and may be of various types such as non-aqueous dispersion type, aqueous solution type and aqueous dispersion type. Paint can be configured as a form. Upon application, the composition is diluted with a solvent such as an organic solvent or water to a viscosity suitable for application. The solid content during production is preferably 30 to 70% by weight, and the solid content during application is preferably 10 to 50% by weight.

The method for forming a coating film according to the present invention comprises a process of base-coating the above-mentioned coating composition on the surface of a substrate to be coated, then top-coating a clear coating, and simultaneously curing the base coat and the top coat. The coated product of the present invention is a product coated by the above-described coating composition or coating film forming method.

Substrates to be coated include inorganic materials such as metals such as iron, aluminum, copper or alloys thereof, glass, cement, concrete, and the like.
Polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyamide, polyacryl, polyester,
Resin molded products such as ethylene-polyvinyl alcohol copolymer, vinyl chloride resin, vinylidene chloride resin, polycarbonate, and polyurethane, and plastic materials such as various FRPs, wood, and fiber materials are applicable. It is optional to perform an appropriate undercoat or precoat treatment on the substrate to be coated in advance.

The coating can be applied directly to the substrate to be coated. For example, in the case of coating of automobiles, undercoating or intermediate coating with an electrodeposition paint or the like is usually carried out after surface conversion treatment, and after the coating film is cured. Paint. The coating operation is performed by air spray coating, electrostatic coating or the like using an atomizing type coating machine. The coating film of the base coat is preferably formed in a dry film thickness range of 10 to 25 μm. If the film thickness is less than 10 μm, the base concealing property is reduced, causing color unevenness.

Then, a clear top coating is applied as a top coat on the base coat. As the clear paint, a transparent resin generally used is generally used, but if necessary, a coloring pigment or various additive components may be blended as long as the transparency is not impaired. Base coat and top coat are 2
The coating is simultaneously cured by a coat 1 baking method to form a composite coating film. The preferred dry film thickness of the formed top coat is 30 to 60 μm.

Preferred embodiments of the present invention are listed below. (1) A coating composition comprising 10 to 50 parts by weight of the following pigment component per 100 parts by weight of a resin for forming a coating film. Average particle diameter (D ₅₀₎ 18～30Myuemu, the particle average thickness 0.5 to 1.5 [mu] m, rosin - gradient n in Rammler diagram is 2.5 or more aluminum flake pigments A, the average diameter of the particles 0. Pigment B having a BET specific surface area of 1 m or more and a BET specific surface area of 30 m ² / g or less, a pigment C having an average particle diameter of less than 0.1 μm and a BET specific surface area exceeding 30 m ² / g, an aluminum flake pigment A and a pigment B Weight ratio [A / B]
The weight ratio of the aluminum flake pigment A to the pigment B and the pigment C [(A + B) / (A + B + C)] is 0.5 or more. (2) The average particle diameter (D ₅₀ ) of the aluminum flake pigment A is 20 to
A coating composition having a thickness of 30 μm, an average particle thickness of 0.5 to 1.2 μm, and a gradient n of 2.6 to 3.5 in a rosin-Rammler diagram. (3) Pigment B particles having an average diameter of 0.2 to 0.4 μm, BE
A coating composition having a T specific surface area of 12 to 30 m ² / g. (4) Weight ratio of aluminum flake pigment A to pigment B [A /
B] is 2/8 to 4/6. (5) The weight ratio of the aluminum flake pigment A to the pigment B and the pigment C [(A + B) / (A + B + C)] is 0.5 or more.
A coating composition of not more than 95. (6) A coating film forming method for forming a clear coating film after applying the coating composition according to any one of the above (1) to (5) on a surface of a substrate to be coated. (7) A coated article coated with the coating composition according to any one of (1) to (5). (8) A coated article coated by the coating film forming method of (6) above.

[0026]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Examples 1 to 5 and Comparative Examples 1 to 5 (1) Preparation of substrate to be coated: A cationic electrodeposition coating [Nippon Paint Co., Ltd.] was applied to a 0.8 mm thick dull steel plate substrate chemically treated with zinc phosphate. Co., Ltd. "Power Top U-50"] was applied so that the dry coating film became 25 μm,
Bake for a minute. The electrodeposited coating film was spray-coated with an intermediate coat “Olga S-90 Sealer” manufactured by Nippon Paint Co., Ltd. so that the dry coating film would have a thickness of 40 μm.
At 30 DEG C. for 30 minutes, and the surface was coated with the coating composition of the present invention so that the dry coating film had a thickness of 16 to 20 .mu.m. The coating was performed using an electrostatic coating machine (Auto REA, manufactured by Landsberg Gemma Co., Ltd.) 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 the application, a coating for forming a clear coating film was applied so that the dry film thickness became about 35 μm. Then about 1
After setting at room temperature for 0 minutes, baking was performed at 140 ° C. for 30 minutes to produce a test plate for a substrate to be coated.

Acrylic resin (copolymer of styrene / methyl methacrylate / ethyl acrylate / hydroxyethyl methacrylate / methacrylic acid, number average molecular weight: about 20,000, hydroxyl value: 45, acid value: 15, solid content: 50
%) And 20 parts by weight of a melamine resin (“Uban 20SE” manufactured by Mitsui Toatsu Chemicals, Inc., solid content: 60%) were mixed to prepare a vehicle resin for forming a coating film.

With respect to 100 parts by weight of the vehicle resin,
The following pigments were mixed at different ratios to prepare coating compositions. Aluminum flake pigment A: A1; average particle diameter (D ₅₀ ) 20 μm, average particle thickness 0.7
μm, gradient n of the rosin-Rammler diagram is 3.0 A 2; average particle diameter (D ₅₀ ) 30 μm, average particle thickness 1.0
μm, gradient n of the rosin-Rammler diagram is 2.6 A3; average particle diameter (D ₅₀ ) 18 μm, average particle thickness 0.4
μm, gradient n of the rosin-Rammler diagram is 2.3 Pigment B: B1; “Taipec CR-97” manufactured by Ishihara Sangyo Co., Ltd., average particle diameter 0.26 μm, BET specific surface area 14 m ² / g B2; BASF "Pariotor Yellow 2140H"
D ″, average particle diameter 0.14 μm, BET specific surface area 25
m ² / g B3; “Irazine DPP Red B” manufactured by Ciba Geigy
O ", average particle diameter 0.23 μm, BET specific surface area 17
m ² / g Pigment C: C1; “Lionol Green 6” manufactured by Toyo Ink Mfg. Co., Ltd.
Y ″, average particle diameter of 0.06 μm, BET specific surface area 52
m ² / g C 2; “Shanin Blue G314” manufactured by Sanyo Dyeing Co., Ltd., average particle diameter 0.05 μm, BET specific surface area 81.5 m ² /
g

After the pigment B and the pigment C were premixed in the vehicle resin, they were sufficiently dispersed by a sand grinder mill. The coating composition thus prepared was applied to a test plate by a wet-on-wet method.
Baking was performed at 40 ° C. for 30 minutes to form a glittering coating film. In addition, an acrylic / melamine resin-based clear paint [“Super Luck O-100” manufactured by Nippon Paint Co., Ltd.] was used as a paint for forming a clear coating film.

With respect to the coating films thus formed, the compositions of the coating compositions are shown in Table 1 (Example) and Table 2 (Comparative Example).
It was shown to.

[0032]

[Table 1]

[0033]

[Table 2]

Further, the formed coating film was visually evaluated according to the following criteria, and the appearance of the coating film was evaluated for metallic feeling and solid feeling. Table 3 shows the obtained evaluation results. : Solid feeling is obtained in the shade part and metallic feeling is obtained in the highlight part. × 1: Low saturation (turbidity) and low brightness in the shade area. Strong metallic feeling in highlights. × 2: The metallic feeling in the highlight area is not sufficient.

[0035]

[Table 3]

From the results shown in Tables 1 to 3, the coating films formed by the coating compositions of the examples satisfying the conditions of the present invention were as follows:
It can be seen that, compared to the coating film of the comparative example, a solid portion is stronger in the shade portion, while a coating film with a high glitter is obtained in the highlight portion.

[0037]

As described above, according to the coating composition, coating film forming method and coated product of the present invention, aluminum flake pigments, opaque pigments and transparent pigments having a specific range of particle properties can be prepared in a specific range. By blending in a vehicle resin at a weight ratio of, a reduction in glitter is small, and a high-chroma solid metallic coating film without turbidity can be formed. Therefore, it is extremely useful as a coating composition for forming a colored coating film and a coating film forming method having both glitter and opacity.

Claims (6)

[Claims] Claims: 1 100 parts by weight of a solid content of a resin for forming a coating film,
A coating composition comprising 10 to 60 parts by weight of a pigment component of the following (1) to (5). (1) Aluminum flake pigment A having an average particle diameter (D ₅₀ ) of 18 to 30 μm, an average particle thickness of 0.5 to 1.5 μm, and a gradient n in a rosin-Rammler diagram of 2.5 or more, (2) particles Has an average diameter of 0.1 μm or more and a BET specific surface area of 30 m ^2.
/ G or less, Pigment C having an average particle diameter of less than 0.1 μm and a BET specific surface area of more than 30 m ² / g, (4)
Weight ratio of aluminum flake pigment A to pigment B [A / B]
Is 2/8 to 5/5, and (5) the weight ratio of the aluminum flake pigment A to the pigment B and the pigment C [(A + B) / (A + B +
C)] is 0.5 or more. 2. The coating composition according to claim 1, wherein the pigment B is a coloring pigment other than titanium dioxide. 3. The weight ratio [(A + B) / (A + B + C)] of the aluminum flake pigment A to the pigment B and the pigment C is 0.
The coating composition according to claim 1, which has a value of 5 or more and 0.95 or less. 4. A method for forming a coating film, comprising: applying a coating composition according to any one of claims 1 to 3 to a surface of a substrate to be coated, and then forming a clear coating film. 5. A coated article, wherein the coating composition according to claim 1 is applied. 6. A coated article coated by the method for forming a coating film according to claim 4.