JP3159884B2 - Paint composition and coating film forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is useful for a metallic composition for automobiles and the like, and a coating composition and a method for forming a coating film which are useful for coloring in fields where design is particularly required such as building materials and home electric appliances. About.

[0002]

2. Description of the Related Art Conventionally, coatings for automobiles and motorcycles are roughly classified into solid coatings and metallic coatings. In coatings for solid coating, color pigments such as copper phthalocyanine pigment, quinacridone pigment and perylene pigment are mixed. The paint color is designed by. On the other hand, in a paint for metallic coating, a metal powder such as aluminum or a mica pigment is usually used in combination with the coloring pigment for the purpose of producing a brilliant feeling.

[0003] A coating film formed using the above-mentioned solid paint and metallic paint is required to have sufficient durability and decorativeness (aesthetics) in order to protect the base.
In particular, reflecting the recent need for emphasis on individuality, there is a strong demand for diversification of coatings, such as the coating color of the top coat and decorativeness (aesthetics). There is a strong need for a paint composition that can be used.

[0004] Under these circumstances, mica pigment coated with titanium dioxide is an epoch-making pigment which can change interference colors such as silver, gold, red, blue and green by changing the thickness of the titanium dioxide layer to be coated. Yes,
In recent years, demand for pigments for automobiles and the like has been expanding as a pigment that produces a unique silky and soft texture that has never been seen before.

[0005] However, the above mica pigment coated with titanium dioxide, despite giving an excellent texture, is different from the pigment used for ordinary solid systems in that the refractive index of the mica itself is small due to the size of the mica itself. Despite being coated with large titanium dioxide, there is a problem that the concealing property is insufficient.Therefore, the paint containing the titanium dioxide-coated mica pigment has a titanium dioxide-containing coating layer as its base coat layer, Often painted on top. When the paint is applied in this manner, there is a problem that when the amount of reflected light is small (shade), the color tone originally perceived as pure white becomes yellowish. Accordingly, it is an object of the present invention to provide a coating composition and a coating film forming method which exhibit a pure white appearance even when shaded and which provide a novel coating film having a brilliant property.

[0006]

The above object is achieved by the present invention described below. That is, in the present invention, the plate surface diameter is 5-7.
A flaky or flake-like substrate surface having a thickness of 0.01 μm and a thickness of 0.01 to 0.5 μm is coated with a titanium dioxide film having a thickness from silver to green, and the surface is further coated with a Co / Al element. The ratio is in the range of 0.1 / 2 to 0.5 / 2
The pearl pigment coated with blue-based composite oxide pigments are, coating composition characterized in that it contains in the coating medium, and a method for forming a coating film using the coating composition.

[0007]

When a pearl pigment obtained by uniformly and uniformly coating a blue pigment on a pearl pigment coated with titanium dioxide having a thickness ranging from silver to green is used in a metallic paint. The coating film exhibits pure white even when shaded, and forms a coating film exhibiting slightly bluish interference light when highlighted. Thus, the undesirable yellowish sensation during conventional shades is improved,
It is possible to provide a coating composition which changes the color tone from each interference light at the time of highlighting to a pure white visual feeling at the time of shading to form a textured coating film with enhanced directivity.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to preferred embodiments. The pigment having a specific property used in the present invention is a flaky or flake-like substrate surface coated with titanium dioxide having a thickness from silver to green to a pearl pigment coated with a blue pigment, uniformly and uniformly. It is a pearl pigment coated.

[0009] The substrate, which is a coating base of the pearl pigment, has a plate surface diameter of 5 to 70 µm and a thickness of 0.01 to 70 µm.
A flaky or flaky substrate that is 0.5 μm is used. If the plate surface diameter or thickness is smaller than this range, it is difficult to coat the surface of the article to be coated with the coating composition in a good condition, while if it is larger than the above range, coating such as peeling of the coating film is difficult. It is not practical because of poor film suitability. When the thickness is within this range, interference colors can be effectively produced. A plate surface diameter of 20 to 50 μm, relatively uniform particles, thickness 0.1 μm
A thin film having a thickness of about m is particularly preferable. Mica flakes, especially muscovite flakes, are preferred as such substrates.

For example, when coating mica flakes with titanium dioxide, a titanium salt is used as a titanium source, and more specifically, reagents such as titanyl sulfate and titanium tetrachloride or industrial materials can be used. As a method of coating titanium dioxide, a solution in which a titanium salt is previously dissolved is added to a preheated mica flake suspension, and the titanium salt is hydrolyzed to form a hydrate or oxide of titanium on the mica flake. This method is known per se. In the present invention, the thickness of the titanium dioxide coating is appropriately adjusted so that the coated mica exhibits a silver to green color. The thus obtained slurry of titanium dioxide-coated mica flakes is washed with water, and the obtained slurry can be subjected to coating with a blue pigment. Also, at this time, the slurry is once filtered,
The obtained cake is dried at 120 ° C. for about 12 hours, and then the dried flakes are heat-treated at 700 to 900 ° C. for about 1 hour, and then can be subjected to coating with a blue pigment.

The blue pigment may be an organic pigment such as copper phthalocyanine blue, but it is effective to use an inorganic pigment in consideration of various resistances such as weather resistance and surface suitability with titanium oxide. For example, Zn, Co, Ti, S
A blue-based composite oxide manufactured by being selected from elements such as n, Al, Si, and W can also be used. In particular, it is desirable to use a material coated with a cobalt blue pigment having easy surface treatment, high coloring power, easy adjustment of the coloring amount, and excellent fastness. Further, it is desirable to use a more transparent one so as not to reduce the intensity of the interference color at the time of highlighting, and a pigment having a small refractive index is desired. In that sense, a cobalt blue pigment is suitable. Pearl pigments coated with these cobalt blue pigments can be produced, for example, by the methods described in Japanese Patent Application Nos. 5-340214 and 5-340215. .

Coating with a cobalt blue pigment is mainly intended to counteract the yellow color tone of the titanium dioxide-coated mica pigment when shaded, and the coating amount of the cobalt blue pigment is determined by the total amount of cobalt oxide and aluminum oxide. 50% by weight or less, preferably 1 to 50% by weight, based on the amount of titanium is sufficient. Also, Co / A at that time
The element ratio is preferably in the range of 0.1 / 2 to 0.5 / 2. When the amount of coating increases, the bluish color becomes too strong,
Aggregation of the flakes occurs, deteriorating the glitter itself.

The method described in the above specification is shown as an example of a method of further coating the titanium dioxide-coated mica pigment with a cobalt blue pigment. In a suspension of a mica pigment coated with a titanium dioxide pigment, a cobalt and aluminum salt which is a source of cobalt oxide and aluminum oxide and a substance which generates ammonium by heating as a precipitant, preferably urea or a derivative thereof, are dissolved and suspended. Make a liquid. The suspension is heated to maintain a constant temperature of 70 to 100 ° C., and urea and the like are hydrolyzed to generate ammonia, and the oxide of cobalt and aluminum or its hydrate is uniform and fine particles. Deposit on top. Since this precipitate is easily adapted to the titanium dioxide layer, it is gradually deposited on the titanium dioxide layer of the mica pigment. The coating reaction is terminated when the pH rises to 7 or more, preferably to 8. After the completion of the reaction, the slurry was filtered and washed with water.
Dry for about an hour and then in an oxidizing atmosphere
Heat treatment at 00 ° C. for about 0.5 to 2 hours. As described above, a pearl pigment obtained by coating a mica pigment coated with titanium dioxide with a blue pigment is obtained. The coating of the mica pigment with the blue pigment is not limited to the above method, and may be performed by another method.

The coating composition of the present invention is prepared by dispersing the pearl pigment in a vehicle in which a film-forming polymer is dissolved or dispersed in a coating medium. As the film-forming polymer used in the present invention, for example, acrylic resins, acrylic melamine resins, vinyl chloride-vinyl acetate copolymer resins, alkyd resins, polyester resins, polyurethane resins and amino resins are used in the field of conventional coatings. The polymer used in the present invention is not limited to the resin described above.

As the organic solvent for dissolving or dispersing the above-mentioned film-forming polymer, those which have hitherto been widely used for coatings can be used. Specifically, toluene, xylene, butyl acetate, methyl acetate, acetone,
Examples include methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, butanol, cyclohexane and the like.

In the coating composition of the present invention, the pearl pigment coated with the blue pigment is used in an amount of 0.005 to 50 parts by weight based on 100 parts by weight of the coating composition.
If the amount is less than 0.005 parts by weight, it is difficult to obtain the coating composition of the present invention. If the amount exceeds 50 parts by weight, the coating composition of the present invention is obtained, but the physical properties of the coating film are deteriorated. It is not preferable. Preferably it is 1 to 30 parts by weight. Various other fillers, antistatic agents, stabilizers, antioxidants, ultraviolet absorbers and the like conventionally used in the field of paints are added to the paint composition of the present invention as necessary. You can do it.

On the other hand, the method for forming a coating film of the present invention comprises a method of forming a coating film by first forming a base coat layer and then forming a clear coat layer on the base coat layer using the above-mentioned coating composition of the present invention; An arbitrary colored base coat layer (first base coat layer) is formed on the first layer of the coating film, a second base coat layer is formed thereon using the coating composition of the present invention, and then a clear coat layer is formed. By employing the coating film forming method, the performance of the coating composition of the present invention can be sufficiently exhibited. In order to form a coating film, the coating composition of the present invention is spray-coated, electrostatic-coated, flow-coated, roll-coated on a substrate such as a metal plate, glass, ceramics, or plastics which has been subjected to a base treatment as necessary. It is applied by coating or the like, dried, cross-linked and cured to form a base coat layer. Further, a clear coat agent prepared by dissolving or dispersing the same resin as the above-mentioned film-forming polymer in an organic solvent is applied thereon, dried, and heat-treated to form a coating film. The same applies to the case where an arbitrary colored base coat layer is formed on the first layer of the coating film before coating.

The coating film formed by applying the coating composition of the present invention to a substrate, which is formed by using a conventional silver pearl pigment, has a silky feel due to its surface smoothness and overall yellow color tone. On the other hand, in the present invention, the surface of the pearl pigment is coated with blue lightly and smoothly, so that the yellowish color is canceled and the color tone becomes almost pure white. This phenomenon is particularly remarkable in the shade portion (the portion where the amount of reflected light is small). The color tone is almost pure white compared to the conventional one having a slightly reddish yellowish color tone, and the difference is obvious. is there. In addition, when a blue-coated pigment having a color tone other than silver is used as an interference color, the interference color appears in a highlight, whereas the pure white color with a yellow tint is emphasized in a shade portion. become. Such an effect is a major feature that cannot be produced with conventional pearl pigments.

[0019]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following, “parts” or “%” is based on weight unless otherwise specified. The coating compositions of each formulation shown below have a spray viscosity (Ford Cup No.
4 for 14 seconds) and sprayed onto an aluminum panel that had been subjected to a base treatment with an air spray gun. Thereafter, in each case, after drying for 10 minutes, clear (acryl melamine) coating was performed. 1
After drying at room temperature for 5 minutes, it was baked and cured at 140 ° C. for 30 minutes to prepare an aluminum panel for evaluation, which was subjected to an evaluation test. In the evaluation, a difference in hue between a highlight portion and a shade portion was visually determined under bright light in the prepared panel. Table 1 shows the results.

EXAMPLE 1 Using scale-like muscovite flakes (thickness: 0.05 to 0.2 μm, average particle size: 40 μm), using titanium sulfate so that the mica flakes coated with titanium dioxide have a silver color. A glittering silver mica flake coated with titanium dioxide was obtained in the same manner as in Comparative Example 1 of Japanese Patent Application No. 5-340215 except that the amount was changed. Then, according to Example 1 of the above specification, a blue-coated pearl pigment (silver) was produced using the glittering silver mica flakes, and a coating composition was prepared using the pearl pigment according to the following formulation. (Blending ratio) (Blending ratio) Blue coating pearl pigment (silver) 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvent 100 / butyl acetate (7/3) mixed solution 30 parts

Example 2 As a first layer of a coating film, a base coat layer was formed with a coating composition having the following composition, and then the coating composition of Example 1 was applied to a second layer.
A coating film as a base coat layer was formed. (Blending ratio) (Blending ratio) Titanium oxide (CR-97) 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvent 100 / butyl acetate (7/3) mixed solution 30 parts

Example 3 A blue-coated pearl pigment (gold) was prepared in the same manner as in Example 1 except that the amount of titanyl sulfate used was changed so as to give a gold color. A composition was prepared. (Blending ratio) (Blending ratio) Blue coating pearl pigment (gold) 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvent 100 / butyl acetate (7/3) mixed solution 30 parts

Example 4 As a first layer of a coating film, a base coat layer was formed with the coating composition described in Example 2, and then a coating film using the coating composition of Example 3 as a second base coat layer was formed. Formed.

Example 5 A blue-coated pearl pigment (green) was prepared in the same manner as in Example 1 except that the amount of titanyl sulfate used was changed so as to exhibit a green color. A composition was prepared. (Blending) (Blending ratio) Blue-coated pearl pigment (green) 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvets 100 / butyl acetate (7/3) mixed solution 30 parts

Example 6 A base coat layer was formed with the coating composition described in Example 2 as the first layer of the coating film, and a coating film was formed using the coating composition of Example 5 as a second base coat layer. did.

Comparative Example 1 A commercially available pearl white pigment was used to prepare a coating composition according to the following formulation. (Blending ratio) (Blending ratio) Commercially available pearl white pigment 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvent 100 / butyl acetate (7/3) mixed solution 30 parts

Comparative Example 2 The procedure of Example 2 was repeated except that the coating composition using the commercially available pearl white pigment of Comparative Example 1 was used instead of using the blue-coated pearl pigment (silver) in the second base coat layer. A coating was formed in the same manner.

Comparative Example 3 A coating composition was prepared in the same manner as in Comparative Example 1 except that a commercially available pearl gold pigment was used instead of a commercially available pearl white. (Blending ratio) (Blending ratio) Commercially available pearl gold pigment 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvent 100 / butyl acetate (7/3) mixed solution 30 parts

Comparative Example 4 A coating was performed in the same manner as in Example 4 except that the coating composition of Comparative Example 3 using a commercially available pearl gold pigment was used instead of using the blue-coated pearl pigment (gold) for the second base coat layer. A film was formed.

Comparative Example 5 A commercially available pearl green pigment was used to prepare a coating composition according to the following formulation. (Blending ratio) (Blending ratio) Commercially available pearl green pigment 30 parts Acrylic varnish (solid content 60%) 82 parts Melamine varnish (solid content 60%) 34 parts Solvent 100 / butyl acetate (7/3) mixed solution 30 parts

Comparative Example 6 A coating was performed in the same manner as in Example 6 except that the coating composition of Comparative Example 5 using a commercially available pearl green pigment was used instead of using the blue-coated pearl pigment (green) for the second base coat layer. A film was formed. Table 1 shows the evaluation results of the above coating films.
Shown in

[0032]

[Table 1] Evaluation results

[0033]

The coating film formed by the coating composition of the present invention has an unprecedented texture by using a pigment obtained by coating a silver to green pearl pigment with a blue pigment as a pigment. That is, by including a pearl pigment having a specific property in the coating composition,
When the amount of reflected light is high (highlight), a silver to green color tone with excellent glitter is exhibited, and when shaded, a coating film having a high whiteness and improved in the disadvantages of the prior art is formed.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromi Terada 1-7-6 Nihombashi Bakurocho, Chuo-ku, Tokyo Inside Dainichi Seika Kogyo Co., Ltd. (56) References JP-A-3-153765 (JP, A) JP-A-2-58582 (JP, A) JP-A-60-60163 (JP, A) JP-A-5-171055 (JP, A) JP-A-62-109869 (JP, A) Int.Cl. ⁷ , DB name) C09D 5/36 C09D 201/00-201/10 C09C 1/40-1/42 C09C 3/06

Claims (4)

(57) [Claims] 1. A flaky or flake-like substrate surface having a plate surface diameter of 5 to 70 μm and a thickness of 0.01 to 0.5 μm is coated with titanium dioxide having a thickness from silver to green. And the elemental ratio of Co / Al on the surface
A pearl pigment coated with a cobalt blue-based composite oxide pigment having a ratio of 0.1 / 2 to 0.5 / 2 in a coating medium. 2. A method according to claim total cobalt oxide constituting the cobalt blue-based composite oxide pigments and aluminum oxide is 50 wt% or less with respect to coated titanium dioxide
2. The coating composition according to 1 . Wherein to form a base coat layer using a coating composition according to claim 1 or 2, then film-forming method characterized by forming a clear coat layer onto the base coat layer. Wherein there is a first layer on the colored base coat layer of the coating film to form a second base coat layer using a coating composition according to any one of claims 1 to 3, then the base coat layer A method for forming a coating film, wherein a clear coat layer is formed on the coating film.