JPH0260972A - Metallic coating composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which scarcely undergoes seeding and thickening during its production and storage and has excellent color stability by using an aluminum powder subjected to chromate treatment. CONSTITUTION:This metallic coating composition is prepared from an aluminum powder subjected to chromate treatment. When an aluminum powder is subjected to chromate treatment, it is converted into a powder having a surface made sufficiently inert within a short time, hardly entering an undesirable reaction with a pigment, especially, an organic pigment an having excellent color stability. Since the treated powder has sometimes a colored surface, it can function as a pigment in a metallic coating composition, so that it is also possible to avoid the use of an expensive pigment or to decrease the number of kinds of pigments to be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating composition used for products that require color design, particularly exterior panels of automobiles, home appliances, etc.

[Conventional technology]

BACKGROUND ART Conventionally, various types of coatings have been applied to various industrial products, crafts, architectural structures, etc. Painting determines the final value of the object being painted, such as making the product more luxurious and adding value. There has been a demand for new functions.

Nowadays, with the diversification of individual requirements for the various products on the market, in painting, not only the performance of various coatings to protect the surface of the object to be coated, but also the beauty of the appearance, especially the color. The proportion of design aspects is increasing.

Here, as an example of metallic paints, we will cite those used for metallic coatings on automobiles. Recently, pale metallic colors have become mainstream as exterior colors for automobiles, but metallic paints, like regular paints, contain pigments and additives in addition to resins that form the film, such as acrylic resins. .

It contains a solvent, etc., and is further mixed with metallic powder such as aluminum powder. Because aluminum powder has an active surface, it can react with other components in the paint, especially organic pigments, causing problems such as seeding, which causes color fading and the paint to aggregate and become lumpy. . Therefore, surface treatment of aluminum powder was considered.
For example, as disclosed in Japanese Patent Application Laid-Open No. 57-2076508, by hydrotreating paste-like aluminum powder, the coexistence stability with color pigments, especially organic pigments, can be improved and We are trying to solve problems such as seeding phenomenon and increase in paint viscosity.

[Problem to be solved by the invention]

However, organic pigments are expensive per se, and the above-mentioned treatments are performed on them, further increasing the cost of the paint. Furthermore, the above process has a serious problem in that it takes a long time. Furthermore, there are also problems with color stability.

In view of these circumstances, the present invention provides a metallic paint composition that contains aluminum powder that also functions as a pigment, requires a short surface treatment time for the aluminum powder, and has excellent storage stability and color stability. The challenge is to provide.

[Means to solve the problem]

In order to solve the above problem, in the metallic coating composition according to the invention as set forth in claim 1, aluminum powder contained therein is subjected to chromate treatment.

In the metallic paint composition according to the second aspect of the invention, the chromate-treated aluminum powder also functions as a pigment.

[For production]

When aluminum powder is subjected to chromate treatment, its surface is sufficiently inactivated in a short period of time, and it becomes less likely to cause undesirable reactions with pigments, especially organic pigments. Since the chromate-treated aluminum powder may have a colored surface, this colored aluminum powder also serves as a pigment in the metallic coating composition.

〔Example〕

Below, the metallic coating composition according to the present invention will be explained in detail based on Examples thereof.

The metallic coating composition according to the present invention basically has the same composition as a conventional metallic coating composition, except that the aluminum powder, which is the metallic component, is chromate-treated. That is, it consists of coating film-forming components, solvents, additives, pigments, etc., and pigments may or may not be used. The coating film forming components are acrylic resin, melamine resin, polyester resin, urethane resin, etc., the solvent is toluene, xylene, n-butanol, etc., and the additive is Bayer Silicon OL (Bayer:
(manufactured by BAYER ■), BYK-P-104S (manufactured by BYKIJf@), and the like. Also 1
, when used with other pigments, such pigments include Chromophthal Yellow A2R (Ciba Geigy: Ci
ba-Geigy @! iri + monolight e o-FR (
F.C.F.: manufactured by ICll1), etc.

As will be described in detail later, by using aluminum powder colored by chromate treatment, the number of types of pigments can be reduced or the use of pigments can be omitted. The aluminum powder that is the metallic component has a thickness of 0.5 to 1.5 μm, for example.
1. Scale-like aluminum pieces with an average particle size of 10 to 50 μm are subjected to chromate treatment. Aluminum powder is generally obtained in paste form.

The chromate treatment referred to here will be explained in detail by giving an example. The scaly aluminum pieces are pre-washed by degreasing and removing oxide films, and then overflowed with water to thoroughly wash off each chemical. However, this step may not be performed due to surface finishing requirements or the like. For example, the main component is chromic acid such as Allozin (a chromate treatment agent made by Nippon Paint 9m, which mainly consists of chromic acid), and it contains an inorganic acid such as phosphoric acid, hydrofluoric acid, or complex fluoride as a reaction accelerator. A scaly aluminum piece is suspended in the treatment liquid. Allodin concentration is 1.5-2.3% by weight
The weight ratio is preferably in the range of 1.8 to 2.3%. The scaly aluminum pieces are added to this treatment solution.
Suspend at a concentration of 50% or less by weight. The processing temperature is 10
The temperature range may be within the range of ~60°C, and the range of 40~60°C is particularly desirable.

The processing time may be in the range of 0.5 to 10 minutes, especially 0.5 to 10 minutes.
．． A range of 5 to 1 minute is desirable. After this, if necessary,
After washing with water and air drying, the desired scaly aluminum pieces are obtained.

As described above, the chromate treatment used in the metallic paint composition according to the present invention has a very short treatment time.
It is also easy to process.

Chromate treatment produces pale colors such as pale yellow or pale green on the surface of flaky aluminum pieces, but there are also chromate treatments that do not cause coloration.

A scaly aluminum piece treated as in the above example is
Without applying too much force, the resin, which is a coating film-forming component, and
When dispersed in pigments, additives, solvents, etc., the desired metallic coating composition can be obtained.

Next, a preferred coating example using the metallic coating composition according to the present invention will be explained.

First, as a pretreatment prior to painting, metal objects such as iron plates and steel plates are subjected to chemical conversion treatment in the usual manner using zinc phosphate, iron phosphate, etc. to remove any particles that adhere to the surface. Prepare the substrate by removing rust, oil, dirt, etc. Thereafter, in order to improve adhesion, corrosion resistance, etc., undercoating is performed using electrodeposition coating or the like to form an undercoat layer. The coating film thickness is not particularly limited, but for example, the dry film thickness is 15 to
Approximately 20 μm is appropriate. Furthermore, it is advisable to perform pretreatment such as degreasing, polishing, and acid treatment on nonmetallic objects such as plastics.

Below, the case where the above metallic paint composition is used as a top coat will be described. In this case, an intermediate coating is applied as necessary to form an intermediate coating layer having a dry thickness of approximately 35 μm to 40 μm, for example. This intermediate coating is performed for the purpose of preventing the topcoat from being sucked in, improving durability, and smoothing the surface of the coated film, and a suitable intermediate coating can be used. Then, on top of this intermediate coating, a base enamel paint containing chromate-treated scaly aluminum pieces is applied. While the base enamel is uncured, a clear paint is applied wet-on-wet and then cured by baking to obtain the desired coating film. The appropriate film thickness of this top coat is, for example, a dry film thickness of about 15 to 20 nm.

The method of applying each of the paints described above is not particularly limited. In other words, spray painting using a spray gun, flow coating using a curtain flow coater, etc.
It can be done by any method such as flow coating), dipping coating, electrodeposition coating, electrostatic coating, brush or roller coating, etc.
For example, regarding electrodeposition coating applied to undercoat etc.
The charge type of the electrodeposition paint may be either a cation type or an anion type. Also, after the intermediate painting is done, #60
Water polishing using No. 0 waterproof paper or the like may be performed to improve the smoothness of each coating surface and to obtain good coating film adhesion. Dry and bake.

The curing conditions and the like are not particularly limited, and it is preferable to set the temperature for 1 hour, etc. as appropriate depending on the thermosetting resin and solvent used, or the object to be coated. Further, the object to be coated is not limited to metals, but includes various objects such as synthetic resins that require metallic coating.

Aluminum powder colored by chromate treatment also functions as a pigment by itself when dispersed in coating film forming components. Therefore, it is possible to omit the use of a pigment corresponding to that color, reduce the types of pigments used, and even omit the use of other pigments altogether.

In the metallic coating composition according to the present invention, the surface of the aluminum powder is sufficiently inactivated by the chromate treatment, so even if it is used together with other pigments, especially organic pigments, it will not cause lumps during production or storage. Problems such as increased viscosity are less likely to occur. It also has excellent color stability and is less prone to discoloration. If it is preferable that the aluminum powder has no color when used with other pigments, it goes without saying that a chromate treatment without a coloring effect is performed.

Next, specific examples and comparative examples will be described in detail.

Examples 1 and 2 - ■ A steel plate (length 90 x width 200 x thickness 0.8 m) was used as the object to be coated.
m) was prepared and subjected to chemical conversion treatment using a zinc phosphate metal surface treatment agent (Granodin 5o5000 manufactured by Nippon Paint N).

■ Work 14 Cationic electrodeposition paint (Nippon Paint ■ Power Top U-
30) to form a coating film with a dry film thickness of 20 μm.

■ Freshly applied melanin resin baking paint (Olga P- manufactured by Nippon Paint)
Spray painting was performed using 21 colors (gray) under the following conditions.

Spray gun: REA (manufactured by Rands) Nozzle cap #6 Coating viscosity = 25 seconds / #4 Ford cup / 20℃ Discharge rate: 400 units/min After that, baking hardening was performed at 140℃ / 20 minutes to obtain a dry film thickness of 35 μm. A coating film was obtained.

■ We will specifically discuss the preparation of aluminum powder that has been subjected to top-coating chromate treatment.

As aluminum powder, a commercially available scaly aluminum piece (thickness 1μ, average particle size 35μ) was degreased, and this was
The mixture was suspended in Allodin 1200 (manufactured by Nippon Paint Co., Ltd.) at a concentration of 2% (weight ratio) at a concentration of 40% (weight ratio) at a temperature of 25° C. for 5 minutes. After thoroughly washing each chemical with water, air dry it.
The desired scaly aluminum pieces were obtained.

Take 15 g of a scaly aluminum piece treated with Chrome-I, add 15 g of toluene to it, mix it with moisture, then add 141.7 g of Almatex NT4480 (thermosetting acrylic resin manufactured by Mitsui Toatsu Chemical ■), Stir with a disper, then add Super Hesokamine J-, a resin for stirring.
820-60 (Melanin resin manufactured by Dainippon Ink@) 28.
3 g was added and further stirred for about 15 minutes using a disperser to obtain the desired metallic coating composition, which was designated as Example 1.

The coating material of Example 2 was prepared using the same raw materials as in Example 1, and the blending amounts are as shown in Table 1.

The metallic coating compositions of Examples 1 and 2 were spray coated under the following conditions.

Spray gun: RF, A (Lands) Nozzle cap #6 Paint viscosity: 13 seconds/#4 Ford cup/20°C Discharge rate: 350 ■! / Film thickness: approx. 15μ■ 1 minute Painting stage: 1st 2nd flash off conveyor speed: 4m/min Spray gun stroke = 25 reciprocations/min Gun distance H
3Qcm Pattern width: 45cm ■ On top of the above 6-sea topcoat of Clear'Pa, apply a thermosetting acrylic resin clear paint (Nippon Paint Fuku Super Rack 0-28L) using a wet-on-wet method, and check the baking on a test board. I got it. The dry film thickness of the clear was 40μ.

Comparative Examples 1 and 2 - In the top coating of (1) above, ordinary aluminum paste (Toyo Aluminum Manufacturing 01) was used instead of scaly aluminum pieces.
Using aluminum foil face 'P4713 ON, NV = 65 [nonvolatile content 65% by weight]), to add a pale yellow color, a paint prepared by dispersing the yellow pigment described in Note 1 of Table 1 in advance was mixed. Comparative Example 1 and Comparative Example 2
A metallic paint composition was prepared. The detailed raw materials,
The blending amounts are as shown in Table 1. A coating film was formed under the same conditions as in the above example.

Table 1 (2): g) Table 2 The obtained coating films of Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated on the following items.

The results are shown in Table 2.

fal Color tone of paint film Determine color tone by visual inspection.

FblPGd value Evaluated using Japan Color Research Institute type PGd-4.

(C) Storage property of paint film After leaving the paint at 50℃ x 10 days, apply the coating.
Evaluate the condition of the painted surface.

○...No abnormality, ×...Bulges occurred fdl Color stability After leaving the paint at 50℃ x 10 days, apply the paint.
Visually evaluate the discoloration of the painted surface.

○: No discoloration, ×: Discoloration As shown in Table 2 of the large box, the metallic coating composition containing the aluminum powder according to the present invention does not require the use of pigments, but can use conventional pigments. It can be seen that not only can a color tone similar to that of metallic paints be obtained, but also that it has excellent storage stability and color stability compared to conventional metallic paints using pigments.

〔Effect of the invention〕

In the metallic coating composition according to claim 1, the surface of the aluminum powder contained therein is sufficiently inactivated by the chromate treatment, so that seeding phenomenon and viscosity increase do not occur during manufacture and storage (and the color does not change). Excellent stability.

In the metallic paint composition according to claim 2, the surface of the aluminum powder contained therein is colored by chromate treatment, so that it can also function as a pigment in the metallic paint composition, and is not expensive. It is also possible to omit the use of pigments or reduce the types of pigments used.

Agent: Patent Attorney Takehiko Matsumoto

Claims (1)

[Scope of Claims] 1. A metallic coating composition using aluminum powder, characterized in that the aluminum powder has been subjected to chromate treatment. 2. The metallic coating composition according to claim 1, wherein the chromate-treated aluminum powder also functions as a pigment.