JPS5985896A - Method for controlling matting of paint film - Google Patents

Abstract

PURPOSE:To control the matting degree of a paint film at a low cost by immersing an uncured coated product coated by electrodeposition using a power source having an arbitrary pulsation rate in an aqueous acid soln., impressing a voltage using the coated product as an anode, and curing the paint film by backing. CONSTITUTION:Coating is carried out by electrodeposition at about 10- about 140% pulsation rate represented by the equation. The resulting uncured coated product is immersed in an aqueous acid soln., and a DC voltage is impressed using the coated product as an anode. The temp. and concn. of the acid soln., the voltage to be impressed, and the current supply time are suitably selected. The treated coated product is washed in water, and the electrodeposited paint film is cured by baking.

Description

[Detailed description of the invention] The present invention relates to a method for controlling the gloss of an electrodeposited product.

With regard to clear-coated aluminum satsushi and other electrodeposition-coated products, due to the recent diversification of the hobbies of general consumers, there are now not only glossy ones, but also matte ones, as well as various matte ones. There is a growing demand for something with a certain level of quality.

Some of the methods proposed as matting methods to meet these demands include, for example, using electrodeposition paints containing matting pigments such as silicon oxide, but with this method, the matting pigments may settle or Not only is paint stability poor due to re-agglomeration, but it is also difficult to obtain coated products with stable gloss without gloss spots, and the alkali resistance of the coating film is also poor.

It is also known to use a matte paint containing a resin with poor compatibility instead of a matte pigment, but this method has drawbacks such as poor stability over time and poor water washability, such that gloss spots are likely to appear.

Furthermore, it is also known to obtain a matte coating film by immersing a coated object coated with a glossy coating in an aqueous solution of an inorganic acid, an organic acid or a salt, and then baking it to dry. There are drawbacks such as the fact that a one-minute matting effect cannot be obtained because the material is washed away by water washing (even without washing, gloss spots may occur due to the chemical solution falling from the hanger or dripping when pulling it up). .

Another matting method for electrodeposited materials is disclosed in Japanese Patent Application Laid-open No. 54-8.
There is a method related to No. 5628. In this method, the electrodeposited coating is energized in an aqueous salt solution, but it has drawbacks such as gloss spots easily occurring and difficulty in obtaining a gloss with a specular reflectance of less than 40 at 60°.

Further, the above matting method has the disadvantage that it is difficult to adjust the degree of matting, and it is difficult to match the taste of general consumers.

The present inventors selected the pulsation rate of the current, which is converted from alternating current to direct current, which is normally used during electrodeposition, within a certain range, and the coating film electrodeposited at this pulsation rate in an uncured state. When the film is immersed in an acid aqueous solution and a voltage is applied, followed by curing, an excellent coating film free of the defects described in 1. It was discovered that articles could also be manufactured. That is, the gist of the present invention is to provide a method for matting an electrodeposited coating film, in which after electrodeposition coating, a floor-cured coating object is immersed in an acid aqueous solution, a voltage is applied using the coating object as an anode, and then the coating is hardened by baking. , consists in a method of controlling the matting of the coating film by selecting the pulsation rate during electrodeposition coating.

In the present invention, the J-th pulsation rate is given by the following formula: If this pulsation rate is selected within the range of 10 to 140%, various degrees of matteness can be obtained. That is, if you want to increase the degree of matteness, you can reduce the pulsation rate during electrodeposition, and if you want to decrease the degree of matteness, you can increase the pulsation rate during electrodeposition. Therefore,
The lower the pulsation rate, the lower the gloss, and the higher the pulsation rate, the higher the gloss.

For electrodeposition, conventional electrodeposition paints are used, such as acrylic resin-melamine resin mixed clear paint, epoxy resin-melamine resin mixed clear paint, urea resin-melamine resin mixed clear paint, alkyd resin-melamine resin mixed clear paint. This is carried out by a conventional method using a monoanionic electrodeposition paint such as a paint (particularly preferred is an acrylic resin-melamine resin mixed clear paint).

The conditions for electrodeposition are those commonly used.

The voltage used ranges from 2 to 300 volts. Preferably it is 50-250 volts.

The acid used in the present invention may be an inorganic acid such as sulfuric acid, nitric acid, phosphoric acid, or an organic acid such as an organic sulfonic acid. Preferred is an organic sulfonic acid. Examples of organic sulfonic acids include methanesulfonic acid, ethanesulfonic acid and 1,
Aliphatic sulfonic acids such as 2-ethanedisulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, dodecylbenzenesulfonic acid, 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 1--1-edge amine- 4-sulfonic acid, ]-naphthylamine-2-
Sulfonic acid, naphtholsulfonic acid, naphtholdisulfonic acid, phenol-2,4-disulfonic acid, 0-phenolsulfonic acid, m-phenolsulfonic acid, P-phenolsulfonic acid, P-bromobenzenesulfonic acid,
1.8-dioxy-3,6-naphthalenesulfonic acid, 1
．． 2-Dioxy-7-anthraquinone sulfonic acid, P-
Diazobenzenesulfonic acid, P-chlorobenzenesulfonic acid, 0-xylene-4-sulfonic acid, 1-anthraquinonesulfonic acid, 0-aminebenzenesulfonic acid, sulfosalicylic acid, P-toluenesulfonic acid, m-toluenesulfonic acid, 5 Examples include aromatic sulfonic acids such as .5'-indigo disulfonic acid and cresolsulfonic acid, and dinonylnaphthalenesulfonic acid, dinonylnaphthalene disulfonic acid, etc. are particularly preferred.

These acids can be used singly or in combination of two or more, usually at a concentration of 0.0
It is used as an aqueous solution of 1 to 1% by weight, preferably 0.05 to 0.5% by weight.

Aqueous acids usually contain ammonia or amines such as diethylamine, triethylamine, dimethylethanolamine, triethanolamine, morpholine, aniline,
The pH is adjusted to 1.0 to 12, preferably 3 to 10, by appropriately adding a base such as amylamine, isobutylamine, or isopropylamine.

If desired, a water-soluble organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl cellosolve, butyl cellosolve, calpitol, acetone, or two or more of these may be added to the acid aqueous solution whose p I-1 is adjusted to 1.0 to 12. Usually, add a mixed solvent of
0.1 to 10% by weight, preferably 0.5 to 5% by weight),
It may also effectively prevent the occurrence of glossy spots on painted objects.

Addition of a water-soluble organic solvent is preferable, especially when the coated article is subjected to a cleaning treatment before being baked and dried, since it improves compatibility with the cleaning solution and more effectively prevents the occurrence of glossy spots.

The substrate used in the method of the present invention is aluminum, aluminum alloy, iron, iron alloy, magnesium alloy, copper, copper alloy, etc., and preferably aluminum and aluminum alloy. After electrodepositing these base materials using a power supply having the above-mentioned pulsation rate, the uncured coating film is immersed in the acid aqueous solution prepared as described above, and the coated material is used as an anode and a counter electrode. Apply voltage between. Acid aqueous solution/I11
The temperature is usually 15-25°C.

(7) Direct current is generally used when applying voltage after immersion in an acid aqueous solution, but a good matte finish can also be obtained with alternating current, pulsed current, or pulsating current. The applied voltage and application time depend on the pulsation rate during electrodeposition, the degree of matte finish, the temperature and concentration of the acid aqueous solution, and are not limited, but for example, in the case of direct current, it is usually 10 to 250 volts, Preferably a voltage of 50 to 250 volts is applied for 0.5 to 15 minutes, preferably 1 to 5 minutes.

The coated article subjected to voltage application treatment by acid immersion is removed from the dipping solution and subjected to heat curing treatment either as it is or after being washed.

Examples of cleaning liquids for painted objects include tap water, pure water, UFr liquid (ultrafiltration ρ liquid), ROP liquid (reverse osmosis furnace liquid), and aqueous solutions containing surfactants.

The heat curing conditions for the painted object depend on the type of electrodeposition paint, alumite, coloring liquid, etc. - There are no particular limitations, but it is usually 150 to 200°C for 15 to 40 minutes, preferably 170 to 190°C. 20 to 30 (8) minutes.

According to the method of the present invention, the pulsation rate during electrodeposition is selected;
By appropriately selecting the temperature and concentration of the acid aqueous solution, the applied voltage of the acid aqueous solution, the energization time, etc., it is possible to create any uniform film without gloss that maintains good coating properties, such as hardness, alkali resistance, cast resistance, etc. A matte painted surface is obtained. In particular, by keeping the concentration, temperature, and other conditions of the acid aqueous solution constant (changing these conditions has the disadvantage of interfering with operation) and selecting the pulsation rate, it is easy to obtain a suitable matte coating surface (usually, 60°
C) A matte painted surface with a gloss level of about 5 to 90% based on specular reflectance is obtained.

Furthermore, according to the method of the present invention, there is no need to worry about paint stability as in the case of matte paints, etc., and there is no need to operate treatment equipment such as UF equipment or RO equipment or deneutralizers using ion exchange. In addition, the processing solution concentration is low, and the operating cost is not only low, but also sufficient coating performance can be obtained even under lower heat curing conditions than when using matte paints, so it is better than the conventional matte method. All of the above-mentioned accompanying problems are resolved.

Although the method of the present invention can be applied to all types of electrodeposited objects, it is particularly suitable for matting aluminum sash.

This will be explained below using examples.

Examples 1-6 Heating Power Mite 3000 (acrylic resin-melamine resin mixed anionic electrodeposition paint made by Nippon Paint Co., Ltd.)
The objects to be coated (aluminum plates and aluminum alloy plates (70++mX150+++mX0. 8+im')
Using this as an anode and a counter electrode, electrodeposition was performed at a voltage of 120 volts for 2.5 minutes using a DC power source with a selectable pulsation rate, and then the coated object was removed and washed by immersion in tap water. .

The obtained electrodeposition coating was coated in an uncured state with a 0.05% by weight aqueous solution of dinonylnaphthalenedisulfonic acid at 20°C (p1
(adjusted with triethylamine so that the ratio is 17 to 8),
Using this as an anode, apply a DC voltage of 150 volts for 2.5 minutes, then pull it up, wash it with tap water, and then heat it to 170°C.
It was baked and dried for 30 minutes.

Table 1 shows the properties of the obtained matte coating film.

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Claims (1)

[Claims of Claims] 1. A method for matting an electrodeposited coating film by immersing an uncured coating object after electrodeposition coating in an acid aqueous solution, applying a voltage using the coating object as an anode, and then curing by baking. In this method, selecting the pulsation rate during electrodeposition coating is a method of controlling matting of the coating film. 2. The method according to item 1, wherein the pulsation rate is selected from 10 to 140%. 3. The method according to item 1, wherein the acid or organic sulfonic acid is used. 4. The method according to item 1, wherein the acid is dinonylnaphthalenesulfonic acid.