JP3124830B2 - Coated zinc-containing metal flake, method for producing the same, and paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated zinc-containing metal flake, a method for producing the same, and a coating material. The present invention relates to a flake, a method for producing the flake, and a paint.

[0002]

2. Description of the Related Art Zinc powder is used as an anticorrosion pigment for metal powders in paints. However, zinc powder used conventionally has a large specific gravity of about 7 and is spherical, so it can be stored in a can or during storage. There is a problem that the particles aggregate and settle. In addition, since it is spherical, the surface area is small, and in order to exhibit sufficient rust prevention, the zinc concentration in the paint must be increased to the extent that the powder particles contact each other, and the coating film strength decreases, Further, the thickness of the coating film is increased, cracking of the coating film, poor welding and fusing are caused, and further, there is a problem in occupational health due to zinc fume during operation.

[0003] In order to solve the above problems, proposals have been made to use zinc powder as zinc powder flakes. The zinc powder flake has a large surface area as compared with the spherical zinc powder, so it is difficult to settle, and since the flake shape makes the contact between the zinc flakes dense, the zinc amount in the paint can be reduced. Can be.

However, in order to flake the zinc powder, a higher fatty acid such as stearic acid and / or a metal salt such as a zinc salt of the higher fatty acid is added as an organic grinding aid. Is coated with a higher fatty acid, the function of the zinc-based metal is not sufficiently exhibited, the rust-preventing ability is reduced, and white rust is generated.

[0005] In the recent field of paint, resource saving,
As a pollution-free measure, a water-based paint using water as a base solvent has been demanded. However, the zinc flakes have a high surface area and thus have good reactivity with water. In this case, there is a problem that water stability is poor. In addition, the zinc flakes whose surfaces are coated with higher fatty acids have higher fatty acids on the surface, so they are hydrophobic and have a problem that a large amount of surfactant must be added in order to disperse them in water. . Therefore, at present, zinc flakes that are stable for a long time in an aqueous solution have not been obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coated zinc-containing metal flake which is stable in an aqueous solution for a long period of time, has excellent rust prevention and does not generate white rust, and a method for producing the same. .

Another object of the present invention is to provide a paint containing a zinc-containing metal flake which is stable for a long time even in an aqueous system and can provide a coating film having excellent corrosion resistance.

[0008]

According to the present invention, there is provided a coated zinc-containing metal flake characterized by having a coating film of colloidal silica on the surface.

Further, according to the present invention, there is provided a method for producing the coated zinc-containing metal flake, which comprises contacting the colloidal silica-containing solution whose pH has been adjusted to 10 to 13 with the zinc-containing metal flake.

[0010] Further, according to the present invention, there is provided a paint characterized by containing the coated zinc-containing metal flake.

Hereinafter, the present invention will be described in more detail.

The coated zinc-containing metal flake of the present invention is characterized by having a coating film of colloidal silica on the surface.

Specific examples of the zinc-containing metal flakes that can be used in the coated zinc-containing metal flakes of the present invention include zinc flakes, aluminum alloy zinc flakes, aluminum-SiO ₂ -zinc alloy flakes,
Preferable examples include nickel mixed zinc flakes and cobalt mixed zinc flakes. The zinc-containing metal flake has an average major axis of 3 to 20 μm and an average thickness of 0.3 μm.
The aspect ratio (major axis / thickness) is preferably in the range of 5 to 20.

In the coated zinc-containing metal flake of the present invention, the colloidal silica used for coating the surface can be used without particular limitation as long as the colloidal silica is used. The colloidal silica preferably has a particle size of 10 nm or less, particularly 4 to 8 nm. Thereby, it is possible to form a porous colloidal silica film on the surface of the zinc-containing metal flakes, without deteriorating the properties of zinc.
Demonstrate stability in water.

The coating rate of the coated zinc-containing metal flakes with the colloidal silica (silicon oxide / metal weight ratio) is preferably in the range of 0.008 to 0.12. If the coating rate is less than 0.008, the metal is insufficiently protected by silica,
If it exceeds 0.12, agglomeration of zinc-containing metal flakes occurs, which is not preferable.

Further, the method for producing a coated zinc-containing metal flake of the present invention is characterized in that a colloidal silica-containing solution whose pH is adjusted to a range of 10 to 13 is brought into contact with the zinc-containing metal flake.

In the production method of the present invention, first, the pH of the colloidal silica-containing solution is adjusted to 10 to 10 with an alkali agent or the like.
Adjust to 13 range. When the pH is out of the range, the zinc-containing metal flake reacts with water during the coating treatment, and the stability of the zinc-containing metal flake in the aqueous solution cannot be obtained. .
As the alkaline agent used at this time, sodium hydroxide,
Preferable examples include potassium hydroxide, aqueous ammonia, methylamine, ethylamine, and ethylenediamine.

The colloidal silica-containing solution is preferably an aqueous solution containing colloidal silica. The content of colloidal silica in the solution is preferably in the range of 0.05 to 40% by weight based on the whole solution.

Further, the colloidal silica has a particle size of 1
It is preferably set to 0 nm or less, particularly 4 to 8 nm. When the particle size exceeds 10 nm, a dense silica coating film is not formed on the surface of the zinc-containing metal flakes, and when dispersed in water, a corrosion reaction proceeds and long-term stability in water is reduced. It is not preferable because it cannot be obtained.

Next, the colloidal silica-containing solution is brought into contact with the zinc-containing metal flake.

At this time, a surfactant or the like may be added to improve the dispersibility of the zinc-containing metal flake. The surfactant is not particularly limited as long as it can disperse the zinc-containing metal flakes in water, but may be a cationic interface such as octadecylamine acetate, alkyltrimethylammonium chloride, or alkyldimethylbenzylammonium chloride. Activator; Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkylamide, and polyoxyethylene fatty acid ester can be preferably used, and commercially available products can also be used. . Further, the proportion of the nonionic surfactant to be added is preferably in the range of 0.1 to 4% by weight based on the whole colloidal silica-containing solution.

As the zinc-containing metal flakes, the compounds specifically listed as the above-mentioned zinc-containing metal flakes can be preferably used.

At this time, the charging ratio of the zinc-containing metal flakes to the colloidal silica is preferably in the range of colloidal silica / zinc-containing metal flakes (weight ratio) = 0.01 to 0.14. If the charging ratio is less than 0.01, coating becomes insufficient, and if it exceeds 0.14, aggregation between colloidal silicas occurs, and the aqueous solution is undesirably solidified.

In the present invention, the step of bringing the colloidal silica-containing solution into contact with the zinc-containing metal flakes is not particularly limited as long as the colloidal silica can be brought into contact with the surface of the zinc-containing metal flakes. And so on.

The stirring temperature during the stirring is preferably 10 to 80 ° C., and the stirring time is preferably 3 hours or more, particularly preferably 5 to 72 hours. When the stirring temperature is less than 10 ° C., it takes a long time to form a coating film. When the stirring temperature is more than 80 ° C., aggregation of zinc-containing metal flakes occurs, and when the stirring time is less than 3 hours,
It is not preferable because the zinc-containing metal flakes are not sufficiently dispersed and the coating becomes insufficient.

Next, by separating into a solution and a flake component, a coated zinc-containing metal flake having a colloidal silica film on the surface is obtained.

In the present invention, in order to separate the coated zinc-containing metal flakes from the solution, the flakes can be separated by settling or filtering.

[0028] The paint of the present invention is characterized in that it contains the above-mentioned zinc-containing metal flakes coated.

The coating material of the present invention is not particularly limited as long as it contains the coating zinc-containing metal flakes. Specifically, the coating material includes the coating zinc-containing metal flakes, binders, pigments, dispersants and the like. And a solvent-based paint in which the above-mentioned paint component is dispersed and dissolved in a solvent such as mineral spirit, n-butanol, xylol, triol, methyl ethyl ketone or ethylene glycol.

The pigment used in the paint component includes
Aluminum powder, nickel powder, cobalt powder, silicon oxide, titanium oxide, zirconium oxide, and the like can be preferably used.

As the binder used for the above-mentioned paint components, in aqueous paints, binders for inorganic aqueous paints such as sodium silicate, potassium silicate, lithium silicate, alkali silicone, silicone emulsion and water-soluble silicone; acrylic resin emulsions, epoxy resins Emulsions, binders for organic aqueous coatings such as phenolic resin emulsions and the like can be preferably used. In solvent-based coatings, binders for inorganic solvent-based coatings such as silicone resins, alkyl silicates and silane coupling agents; polystyrene resins, chlorides Binders for organic solvent-based paints such as rubber, epoxy resin, phenol resin, polyurethane resin, phenol-modified alkyd resin, and melamine resin can be preferably used.

When the pigment is not used in the water-based paint, the dispersant is not particularly required to be used because the coated zinc-containing metal flake has excellent dispersibility in water. When used and in solvent-based coatings, it is preferably used. Specifically, cationic surfactants such as octadecylamine acetate, alkyltrimethylammonium chloride, and alkyldimethylbenzylammonium chloride; polyoxyethylene alkyl ether, polyoxyethylene Nonionic surfactants such as alkyl phenyl ether, polyoxyethylene alkylamide, and polyoxyethylene fatty acid ester can be preferably used.

In the paint of the present invention, if necessary, a wetting agent, a leveling agent, a thixotropic agent, a thickener, an anti-sagging agent, a fungicide, a film-forming aid, a stabilizer, etc. may be added to the paint. It can also be added to the components.

[0034] The addition ratio of the coating zinc-containing metal flake used in the coating material of the present invention is such that the coating component (weight ratio) other than the coating zinc-containing metal flake / coating zinc-containing metal flake is in the range of 0.5 to 20. Preferably, it is particularly preferably in the range of 2 to 10. If the addition ratio is less than 0.5, the sacrificial positive effect of the zinc-containing metal flakes is not exhibited, and if it exceeds 20, the amount of the vehicle is reduced, the strength of the coating film is reduced, and sufficient It is not preferable because good paint adhesion cannot be obtained.

The coating material of the present invention can be prepared by dispersing or dissolving the coating components in water or the solvent by a known method. When preparing an aqueous paint, the coated zinc-containing metal flakes can be used as a slurry, and the water content in the slurry is preferably in the range of 20 to 70% by weight.

[0036]

Since the coated zinc-containing metal flake of the present invention has a colloidal silica film on the surface, it has the effects of being stable for a long time in water and free of white rust.

In the method for producing coated zinc-containing metal flakes of the present invention, since the colloidal silica-containing solution has a specific pH value, the coated zinc-containing metal flakes can be used without reacting zinc with water during the coating treatment. It can be obtained easily and in high yield.

Further, since the paint of the present invention contains the zinc-containing flake, it is stable for a long time even in an aqueous system.
It is possible to form a coating film having excellent rust prevention.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

[0040]

EXAMPLE 1 20 of colloidal silica having a particle size of 8 nm
The 1 wt% aqueous solution was diluted with pure water to obtain a 1 wt% colloidal silica-containing solution. Then, a 1% by weight aqueous solution of sodium hydroxide was added to the obtained colloidal silica-containing solution to adjust the pH to 11. For 1 liter of the obtained colloidal silica-containing solution, an average major axis of 20 μm and an average thickness of 1 μm were produced using stearic acid as a grinding aid.
200 g of zinc flakes of colloidal silica /
A solution with a zinc flake (weight ratio) = 0.05 was obtained.
Next, the obtained solution was stirred at 60 ° C. for 12 hours, and then allowed to stand to precipitate zinc flakes. After sufficient precipitation, the supernatant was discarded to obtain a zinc flake whose surface was coated with colloidal silica.

The following tests were performed on the obtained coated zinc flakes. Table 1 shows the results.

1) Water dispersibility of flakes and flake-containing slurry 5 g of coated zinc flakes were charged into a 50 ml beaker, preliminarily dispersed using a small amount of water, and then 50 m
l of water was added, the mixture was stirred well, and the dispersion state of the flake particles after standing for 10 minutes was visually determined.

2) Water stability 20 g of the obtained flake was put into a 200 ml Erlenmeyer flask, and 100 ml of pure water was added to diffuse the flake to disperse the flake. Then, attach a female pipette with rubber.
The amount of gas generated after standing at 24 ° C. for 24 hours was measured to determine the reactivity to water.

3) Storage stability 50 g of the coated zinc flake was put into a 100 ml glass bottle and stored at room temperature for 3 months, and then the stability was visually judged. The oxidation state of the flake was measured using an X-ray diffractometer, and the element analysis of the flake surface was performed using an X-ray microanalyzer (XMA).

To 100 parts by weight of the slurry containing the coated zinc flakes (water content: 45%) was added 65 parts by weight of lithium silicate, and 20 parts by weight of pure water was further added and mixed to prepare a lithium silicate paint. did.

Separately, 22 parts by weight of an epoxy resin emulsion (60% solid content) and 63 parts by weight of pure water were added to 100 parts by weight of the slurry and mixed to prepare an epoxy resin paint.

The following tests were performed on the obtained lithium silicate paint and epoxy resin paint. Table 2 shows the results.

4) Storage stability of paint The paint was put into a 300 ml glass bottle, and after storing at room temperature for 3 months, the properties were visually evaluated.

5) Corrosion resistance A 150 × 70 × 0.8 mm mild steel test panel was degreased with alkali, and the above-mentioned paint was applied using a bar coater # 16.
Preheat at 80 ° C for 10 minutes, and then
After baking for 5 minutes, the same coating and baking were further performed to prepare a 2-coat test panel.

Regarding the obtained test panel, JIS-
The salt spray test specified in Z23711 was performed, and the occurrence of white rust and red rust was visually observed.

[0051]

Example 2 Colloidal silica 2 having a particle size of 10 nm
The 0 wt% aqueous solution was diluted with pure water to obtain a 2 wt% colloidal silica-containing solution. Next, a 1% by weight aqueous solution of sodium hydroxide was added to the obtained colloidal silica-containing solution to adjust the pH to 13. To 1 liter of the obtained colloidal silica-containing solution, 5 g of "Nopco 1529" (trade name, manufactured by San Nopco Co., Ltd.) was added as a nonionic surfactant, and then stearic acid was used as a grinding aid. Manufactured, average major axis 19μ, average thickness 3μ
200 g of zinc flakes of colloidal silica /
A solution in which zinc flakes (weight ratio) = 0.10 was obtained.
Then, after stirring the obtained solution at 15 ° C. for 6 hours,
On standing, the zinc flakes settled. After sufficient precipitation, the supernatant was discarded to obtain a zinc flake whose surface was coated with colloidal silica.

Each test was carried out on the obtained coated zinc flakes in the same manner as in Example 1. Table 1 shows the results.

With respect to the obtained coated zinc flake slurry (water content: 45%), a paint was prepared in the same manner as in Example 1, and each test was performed. Table 2 shows the results.

[0054]

Example 3 20 of colloidal silica having a particle size of 5 nm
The wt% aqueous solution was diluted with pure water to obtain a 0.8 wt% colloidal silica-containing solution. Next, a 1% by weight aqueous solution of sodium hydroxide was added to the obtained colloidal silica-containing solution to adjust the pH to 12. To 1 liter of the obtained colloidal silica-containing solution, 1 g of "Nopco 1529" (trade name, manufactured by San Nopco Co., Ltd.) was further added as a nonionic surfactant, and then stearic acid was used as a grinding aid. Manufactured, average major axis 10μ, average thickness 0.
200 g of 3 μm zinc flake was added to obtain a solution in which colloidal silica / zinc flake (weight ratio) = 0.04. Next, the obtained solution was stirred at 30 ° C. for 5 hours, and then allowed to stand to precipitate zinc flakes. After sufficient precipitation, the supernatant was discarded to obtain a zinc flake whose surface was coated with colloidal silica.

Each test was performed on the obtained coated zinc flakes in the same manner as in Example 1. Table 1 shows the results.

With respect to the obtained coated zinc flake slurry (water content: 45%), a paint was prepared in the same manner as in Example 1, and each test was performed. Table 2 shows the results.

[0057]

Example 4 20 of colloidal silica having a particle size of 8 nm
The wt% aqueous solution was diluted with pure water to obtain a 1.6 wt% colloidal silica-containing solution. Then, a 1% by weight aqueous solution of sodium hydroxide was added to the obtained colloidal silica-containing solution to adjust the pH to 10. To 1 liter of the obtained colloidal silica-containing solution, 1 g of "Nopco 1529" (trade name, manufactured by San Nopco Co., Ltd.) was further added as a nonionic surfactant, and then produced using stearic acid as a grinding aid. The average major axis 15μ, the average thickness 1μ
200 g of zinc flakes of colloidal silica /
A solution in which zinc flakes (weight ratio) = 0.08 was obtained.
Next, the obtained solution was stirred at 80 ° C. for 12 hours, and then allowed to stand to precipitate zinc flakes. After sufficient precipitation, the supernatant was discarded to obtain a zinc flake whose surface was coated with colloidal silica.

Each test was carried out on the obtained coated zinc flakes in the same manner as in Example 1. Table 1 shows the results.

With respect to the obtained coated zinc flake slurry (water content: 45%), a paint was prepared in the same manner as in Example 1, and each test was performed. Table 2 shows the results.

[0060]

Example 5 20 of colloidal silica having a particle size of 8 nm
The wt% aqueous solution was diluted with pure water to obtain a 0.4 wt% colloidal silica-containing solution. Next, a 1% by weight aqueous solution of sodium hydroxide was added to the obtained colloidal silica-containing solution to adjust the pH to 12. To 1 liter of the obtained colloidal silica-containing solution, 200 g of zinc flake having an average major axis of 5 μm and an average thickness of 0.5 μm, which was produced using stearic acid as a grinding aid, was added, and colloidal silica / zinc flake (weight) was added. Ratio) = 0.02 was obtained. Then, the obtained solution was stirred at 20 ° C. for 24 hours, and then allowed to stand to precipitate zinc flakes. After sufficient precipitation, the supernatant was discarded to obtain a zinc flake whose surface was coated with colloidal silica.

Each test was carried out on the obtained coated zinc flakes in the same manner as in Example 1. Table 1 shows the results.

With respect to the obtained coated zinc flake slurry (water content: 45%), a paint was prepared in the same manner as in Example 1, and each test was conducted. Table 2 shows the results.

[0063]

EXAMPLE 6 Colloidal silica 2 having a particle size of 10 nm
A 0 wt% aqueous solution was diluted with pure water to obtain a 2.2 wt% colloidal silica-containing solution. Then, a 1% by weight aqueous solution of sodium hydroxide was added to the obtained colloidal silica-containing solution to adjust the pH to 11. To 1 liter of the obtained colloidal silica-containing solution, 5 g of "Nopco 1529" (trade name, manufactured by San Nopco Co., Ltd.) was added as a nonionic surfactant, and then stearic acid was used as a grinding aid. Manufactured, average major axis 9μ, average thickness 0.
200 μg of 2μ zinc aluminum alloy flake was added, and colloidal silica / zinc aluminum alloy flake (weight ratio) =
A solution that was 0.11 was obtained. Then, the resulting solution was
After stirring at 0 ° C. for 12 hours, the mixture was allowed to stand to precipitate zinc aluminum alloy flakes. After sufficient precipitation, the supernatant was discarded to obtain a zinc aluminum alloy flake whose surface was coated with colloidal silica.

Each test was performed on the obtained coated zinc aluminum alloy flakes in the same manner as in Example 1. Table 1 shows the results.

The coated zinc aluminum alloy flake slurry (water content 45%) obtained in Example 1 was used.
A paint was prepared in the same manner as described above, and each test was performed. Table 2 shows the results.

[0066]

Comparative Example 1 Using zinc flakes having an average major axis of 10 μm and an average thickness of 0.5 μm, the surface of which was coated with stearic acid and manufactured using stearic acid as a grinding aid, in the same manner as in Example 1, The test was performed. Table 1 shows the results.

With respect to the obtained coated zinc flake slurry (water content: 45%), a coating material was prepared in the same manner as in Example 1, and each test was performed. Table 2 shows the results.

[0068]

Comparative Example 2 Colloidal silica 2 having a particle size of 10 nm
The 0 wt% aqueous solution was diluted with pure water to obtain a 2 wt% colloidal silica-containing solution. When the pH of the obtained colloidal silica-containing solution was not particularly adjusted, the pH was 9. Then, the obtained colloidal silica-containing solution 1
5 g of “Nopco 1529” (trade name, manufactured by San Nopco Co., Ltd.) as a nonionic surfactant was further added to the liter, and then 200 g of zinc flake having an average major axis of 8 μm and an average thickness of 0.3 μm was added. . After stirring the obtained solution at 40 ° C. for 12 hours, the solution was allowed to stand to precipitate zinc flakes. After sufficient precipitation, the supernatant was discarded to obtain zinc flakes.

Each test was carried out on the obtained zinc flakes in the same manner as in Example 1. Table 1 shows the results.

A paint was prepared from the obtained zinc flake slurry (water content: 45%) in the same manner as in Example 1.
Each test was performed. Table 2 shows the results.

[0071]

[Table 1]

[0072]

[Table 2]

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Claims (4)

(57) [Claims] 1. A coated zinc-containing metal flake having a colloidal silica film on its surface. 2. The method for producing coated zinc-containing metal flakes according to claim 1, wherein the solution containing colloidal silica whose pH is adjusted to 10 to 13 is brought into contact with the zinc-containing metal flakes. 3. The colloidal silica has a particle size of 10 nm.
The method for producing a coated zinc-containing metal flake according to claim 2, which is as follows. 4. A paint comprising the coated zinc-containing metal flake according to claim 1.