Description of the aluminum silver paste properties

June 01 12:22 2021
Description of the aluminum silver paste properties
As a kind of metallic pigment, aluminum silver paste can produce special effects different from other ordinary pigments. Some techniques in the use process of water-based aluminum silver paste will be briefly explained.

As a kind of metallic pigment, aluminum silver paste can produce special effects different from other ordinary pigments. Some techniques in the use process of water-based aluminum silver paste will be briefly explained.

1. In order to achieve satisfactory special effects, the aluminum silver paste must be completely dispersed in the coating system, and the coating should be in a uniform state without fine particles. The aluminum flakes are easy to bend and break, and if high-speed stirring or In other continuous intensive processing, its geometric structure is easily destroyed, resulting in coarse particles, dark color, reduced coverage, and metal migration. Therefore, high shear force dispersion methods should not be used.

Suggestion: Use the pre-dispersion method: first select an appropriate solvent or a mixture of several solvents, and add the solvent to the aluminum-silver paste at a ratio of aluminum-silver paste to solvent of 1:1 or 1:2, and slowly stir until uniform ((About 10-20 minutes). Add the base material to the system. Generally, the aluminum silver paste is soaked in the solvent for 30 minutes in advance and then slowly stirred.

2. The dilution selection of aluminum silver paste is mainly determined by the paint material determined by the formula. Non-floating aluminum silver paste can be widely used in polar and non-polar solvents, such as aliphatic or aromatic hydrocarbons, lipids (such as butyl acetate)), ketones (such as methyl ethyl ketone, methyl isobutyl ketone), alcohols (such as ethanol).

3. Chlorine-containing solvents (halogenated…) are not suitable for any aluminum silver paste pigments. Chlorinated solvents will release HCL and chemically react with fine aluminum pigments.

4. Many commonly used paint base materials such as oily varnish base materials, acrylic esters, alkyd, cyclic itch esters and water-based base materials can be applied to non-floating aluminum silver paste pigments. Generally speaking, any paint base material Or the solvent is suitable as long as it is compatible with the solvent carrier of the aluminum silver paste and will not cause chemical damage to the aluminum silver paste. Special attention: aluminum is a kind of active metal, and the acid value of the paint should be controlled below.

5. When a coating system containing aluminum silver paste needs to add a metal drier, for non-floating aluminum silver paste, only driers that will not react with the fatty acids on the surface of the aluminum flakes can be used. It is recommended Use diamond, zirconium, and manganese driers.

6. ​​Addition ratio:

Colored primer > aluminum silver paste addition ratio 1%-4%
Pure silver primer with aluminum silver paste addition ratio 4%-10%
The proportion of aluminum silver paste added in single-layer metallic flash paint is 5%-13%
Anti-corrosion paint, canning, and coil coating aluminum silver paste addition ratio 10%-13%

7. When the surface of the coating film is oriented in parallel, the best effect is achieved. Poor parallel orientation will cause turbidity or diffuse reflection. The orientation of the flake pigment is related to the formulation and construction conditions. The volatilization of the solvent causes the shrinkage of the wet coating film, which will eventually The aluminum pigment is pressed into a horizontal orientation position. The higher the solvent content in the paint, the stronger this effect. This explains the phenomenon of flake pigment orientation. Therefore, the optical properties of low-solid coatings are better than those of high-solids coatings. 

The volatilization of the solvent will cause a strong vortex inside the wet film, but if the solvent volatilizes too slowly, it will form the so-called Naard vortex, which hinders the parallel orientation of the aluminum pigment (producing turbidity).

Resins can be used to promote the volatilization of solvents (such as butyl cellulose CAB), and some additives are also used. They can fix flake pigments. There are reports in the literature that wax dispersions can have a “spacing effect”, and surfactants also have similar functions. But The function should be tested before use.

Water-based aluminum silver paste editor hopes that consumers should pay attention to: In a certain range, the optical properties of relatively low solids coatings are better than relatively high solids coatings.

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