1. What is aluminum silver paste?

 

Aluminum-silver paste is a kind of inorganic metal pigment, which is mainly composed of aluminum flakes, solvents and additives. The ratio is about 60%-70%: 30%-40%:0-10%. After special processing technology and surface treatment, the surface of the aluminum sheet is smooth and flat, the edges are neat, the shape is regular, the particle size distribution is concentrated, and the matching with the coating system is excellent. The aluminum-silver paste is mainly in the form of paste or paste, among which the shapes of aluminum flakes are silver dollar, snowflake and scaly. The industry uses special terms such as solid content, particle size, whiteness, brightness, metallicity, hiding power, and cleanliness to describe the physical properties of aluminum silver paste. The particle state of the aluminum-silver paste is in the form of scales. In most processes for producing aluminum silver paste, lubricants are required to prevent "cold welding". When used in coatings, these lubricants can impart floating or non-floating characteristics to the aluminum silver paste.

 

2. Types of aluminum paste and its coating effect

 

The main raw materials for preparing floating aluminum silver paste are atomized aluminum powder, solvent oil and stearic acid (saturated fatty acid, density: 0.847g/cm3). In the ball milling stage, saturated fatty acids such as stearic acid are used as lubricants. Stearic acid is adsorbed on the surface of the aluminum sheet to make the aluminum silver paste hydrophobic and oleophobic. The aluminum flakes coated with stearic acid in the coating system cannot be wetted by the base material, and the density is relatively small, thereby reducing the downward gravity of the aluminum flakes. On the other hand, with the upward thrust of the molecules moving to the surface of the carrier when the solvent volatilizes, the sinking force formed by the weight of the aluminum sheet is offset to make it float to the surface of the paint film, and an opaque silver film is formed on and near the surface of the paint film. Since the aluminum flakes float on the surface of the paint film, and some of the aluminum flakes overlap, there will be silver drop, and recoating is also difficult. Floating aluminum silver paste is generally used for roof coating, maintenance, anti-corrosion coatings, reflective coatings, and imitation chrome-plating effect coatings that require high protection. Its appearance varies according to the thickness of the particles (particle size), which can range from rough, white appearance to gray, highly reflective or mirror-like effects, and can produce effects from flat, silver, and high-gloss (chrome-plated). The coarse-grained floating aluminum silver paste has the lowest hiding power and rough structure, but it can obtain the whitest and brightest coating. On the contrary, the fine-grained floating aluminum silver paste has the greatest hiding power, the smoothest structure and high reflectivity. These floating aluminum silver paste aluminum sheets have a smooth surface, which can reflect light (visible light, ultraviolet light and infrared light), and have good heat insulation effects; the densely laminated aluminum sheets can also provide shielding effects to prevent moisture and other reaction media from entering the paint film , It has a good protective effect on the coating substrate.

 

②Non-floating aluminum silver paste and its coating effect

 

The main raw materials for preparing non-floating silver paste (except electroplating silver) are atomized aluminum powder, solvent oil, and oleic acid or erucic acid (unsaturated fatty acid). The non-floating aluminum silver paste uses unsaturated fatty acid as the aluminum sheet coating material to make the aluminum sheet have lipophilic and hydrophobic properties, so the aluminum sheet can be completely wetted by the oily solvent and resin system, evenly distributed in the entire paint film, and has The tendency of sinking, so the adhesion is very good, the coating film is firm and stable, and it can be recoated and finished (see Figure 2 for the effect). Compared with floating aluminum silver paste, in terms of surface performance, non-floating aluminum silver paste can provide a more significant improvement and has a very good decorative effect. It is widely used in vehicles, furniture, electronic products, coils, etc. Various occasions, automobile paint, motorcycle paint, bicycle paint, plastic paint, architectural paint, ink, mobile phone shell and buttons, electromechanical shell, electric shell, industrial paint and many other fields. Non-floating aluminum silver paste can also be generally divided into imitation plating, flash silver, and fine silver. The average particle diameter of fine silver is the smallest and the brightness is the lowest; the average particle diameter of flash silver is the largest and the brightness is the highest; the average particle diameter of imitation electroplated silver is between fine silver and flash silver, and the brightness is also between fine silver and flash silver.

 

There is also a special effect aluminum silver paste in the non-floating aluminum silver paste, which is electroplated silver. Electroplating silver is also called mirror silver, mirror aluminum silver paste, super bright aluminum silver paste or vacuum aluminum plating suspension. It is not produced by the HALL ball milling method. It is a non-floating aluminum silver paste produced by using high-purity aluminum as raw material and using a unique vapor phase metallized pigment process (VMPs). The aluminum content is 10%-20%, and the average particle size is The D50 is between 5-12 microns, the thickness of the aluminum sheet is nanometer, the surface hiding power and brightness are great, and the excellent electroplating effect or mirror effect can be obtained with a small amount.

 

Electroplating silver can replace electroplating, with little harm, good hiding power and simple construction. It is widely used in paint (cosmetic bottle paint, wine bottle paint, plastic paint, car paint) and printing ink (home improvement glass mirror ink, home appliance glass mirror ink, Mobile phone lens mirror ink, gravure printing ink for tobacco and alcohol packages) and many other industries.

 

3. Precautions for storage of aluminum silver paste

 

Store in an airtight tank indoors at a storage temperature of 15-40°C (special attention should be paid in winter or when the ambient temperature is equal to or lower than 10°C). Avoid direct exposure to sunlight, rain, or high temperatures; excessive jolts and vibrations during transportation, and storage under certain conditions may cause partial separation of aluminum and solvent components. Once it is unpacked and used, it should be used up as soon as possible. If it cannot be used up at one time, it should be completely sealed immediately to prevent the solvent in the aluminum-silver paste from evaporating. If it is left for too long, please test before use.

What is aluminum silver powder?

 

Aluminum-silver powder is a deep-processed product of aluminum-silver paste. It is divided into powder metal pigments produced by dry ball milling process and wet ball milling and coating treatment process, with stable quality and excellent weather resistance. Generally, it is mainly used for thermosetting powder coatings (thermosetting refers to heating and solidification molding without changing the chemical structure, and cannot be reversed after molding), outdoor decoration products, plastic masterbatch and some ink products. The solid content of aluminum silver powder is very high, so the added amount in the terminal application is relatively low, from 0.5% to 3% of the added amount.

What is a silver bar?

 

Silver bars are mainly used to solidify and strip the paste-like aluminum silver paste to make it more suitable for the application of end products, such as high-end inks, injection molding, and color masterbatches. The principle is very similar to the color masterbatch. They are all carrier pigments made of aluminum silver paste plus soluble resin or PE wax and a small amount of additives. Silver bar products have five major advantages: very few bad odors, safe and environmentally friendly; good stability, can be stored for a long time; easier to disperse; almost no solvent, rarely incompatibility with plastic or ink systems; safe transportation.

 

Aluminum pigments also have more extended products, such as environmentally friendly aluminum silver paste, odorless aluminum silver paste, water-based aluminum silver paste, resin-coated aluminum silver paste, colored aluminum silver paste, nano-aluminum silver paste and so on.