Powder coating is a dry finishing process that has become extremely popular since its introduction in North America over in the 1960s. Representing over 15% of the total industrial finishing market, powder is used on a wide array of products. More and more companies specify powder coatings for a high-quality, durable finish, allowing for maximized production, improved efficiencies, and simplified environmental compliance. Used as functional (protective) and decorative finishes, powder coatings are available in an almost limitless range of colors and textures, and technological advancements have resulted in excellent performance properties.
How Powder Coating Works
Powder coatings are based on polymer resin systems, combined with curatives, pigments, leveling agents, flow modifiers, and other additives. These ingredients are melt mixed, cooled, and ground into a uniform powder similar to baking flour. A process called electrostatic spray deposition (ESD) is typically used to achieve the application of the powder coating to a metal substrate. This application method uses a spray gun, which applies an electrostatic charge to the powder particles, which are then attracted to the grounded part. After application of the powder coating, the parts enter a curing oven where, with the addition of heat, the coating chemically reacts to produce long molecular chains, resulting in high cross-link density. These molecular chains are very resistant to breakdown. This type of application is the most common method of applying powders. Powder coatings can also be applied to non-metallic substrates such as plastics and medium density fiberboard (MDF).
Sometimes a powder coating is applied during a fluidized bed application. Preheated parts are dipped in a hopper of fluidizing powder and the coating melts, and flows out on the part. Post cure may be needed depending on the mass and temperature of the part and the type of powder used. No matter which application process is utilized, powder coatings are easy to use, environmentally friendly, cost effective, and tough!
Durability of Powder Coating
Powder coating is a high-quality finish found on thousands of products you come in contact with each day. Powder coating protects the roughest, toughest machinery as well as the household items you depend on daily. It provides a more durable finish than liquid paints can offer, while still providing an attractive finish. Powder coated products are more resistant to diminished coating quality as a result of impact, moisture, chemicals, ultraviolet light, and other extreme weather conditions. In turn, this reduces the risk of scratches, chipping, abrasions, corrosion, fading, and other wear issues.
It's tough. It looks great. And it lasts a long, long time. In addition to being durable, powder coating is an attractive choice due to environmental advantages.
Spray coating is a very important process in the manufacture of aluminum wall panel (aluminum cladding). Electrostatic spraying uses electrostatic spray guns for spraying. Strictly speaking, electrostatic spraying is divided into electrostatic liquid spray coating (Polyvinylidene fluoride, short for PVDF) and electrostatic powder coating (powder coating). Generally, in accordance with different spraying objects and specific effects, the spraying methods are relatively different as well. Each of them has its own characteristics
PVDF spray coating uses a well-tuned (modulated) paint, which is a fluid, and powder coating uses a powdered solid.
PVDF spray coating is mainly carried out in a paint booth, and powder spraying is carried out in the powder spraying chamber.
PVDF spray coating uses a diaphragm pump or a plunger pump to apply pressure and static electricity for spraying. The powder coating is sprayed by shaking or inhaling, and electrostatic powder is sprayed on the gun mouth.
Drying of PVDF can be both natural leveling drying and baking. Drying of Powder coating is mainly by baking.
After natural leveling drying of PVDF, the coating film is very thin. The powder coating has good performance of anti-corrosion, high adhesion, and thick coating film, but it tends to discolor (color fade) if exposed to sunlight for a long time in the exterior area.
We normally suggest our customer use PVDF coating in the conditions of exterior usages, especially for the places with strong sunlight, or the places are humid like the seashore. And powder coating can be used for interior decoration.
For the same brand, the price of powder is generally 10 dollars cheaper than paint.
The same treatment before spraying.
The pre-treatment of the process is mainly anti-oxidation treatment and chromate treatment, which aim to clear oil, dust, and rust on the aluminum plate surface. The treatments not only prevent the rust but also increase the adhesion of the paint film.
Powder coating has the advantages of high efficiency, energy saving, less pollution, environmental protection, high paint utilization, and good coating performance. The disadvantage is that it is not resistant to sunlight.
The advantages of PVDF spray coating is high brightness, thin coating and stable color, strong weather resistance, not easy to fade, and discoloration.
We need to choose different spray coating methods according to specific products and requirements. In the aspect of the aluminum wall panel, powder coating can be used to produce special effects such as various wood grain or stone pattern.