What is Powder coating?
Powder coating is one of the methods that used 100% solid coating material. In powder coating, preprepared coating powder in the solid form is deposited directly onto the substrate. Powder coating is an environmentally friendly process compared with a fluid-based coating method that does not use solvent, releases meager amounts of VOC, and generates few waste materials or hazardous chemicals. No drying is necessary since there is no use of water, resulting in energy savings. Beyond its environmental attractiveness, powder coating also has unique characteristics because the particles have a high surface area. It is also possible to create luxurious coats with minimal penetration.
Powder coating is a way of applying dry paint to a surface. Most people have used liquid paints. They may have painted with a brush, a spray can, or even with their fingers. Powder coatings are dry because there are no liquid solvents. The dry powder is applied to the item (substrate) to be painted. Then the dust of the powder coating is turned to liquid by melting. Powder in its molten state subsequently flows out to cover the substrate; it blends, and sometimes it cross-links. The result is a painted object.
The Powder Coating Institute publishes one of the best references1although there are numerous others.2 There are several ways to apply fluoropolymer powders. Just like with liquid finishes, we classify them as spray techniques or bulk application techniques. The spray techniques are called electrostatic spray application and hot flocking. The bulk application techniques are based on a fluidized bed.
Powder coating is similar to painting, where the substrate to be coated in the form of a powder. The substrate to be covered first made ground and the powder is electrostatically charged. Then the powder is sprayed evenly on the substrate and then baked in an oven so that the powder particles melt and fuse to form a continuous film. There are two main types of powder coatings available in the market: thermoplastic powders, which will remelt when heated and thermosetting powder, which will not. During the curing process (in the oven), a chemical cross-linking reaction is triggered at the curing temperature, and it is this chemical reaction which gives the powder coating many of its desirable properties.
History of Powder coating
Powder coating is the youngest of the surface finishing techniques. Its inception was in Australia in around 1965. The use of Powder coating is to produce hard, wear-resistant coatings mainly for coating of metals, viz., household appliances, aluminum extrusions, drum hardware, and automobile and bicycle parts.
Application methods of Powder coatings
One of the oldest powder coating methods is fluidized bed coating. Air passes through a container filled with coating particles and raises the particles gently. As a result, fluid-like particle emotions are generated. When a heated substrate is dipped into a fluidized bed, the particles touching the substrate melt and adhere to it, the particles this has the advantage of creating a uniform coating thickness but requires the substrate to be preheated above the coating powder’s fusion temperature. Hence it may not be appropriate for most textile substrates. Therefore powder coating is mostly used for metal coating processes. An electrostatic fluidized bed coating process overcomes preheating problems. Instead of air, it uses electrostatic charges to separate the powder particles and generate the necessary fluid-like motion before deposition.
Scatter coating is a powder coating method where the coating powder is spread evenly on the substrate surface with a rotating scatter roller. The dosing roller determines the amount of powder applied, its rotation speed, and the substrate line speed (Jarrell, 1992; Glawe et al., 2003). In powder dot coating, the coating powder is delivered directly onto the substrate surface utilizing an engraved roller
Benefits of powder coating
Powder Coating is an advanced method of applying a decorative and protective finish to virtually any type of metal that can be used both by industry and consumers. The powder used in the process is a mixture of finely ground particles of pigment and resin, which is electrostatically sprayed onto the surface to be coated. The charged powder particles adhere to the electrically grounded surfaces until the powder is heated and fused into a smooth coating in the curing oven. The result is a uniform, durable, high quality, and attractive finish. Powder coating is the fastest-growing finishing technology in North America, representing over 10% of all industrial finishing application
1. Powder Coating is More Durable
Powder Coating gives consumers, businesses, and industries one of the most economical, longest-lasting, and most color-durable quality finishes available on virtually any type of metal. Powder-coated surfaces are more resistant to chipping, scratching, fading, and wearing than other finishes. Colors stay bright and vibrant longer.
2. Powder helps reduce the health hazard to operators.
As powders do not contain solvent, there is a marked reduction in nose, mouth, and throat irritation. With liquid coating, any liquid paint which comes into contact with an operator’s skin needs to wash off with solvent, and then removed by emulsifying with soap in hot water. In general, the powder coating does not cause skin irritation though individuals may react to certain types of powder in rare cases. The dust (powder coating) can be removed from the skin quickly by washing with warm water.
3. With a powder, there are low air requirements – hence more cost savings.
The air extraction in a powder spray booth is a lot less than for solvent-based paints. Great news if you’re looking for economies in ventilation and the consequential heating of work areas. As less warm air has to be replaced in workshops, less dust is attracted, and there is less air-draught for the operators to battle
4. Powder Coating is cleaner to use
Applying powder is much cleaner than applying wet paint. A spray booth can be cleaned down quickly and easily using a rubber squeegee while the standard air extraction in the booth is operating. Brushes or an air hose should not be used for this purpose. Any spillages of powder outside the booth can be removed with an industrial vacuum cleaner that is fitted with an air-driven or dust-tight motor.
5. Powder Coating is More Environmental Friendly
Powder Coating is also highly protective of our environment. While liquid finishes contain solvents with pollutants known as volatile organic compounds (VOCs), powder coating contains no solvents and release negligible amounts, if any, VOCs into the atmosphere. Therefore, there is no longer a need for finishers to buy and maintain costly pollution control equipment.
6. With a powder, the processing time lowered
Powder processing times are generally shorter than those used for wet stoving paints since, as there is no solvent, no flash off period is required. Instead, the powder-coated articles can pass directly into the oven, which gives substantial savings in space and time.
Issues with powder coatings
Powder coating is a solventless system; it does not depend on the use of a solvent. It uses the performance constituents of solid TP or TS materials. It can be a homogeneous blend of the plastic with fillers and additives in the form of dry, fine particles of a compound similar to flour. The advantages of powder coating include minimum air pollution and water contamination, increased coating performance, and consequent cost savings. It has many of the same problems as solution painting. If not correctly formulated, the coating may sag, particularly for thick coats, show poor performance when not wholly cured, show imperfections such as craters and pinholes, and have poor hiding with low film thickness. There are various methods to apply powder coatings.
The benefits of powder coating for consumers are simple: powder coating will make your purchase look better and last longer – not to mention its reduced environmental footprint!
Epoxy Oilserv is Nigeria’s prominent promoter for the use of Powder coating in Nigeria and provides the powder coating products and services! Kindly contact us for further information about your project.
Epoxy Oilserv Nigeria Limited in Nigeria is constructing an Ultramodern powder coating plant.