The powder coating process was invented around 1945 by Daniel Gusting. With the latest in powder coating technology & equipment, powder coating is able to deliver a superior finish, consistently. Powder coating is applied with specialized electrostatic equipment as a free-flowing & dry powder. A powder spray gun is used, which when triggered gives an electrostatic charge to the powder particles passing through it. Once the powder is applied, the coated parts are cured in an oven. This melts the powder and helps to crosslink the powder over the surface of the part & creates a tough, scratch-resistant & beautiful finish. Powder coating also offers a wide range of specialty finishes such as texture, structure, crocodile, etc. that is hard to achieve through liquid coating methods. Major applications of powder coating involve household appliances, aluminum extrusions, automobile parts, bicycle parts. Brief illustration of powder manufacturing:

• The polymer granules are mixed with the hardener, pigments & other powder ingredients in an industrial mixer.
• The mixture is heated in an extruder.
• The extruded mixture is rolled flat, cooled and broken into small chips.
• The chips are milled & sieved to make a fine powder.

There are two major types of powder coating: Thermoplastic powder coating & Thermosetting powder coating:

• Thermoplastic Powders maintain their chemical composition as they cool & solidify, but they can re-melt after curing when exposed to sufficiently high heat. These powders are functional coatings that provide a variety of features including thick film coating, electrical insulation, and extreme mechanical and chemical resistance. Typical applications of thermoplastic powder coatings include road marking powders, stadium seat frames, dishwasher baskets and pipelines.
• Thermosetting powders are used much more frequently in the world of powder coating; they cannot re-melt after undergoing an irreversible chemical bonding process. Thermosetting powders are extensively used in industrial powder coating applications, mainly used to create a hard film.

Thermosetting powder coatings are derived from three major subtypes i.e. Pure Epoxy, Epoxy Polyester & Pure Polyester powders:

• Zinc Rich Primer “GP ENVIROCOAT 205 ZR is a powder coating primer containing Zinc which is designated to impart excellent corrosion protection. It consists of two-coat system with Zinc Rich primer followed by powder coating Topcoat. This product is ideal for usage in C-3 & C-4 corrosion Environment system as per ISO 12944.”
• Epoxy Primer “GP ENVIROCOAT 200 CR is a powder coating primer, totally free from Zinc. ENVIROCOAT 200 corrosion resistance primer can be over-coated with powder coating topcoat. Product designated with Anticorrosive Pigments gives superior corrosion protection & better inter-coat adhesion property for 2 coat system.”

Major advantages of powder coating over liquid coating:

• Powder coating production lines produce less hazardous waste than conventional liquid paints.
• Zero VOC – there is no discharge of any volatile organic compound into the atmosphere means environmentally ecofriendly.
• Powder coating- A wide range of specialty effects is easily accomplished which would be impossible to achieve with other coating processes.
• Powder coatings can produce much thicker coatings than conventional liquid coating without run down or sagging.

Major disadvantages of powder coatings:

• The startup cost is very high – since heating is through an oven, the cost of running the oven tends to be very high. Hence Grand Polycoats is the best powder coating manufacturer in India that offers low bake powder technology for reduced energy consumption during application.
• Restriction on the size of objects/components being coated – only items that can fit inside an oven can be coated with powder coatings.
• Contamination problem – Due to the size of the particles, there are chances of contamination through external dust or powder of different origin.
• Thin layer coating system – In powder coating, it is difficult to achieve a thin layer of powder coating. The minimum DFT is 25-35 micron.
• Change over time – changing from one color to another or one product to another, the change over time is very high because cleaning is very tedious.