What is powder coating
What is powder coating – Powder coating is a kind of coating that is used as a free-flowing, dry powder,and does not need a solvent to keep the binder and filler parts in a liquid suspension form , and is typically applied electrostatically and is then cured under heat to allow it to flow and form a hard finish that usually is tougher than conventional paint.
Powder coating is widely used for coating of metals, such as drum hard,aluminium extrusions,warehouse,hold appliances and automobile and bicycle parts.Newer technologies allow other materials, such as plastic,glass,MDF (medium-density fibreboard) coated using different new methods.
The main types powder coatings
These coatings are produced as a result to reaction of epoxy resin and a hardener agent .These coatings have a significant chemical resistance and corrosion tolerance as well as proper mechanical qualities ; but tend to chalking when exposed to sunlight . Thus ,these coatings are applied for indoor purposes.
These coatings are based on polyester carboxylic resins ; and are made as a result to reaction of polyester resin and an epoxy active curing agent with a low molecular weight . These coatings are applied for outdoor purposes due to their sufficient resistance against sunlight exposure. It’s worth mentioning that these coatings have high appropriate chemical and mechanical properties. Therefore, these coatings are used to paint aluminum profiles ,switchboards , air-conditioners ,car accessories ,etc.
Resins of epoxy and polyester are used in these coatings . General properties of hybrid coatings are more similar to the epoxy coatings rather than polyesters . These coatings have proper chemical and mechanical qualities and make a perfect uniform and even surface after curing . Also ,they sufficiently tolerate yellowing and UV exposure .
Chemically based on epoxy resin ,these coatings tend to chalking and are not sufficiently resistant against sunlight (UV ray) . Therefore, these coatings are generally applied for indoor uses, which are not exposed to sunlight . Applications of these coatings include domestic appliances, nonstick utensils, office equipments , electrical and communicational industries ,etc .
Polyurethane coatings are another types of powder coatings consisting polyester hydroxyl resin . These coatings have a proper chemical and exterior tolerance and are widely used in production of decorative paints that are increasingly applied in various industries such as aluminum , nonstick utensils and cabinetworks. The cost of these coatings is also notable compared to epoxy, hybrid,and TGIC polysester coatings .
Of the major and principal properties of acrylic powder coatings, sufficient weather ability and smooth filming with a low curing temperature are notable. These are used in varnish coatings , and their high sensitivity at mixing with other resins is one of the main problems in the application of these powders .This is why curing and application processes of these coatings should be done more carefully .