Developments in Powder Coatings
Powder Coating is a dry finish process that uses finely ground powder particles to coat metal surfaces. Introduced in the mid 1950s, it is the youngest of the finish techniques in common use today and by far the fastest growing. The early powder coatings, applied by means of fluidized-bed applications, had typical film thickness ranging between 150 mm and 500 mm and used to deliver functional rather than aesthetic properties.
It was not until the introduction of the electrostatic spraying processing that powder coatings became a commercially viable solution, delivering on both functional and decorative features. In fact, not only did the electrostatic spraying process enable the application of relatively thinner film layers of powder coatings but it also allowed for the possibility to coat those parts of the object that could not be previously treated through the fluidized process.
Between the 1960s and 1970s most of the thermosetting resins we know today were already developed and used by the main powder manufacturers. These are epoxy, epoxy polyester hybrid, polyurethane and polyester resins.
Due to the increasing concerns over health and pollution associated with the use of organic solvents, the powder coatings technology gained popularity throughout the 1970s, albeit the still expensive application systems, the elevated curing temperatures and the high film thickness.
Driven by technology improvement in terms of application efficiency, colour range and texture availability, powder coatings found its commercial breakthrough at the beginning of the 1980s and has been growing steadily ever since. Today, powder coatings represent 8-9% of all industrial coatings used in the finishing industry.
While it is arguable whether powder coatings’ double-digit growth is going to be achievable in the future, the demand for environmentally friendly, low VOC coating solutions will undoubtedly fuel the growth of this coating technology, especially in Europe where the legislation is particularly intense, but also in North America, Middle East and Asia Pacific where green sustainable practices are rapidly growing. Industry specifiers are today giving environmental considerations a more decisive weight in the material selection process. Issues such as indoor environmental quality, control of VOC emission and amount of energy dissipated during the material’s manufacturing are becoming as critical as the product performance.
Technology advancement on low temperature and high speed curing will significantly continue to expand the market opportunities in the future not only by creating commercially viable solutions for heat sensitive substrates, such as wood and plastic, but also by improving the user’s overall energy efficiency and productivity, which will positively contribute to their bottom line.
In addition, recent developments in the field of outdoor weatherability have allowed powder coatings to compete in the high performance architectural market, traditionally held by liquid coatings. Superior exterior durability is also an important requirement for the automotive finishes and the agricultural construction equipment segment where powder coatings so far remain a marginal player.