The rise of new coating technologies

Infograph: TBS

At the heart of the enthralling world of painting lies the essential element known as "coating" that refers to any type of covering that is applied to an object's surface for various purposes, including protection, decoration, and functional enhancements. 

The coatings industry, one of the most heavily regulated industries in the world, includes various types of paint, varnishes, stains, clear coats, and specialty coatings, with each type of coating being formulated to meet specific requirements and perform particular functions.

S&P Global's "Chemical Economics Handbook – Paint and Coatings Industry Overview" reveals that approximately 52% of global coatings production serves the dual purpose of enhancing and safeguarding structures, including residential homes, public buildings, and industrial facilities, while another 35% is dedicated to beautifying and protecting various industrial products.

The same report also suggests that the coatings industry has undergone a transformative shift in the past four decades, primarily driven by the necessity to embrace low-solvent and solventless technologies. This shift marks a significant change, highlighting the industry's adaptation to new coating technologies.

The coatings industry has undergone a transformative shift in the past four decades, primarily driven by the necessity to embrace low-solvent and solventless technologies. Photo: Collected

According to Md Kamrul Hasan, executive director of Rainbow Paints, in the 21st century, the coating industry has streamlined its operations to minimise their environmental impact. 

Substantial progress has been made in this regard over the last 50 years, with notable achievements such as the elimination of lead carbonate as a pigment and the discontinuation of mercury as a preservative.

He further said, "There have been substantial reductions in the use of volatile organic solvents (VOCs) through the introduction of waterborne formulations, high-solids coatings, radiation-curable coatings, and powder coating technologies. These advancements have significantly contributed to making the industry more environmentally-friendly."

Waterborne coatings: These represent an environmentally conscious surface treatment methodology that relies on water as the primary solvent for dispersing the coating or paint resin. Approximately 80% of the solvent component is replaced by water in this process. The primary objective is to facilitate the application of coatings and paints while prioritising eco-friendliness. 

Waterborne coatings have gained extensive popularity due to their minimal volatile organic compound (VOC) content, typically containing less than 3.5 pounds per gallon of water. They find versatile applications on substrates like wood (e.g., furniture) and plastics.

In the architectural coatings market, the growth of waterborne coatings is expected to persist, driven by consumer preferences for coatings that are odour-free and devoid of potentially harmful ingredients.

High-solids coatings: A high-solids coating, whether single or two-component, is purposefully designed with a notably elevated solid content, typically exceeding 65%. This solid component comprises binders, pigments, and additives. Despite the reduced proportion of volatile organic compounds (VOCs), high-solids coatings manage to maintain their coating and application properties at a satisfactory level. These coatings can be either solvent-based or water-based.

High-solids coatings are generally recognised as more environmentally sustainable than conventional coatings, primarily because they emit fewer solvents during the drying or curing process. Such formulations may also be referred to as high solids formulations.

These coatings gained prominence in various industries, including aerospace, as a means to adhere to the Environmental Protection Agency's (EPA) emissions regulations.

Two-component systems: These systems, often referred to as 2K coatings or two-part coatings, are a type of coating formulation that consists of two separate components that are mixed just prior to application. These two components are typically a base (resin) and a hardener (curing agent). When combined, they initiate a chemical reaction that leads to the curing or hardening of the coating. 

These systems are suitable for Airless, AirCoat and compressed air spray processes. One or two additional cleaning pumps per paint system are necessary to rinse the mixing tube, material hose, gun and nozzle during pauses in operation. They can also be grouped into mechanical and electronic mixing systems.

Powder coatings: A powder coating is a unique type of coating that is applied in a dry, powdered form, flowing freely. It stands in stark contrast to traditional liquid paint, as it doesn't rely on a solvent to create the suspension of the filler and binder components. 

This coating is primarily employed for the protection and enhancement of metal surfaces, including aluminium extrusions, household appliances, bicycle and automotive components, as well as drum hardware.

Radiation-curable coatings: These coatings, often referred to as radcure coatings, are specialised materials engineered to undergo cross-linking or curing processes when exposed to intense radiation energy, such as electron beams or ultraviolet (UV) light radiation. These formulations consist of a reactive liquid vehicle, pigments, and conventional additives, all meticulously designed for radiation-induced curing.

The adoption of radiation-cured coatings offers numerous benefits, including rapid curing times, minimal energy consumption, and notable enhancements in surface characteristics. Among these improvements is the enhanced corrosion protection provided to metallic surfaces, making them particularly advantageous in various applications.

In addition to these, various other emerging coating technologies like nano coatings, smart coatings, bio-based coatings, antimicrobial coatings, and functional coatings are contributing to advancements in performance, sustainability, and functionality across an array of sectors. 

Among them, nano coatings are currently garnering the most attention, with tens of thousands of patents already issued in the coatings industry. These coatings incorporate ultra-small ceramic or metallic particles, typically measuring 10-70 nanometers and containing fewer than 6.5 million atoms. This minute scale results in a noteworthy surface area-to-mass ratio, conferring distinct properties. 

For instance, at 2 nanometers, metal particles exhibit altered conductivity, while at 20 nanometers, ceramic particles change transparency. Gold particles, at 20 nanometers, shift to a red hue and lose their plasticity, offering diverse applications in specialised areas like scratch resistance, wear protection, corrosion prevention, and UV resistance.

In recent years, environmental concerns and stricter regulations, including the "haze war" (efforts and measures taken by governments and environmental agencies to combat air pollution) and stringent environmental laws, have emphasised the need for eco-friendly coatings. Traditional solvent-based coatings with high VOC content contribute to air pollution, leading to policies like the paint consumption tax that promote low-VOC, environmentally friendly coatings.

Over the upcoming five years, while air pollution regulations will remain influential in shaping the adoption of new coating technologies, consumer preferences are poised to exert an even greater impact on the industry.

Meanwhile, there are also some key challenges in the Bangladeshi coating market in particular. Rajesh Sircar, deputy general manager at Nippon Paint Bangladesh which has captured 5% of the total coating market in Bangladesh, shed some light in this regard. 

"The coating market in Bangladesh is highly competitive, with both national and foreign companies vying for market share. Surviving in this competitive market, which is largely controlled by foreign firms, requires supplying innovative, technology-based products," he said.