A Sure Cure: Sustainable solution solidifies finish in seconds

Above: Flexibility and weathering resistance is a feature of DuraNEXT coatings

January, 2025- In seconds. That’s the newest curing time target for PPG’s DuraNEXT portfolio of electron beam (EB) and ultraviolet (EV) curable backers, primers, base coats and clear coats for metal coil coaters. The technology, commercially launched in July 2024 and debuted at MetalCon in October, was developed in response to customer requests for better energy efficiency and a more sustainably coated coil.

Pittsburgh-based PPG had the foundation for DuraNEXT in the company’s DNA nearly 20 years ago. It has a 30-year legacy of energy-curable coatings for wood. Three years ago, in collaboration with its sister laboratory in France, PPG’s lab in Springdale, Pennsylvania, set out in earnest to develop a metal coil coating that would cure almost instantly through EB or UV processes.

“Also intriguing for our customers is the potential for greater efficiency in their processes, the ability to cure coatings faster than traditional coil coatings,” says Craig Smith, global technical platform director for PPG coil coatings.

NO HEAT

Unlike traditional thermal metal curing that requires solvents and heat, energy curing is performed at or near ambient temperatures. “With thermally cured coatings, the coating must be heated, requiring energy. The metal substrate must be heated as well, which absorbs a lot of heat —really for no value,” explains Smith. Conversely, energy curing uses either ultraviolet light or an electron beam to initiate the chemical reactions. “The process is very energy efficient, simply targeting the coating and consuming very small amounts of energy,” he says.

With UV and EB curing, there is no longer a need for solvents, thus removing volatile organic compounds (VOCs) from the processing environment. By eliminating solvents from the operation, coil coaters can reconsider ventilation measures as well as storage practices— gaining cost efficiencies.

The DuraNEXT technology is suitable for coaters using various application methods including roll-, curtain- and slot-die coating.

SUSTAINABILITY

With UV and EB processing, coating customers can realize lower energy costs as well as a potential reduction in carbon footprint.

DuraNEXT basecoats offer a range of glosses and colors for interior and exterior application.

“The number one benefit of DuraNEXT is the lower energy requirements for curing the product, which directly impacts the carbon footprint,” Smith says. “The coating itself, as produced by PPG, has a lower carbon footprint than a conventional solvent-borne coating. And then the process of curing that coating—using relatively low amounts of electrical energy versus large amounts of natural gas—can enable additional sustainability benefits,” notes Smith.

He shares another benefit: reduced VOCs. “A traditional solvent-based coating is roughly 50 percent solvent, which needs to be evaporated and incinerated during the coating process,” Smith explains. With DuraNEXT, there’s effectively no solvent.

ON PAR PERFORMANCE

The performance of energy-curing coatings is comparable to air or heat curing. DuraNEXT formulations meet the requirements for flexible substrates, good bonding strength and resistance to impact and bending. Energycure coatings maintain nearly the same lm thickness before and after the cure, with virtually no loss in weight. This technology also provides hardness and abrasion/chemical resistance. DuraNEXT was developed to work with transparent and pigmented coatings across a wide variety of glosses and embossed finish options.

UV and EB curing do not require solvents so there is less impact on the environment.

“Another benefit of using DuraNEXT is increased resistance to mechanical damage— whether it occurs during transportation, installation or while fabricating,” says Scott Frankert, business development manager for PPG coil coatings. For example, a coater may be trying to protect an image or print. “With DuraNEXT, the image will last longer. One of PPG’s mottoes is: We protect and beautify the world. Keeping that image beautiful for a longer period of time is certainly an advantage of using a product like DuraNEXT,” Frankert claims.

TIME STAMPS

A highlight of DuraNEXT performance metrics is the almost immediate curing time. “If you look at electron beam curing time, it’s probably milliseconds. It’s almost instantaneous,” reports Smith. “With UV curing, that time could be extended into seconds. But we’re talking 1 to 3 seconds, whereas normal thermally cured coil coating products would take 20 to 30 seconds. So the curing time of DuraNEXT products is at least 10 times faster,” estimates Smith.

The DuraNEXT portfolio of electron beam and ultraviolet curable coil coatings cure in 1 to 3 seconds.

A coil coater can also realize footprint optimization with DuraNEXT. Traditional coil ovens may be nearly 150 feet in length, to accommodate the 20 to 30 seconds of drying time for a coil. “The ability to cure the paint in a second or less means that the footprint or the curing zone can be much smaller. So now a coil coater’s curing equipment can be one tenth of the size of a traditional coil oven,” explains Frankert.

A smaller coating footprint opens up the possibilities for coaters to establish lines in locations that historically were not conducive for such operations—and potentially closer to key customers. “So the curing window impacts the footprint, which gives a lot of flexibility to the supply chain,” Frankert adds.

DuraNEXT had to be made suitable for both interior and exterior applications. The product does perform well under exposure to sunlight and other environmental conditions. “We had to make sure that the DuraNEXT system could address weathering properties,” Smith says.

EXPANDED PORTFOLIO

Wood flooring is a big market for PPG UV products, says Frankert. “In this case, only one side of the system requires coating, even multiple layers of coatings. Typically they’re all clear, or slightly tinted, so the wood substrate is still visible,” Frankert explains.

In contrast, PPG’s coated coil products— coated on two sides—include a range of applications: curable backers, primers, base coats and clear coats. “It’s a dierent type of coating system. We need primers to assure corrosion performance for the metal substrate. Most of the coatings we use are pigmented. We also offer clear coats,” reports Frankert. Clear coatings for coil require flexibility and weathering resistance.

DuraNEXT backers are available in both UV and EB formulations to accommodate various application equipment setups and can be applied over a primer or used as a direct-to-metal application. Primers are available in UV-curable formulations that can be used under an EB topcoat or with a conventional thermal cure topcoat. These primers can also be used in conjunction with a wet-on-wet applied topcoat then cured with EB in a single pass.

The DuraNEXT base coats are available in multiple glosses and colors, both for interior and exterior application. Finish options include smooth, textured and wrinkled. These base coats can be formulated as a onecoat direct-to-metal solution. DuraNEXT clear coats were engineered to preserve digitally printed inks via a protective layer that adds weatherability as well as scratch- and abrasion-resistance.

PIONEERING

Frankert shares that customer feedback to DuraNEXT has been positive, especially among companies with a reputation for innovation. “The types of customers expressing interest in DuraNEXT tend to be market leaders, businesses that are looking to push things to the next level to dierentiate themselves,” he says.

Frankert and the PPG team is meeting with customers, “trying to tackle very specic challenges,” he reports. These meetings become very collaborative, including equipment suppliers as well.

“Energy curing is the future of coil coating. It’s a matter of working together to get there,” adds Smith.

DuraNEXT was awarded top new product honors in the paints and coating category at MetalCon.

PPG, 888/774/2001, www.ppg.com.