UV LED … what’s it all about?

According to Phoseon, UV LED curing systems allow printing of high-quality materials at maximum speeds. For label printing, it shows measurable advantages in high productivity, low energy usage, reduced heat load for thinner substrates, and clear environmental benefits. Being solid-state devices, LEDs offer instant on/off with no warm-up time and without ozone creation there’s no need for air ducts or ventilation.

Phoseon’s FirePower line allows increased speed in flexo printing. The intense UV output (up to 20W/cm2) paired with UV LED flexo inks have achieved record press speeds. The low heat output of the FirePower has enabled new capabilities such as heat-sensitive materials, unsupported films and thinner substrates.

Award-winning press

When it comes to press suppliers, Mark Andy has been a trailblazer in adopting the technology, working in partnership with Phoseon Technology to develop UV LED curing for its narrow-web presses.

At Labelexpo Europe in 2013, the Label Industry Global Award for Innovation went jointly to Flint Group Narrow Web and Mark Andy. Flint Group was honoured for its Ekocure UV LED ink technology that provides improved cure response, cost and productivity savings, waste reduction, energy savings and enhanced safety; and Mark Andy was singled out for its complementary ProLED ink curing technology that delivers high production rates and energy savings in excess of 50% when compared to traditional HgUV systems. Mark Andy’s ProLED technology also won the FlexoTech award for innovation in 2013.

The low running temperature of the UV LED system means that filmic substrates can be handled easily without chill drums. The curing system also reduces electricity consumption.

LED inks

Dedicated UV LED inks are a necessity and ink makers have been busy developing suitable products.

One is Flint Group Narrow Web, offering its award-winning EkoCure UV LED flexo ink technology (as mentioned above). Since gaining this enviable recognition, EkoCure inks have become globally available and include products for rotary screen whites, various coatings and adhesives, and flexo shrink whites.

Scotland’s Paragon Inks has also been busy in this market and has released a low-migration LED range. This meets all the requirements of low migration, low odour and low taint. Based on world-class European-grade materials, these inks offer fast curing at speeds up to 150m/min.

As printers worldwide fast become part of the LED revolution, Paragon has worked closely with key OEMs, co-suppliers and printers to bring these next-generation energy-curable ink and coating systems to market.

Since the creation of Paragon Inks three decades ago, the company has followed a strategic development plan, reacting to industry demands, and in the process becoming established as a global brand. Although still privately owned and manufacturing from one site in Scotland, the company now produces over 60% of its UV inks and coatings for the world’s unsupported web-printing market.

‘We see UV LED inks and coatings as the next rung on the technology ladder,’ asserts Amanda Jones, Paragon’s international sales manager. ‘These products not only offer printers and converters considerable cost savings but also the flexibility of being able to print on both supported and unsupported materials using UV LED curing.’

A significant part of the company’s success has been in Africa, where the establishment of Paragon Inks South Africa three year ago underlined its commitment to this market and to multinational brand owners operating on this continent. The South African company offers a facility for local supply, payment and service, and mirrors Paragon Inks’ Australian operation. ‘This is just another part of the equation in meeting global demand,’ comments Amanda, who is a regular speaker – imparting her considerable knowledge – at packaging and printing conferences in South Africa. Early next month, she’s scheduled to take part in the Innovations Conference being held in Johannesburg.

Viability still debatable?

In November last year, IST Metz held a seminar to debate UV LED technology and its application. Led by Stefan Feil, technical marketing manager, discussions centred on the differences between conventional and UV LED curing and importantly asked the question ‘When is it worth switching?’

The company’s MBS-6 LED-prepared concept was also demonstrated on a narrow-web flexo press.

In 2014, according to Stefan, Integration Technology (with whom IST Metz has a strategic partnership) sold an equal number of systems with UV lamps and LEDs.

He addressed the possibility of saving energy, explaining that the more highly reactive ink does mean that energy savings are possible in principle. A comparison would have to take into account that UV LED systems also change the chemistry of the inks. ‘An effective comparison needs to be made on the basis of a defined drying outcome, which in turn allows the necessary drying output to be derived,’ Stefan argued.

Standby/production times and average print format also have to be taken into account to make the result meaningful.

IST has designed the ‘LED-prepared’ concept to allow users to change from established UV technology to UV LED technology at short notice, when the need arises. This is achieved by leaving the outer housing in situ and replacing the MBS-6 conventional unit with an equivalent UV LED cassette unit that simply slots into its place.

The company’s stated position is this: printers planning investment in new technology may see themselves faced with a dilemma. If they go for conventional UV units and rely on the security provided by a long-established technology, they might miss their chance to make the most of UV LED. However, users who focus on this new technology too soon run the risk of paying dearly as they wait for the rest of the market to catch up.

Differences minimal?

GEW is another company that has been engaged in researching the potential of UV LEDs. According to MD, Malcolm Rae, at 25% to 30%, the percentage of electrical energy converted to UV radiation by an LED is actually very similar to that of an arc lamp. The total power requirement for an LED system is also similar to that of an arc lamp at around 100W/cm2, he maintains.

‘It’s true that LEDs are substantially more efficient than older UV systems, but the differences compared to modern arc lamp systems in operation are minimal,’ he continues. ‘The real energy advantage for LEDs is that they switch on and off instantly. This reduces the non-production energy consumption significantly and can make LEDs an attractive energy-saving alternative in environments with short production runs and high standby cycles.’

The second important consideration is lifetime cost. LED arrays potentially last over 20 000 hours – about seven to ten times longer than arc lamps, but it’s important to remember that a replacement LED array can cost around 15 times more equivalent lamps over the same period.

‘However,’ he concludes, ‘the costs of LED inks and curing systems are likely to come down and performance of both will increase further. Today LEDs are a more expensive alternative but if current trends continue, they will become an attractive proposition in the future.’

GEW latest version of its LED UV curing lab system, which incorporates the same curing module designed for full-scale production printing and coating applications, reflects actual production scenarios. Called the ‘Magic Carpet’ LED lab system, it simplifies the task of developing and testing new UV LED ink formulations. It has a maximum curing power of 18W/cm² and run speeds up to 100m/min.