Sunday, 26 Sep 2021 20:11 GMT

Drying Technology

Fast turnarounds, substrate versatility and environmental benefits are just some of the pros of using UV curing technology.Carys Evans looks at the latest solutions in this area

The magic cure

Curing with UV technologies offers many benefits, from the low temperature used, the high speed of the process and the lack of harmful solvents. As well as speeding up the production process, this technology also helps with higher quality of print as dust and other airborne items don’t have as much time to settle on the substrate.
Printing with UV curable inks also provides printers with the option to print on a wide range of substrates including plastic, paper, canvas, glass, metal, foam and other materials – broadening the services you can offer.

The good news is that, while it is certainly an option, there is no need to go out and buy a brand-new LED-UV printer if you don’t already want to. LED-UV and traditional UV curing units can be retrofitted to most existing presses.

So, what are the latest solutions in UV drying systems and what impact can these have on the production process?

All guns blazing

Phoseon has been offering high powered air-cooled or water-cooled LED systems which can be fitted to narrow web flexo presses for the last 12 years.

For Alan Mills, regional sales manager for UK, Ireland and Scandinavia at Phoseon, some of the benefits of such systems are increased machine speed, improved reliability and reduced power consumption.

Phoseon’s latest solutions in UV drying technologies are UVC short wave systems and ultra-high dose systems – both of which Mills describes as great for high build varnishes.

In addition to this, some other benefits include improved efficiency with faster jobs achieving 20-30% higher speeds. According to Mills, these speeds are possible due to better through cure with opaque white and black inks. “Normally curing with mercury is a speed limiting factor on unsupported web such as shrink sleeve and lamitube, and supported web with rotoscreen and heavy blacks, darks and whites,” he explains.

The new systems also promise to deliver better quality with stronger adhesion. Printers have the ability to start and stop the machine instantly, allowing for quicker job changes. There are also environmental benefits such as a power reduction of 80% and no power consumption when the machine is on stand-by. There is less waste produced too due to better through cure.
The PrintFlood entry-level 1000PRO can run B3 format

In terms of where UV drying technology is headed, Mills says: “Our LED systems will have advanced features that will further improve process control which is important when running low migration inks for food-safe applications. This will be linked to the ’internet of things’ for customers’ peace of mind.”

Providing a cure

IST-UV offers a comprehensive range of LED UV curing systems for a number of applications. One option is the newly developed LEDcure for sheetfed printing. LEDcure allows printers to achieve maximum speeds on sheetfed presses. The system comes in a compact design to allow for flexibility and versatility and is freely scalable in length to adapt to any machine format and installation need.

The new LEDcure completes IST’s entire redesigned LED solution range which comes with its subsidiary Integration Technology (ITL). According to IST, the system offers high quality from the usual distance of 50mm to 100mm from the substrate. This is due to the wide irradiation field of the LEDcure.

Another system available for label printing is the new generation of IST’s MBS product series, the MBS LEDcure. Ready for operation as soon as it is switched on, the system also provides environmental benefits by switching off during machine downtime. Another feature is that both the exhaust air quantity and air flow for cooling the MBS unit have been optimised to reduce the contamination of the lamp and reflector of the LEDs, meaning cleaning is kept to a minimum, and as a result so is downtime.

One size doesn’t fit all

Benford UV has been in the UV curing business for over 30 years through manufacturing and installing UV and IR (infrared) systems onto sheet-fed, web and metal presses.

Enca Plaza, sales manager at Benford UV describes the latest solutions in UV drying solutions: “In 2019 we launched a new product called MAC2. MAC2 is the result of improving the design for UV conventional mercury lamps by adding a quartz heat barrier that helps avoid distortions while printing on heat sensitive substrates.
“We have also focused our resources to improve our range of LED products for sheetfed, web and narrow web machines.”

Plaza raises the point that different customers decide to invest in UV equipment for different reasons. However, she lists high value special printing effects such as glossy varnish or sharp colours, and no marking and consistent print quality as two benefits.

“LED UV is a new technology that was developed with the intention to reduce the power consumption of a conventional UV system,” she says.

Despite this, Plaza mentions a couple of limitations and setbacks currently facing this technology such as the price of LED inks, problems trying to dry jobs on non-adherent substrates such as plastics or even finding suitable coatings for this technology.

She elaborates: “LED coatings are very expensive. LED technology is not powerful enough to dry a thick layer of varnish and LED UV coatings tend to go yellow due to the amount of photo initiator added to them.”

That being said, Mills notes that LED ink prices are beginning to drop down to meet the level of UV inks. He says: “You can now get inks which run on both arc lamps and LED so the convertor doesn’t need to have two different inks on the shop floor.”

O Factoid: UV curing was invented in the 1960s, but is still believed to be only just reaching its full potential  O

For Plaza, the company has found by experience that every technology presents different advantages and disadvantages. She adds: “The key factor here is to assess the customer’s printing needs and provide them with the right UV technology for the right application.”

West Midlands-based label printer, Aztec Labels, has recently invested in its first Benford UV drying system on a two-colour press. Colin Le Gresley, managing director of Aztec says it was Benford’s development of new UV drying technology over the past five years that meant there were solutions that benefitted the company’s narrow web printing.

Aztec Labels recently invested in its first Benford UV curing system

Le Gresley says: “The LED system requires no lengthy warm-up, which increases our throughput. The system produces very little heat, while the energy output also adjusts automatically to the press speed to ensure perfectly cured inks. This helps us avoid web distortion and also improve consistency in the finished print.

“The elimination of distorted and improved consistency reduces waste and the need for re-runs, which when coupled with low operating costs delivers obvious efficiency gains.”

He adds: “And perhaps most importantly, the technology is entirely in line with our business sustainability objectives. Not only is the machine produced in a facility that, like our own, runs on solar power, but the LED UV system actually uses up to 35% less power than standard dryers, and is entirely ozone and mercury free.”

A greener solution

As well as being used in ink production, UV curing can also be utilised for print finishing. Duplo has recently become the sole distributor of a new range of UV aqueous and soft touch flood coaters which are designed to enhance print.

The Ultra PrintFlood range of coaters includes the entry-level 1000PRO able to run B3 format, and the 200PRO and 300A, both of which offer B2 format short edge feeding. The latest addition to the range is the Ultra 1000A which can run B2+ format long edge feeding.

According to Rob Thurston, Duplo’s new national sales manager, something that makes the range unique is an auto-gap feature. He says: “Our auto-gap feature on the Ultra range of coaters is something that is unique to us and not features, even on the much larger and expensive coaters available on the market.

“The auto-gap will guarantee that the top ‘application’ and the bottom ‘pressure roller’ will never be in contact with each other, preventing smearing on the reverse of the sheet.” This is a common issue in coating which is traditionally addressed using scraper blades to remove excess coating.

Réginald de Ghellinck, managing director of Mark Hunting – the company which owns the Ultra brand – says: “For many digital printers, lamination has historically been the standard way to enhance and protect digitally printed substrates. In comparison, UV and aqueous coating has been very common in the conventional offset market. With the evolution of digital printing, new types of varnish have now been manufactured making UV and aqueous more accessible and easier to use.”

According to Ghellinck, a shift away from lamination towards UV and aqueous coating has begun which he puts down to the Ultra range being 30% cheaper to run as well as the reduction of plastic. The Ultra range contains fully recyclable substrates and there is no need for stocks of different films sizes and thickness and no need to trim.
That being said, Thurston says there will always be a place for lamination in the finishing processes. “Some products are either not economical or viable to go down the route of either UV or aqueous coating,” he says, adding: “Lamination will always be the more practical choice for a small printer who doesn’t need to do much coated work.

“The cost of a small-format laminator is much lower than that of traditional UV coaters, but much slower and more steps in the finishing process are needed. However, due to the recent war on plastics, printers will need to start proposing alternatives to their customers.”

The first installation took place in Holland in May at a digital print firm using a HP12000 press. The firm wanted to move into aqueous coating so decided to try out the PrintFlood 300A. Through doing so, they realised that by investing in the PrintFlood 1000A, it could increase its production by 25% by turning the sheets 90° using B2+ portrait instead of landscape.

An unsurprising milestone

Highlighting the ongoing demand for UV curing systems, UV curing technology manufacturer, GEW, has celebrated an installation milestone. Two months after the manufacturer celebrated its 30th anniversary, it reported its 20,000th GEW UV curing system installation.

Installed in the Czech Republic, the system is 35cm-wide and features a four-lamp configuration of GEW’s GD3 lampheads, and was retrofitted to a Gallus Labelfire 340 press.

FlexON’s label printing facility in Vestec is the company that received the 20,000th order. The firm produces self-adhesive label and flexible packaging products for cleaning, hygiene, food and beverage brands.

To celebrate the milestone, each UV lamphead has been anodised with a gold finish to the front.

Each of the GEW UV lampheads has been specially anodised with a gold finish to the front

Manufacturer of FlexON’s original press, Gallus Ferd, oversaw the integration of the new system with the technology pre-checked and automatically connected to GEW’s Remote Monitoring Service by GEW for a simpler installation.

Holger Frenzen, field installation manager at Gallus says: “The GEW GD3 system is the default UV solution for the Labelfire 340, so I have to say that the installation itself was nothing remarkable. We have installed so many similar GEW systems, the process is now fairly routine.

“The fact that this is GEW’s 20,000th system is what makes it special. The number is impressive but unsurprising, these UV systems are so widely used because of their build quality and reliability.”

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