UV LED curing is ideal for a wide range of packaging applications, enabling its users to print on a variety of packaging materials at high speeds. The intense output, low heat, and reduced energy usage of UV LED systems can enable printers to decrease material waste and operating costs while providing customers with superior product.

Phoseon Technology, based in Hillsboro, OR, USA, was founded in 2002, and is 100% devoted to the advancement of this relatively new technology. The company believes the use of UV LED curing in the label industry increases productivity, improves workplace safety and minimizes adverse environmental impacts, in comparison to existing alternative curing methods.

L&NW recently caught up with Sara Jennings, Phoseon’s customer program manager, who also serves as the company’s narrow web expert. Here, she shares with the label industry the answers to some potential questions converters may have regarding the adoption of UV LED technology.

L&NW: How compatible is UV LED curing with the specific requirements of the label printing industry?

Sara Jennings: UV LED light sources are ideal for high-speed curing in narrow web presses and other forms of label printing. Users of UV LED curing systems can process a variety of materials – including thin and heat-sensitive substrates – at maximum production speeds with low-input power.  UV LED technology drastically reduces energy consumption and the surface temperature of the items being decorated.
Because of the wavelengths at which they operate, LED light sources provide excellent through-cure that improves adhesion. The light sources deliver high uniformity and consistency over time, giving the end user confidence in the quality of the process. Now that UV LED curing has gained worldwide acceptance, more and more users are recognizing the real-world benefits.

L&NW: What effect does UV LED curing have on press performance?

SJ:  Presses with UV LED perform at 20-30% faster speeds on average. And with shop floor space valuable, UV LED light sources can be used to build more compact printers, with shorter web paths that minimize waste. Compact printing devices for product decorating can be used in a wider range of printing environments.

L&NW: Can you describe the comparison between UV LED curing versus existing alternatives?

SJ:  Users report that UV LED curing light sources produce better cures and better adhesion on a wide range of materials, including recycled materials. They can also achieve higher speeds with black and white inks. Tough opaque whites and dense blacks are much easier to cure. UV Metallic range inks are stable and print well. UV Adhesives for lamination and PSA, as well as for cold foil perform well. Inks do not cure prematurely in the press when exposed to overhead lighting.

L&NW: Are there energy savings UV LED adopters can enjoy?

SJ:  Users can save up 50% or more on energy bills. Energy cost savings can be substantial, particularly if energy costs continue to rise.

L&NW: Phoseon touts UV LED as a low maintenance curing method. Can you elaborate?

SJ: UV LED curing units have been proven to support trouble-free press operation. There is no warm up time required and less down time due to the instant on/off of UV LED. The technology also offers higher consistent yields and reduced waste compared to traditional UV curing – there are no reflectors to clean or shutters to replace. With no moving parts, the maintenance is minimal.

L&NW: Can you discuss the heat output of UV LED curing units?

SJ: Because UV LED light sources do not radiate infrared waves, they produce significantly less heat than arc lamps – for example 60° vs. 350°.  As a result, chill rolls or plates aren’t required when printing on heat-sensitive or thin substrates. UV LED offers the ability to run unsupported and shrink films due to the low heat.  Less operating heat also prevents material distortion, making it easier to rewind and re-register colors. And because of the uniformity and long-term consistency of LED lights, designers can develop safer, more stable and more reliable processes for low-migration printing. UV LEDs last more than 20,000 hours of operation, with only a minimal drop-off in power over the life of the curing unit.

L&NW: How does UV LED contribute to improving workplace safety?

SJ:UV LEDs contribute to workplace safety because they don’t generate dangerous UV-C radiation, excessive heat or noise. In addition, the 395nm wavelength UV-A light is not harmful to the eyes. Besides being mercury-free, UV LED light sources generate no ozone, and about 50% lower CO2 emissions. Studies have shown that in certain applications, replacing mercury lamps with UV LED light sources can lead to 25 tons of CO2  reduction.The rising tide of government regulations is causing all types and sizes of manufacturing firms to be more proactive in adopting safer, less toxic equipment and processes. This is where UV LED curing can really be a plus. Companies that have already installed more environmentally sustainable printing processes report that it has helped them attract younger workers and also customers that prefer eco-friendly processes.

L&NW: How does UV LED rate with regard to substrate compatibility?

SJ: UV LED opens the door to a wider variety of substrates and new applications, enabling end users to print on a wide range of packaging materials at high speeds. Some substrates and applications that have been validated by UV LED include 0.75 to 2 mil BOPP, 64% PVC shrink film, semi-gloss, 1.4 mil polypropylene, 2 mil polystyrene, direct thermal paper and metalized pouch material.

L&NW: What advice would you give to a label converter interested in exploring UV LED technology?

SJ: UV LED curing offers many benefits to converters that make it an appealing option for any size operation. Although there is an expense associated with upgrading to UV LED equipment, the return on investment can be quite fast due to the overall cost savings and operating benefits. If you are uncertain how to get started with UV LED, here are some options:

The first option for integrating UV LED is to ask your OEM (Original Equipment Manufacturer) for a new press equipped with UV LED capability. Most press manufacturers today offer UV LED curing capability if you ask for it.

If buying a new press is not feasible, or you are looking to add new capability to your existing equipment, the second option would be to upgrade one or two of your press stations to start, and see how the technology performs. For example, if you have a six station press, you could upgrade station one and station six for a first down white and dense black. 

To make this upgrade possible, the  printer would need two LED light sources, a modular system to support the light sources equipped with cables and brackets to connect it to the press.  Another consideration is make sure to select an ink that has been formulated for UV LED.  Some inks formulated for UV LED technology are also backwards compatible with traditional UV.  One should check with the ink supplier to confirm.

If everything goes well with the station one and station six, you can also try the UV LED on different stations for a variety of job setups.  You can move the stations around as you see fit and test the curing quality.

The next option would be to upgrade the entire press to UV LED technology.  In order to do this, the entire press would need to reconfigure the modular system to support the number of light sources on the press. It is important to make sure the power and cooling systems are set up to support the extra light sources. 
              
L&NW: Have there been developments in ink formulatations for UV LED?

SJ: Ink formulation for LED technology has evolved significantly, and today, there are a growing number of suppliers developing inks that work well with LED technology.  As the technology has become more powerful and more compatible inks are available, this has resulted in substantial advanced capabilities for UV printing. Material suppliers have responded to the demand and challenge from the printing world to formulate raw materials that absorb energy corresponding to the wavelength of UV LED light sources.

One of the key ingredients in the chemical formulation is a photoinitiator that serves as a catalyst to initiate the polymerization process when exposed to narrow spectrum UV LED energy.

With the continued widespread acceptance of UV LED systems, availability of suitable base materials continue to grow. The driving factors in advancement of chemistry of raw materials are increased capability and cost effectiveness of commercially available UV LED light sources.

L&NW: With regard to food packaging, how does UV LED fit into the low migration requirements of this sector of the market?

SJ: UV LED curing continues to grow at a rapid pace, with broad usage across digital inkjet printing, adhesives and coatings. As it moves further into the more traditional printing processes of flexographic and screen printing, the UV LED ecosystem is creating low migration processes that will enable food packaging to become the next major market to realize UV LED curing benefits.

The market has seen a steady increase in demand for low migration energy cure systems across all print processes. The growth will be driven by regulations of the printers and brand users – and consumers. Most low migration inks are specifically formulated for traditional mercury based lamps, but as UV LED curing technology goes mainstream, there has been more talk about low migration inks formulated for LED.

UV LED technology benefits in conjunction with low migration printing processes make for an ideal application. LED offers excellent through-cure due to the narrow LED wavelength (UVA). It offers more than 20,000 hours of operation with only minimal power drop over time. This process stability is very important to product manufacturers as they can ensure their products are cured consistently run after run without having to worry about bulb degradation. Additionally, UV LED technology provides a uniform output across the print width which again ensures a fully-cured product.




Constantia Flexibles adopts UV LED technology
Constantia Flexibles has announced the inception of LED UV technology at its facility in Mason, OH, USA. Flint Group Narrow Web and Phoseon Technology have worked with the company since 2014 to implement the technology in its Spear printing presses.

The initial discussion revolved around the various ecological and economical advantages available when running LED UV lamps and inks. The Spear plant was interested in the possibility of increased run speed, improved performance and the reduced energy consumption as compared to a conventional mercury system.

Constantia Flexibles decided to retrofit existing presses with UV LED lamps. “For us, the initial investment into LED started with a challenge; screen ink curing is the limiting factor when it comes to speed,” explains Bob Feldman of Spear. “We wanted Flint Group to help drive our costs down and the biggest obstacle was run speed. Flint Group came in with an Uptime Solutions program aligned to our Lean Six Sigma. Using both, we initiated a challenge to test the limits of our press. Over the course of one week, a 12-person team performed 48 different trials with six inks, two curing systems and two workflows in two press conditions. Performance indicators were defined and measured carefully.”

The Mason plant experienced over 50% run speed improvements with UV flexo and screen inks. In addition, the LED UV system used 25% of the power that a conventional mercury system used.

“What really excited us was speed improvement,” adds Feldman. “With LED UV curing, we were able to increase our speeds by 50% of our baseline, and that was just the initial result. Operating temperatures were lower than with mercury curing equivalents. And, there were no cure issues and no discernable performance differences with ink coverage and mileage.”

The lamps chosen for the Spear plant are Phoseon Technology Firepower LED lamps and the LED UV inks by Flint Group Narrow Web are under the brand name of EkoCure.

“Flint Group and Phoseon would like to thank Constantia Flexibles for the opportunity to perform extended tests with LED UV,” says Guillaume Clement, vice president, Global Narrow Web. “This testing helps both companies, and the industry, see the true possibilities that can be achieved with new technology. Innovation, which delivers sustainable economical advantages for our customers, is our mission. It is greatly appreciated to have a partner like Spear, who is willing to push the technological boundaries of success.”