UV LED light sources are ideal for high-speed curing in narrow-web presses, enabling end 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 has enabled end users to decrease material waste and operating costs while providing customers with superior product. 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 which improves adhesion. The light sources deliver high uniformity and consistency over time giving the end-user confidence in the quality of their process.

Now that UV LED curing has gained worldwide acceptance, more and more users are recognizing the real-world benefits.

Increased Revenue

Faster Throughput: Presses with UV LED perform at significantly faster speeds.

More Compact Designs: Floor space is valuable in all types of businesses. 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.

Better Cures: 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.

UV LED brings increased opacity, improved adhesion and faster press speeds for opaque whites:

Energy Consumption:  Users can save up 85% or more on energy bills.  Energy cost savings can be substantial, particularly since energy costs continue to rise.

Increased Productivity

More Uptime: 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.  UV LED 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.

No Bulb Replacements: Mercury bulb replacements are required every 1000 hours ($200 per bulb).
For one 8 stations flexographic press:

·       80 bulbs After 10,000 hours

·       160 bulbs after 20,000 hours

·       240 bulbs after 30,000 hours

Prevent Toxic Mercury Bulb Waste
(Video) https://www.youtube.com/watch?v=s28QhOeCRnE

Less Heat: Because UV LED light sources do not radiate infrared waves, they produce significantly less heat than arc lamps (e.g. 60° vs. 350°). 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.

Greater Stability: 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 60,000 hours of operation, with only a minimal drop-off in power over the life of the curing unit.

Applications

UV LED curing technology offers new capability for converters. It opens the door to a wider variety of substrates and new applications, enabling end users to print on a variety of labels and packaging materials at high speeds. 

Flexographic labels can be printed for beverage, household, medical, personal, promotional, and many other industrial markets.  UV LED curing can also be utilized for printing on flexible films, boxes, cartons, corrugated containers, and a wide variety of other packaging materials.

Decorative printing processes allow for ultra-high gloss, matte and holographic effects. “Cast and Cure” is a fast-growing technology that creates a holographic style decorative finish on a variety of substrates for sheet-fed and web applications. “Cold Foil” allows the decorative printing application of metallic foil, in line, at press speed in an infinite spectrum of colors. These effects can be created in a variety of label and narrow web environments.

Inks formulated for UV LED

Ink formulation for LED technology has evolved significantly, and today all the major suppliers offer inks compatible with LED technology.  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 continues 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.

Low Migration

UV LED technology benefits in conjunction with low migration printing processes makes for an ideal application. LED offers excellent through cure due to the narrow LED wavelength (UVA). It offers more than 60,000 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 fully cured product.

Conclusion

More and more users are choosing UV LED curing light sources for printing processes because they deliver advanced capabilities, improvements in operating economics, and environmental advantages. Over the past few years, a growing number of ink companies have been working hand-in-hand with printing equipment developers to develop ink formulations that that are optimized for both UV LED curing and the specific application.