UV Curing Technology

By Catherine Diamond, Associate Editor | July 10, 2012

Thanks in part to a rise in eco-friendly manufacturing processes, UV curing technology has steadily grown in popularity.

The ultraviolet curing of inks and coatings has seen a steady, healthy growth in the narrow web segment of the packaging market. As converters make strides towards more eco-friendly practices, UV curing offers many benefits that other methods don’t, including the reduction or elimination of environmentally harmful chemicals, reduced cleanup times and high-gloss capabilities.

According to Dave Snyder, southern regional sales manager for American Ultraviolet Company, Lebanon, IL, USA, the UV curing market has grown considerably since 2009. “Global use of UV inks and coatings has increased annually at a rate of 8-10%, and all predictions are that it will continue to do so,” he says. “In addition to the benefits that UV can offer the printer, the tightening of environmental emissions, elimination of hazardous chemicals, and regulatory laws will continue to move companies towards UV printing. Companies used to move from state-to-state to avoid the regulatory restrictions, but there are less and less places now to move as the laws are being implemented most everywhere.”

Benefits and challenges
Jim Brewer, president of Brewer UV Systems, Riverside, CA, USA, has been in this business a long time. “I’m one of a handful of people that helped start this industry 40 years ago, and one of two people – that I know of – who is still working in it since then,” he says. Brewer has stayed in the industry so long because, well, he believes in it. “There are serious cost advantages of UV coatings, because UV is ½ to 1/3 the cost of most mylar laminates,” he says. “UV inks and coatings can be used on lighter, lower-cost paperstocks, which means lower postal rates for customers. The paper remains stronger and is not dehydrated or blistered, with shrinkage eliminated.

The benefits of UV LED curing

“UV inks and coatings provide lower cost wash-ups, and the presses running UV inks and coatings can be shut down for weeks and provide acceptable prints when restarted,” he adds. “Presses in daily use will not require full wash-ups for months at a time when running the same colors or coatings. Fewer personnel is required due to ease of drying and less paperstock movement and handling. Less maintenance is required as UV system maintenance is usually restricted to lamp and reflector replacement,” Brewer says.

Jeff Bade, sales manager at Baldwin Technology, the parent company of Primarc, a UV curing company based in Slough, Berkshire, UK, emphasizes the customization options when discussing the benefits of UV curing. “Generally, benefits are associated with the application and specific business involved,” he says. “For example, aqueous (water-based) formulas may not be the best product for the industrial markets, like wood finishing, electronics printing and metals finishing. Similarly, aqueous formulas do not work well in digital inkjet equipment because their evaporation rates can cause clogging within the print heads. UV formulas typically work well in these areas for they have low to no evaporation rate, nor reaction with metallic or wood surfaces.  Aqueous formulas work very well for interior applications like point-of-purchase and sign/display uses.”

Bade also emphasizes the that when it comes to cost, it’s critical to take into account other parts of the converting process. He says, “Economically, the overall cost of using aqueous inks may be higher than UV. For example, aqueous inks – whether they be made with dye or pigments – typically require a coated media for printing. UV formulas are more easily printed on non-coated and plastic materials. Similarly, depending on a company’s process steps, thermal drying equipment typically covers a larger footprint within a plant and energy costs can be twice as much for the same printed product.”

Snyder, of American Ultraviolet, points out that one challenge of the UV market can be retrofitting older presses. “Physical space can many times be challenging, especially on older presses that were not designed for UV equipment,” he says. “So, too, can educating end users on the benefits of UV versus waterborne and solvent systems, along with the capital equipment investment and their return-on-investment.”

The LED trend
Much like traditional UV curing methods, UV LED curing has seen tremendous growth. Stacy Volk, marketing and communication specialist at Phoseon Technology in Hillsboro, OR, USA, says, “The UV LED curing market has grown 50%+ per year since 2009, with the majority of the growth being in international markets.”

Bade, of Baldwin Technology, says that LED technology has not had the power required to cure UV materials – until recently. “As their power and efficiency have improved, we see them being used in more processes, such as digital flatbed applications,” he says. “In the world of graphic arts, LEDs are diverging into two segments: low-power, air-cooled systems and high-power, water-cooled systems.  The low-power systems are typically fitted to the inkjet scanning applications and the high-power systems are slowly finding their way into traditional high speed printing equipment. Apart from cost, current growth of LED use is constricted by the availability of materials that can be cured by the singular wavelengths produced by them.

“In the interim, several companies have developed several new styles of additive arc lamps which enhance the efficiency of their curing lamps while using traditional design. These lamps fill the gap between the traditional designs and the more efficient but currently under-powered LED,” Bade says.

Dave Lyus, marketing manager at GEW (EC) Ltd., Crawley, UK, says that arc lamps are indeed still the standard for flexographic printing. “There are niche applications for LED technology that are showing strong growth. However, in the flexographic printing industry, where a consistent output of high-power UV needs to be delivered cost-effectively, arc lamps remain the solution of choice due to LED’s high total cost of ownership, limited ink choices and low production speeds,” he says. “A key challenge in UV curing is for printers to find a cost-effective way of ensuring that all inks are fully and safely cured, so that they can profitably deliver products of a consistently high quality to their customers. The future for printers in the flexo industry is a UV solution that can achieve this,” Lyus says.

According to Jim Lambert, digital division vice president and general manager of INX International Ink Company, a Schaumburg, IL, USA-based supplier of ink and coating products, the inks used in UV LED curing have evolved over more than a decade, which is contributing to the process’s overall popularity.

“The inks employed today are extremely well-defined and tuned to the narrow band or wavelength of light emitted by UV LEDs. Combined with recent improvements in UV LED energy output and efficiency, this means that we can now achieve better cures at much higher rates of speed. As more UV LED printing systems penetrate the market, end users are becoming more comfortable with the technology and are starting to understand where UV LEDs fit and where improvements still need to be made.  As a result, UV LED curing is rapidly gaining acceptance in single pass, multi-color inkjet applications where presses like our NW140 are targeted.”

Snyder, of American Ultraviolet Company, points out that inkjet applications have quickly adapted UV inks and coatings, and that inkjet systems provide for on-demand short run label printing with fast turnaround and little or no inventory. He also emphasizes how linerless labeling is on the rise. “The use of linerless labels is a growing market also, and uses UV inks and UV curable silicone, which eliminates the need for a release liner. This can save costs.

“There is definitely a trend toward electronic digital printing, though often the inks involved are UV inks. Therefore, small short run workhorse presses have almost disappeared from the market because of the immergence of digital printing for shorter run applications. Often lower cost digital printers do not have the ability to coat or laminate their printed product,” Snyder says.

Like so many other processes in this industry, Volk of Phoseon Technology points out that communication between the people who build, install and operate equipment is essential – otherwise, the technology may not be utilized to its full potential. She says, “UV LED curing requires a systems approach with the machine builder, curing supplier, and ink supplier working together to ensure the end customer is provided with an optimized system.”

In spite of the considerable cost of UV curing systems and the sometimes-difficult task of retrofitting them to older printing presses, the industry as a whole shows no signs of slowing down. Driven by environmental regulations as much as customer satisfaction, this technology is likely to be an integral part of the converting process for years to come.

“The use of UV curable chemistries offer printers a very favorable value proposition, and therefore will continue to grow in all printing markets, replacing waterborne and solvent systems, and becoming the dominant chemistry system,” says Snyder of American Ultraviolet Company.

Bade, of Baldwin Technology, points out that domestic growth rates for food packaging and inkjet printing are between 10-15% over the next few years, which is reason enough to expect UV curing to have a strong future. Bade says that while label growth in the US and Canada is projected to be a more modest 2.5-4%, export opportunities exist in Mexico and Latin America to the tune of 10-15%. “Elsewhere in the world, label growth in China, Mexico, Brazil, India and Africa are projected to be 10-25%. UV technology is commonly used in the label and packaging industries, hence I see a strong future,” he says.

Bade adds that the future of not only UV, but also UV LED technology is strong. “LED technology offers a long term solution to the limits of traditional arc technology.  As a result, there are now two UV solutions for the UV curing market,” he says.

What’s new in UV

Here are some of the latest UV curing products for the label industry.

PHOSEON Technology
Phoseon Technology has introduced the highest-powered member of its air-cooled product line, the FireJet FJ200 series. These 8 W/cm2 products are designed for the coating and digital inkjet markets where rock-solid reliability and simple integration are key requirements. The FireJet FJ200 UV LED lamp scales simply by placing a second unit next to the original. Phoseon’s optics ensure consistent uniformity at the substrate surface. The FJ200 is simple to integrate by being a fully self-contained unit, not requiring external control boxes, and scaled systems are simply daisy-chained together. Additionally, the unit can be controlled via RS485 or PLC signals to provide for instant on-off and intensity control from 10-100%.

The FireJet FJ200 series is the highest-powered member
of Phoseon’s air-cooled product line.
The new FireEdge FE200 UV LED pinning lamps specifically addresses the rapidly growing inkjet market by matching the length of today’s most popular inkjet print head dimensions. This product is a fundamentally new design based on customer input from around the world to enable higher quality at higher speeds. The FE200 top air intake and exhaust eliminate inkjet print head interference and the units can be scaled to meet a variety of print width applications. The optional patent-pending Angle Reduction Technology reduces the angular spread of UV light by up to 67% with no loss of power, minimizing the risk of reflected light curing ink in the nozzles.

The FirePower products are high performance water-cooled LED curing lamps offering either 12W/cm² or 16W/cm² peak irradiance and come in standard various widths.  The 225mm wide product is ideal for 10" flexographic web presses. In addition, the products can be scaled to offer wider products to fit 13", 17", 22" or even wider presses. The long-term goal for the narrow web flexographic press builders is to improve their customers’ productivity, efficiency and revenue generating potential.  The company says that working with leading printing press and ink manufacturers in the flexographic market has enabled it to build rugged products that provide superior performance and allow for easy integration into flexographic presses.

Brewer UV Systems, which has offered its customers a range of UV curing products for 40 years, now offers super compact shuttered lamp housing, which features a shutter design that enables the reflector insert panels to be changed without taking the lamp housing apart. No other lamp housing ever produced has this feature, the company says. The F Series lamp housing is designed to fit into the smallest press applications with reliable, durable shutter actuation that Brewer UV Systems is known for. Brewer also offers the fourth generation “R” series and the special heavy-duty fourth generation RH series lamp housing assemblies.

“We still custom design and build equipment to order for each press application,” says Jim Brewer, president. “We offer UV coating applicators for digitally printed web and sheetfed applications. New UV arc lamps and reflectors are available for any brand or type of UV system.”

UV curing systems manufacturer GEW launched a range of new UV systems designed to reduce running costs and extend the production capabilities of both analog and digital printing and coating machinery at this year’s drupa. Focusing on the needs of web and sheet-fed media converters alike, GEW’s multi-substrate curing platforms enable the widest range of heat-sensitive materials to be processed without risking job scrappage due to heat damage. In addition, profitability is increased as significantly less electrical power is required to run the UV while energy is efficiently converted to UV, ensuring production output is maximized.

For low-migration inks and specialized coatings, GEW also launched an economical inert atmosphere curing solution that uses around 35% less nitrogen gas than conventional solutions.  One of these new systems was installed on a 2.3 meter wide converting line in Belgium last year, while an inline printing press in the US was also equipped with a straight-through web path solution, enabling silicone release coatings to be produced without the chill rollers that are usually needed.

A priority for GEW has been to reduce its customers’ total cost of operation to a minimum by providing equipment that is inexpensive to maintain, as well as to run. The company says energy used to be the main variable in the equation of cost reduction with potential savings easily negated by excessively priced consumable parts and time-consuming replacement procedures. GEW claims to offer the lowest cost OEM consumable parts on the market and its quick-change lamps are replaced safely in under two minutes, with no special tools required.

INX international
INX International Ink Company offers its customers the NW140 digital press. It delivers single

The INX NW140 digital press uses two types of UV LED
pass printing and brilliant color at speeds up to 80 feet per minute on any label stock. It uses two different types of UV LED technology: the first is a cost-effective pinning technology that delivers a low dose of UV energy to freeze or stabilize the dot immediately after jetting. This is done to limit dot gain and improve the overall image quality of the label. The second LED source provides a much higher intensity and a much higher UV dose, both of which are necessary to fully cure the ink from the surface through to the substrate.

Pinning is a cost effective and elegant method of improving inkjet image quality. It is integral to the printing process as the compact LED arrays are positioned in between the closely mounted inkjet print heads; whereas, the larger and more powerful final cure UV LED array is located separately after the print zone. All of the inks are tuned to the same particular wavelength of light, which is emitted by both the pinning and final cure LED arrays.

Rainbow Technology Systems
The Panda Coater unit from Rainbow Technology Systems, Glascow, Scotland, has been designed to offer high performance coating for sheet and reel-to-reel materials. The device has multiple applications from the electronics sector to digital graphics and other in-line coating applications. The unit offers many advantages over conventional methods of coating. Its patented Smart Coating Dispenser system ensures that only the optimal amount of coating fluid is used to coat the material. Coventional “roller in bath” systems can be extremely wasteful, expensive to run and messy.

A thin, transparent, scratch and chemically resistant coating is applied to the substrate. It then passes through the integrated, controlled-environment UV curing tunnel and is ready for immediate use. Both thick and thin caliber materials can be processed and the unit automatically senses the exact size of the sheet so only that area is coated.

At the front end of the unit is a Teknek contact cleaning unit which ensures the material is completely free of any contamination (particles down to one micron) before being processed. Other key features of the Panda Unit include: small footprint (1m x 1.2m); it accommodates material widths up to 660mm; easy access for maintenance and cleaning; rapid startup and low energy consumption; a small fluid reservoir (5 liters) means easier and cleaner maintenance; the unit sits on  a custom-built stand with storage and leveling facilities; and clean-room compatible paint finish.

IST metz
IST Metz, Nürtingen, Germany, recently launched the MBS-6 UV system. The MBS-6 requires a lamp output of just 120 W/cm in order to achieve the same drying results as standard UV units, which require up to 200 W/cm. This has primarily been achieved through the optimization of individual components such as reflectors, lamps and electronic components, all of which are coordinated with each other and which have been developed and manufactured in-house.

IST Metz’s MBS-6 UV system features new reflector
The MBS-6 system also features a new reflector system that uses the company’s URS Duo technology. A combination of special URS and URS-A reflectors allow for a considerably higher degree of reflection. Furthermore, raytracing technology has been used to change the geometry of the reflectors to facilitate their use in label printing. In contrast to conventional reflectors, the URS series from IST METZ comprises what are known as cold light reflectors, which have more than 60 different metallic oxide layers. They ensure that the infrared radiation is conducted via the coating directly to the air-cooled aluminum profile. Thanks to the specially designed rotary reflector, the MBS-6 system features a compact design and can therefore be easily integrated into label printing machines. In addition, the dryer is easily accessible at all times for any maintenance work. The standard features of the MBS-6 UV system with the ELC electronic power supply device offer further potential for saving energy. The system’s intelligent electronics allow for a smooth, step-less dimming of the UV lamp and a clever, compact ELC stacking concept allows space requirements to be reduced by up to 50%.

The MBS-6 system has been classified as being particularly energy efficient by the Professional Association for Printing and Paper Processing (BG ETEM) and may now display the “energy-minimized UV printing” label. Also, as the first system of its class, it has received the DGUV Test Seal of Approval (German statutory accident insurance, formerly BG Mark), a legally regulated and internationally recognized symbol for product safety.
  • Dscoop Post-Show Report

    Dscoop Post-Show Report

    Greg Hrinya, Associate Editor||April 7, 2017
    “Imagine” was the theme for the annual gathering of users of HP Indigo digital print technology.

  • Materials Handling

    Materials Handling

    Steve Katz, Editor||April 7, 2017
    Working without these products may cause employee injury, damaged goods and lost revenue.

  • Adhesives Update

    Adhesives Update

    Greg Hrinya, Associate Editor||April 7, 2017
    Label adhesives must meet a variety of performance and manufacturing requirements.