Categories
Resources

Flint Group Narrow Web Introduces EkoCure® XS

Flint Group has globally launched EkoCure® XS – a UV LED ink series with the best adhesion and post shrink performance on shrink substrates, that is also dual-cure, and provides consistent cure at the highest printing speeds.

EkoCure® XS is specifically designed for the demands of shrink sleeve applications.  “We knew from interviews with clients specializing in the short run shrink sleeve market, that they want a UV dual-curable ink with better adhesion and increased curing speed to boost productivity and reduce yield losses” states Kelly Kolliopoulos, Global Marketing Director for Flint Group Narrow Web.  “Our experience in LED and conventional mercury curable ink system technology, combined with our understanding of the shrink market, enabled our R&D team to develop this best-in-class system.”  She concludes, “EkoCure® XS combines the latest ink chemistry including novel binders that provide perfect cure and sufficient flexibility of the cured ink allowing the adhesion to remain fool-proof – especially after post shrink processing is completed.  The full range of pantone shades and opaque white are available.”

“EkoCure® XS is the first Shrink Sleeve System that is dual-cure.  “Our scientists have developed a unique combination of photo-initiators and binders allowing the ink to cross link from top to bottom and therefore cure fully when exposed to the UV wavelengths from either Mercury or LED lamps” explains Dr. Paulo Vieira, Director of Research and Development, Narrow Web NA. “In depth tests comparing EkoCure® XS with existing UV curable inks on the market show that EkoCure® XS exhibits the best adhesion performance at the highest printing speeds when run using standard 355 W/inch mercury lamps.  This is in addition to having the best performance when compared to other LED curable products”

EkoCure™ XS inks enable converter productivity, yield and finished product quality:  Recognized as a pioneer in the Canadian market, Groupe Lelys is an early adopter of the EkoCure® XS ink series.  “We provide our customers with high quality sleeves and labels,  and impeccable service, and we needed a shrink sleeve ink series that would improve our production rates and meet our high quality standards,” said Mr. Aureo Azevedo, Groupe Lelys Procurement Leader.  “Overall adhesion and capacity release have been our biggest concerns.  EkoCure® XS by Flint Group Narrow Web eliminated our adhesion issues, and significantly increased the satisfaction of our customers.  Additionally, we are able to run at 15-20% faster press speeds now that we print with EkoCure® XS.  Our colors are brighter and our products are more appealing.  We anticipate the expansion of our business via the high quality shrink sleeves our customers expect from Groupe Lelys.”

EkoCure® XS is designed to be easy for any converter to adopt for the full range of shrink sleeve applications.

https://packagingeurope.com/flint-group-narrow-web-introduces-ekocure-xs/

Categories
Resources

LED the UV Technology for Future Applications

For a number of years, UV technology has been a reliable technique for the curing of photo-reactive chemicals. In response to increasing production speeds and new applications, for instance in the field of 3D, UV lamp technology has also developed. Presently, a significant range of different systems are available, each specific to the particular application.

Users and providers of chemistry are continually developing new applications for UV curing. Their groundbreaking ideas mostly mean increasing demand on UV curing devices – where at times conventional UV technology has touched its technical limits. Therefore, within the recent years, a totally new branch of UV technology has formed: UV LEDs. This article offers the reader with an objective comparison between both technologies, UV and UV LED. It should help the user determine to what degree LEDs can provide a substitute to conventional UV solutions.

The operating technology of conventional UV lamps is based on plasma physics and optics, while UV LEDs are based on optics and semiconductor technology.

LEDs are founded on semiconductor technology. Specific wavelengths are directly discharged by the current input. The spectrum is a quasi-monochromatic radiation in distinct wavelengths, for example 365 nm, 385 nm or 405 nm.

Categories
Resources

Phoseon Technology develops new solutions for UV LED curing

The company says it is 100% focused on LED technology and providing rugged, high-performance products.

When it comes to label and packaging solutions, Phoseon Technology has the (LED) cure. Phoseon’s UV LED (light emitting diodes) curing products are currently being utilized in the printing, coating and adhesive industries, and the technologies are available to clients in custom configurations.

According to Phoseon, the company is 100% focused on LED technology–providing rugged, high-performance products for application specific solutions. Phoseon’s patented Semiconductor Light Matrix (SLM) technology encapsulates LEDs, arrays, optics and thermal management to ensure curing performance. Each of these four components is a strictly engineered system that provides maximum UV energy and superior performance while also increasing long-term robustness for demanding applications.

While arc and microwave curing technologies rely on the vaporization of mercury within a sealed quartz tube containing an inert gas mixture, LEDs are solid-state semiconductors. They contain no moving parts or mercury plasma gas and operate at temperatures that are often less than 1/10 the operating temperatures of conventional lamps. When connected to a DC power source, an electric current flows through the semiconductors, dropping electrons into a state of lower energy as they travel from the negative to the positive side of each discrete LED. The energy differential is released from the device in the form of a relatively monochromatic spectral distribution.

Commercially, UV LED technology has significant market adoption with longer UVA wavelengths (365, 385, 395 and 405 nm), and development work in shorter UVB and UVC bands continues, says Phoseon.

Phoseon describes UV LED curing sources as “high-tech electronics,” so the technology has blossomed with that of smartphones, laptops, tablets and televisions. During the technological boom, which has occurred between 2010 and 2017, UV LED sources have become more powerful, more efficient, more reliable and less expensive.

“UV LED curing technology has arrived,” the company says. “It is no longer an emerging technology but an enabling technology− one that is bringing a host of advanced capabilities to screen printing, flexographic and digital printing. These advances and new capabilities are helping industrial, graphics and specialty printing operations be more productive, versatile and energy efficient.”

Categories
Resources

Why the UVA LED Curing Industry Needs Nanoceramic Thermal Management

By John Cafferkey, Marketing Manager, Cambridge Nanotherm

Over the past 30 years or so, UVA curing has revolutionised the way manufacturers have made products. UV’s ability to change a liquid to a solid has paved the way to widespread ink curing, adhesive bonding and coatings used in a large number of applications, like general consumer electronics, automotive, telecoms, graphic arts and more.

For decades UVA curing used high-intensity discharge (HID) UVA lamps. Only recently has the industry seen LED alternatives come to the fore. Compared to HID lamps, LED form factors are smaller and less fragile, while operationally they use less power, run cooler, and power cycle instantly when needed. These characteristics are improving the efficiency of the UV curing industry while opening up new curing techniques through hand-held devices — something that would not have been possible with HID lamps.

While LEDs run cooler than HIDs, they are still relatively inefficient. LEDs only convert around 40% of the power that goes into them as light, converting the remaining 60% as heat. This heat is a huge problem because if it can’t escape quickly enough, it can cause the quality of the UVA light to deteriorate or, worse, cause the LED to fail and/or shorten its lifecycle. And as designers today seek to pack more, and more powerful, UVA LEDs closer together on modules, this heat problem is only set to worsen.

Why heat is a problem for LEDs
LEDs cannot convect or radiate enough of the heat away from the source through the ambient air surrounding them because the surface area is too small and the temperature too low for this process to take place. The only way LEDs can shed excess heat is by conduction out of the back of the die, through the materials in the PCB, to a heatsink and the surrounding environment.

Therefore, the substrate material that the PCB uses needs to a high level of thermal efficiency. With UVA applications, the module substrate tends to be either a thermally effective metal-clad PCB (MCPCB) or electronics-grade ceramics like aluminium nitride (AlN). In higher-power density applications, epoxy-based MCPCBs do not have the requisite thermal performance (<100W/mK vs 170W/mK for AlN), making AlN the substrate of choice where heat is a significant issue.

However, AlN isn’t perfect. First, the material itself is expensive. Secondly its characteristics can pose problems for manufacturers — AlN is inherently brittle, making it difficult to manufacturer into circuits. That brittleness restricts the tile size to just 4×4-inches (occasionally 7×5-inch). Any larger and the brittleness begins to wreck the yield rate. Even with 4×4-inch tiles, a yield loss of 20% is not uncommon.

The other issue with brittleness is when mounting the finished module onto its heatsink. Ideally, the circuit should be attached as firmly as possible to reduce any air gaps between the circuit and the heatsink. But screwing a brittle AlN module to a heatsink is likely to fracture it if too much pressure is applied.

Now, however, there exists an alternative material that offers a comparative thermal performance to AlN without the issues around manufacturing. That alternative is nanoceramics.

Nanoceramics — a better choice than AlN
LED thermal management innovator Cambridge Nanotherm has devised a way to produce nanoceramics specifically for the UV curing industry. The secret is in the process. Using a patented electro-chemical oxidation (ECO) process, Cambridge Nanotherm converts the surface of an aluminium board into thin layer of alumina (Al2O3) just tens of microns thick. This alumina layer performs the dielectric function, insulating the circuits from the aluminium below, while conducting excess heat through the back of the LED quickly. And while alumina is far less thermally conductive than AlN the sheer thinness of the layer more than cancels that issue out, removing heat efficiently.

After the ECO process, Cambridge Nanotherm sputters the copper circuit layer directly to the nanoceramic dielectric via thin-film processing, further improving the thermal efficiency of the stack. Nanotherm DMS (a direct replacement for AlN for UV modules) has a composite thermal performance of 152W/mK, slightly lower then high-grade AlN but more than enough to cope with all but the most demanding UVA applications.

In terms of manufacturability, nanoceramics can be treated in the same way as a standard MCPCB. Because it’s less brittle, there’s less loss of yield, and the product can be screw-mounted to a heatsink without breaking. In short, nanoceramics offer the best of both worlds — the thermal performance of AlN and the robust characteristics of an aluminium MCPCB.

LED technology is having a profound impact on the UVA industry, and has seen costs drop and efficiencies increase. However, heat remains a central issue with LEDs, and a challenge that needs addressing if the curing industry is to see further cost and efficiency benefits.

Categories
Resources

Photoinitiator Selection for LED-Cured Coatings

LED sources are rapidly gaining in popularity in the UV-cured coatings market as they offer reduced cost, longer life and environmentally-friendly alternatives to conventional lamps. Transitioning to UV LED, however, often requires more than just a simple equipment change. Modifications to the chemistry also might be needed to effectively compensate for the lower energy levels and narrower wavelength range. This is particularly true in coatings applications, where oxygen inhibition can have a detrimental effect on cure properties. In this paper, we will examine how proper photoinitiator selection and concentration can be used to optimize the performance of LED-cured coatings.

Poor surface cure, due to oxygen inhibition, is one of the most challenging aspects associated with LED-cured coatings. Oxygen, in its ground state, has a “diradical” nature and is highly reactive toward radical species. As a result, oxygen can scavenge radicals to form less reactive peroxy compounds, which can terminate the growing chain via radical-to-radical interaction. The result of oxygen inhibition is observed as a decreased rate of polymerization and, ultimately, compromised coating performance.

Increased energy is another way of improving curing of coatings under UV LED. Upon inception, LED lamps were limited in the amount of energy they could produce, but as the technology evolved, higher energy lamps capable of producing more free radicals and faster cure speeds were developed. While this significantly improves surface cure, the higher rate of polymerization can have a detrimental effect on depth of cure, depending on the photoinitiator package the formulator has chosen. This is particularly true with thicker coatings, where the poor depth of cure can lead to poor coating performance in the field.

Similarly, increasing the concentration of photoinitiator in the coating allows for more free radical formation, which, in turn, provides for better through-cure. Depending on the type of photoinitiator chosen, this approach can have a detrimental effect on depth of cure, as well as obvious economic implications. Care also should be taken that the concentration of free radicals produced does not exceed available sites, as this could result in a reduction of cure speed.

One variable that has yet to be completely explored is the effect of the type of photoinitiator used in the formulation. Formulators frequently use combinations that have succeeded in the past, but photoinitiator performance under conventional UV lamps is not necessarily indicative of how it will do under UV LEDs. In some cases, particularly thick coating applications, entirely new combinations that work using a completely different mechanism can produce significantly better results. In this paper, we will evaluate not only how the concentration of photoinitiators can affect coating performance but, more importantly, why the choice of material also is critical.

Categories
Resources

UV-Led has Gained Higher Acceptance

The most important fields in which the use of UV-LED technology has increased are wood coatings and printing inks. We spoke to Frédéric Taché and Charles Bourrousse of Sartomer about the current state of the art in UV-LED technology and UV-curable adhesives.

How prevalent is UV-LED technology?
Frédéric Taché: Today, the perceived advantages of UV-LED, including increased productivity, higher quality and a more environmentally friendly technology, have enabled UV-LED curing to play a major, if not dominant, role in many UV-curing applications, as well as to convert traditional processes to UV. The most important fields in which the use of UV-LED technology has increased are wood coatings and printing inks – even to the extent that some lines are now “full” LED. More recently, the development and marketing of low-migration systems specifically developed for use with LED has led to greater acceptance across all sectors of the coatings and printing inks industry in the EU wherever indirect food contact is critical.

Charles Bourrousse: Moreover, the reduction in heat generated during curing has paved the way for the use of thin-film, heat-sensitive plastic substrates. This has facilitated rapid development in flexible packaging applications. Further progress in UV-LED will be based on the development of new wavelength lamps and/or better-adapted photoinitiator packages. As a key supplier to the UV industry, Sartomer continues to develop and recommend market-leading solutions for the highest surface cure performance.

Categories
Resources

Jochen Christiaens Promoting Growth of UV LED Curing Community in Europe

The UV LED community is increasing its number of members in Europe

In just a few years, the UV LED Community has reached over 100 members. This shows the growing interest and the acceptance of UV LED technology in a wide range of applications. Now uvledcommunity.org is getting some additional support in Europe to increase its reach and to promote the adoption of UV LED technology.

Members who join the Community are key players in advocating for of UV LED in various fields. Members include suppliers of materials, resins, photo-initiators, adhesives, inks, coatings, equipment, measurement and end-systems. These companies have the common goal of accelerating the adoption of the LED curing technology through education and knowledge sharing.

Following the rapid growth of UV LED solutions in Europe, the UV LED Community will now be supported locally by Jochen Christiaens, European site editor. Jochen will be assisting local suppliers and manufacturers to promote the community site and grow the number of new members (membership is free to qualified suppliers and end users of LED technology).

The Community website is an educational forum that enables participants to share their knowledge of UV LED curing technologies, applications and chemistry, as well as to exchange news and information.

The Community has two primary goals:

  • To provide a forum for UV LED curing conversations.
  • To foster communication between suppliers and consumers of UV LED solutions.

“As an advocate of UV LED curing technology for years, I have been involved in the development of various inkjet printing projects for over 15 years. It is a great pleasure and honor to be part of educating the market and support the UV LED technology, and help growing the community web site,” said European site editor Jochen Christiaens.

To date, we have posted over 200 industry articles on LED curing, and we are looking forward to our members to contributing to the unique content of the UV LED Community by providing news, technical articles, and in joining the active discussions about UV LED applications.”

Categories
Resources

LED Technology Gains in Importance as UV Curing Solution

Printers working with UV curing have a new technology to learn about, if they are not already acquainted with it: UV LED

Curing inks and coatings with ultraviolet (UV) radiation has long been SOP for many printers, especially those producing packaging and labels. But, as well established as it is, conventional UV curing has had persistent drawbacks: high operating temperatures and energy requirements; ozone emissions; safety concerns about skin and eye exposure; and regulatory issues stemming from the presence of mercury in standard UV lamps.

Although conventional UV curing remains the norm for most kinds of printing, an alternative to it is making rapid technical advancements and is starting to attract the kind of attention that leads to mainstream adoption. This is curing with UV radiation generated by light emitting diodes, or UV LED for short. Its proponents say the technology works well with all printing processes and may even become the curing method of choice in some applications that now belong to conventional UV.

The scientific difference between UV radiation from LEDs and conventional, mercury-based lamps is in wavelength. The spectral output of UV LED lies in a narrow band of wavelengths from about 355 to 415 nanometers, just below and slightly overlapping with the spectrum of visible light. (Wavelengths from conventional UV units are more broadly distributed and produce more types of UV radiation.)

With their microchip-like arrays of miniaturized diodes, UV-emitting LED units bear little resemblance to the designs of the mercury-using arc lamps and microwave lamps that are the fixtures of conventional UV. As one conference speaker, Jennifer Heathcote (Phoseon Technology), put it, “the construction and operation of a UV LED curing system has more in common with a smart phone and a tablet” than with either of the conventional sources.

In practical terms, said Heathcote and other experts, UV LED systems set themselves apart from the other methods by being longer lived; more consistent in UV output; more energy efficient; simpler to work with because of their fast on/off operation; cooler in curing and therefore easier on heat-sensitive substrates; and free of ozone and mercury (the latter coming under increasing regulatory pressure, especially in Europe).

As an emerging technology, UV LED has had to deal with technical hurdles and market resistance. A panel of representatives from UV LED solutions vendors, moderated by WhatTheyThink, discussed the extent to which the problems and objections have been set aside.

Because of technical progress, they said, no longer valid are claims that UV LED curing units are underpowered or that they are too costly to use. The panelists noted that UV LED has been successfully installed on inkjet, flexo, screen, and offset printing systems and that with the help of ongoing R&D, the units will continue to become less expensive and more capable.

Institutions outside the industry are taking notice. RadTech put on the conference with the help of a grant from the New York State Energy Research and Development Authority (NYSERDA), a state agency that promotes clean and efficient energy use. And, the ERC at Rensselaer Polytechnic isn’t the only academic center in the state with a focus on UV LED. The subject also is covered in non-credit, credit, and advanced certificate courses presented by the Radiation Curing Program (RCP) at the SUNY College of Environmental Science and Forestry in Syracuse.

RadTech’s next major event for UV/EB will be RadTech 2016 in Chicago. Earlier this year, it launched UV+EB Technology, a quarterly magazine available free to qualified subscribers in print and digital editions. Issues can be examined here.

Another helpful information resource is the UV LED Curing Community, an online forum that lets market participants share their knowledge of UV LED curing technologies, applications, and chemistry.

Categories
Resources

Is Deep UV a Shallow Answer?

Editorial by Paul Mills

For over a decade the advocates of UV LED have spent a lot of time promoting the virtues of narrow wavelength sources — particularly those that leave out all the “bad stuff” like infrared and potentially harmful short-wave UV.

But those were the days when the trip from 395nm to anything below 365 seemed –well, like light years away. Today “deep UV” LEDs are all the rage – with a number of suppliers talking about UVC diodes just a few years away from affordability.

This gives me pause. Is this what we had in mind when we started down the LED path? Is grabbing for the digital analogue of a mercury lamp less than we originally reached for? Clearly, it helps bridge a persistent gap between mercury-ready formulations and LED-optimized chemistry, but at what cost?

The simple physics dictates that 395nm is, and always will be more cost and energy efficient than shorter wavelengths. But longer wavelength sources also steer well clear of the UVB and UVC wavelengths acknowledged to pose health threats associated with actinic UV.

I was struck by a discussion on the Climate Reality Project web site that posed:

“But we still have to keep the lights on, right? Yes, but coal is really a 19th-century fossil fuel, and it’s clean energy that’s moving us into the future. ..We know that the shift from dirty fossil fuels to clean energy is not going to happen overnight…and we’re all going to need time to make this adjustment. But the bottom line is that coal is no longer an appropriate way to power our society.”

I understand that the lure of surface cure and stomping out oxygen inhibition are tempting reasons to go fishing in the deep end of the UV spectrum for an answer. But it means that a long-wavelength solution may be the one that got away.

For a technology that prides itself on speed – changes in UV curing chemistry come at a snail’s pace. When UV powder was poised to revolutionize the office furniture industry, the pace of overcoming technical problems allowed laminate suppliers to develop better substitutes. And, in the late 1990’s when concerns over cancer-causing styrene threatened composite manufactures, the sluggish response of UV formulators allowed existing resin suppliers to develop low-styrene products before UV could get a foot in the door.

Formulators have had a decade to develop materials that take advantage of the user-friendliness and low-cost of long-wavelength LEDs, but precious little innovation has occurred. And while the chemists dawdled, the diode suppliers progress on sub-365 sources has brought LED sources within reach of existing formulations. But outside of the germicidal world, this new breed of LEDs will be more costly, have lower irradiance, and provide fewer health, safety and environmental benefits than many UV LED supporters may have originally hoped for.

(I’d like to hear your opinion. If you want to respond to this editorial mail to:pmills@uvledcommunity.org)

Categories
Resources

UV LED Photoinitiator and Cure Study

Traditional medium-pressure mercury (Hg) lamps produce a wide spectrum of radiation, including significant emissions in the ultraviolet region, specifically UVC, UVB, UVA and UVV. This spectral breadth allows for the selection of photoinitiator(s) to optimize the cure of acrylate-based inks, coatings, adhesives, sealants and composites according to the type and intensity of the light source, as well as accounting for species within the formulation that block and/or absorb UV light (e.g., pigments and fillers).

Download PDF