Drying, Curing & UV
‘Dual Cure’ UV-LED inks for improved performance and sustainability in label printing
by Keith Redmond, regional manager UK & Ireland, Flint Group Narrow Web.
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V-LED curable flexo inks bring long-term cost savings, environmental benefits and performance improvements in label printing. These are being reformulated as ‘Dual Cure’ inks, that also cure under conventional mercury lamps. This allows converters to switch to LED curing with minimal disruption or waste – even one colour at a time – minimising risk. Introduced over a decade ago, UV-LED curable flexo inks offer strong advantages over ‘conventional’ mercury-curable inks: thorough and faster curing, improved sustainability and lower operating costs.
First, UV-LED curing systems use less energy: there is no infra-red emission and thus produce less heat as a by-product. The lower heat emission is a major contributing factor to the longer lamp life of up to 20,000 hours – several times that of mercury lamps. No exhaust systems are required for ozone removal, also reducing heat management and maintenance time and costs.
Additionally, UV-LED inks offer better anchorage to the substrate as they are cured from the bottom upwards. Combined with reduced curing times, this can lead to faster press speeds and more reliable results. At Flint Group, for instance, we validate inks at test speeds of up to 230m/ min (750fpm). More production time is possible, because UV-LED lamps can be switched on and switched without the need for warm-up or cool- down.
Environmental and safety benefits include avoidance of mercury use, ozone creation and
excessive heat generation through infra-red emissions.
When LED inks first arrived on the market, label printers were concerned about the disruption and costs associated with switching to the new technology. An LED lamp radiates energy at a different wavelength from that of the conventional UV lamp – and the UV-flexo inks’ photoinitiators must be sensitive to the lamp’s energy waves in order to cure. The early LED inks would not react under conventional lamps – and so transitioning to them had to be done in one abrupt step. That meant a full press refurbishment, disposing legacy ink stocks, interruptions and a delayed return on investment.
PHASED TRANSITION: FASTER ROI Today though, adopting LED-UV technology has never been easier: not only is there is a wide choice of competitively priced, high-performance lamp systems, but a new generation of versatile LED inks is available, capable of curing under both LED conventional lamps. This makes a much smoother, phased transition possible.
Coming under the Flint Group’s EkoCure brand, the Dual Cure ink range has a carefully developed mix of photoinitiators for optimum results under either curing process. They are formulated at the same colour strength as their conventional counterparts. This simplifies colour matching when switching over, and makes it possible to run the inks side-by-side with conventional UV inks on the same press, without compromising image quality.
REDUCED RISK, NO WASTE
As a result, changing to UV-LED curing does not have to be a disruptive, major capital investment process. Rather, UV-LED curing technology - ink and lamps - can be introduced over time. The converter has the freedom to upgrade the press one station at a time, reducing the financial risk while immediately reaping and delivering the benefits of UV-LED curing.
In a phased introduction, you can continue to use conventional UV ink stocks until they are run down, or they can be replaced with Dual Cure inks ahead of any equipment changes, ensuring zero ink waste and a smooth changeover. This avoids the costs of disposing of redundant inks normally associated with a switch to UV-LED inks.
Dual-curable inks are available for narrow web applications including labels, tags, cartons and shrink sleeves. The range has recently extended to a special food contact ‘low migration’ series, compliant with the Swiss Ordinance list and manufactured in accordance with EuPIA good manufacturing processes.
The development of a more versatile ink range reduces the risk of moving to UV-LED curing and allows the changeover to be financed from revenue rather than capital – and finally makes the clear efficiency, environmental and quality advantages of LED more accessible to converters.
Xwww.flintgrp.com
14
October 2021
www.convertermag.com
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