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 that realizes UV LED curing benefits.
“The term ‘low migration’ packaging is commonly used to designate materials used in the packaging structure whose components will not migrate, or move, from the packaging into the product.” (Sun Chemical, http://www.sunchemical.com/low-migration-inks-and-coatings/) It is very important to point out that low migration is not about an ink, but about a process. The process includes the following: press, substrates, ink, curing, rollers/screens (in case of flexography/screen respectively), ink film thickness, color print order and max ink deposition.
“To qualify as low migration packaging, compounds contained in the packaging structure, including printing inks, coatings and adhesives, must not have any effect on the appearance, flavor, odor, taste, or any negative effect on the safety of the product contained within the packaging,” Sun Chemical added.
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.
In the approximately 10 years since ultraviolet light-emitting diode (UV LED) curing lamps appeared in the market, there have been significant technological advances in LED efficiency and curing lamp performance. The initial challenges have been met and overcome allowing rapid technology adoption across a broad array of industries.
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.
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 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 fully cured product.