Why UV LED Curing is the Right Choice for Label and Package Printing

If you are a narrow web converter interested in UV LED curing, this article will explain why LED technology is the right choice for all label and package printing applications. We will start by highlighting all the benefits brought to converters when they upgrade from traditional mercury UV curing to Phoseon LED technology. We will also discuss why UV LED outperforms for some of the more challenging applications such as opaque whites, dense blacks and metallic, laminating and cold foil adhesives.

UV LED Benefits

The benefits of UV LED apply to all label and package printing applications. The long life and reliable output of UV LED lamps provides consistent cure and stability of process. This translates into improved up-time and predictability of cure which benefits all who are involved. Since UV curing issues on press are typically the result of a faulty mercury lamp, the formulation, or the converting process, the use of UV LED technology eliminates the UV curing system as the source of the problem. This saves time in troubleshooting and ultimately has a positive impact on the bottom line. UV LED opens the door to new revenue opportunities with the ability to print on heat-sensitive and thinner substrates, offering increased profitability for printers and converters.

Conventional mercury lamps have a very short lifetime and need to be replaced every 1000-1500 hours. LED curing lamps extend beyond 60,000 hours if maintained properly. Upgrading to UV LED technology eliminates these replacement costs, offering significant environmental benefits with the elimination of mercury.

LED Benefits Compared to Mercury

Opaque Whites, Dense Blacks, Metallic and Other Dark Colors

Beyond general label and package printing, UV LED technology is vastly superior to mercury systems for the curing of opaque whites, dense blacks, metallic and other densely pigmented colors. The critical element that each of these has in common is the requirement that UV energy travel through dense pigments, additives, or films without being redirected or prematurely absorbed before full cure is achieved.  Due to the physics of light and nature of UV LED output, depth of penetration is exactly where LED technology excels.

Due to longer UV-A (395 nm) wavelengths as well as intensities that are four to eight times greater than mercury lamps, UV LED technology drastically outperforms mercury lamps. The longer UV LED wavelengths naturally penetrate deeper, and by starting with a much higher irradiance, even if intensity diminishes as light travels through the formulation (due to absorption, scattering, and reflection), more light is still reaching the substrate. 

For label and packaging applications where black, white, metallic inks represent process bottlenecks, switching to a UV LED process with its ability to penetrate deeper into the ink will result in increased press speed, more opacity, stronger color, greater adhesion, better cure, greater yields, and less scrap.

 Laminating and Cold Foil Adhesives

The longer, near visible output of UV LEDs is advantageous in the case of laminating and cold foil adhesives since the UV energy must first pass through a film or foil construction in order to reach the adhesive.  Longer UV-A and UV-V wavelengths have superior luminous transmittance through materials compared to shorter UV-B and UV-C wavelengths. The fact that the adhesive is cured between two films also eliminates any need for UV-C wavelengths as none of the adhesive is exposed to oxygen which can inhibit cure.

UV LEDs are significantly more efficient and effective at curing laminating and cold foil adhesives than mercury lamps. In addition, when compared to solventless chemistry, UV cured laminations and cold foils can be immediately processed following exposure. The one to three day curing time required with solventless adhesives is completely avoided with a UV process. The higher irradiance and ability of UV LEDs at 395 nm to penetrate deep into the chemistry makes the technology ideally suited for label and flexible packaging applications.

If you find yourself interested in UV LED curing, consider upgrading one or two stations on your press to see how the UV LED system performs. This is the best way to become familiar with what is possible and demonstrate first-hand the many ways in which UV LED systems are superior to mercury arc lamps.

Find out more at phoseon.com.