Time for another look?
By Jerry Davis
Curing UV ink in a nitrogen environment is something that we don't hear much about today. The technology seems like a well-worn hat that has seen better days. But recently, nitrogen curing has been taken down from the rack, dusted off, and restyled. Improvements in nitrogen-curing equipment and a continuing demand for its unique capabilities have led to a comeback of sorts.
In the early days of UV printing, nitrogen curing was prized for the distinct benefits it brought to cured ink. Nitrogen curing was used when textured surfaces were required on nameplates and graphic overlays for automotive products, appliances, and electronics, to name just a few applications. The ability to create a distinct surface differentiation within a monochromatic color scheme was considered a value-added benefit for many finished products.
Beyond aesthetics, nitrogen-cured products were appealing for their functionality. Nitrogen curing imparts the utmost in surface hardness and abrasion resistance to the ink film. These much sought-after characteristics made nitrogen curing the clear choice for screen printers who supplied the most demanding market segments.
So, ten years ago, when we viewed an auto dashboard or microwave oven control panel with various surface textures, we were looking at nitrogen-cured parts. Today, those parts might be cured with nitrogen, but then again, they might not. (For a closer look at the history of nitrogen UV curing, see Nitrogen Curing: A Textured Past below.)
Eventually, nitrogen curing gave way to curing of a less specialized, more conventional type--one that takes place in the presence of ambient air, which includes oxygen as well as nitrogen. As the popularity of UV curing gained momentum, ink manufacturers were able to create formulations that replicated the textured effects once possible only with nitrogen curing. While the newer textured surfaces did not offer the same degree of consistency or abrasion resistance as their nitrogen-cured counterparts, they were less costly to produce and perfectly suitable for many applications that did not require a "bulletproof" coating.Most importantly, conventionally-cured UV coatings did not mandate the use of expensive nitrogen-curing equipment. This opened the door for more and more shops to tap into the lucrative markets for decorating polycarbonate and polyester nameplates, faceplates, and later on, membrane switches.
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