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Q&A: Green-er UV Coatings

Going green is easier than ever before ... depending on the definition of "green". Some understand it to be low or no VOC content; the use of renewable resources in the finished product; having a low carbon footprint; or even the ability of the product to be recycled. Many of these aspects of "green" have long existed in UV-curable coatings, which always have been low or no VOC, have a low carbon footprint (compared to solvent-based inks and coatings) and are repulpable and recyclable.

Question: How do renewable UV raw materials compare to traditional, oil-derived UV raw materials?

Answer: Over the past few years, UV raw material manufacturers have created new methods to produce raw materials that no longer are derived from oil. These new raw materials now are derived from renewable resources such as vegetable oils and fats, about a dozen crop plants and even wood. Not surprisingly, among all of these, soy-based materials have become the most widely used raw material.

Renewable (plant-derived) UV raw materials offer the properties that traditional, oil-derived UV raw materials offer. If you currently use an imprintable or foil stampable UV coating, you can get that same coating made "green". Maybe your existing UV coating is used for a high co-efficient of friction, scuff-resistant wine box carton. Either way, using renewable UV raw materials, such as soy-based acrylated oligomers and even carnauba wax, ‘green-er’ UV coatings can be produced.

Question: When using "green" UV coatings, does the printer have to use different inks or primer coatings?

Answer: No, the printer can use its coat-able inks and aqueous primer coatings as it always has with typical UV coatings. If a print finisher is utilizing a "green" UV on its offline UV coater, there should not be any special instructions that need to be communicated to the printer, other than the normal information needed to ensure that the inks are coat-able.

Question: Is there a change in flexibility, adhesion or gloss values?

Answer: One of the attributes of "green" coatings is that the formulation of the renewable raw materials actually tends to increase the flexibility and adhesion properties of the finished product. The gloss level should remain the same as a typical UV coating – being mindful of the following factors that can affect gloss values:

  • Substrate absorption
  • Applicator type
  • Optical clarity of the coating
  • The coating’s ability to flow out and lay smoothly on the surface of the substrate

Other than flexibility and adhesion, you should not expect to see any significant differences in performance between a typical UV coating and a "green" UV coating.

ACTEGA Kelstar, Inc. assisted with this Q&A, which was originally published in the May-June 2011 issue of InsideFinishing.