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Question and Answer

Green-er UV Coatings

by Staff

May-June, 2011
Years ago, Kermit the Frog told the world, “It’s not easy being green.” Since then, there has been a big push for everyone to ‘go green’ – an important step in cleaning up the environment and lessening the world’s dependence on petroleum and non-renewable resources.

These days, going green is easier than it ever has been…depending on the definition of ‘green’. Some understand ‘green’ as meaning a 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. UV-curable coatings always have been low or no VOC, have a low carbon footprint (compared to solvent-based inks and coatings) and UV coatings are repulpable and recyclable.

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

Q: What specific ‘green-er’ coatings are available on the market?
It is best to consult with your current UV coating supplier on what specific UV coating products it offers. One specific coating for screen applications offered by ACTEGA Kelstar is the Ultra Sheen UV-3400. This series of ‘green’ coatings offers excellent flexibility, good scuff resistance and covers the various aspects of being ‘green’: they are based on renewable resources, low or no VOC and have a low carbon footprint. Printers, in conjunction with finishers, can make their finished product even ‘green-er’by using low VOC or soy-based inks and then applying a green UV coating made of renewable resources. Therefore, utilizing the three components of recyclable paper and low VOC or soy-based inks coated with green UV coatings will ensure a finished product that is very environmentally friendly.

Q: When using ‘green’ UV coatings, does the printer have to use different inks or primer coatings?
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 off-line 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.

Q: Is there a change in flexibility, adhesion or gloss values?
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 the flexibility and adhesion, you should not expect to see any significant differences in performance between a typical UV coating and a ‘green’ UV coating.

Q: What is the cost impact of using ‘green’ UV coatings?
As with all new chemistries and processes, the initial costs are higher. Through time, as the processes are refined and improved, the costs are certain to have a lesser impact (every new product costs more than the ‘new generation’ does – think of how the prices on computers have dropped through the years, due to process improvements of the components). ‘Green’ materials and coatings are still relatively new. As such, in time, lesser cost impacts should be seen.

So, the next time a job arises where the question is asked, “Do you have a ‘green’ coating?” consider what ‘green’ means to the customer…and to you. You may already have a ‘green’ coating in-house or in the alternative, can present a ‘green-er’ coating that will meet your customer’s specifications.

1992 Beloit Corporation study presented by David J. Korn at RadTech

InsideFinishing would like to thank Robert Andrews, laboratory director and Steven Barry, senior technical service specialist, pressroom chemistry, with ACTEGA Kelstar, Inc. for their assistance with this Q&A. For more information on ‘green-er’ UV coatings, call 800.255.0021 or visit www.actega.com.