Research Highlights Why it is Important to Develop Deinkable Products in UV Offset Printing

A study by the Saxon Institute for the Printing Industry (SID) and Darmstadt Technical University has looked at the consequences of using UV inks in sheetfed offset printing. The results show that a considerable proportion of the print products produced in UV offset printing are not deinkable. Here’s why.

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UV offset inks are being used more and more frequently in the printing industry. Unlike conventional printing inks, they place different demands on processing and workflow. In Germany, several manufacturers currently offer UV offset inks. Consumers and clients see UV offset inks as being of higher quality than products printed with conventional inks. This is due to

“the brilliant color reproduction that can be achieved when using these inks“,

according to a research report by the Saxon Institute for the Printing Industry and the Department of Paper Manufacturing and Mechanical Process Engineering at Darmstadt Technical University.

What Are The Consequences of Using UV Inks in Sheetfed Offset Printing?

In a joint study, the institutions looked at the consequences of using UV inks in sheetfed offset printing. Commercial UV printed products from printers as well as print samples produced in the technical center were examined. The investigation was carried out with regard to two things: The deinkability of the products and the presence of photoinitiators. Deinkability is considered an important criteria for the recyclability of a product, especially when aiming for a sustainable resource management. The research report states

“In the course of sustainable product development, increasing importance is being attached to the recyclability of printed products both by ink manufacturers and by printers and their customers. If the printed papers end up in the paper cycle, deinkability, i.e. the removal of the printing inks from the paper mash as completely as possible, is of great importance. However, some of the UV printed products also reach the packaging cycle. Some of the UV photoinitiators are among the substances of health concern if transfer of these substances from the packaging material to a packaged food product can occur“.

40% of Commercial Printed Products Are Not Deinkable

Sample parts printed in the technical center with the papers and UV inks or coatings provided by manufacturers were also observed to have a more difficult deinking process. The study suggests, that among other things, the chemical composition of the inks and the ink coverage are decisive for the deinking result. Factors such as the paper type or the radiation technology are of little importance for deinkability. No significant correlation was found between the curing of the ink film and the deinkability either.

Photoinitiators of various mixtures and concentrations were identified in all commercial and pilot UV printed products. A total of twelve were systematically investigated. Although substances of health concern were also found among the photoinitiators measured in higher concentrations, they do not pose a problem either for the use of the UV printed products or for their return to the graphic paper cycle, since they can be removed from the paper cycle as part of the deinking process.

Is More Research Coming on The Topic?

The current research work of ink manufacturers to improve the deinkability of UV printed products and to adapt formulations with regard to UV photoinitiators is expected to provide further impetus for the development of more recycling-friendly UV-printed products.

Did you know that UV-printed products are sometimes difficult to recycle? Let us know in the comments!

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