In what is claimed to be a first, Siegwerk has introduced a nitrocellulose (NC) free ink series specifically designed for surface printing on polyethylene (PE) and polypropylene (PP) packaging solutions.
The company said the new offering includes NC-free surface solutions for both flexo and gravure printing and has been developed to meet the latest packaging design guidelines from RecyClass and Ceflex. Together with the company’s NC-free solutions for lamination, these new surface ink systems will be part of the company’s recently introduced NC-free toolbox for flexible packaging.
Björn Ewig, head of technology for flexible packaging EMEA at Siegwerk, said, ‘With our new NC-free toolbox we now enable printers and converters to better meet the demand for NC-free flexible packaging, ensuring excellent recyclate quality that meets the latest design for recycling guidelines without compromising on print or packaging performance.’
Despite the positives of NC’s ‘excellent’ printability, high heat resistance, quick drying capabilities, and ‘excellent’ adhesion to surfaces; it also has negatives such as an unpleasant odour, discoloration, and a lower mechanical strength of the recyclate, due to its limited thermal stability. The company’s new solution offers the same technical and mechanical performances as NC-based inks, but with the added benefit of being recyclable, explained Mr Ewig.
For all its NC-free solutions, Siegwerk relies on a set of proprietary, self-developed polyurethane binders as a replacement for nitrocellulose. The company stated that industrial applications of the new flexo and gravure surface inks have already shown good sealing resistance and high rub resistance, confirming suitability for surface printing without the use of an additional overprint varnish.
