Ink and coating supplier Siegwerk has received a RecyClass Technology Approval for two of its nitrocellulose-free (NC-free) ink series.
The approval applies to the company’s flexo ink system UR 62 and gravure ink system UR 74, confirming that they meet recyclability requirements for surface-printed polyethylene (PE) and polypropylene (PP) flexible packaging in Europe. Specific conditions are outlined in the official approval documentation.
The approval relates to inks designed to avoid the use of NC, a material commonly used in solvent-based inks for flexo and gravure printing. NC-based inks are valued for their printability, heat resistance, drying speed and adhesion to multiple substrates. However, industry groups and recyclability guidelines increasingly identify nitrocellulose as a potential barrier to high-quality mechanical recycling of flexible packaging.
According to industry research, the limited thermal stability of nitrocellulose can contribute to odour formation, discoloration and reduced quality of recycled plastic during processing. As design-for-recycling standards evolve in Europe and other regions, some packaging developers are exploring alternatives that avoid the material.
Siegwerk said it has been developing a portfolio of NC-free inks intended for flexible packaging applications. These inks are designed to support recyclable packaging structures while maintaining printing and converting performance in industrial flexographic and gravure processes.
Historically, polyurethane (PU)-based lamination inks have provided NC-free options that are recognised by RecyClass as recyclable. However, these have generally been used in lamination rather than surface printing, which has limited their application in certain packaging designs. Siegwerk said the development of NC-free surface-printing systems aims to address that gap.
The company groups these products within what it describes as an “NC-free toolbox”, which is intended to help converters and brand owners adopt nitrocellulose-free printing systems across both lamination and surface printing processes.
“Switching to NC-free inks is a decisive step for recyclable flexible packaging, especially in surface printing,” said Dr. Björn Ewig, head of technology for flexible packaging EMEA at Siegwerk. “Our focus has been to develop NC-free alternatives that work reliably in industrial production and meet recyclability requirements without compromising on print or packaging performance.”
For its NC-free ink systems, Siegwerk uses proprietary polyurethane binders designed to replace nitrocellulose while maintaining printing performance and resistance to heat and mechanical stress.
With the RecyClass Technology Approval for UR 62 (flexo) and UR 74 (gravure), Siegwerk said the inks have been independently assessed for use in recyclable PE and PP flexible packaging structures.
“Our customers need solutions that combine print performance with proven recyclability,” said Ralf Leineweber, head of global technology development at Siegwerk. “This approval now gives them the confidence to make the right decisions, supporting the overall trend toward circular packaging concepts.”
