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  • 13 Jun 2022

Siegwerk develops deinking technology

Siegwerk has introduced an improved UV-curing deinking primer suitable for pressure sensitive and wrap around labels, and shrink sleeves

Siegwerk has introduced an improved UV-curing deinking primer suitable for pressure sensitive and wrap around labels, and shrink sleeves made of polyolefin- and polyester-based materials. The primer is especially developed for rigid plastic packaging in industrial mechanical recycling process as well.

This development now allows an inline printing of deinkable materials in a 100 percent UV- flexo press setup.  
‘Achieving this 100 percent packaging circularity requires a sufficient and consistent quality of recyclates,’ explained Ralf Leineweber, head of Global Technology Development at Siegwerk. According to Siegwerk, in mechanical recycling as today’s only established industrial recycling process, deinking of printed packaging material is one – if not the most – viable technology to meet this requirement. Only deinking can bring clean and clear recyclates with a suitable quality back into the packaging stream to consequently reduce the need of more virgin plastic material.  
Guido Lander, vice president, Narrow Web EMEA at Siegwerk, added: ‘That’s why we are committed to support customers with innovative solutions facilitating deinking and thus contribute to establish deinking as industry standard further improving packaging recyclability and circularity.’ 
To integrate deinking into the recycling process, recyclers need to implement a hot washing step first. Here, it is critical that the deinking does not negatively impact the recycling process for example by contaminating the wash water. More and more recyclers focusing on rigid plastic packaging such as trays, cups and plastic containers are implementing hot washing processes to improve the quality of their recyclates. 
‘We consider deinking primers as a key lever for smart deinking of crosslinked ink systems especially at low washing temperatures for sleeves, labels and other printed decoration for rigid plastic packaging,’ Leineweber explained. 
Siegwerk’s deinking primers are claimed to enable deinking at any hot washing condition currently used in the recycling industry. They are compliant with film materials such as cPET, PE or PP and do not require the use of a dedicated ink series. Any printing process can be used in combination with its deinking primer portfolio – from flexo, offset and screen printing to foiling, metallic and other decorative embellishments.  
With its UV-curing deinking primer, the company offers a solution to converters using a pure UV flexo press and are not able to process a water-based primer. This primer is said to be compatible with UV-curing inks facilitating quantitative deinking according to the washing protocols of EPBP and APR. Applied under bleeding resistant UV-cured ink layers, the primer layer dissolves in the hot washing process and thus enables the generation colorless recyclates, while the non-bleeding ink formulations ensure a clean and reusable washing solution.  
The manufacturer is currently engaged in various deinking projects for all kind of rigid packaging with in-mold and pressure sensitive labels as well as for direct printed rigid containers.  
‘The greatest opportunities to improve plastic recycling in line with a circular economy obviously lay in areas where hot washing already became a standard step within the recycling process, such as in the PET bottle 2 bottle recycling,’ added Leineweber.  
Siegwerk has for example developed deinking technologies for shrink sleeves claiming 100 percent recyclability of bottle and sleeve in food contact grade quality. Furthermore, the ink expert sees opportunities to recover high-quality recyclates from postindustrial flexible packaging waste via deinking. Post-consumer waste is supposed to follow as well at a certain time due to its volume related importance.  
The company also offers its customers technical services along the value chain to support an optimized and consistent deinking process. The company can also provide optimized deinking chemistry based on a systematic development to ensure fast deinking resulting in clean flakes with almost virgin quality of the recyclate.  
‘Deinking is not a product for us, it is a “Full-Service Offering” where everything needs tie together,’  Lander said. ‘That’s why we follow a holistic approach and also offer the execution of deinking tests according to the most common washing protocols in our specialized laboratories.’ 
Based on its deinking expertise, Siegwerk can guide customers through the entire process, from the unprinted substrate to the deinked and recycled packaging material. 


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