Siegwerk adds 'revolutionary' anti-bac coating to range

Darryl Danielli
Friday, June 19, 2020

Ink manufacturer Siegwerk has signed an exclusive deal to supply a “revolutionary” water-based, light-activated anti-microbial flood coating that is fully recyclable and remains active for up to three years.

L-R: Hanns Martin Kaiser, Siegwerk VP paper & board EMEA, and Jens Frings, Varcotec MD ink the deal
L-R: Hanns Martin Kaiser, Siegwerk VP paper & board EMEA, and Jens Frings, Varcotec MD ink the deal

The German headquartered group signed the deal to exclusively supply Varcotec’s Lock 3 coating across EMEA last week.

The product is available in Germany and the UK with immediate effect, other countries will come on stream in the coming months.

According to the two firms, water-based Lock 3 is the first anti-microbial coating based on photodynamics.

“Until now, it has not been possible to apply a reliable coating onto absorbent substances, such as paper and cardboard, which would continuously and permanently destroy those germs,” said Joachim Frings, Varcotec sales and development director.

Lock 3 contains a patented photocatalyst substance that when activated by visible light absorbs the surrounding oxygen, creating a “singlet oxygen” across the coating’s surface to a range of 1mm efficiently killing germs by “oxidizing their shells”.

The singlet oxygen process has been used in medicine to treat tumours and degenerative diseases for two decades.

The technology was developed for printing applications by German varnish specialist Varcotec, which overseas production, in collaboration with a spin-off company affiliated with the University of Regensburg.

Lock 3 has been independently tested proven to kill 99% of bacteria and viruses to ISO 22196 and 21702 respectively, and is currently being tested against other virus strains, including three members of the coronavirus family.

According to Graham Tattam, sales manager, paper and board at Siegwerk’s Midlands-based UK & Eire operation, it is odourless and colourless and can be applied to any paper or board via the flexo process or a flexo unit in hybrid press and, unlike most antimicrobial coatings, doesn’t use heavy metals such as copper or silver.

Coating weight varies dependent on substrate absorbency.

“It’s guaranteed effective up to a year, but there have been tests where it’s lasted three years. It’s dormant in darkness and keeps reactivating when it’s in light.”

While it can only currently be applied via the flexo process, Tattam said Siegwerk and Varcotec were keen to develop new applications in the future: “As you would expect, this is brand new and a number of these things are market-led in terms of interest and scale.”

While the new coating taps into the Covid-19 zeitgeist, Tattam said the sustainability story of Lock 3 was just as important.

“It’s biodegradable, it’s compostable, it’s not got any heavy metals in it. It’s a water-based environmentally-friendly product that doesn’t impact the recyclability of the products it’s applied to.”

It is currently being tested on plastic films and, separately, migration tests for food packaging approval.

However, Tattam said the coating already has a multitude of applications, from outer packaging for deliveries, books, school exercise books, pharmaceutical and medical products, and back-to-work safety products.

Siegwerk has already sold Lock 3 to several customers in Germany, and according to Tattam, the level of interest he has already received indicates the UK won’t be far behind.


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