UVFoodSafe group clarifies mission

Shifting the group’s emphasis to explaining the benefits of UV flexo compared to solvent- and water-based wide web presses also opens the door on non-food flexible packaging opportunities. 

Finat president Chris Ellison is joint owner of OPM Labels & Packaging group, which has long championed printing flexible packaging on in-line flexo presses. ‘There are huge opportunities for narrow web label converters to play in the short run flexible packaging market, and not all these opportunities are in food,’ says Ellison. ‘Areas like agro chemicals, other industrial applications and cosmetics don’t involve migration issues. Food and drink are actually the most commoditized areas of the market.’

The UVFoodSafe group aims to disseminate best practice to narrow web label converters looking to enter the flexible packaging market, providing ‘a roadmap to compliance’, as Ellison explains it. Facing end users, the UVFoodSafe group will tackle the perception that UV cannot safely be used for indirect food contact packaging while promoting the benefits of UV flexo: fast changeovers with minimal waste for short runs; faster time to market with smaller SKUs; ability to add decoration processes in-line; and color strength and consistency between presses and between plants.

Converter challenges 
As Chris Ellison can attest, making the transition from PS labels to narrow/mid web flexible packaging is not an easy option. Implementing a low migration regime is a much more complex task than simply switching to LM ink: it involves the whole plant and the way it operates. In addition, low migration inks present their own challenges in reduced color gamut compared to conventional UV inks, so some reeducation of customers is required.

At the same time, there is are a range of variables to take into account to ensure adequate curing on flexible packaging materials. These include the enormous number of structures used in flexible packaging (some of which act as a functional barriers to migration). Other variables include ink density and film weight, and use of different pigments or varnishes.

A recent development by GEW is sensor technology which allows measurement of UV dose in-line close to the web surface. But this is not a simple pass/fail measurement because of the range of variables noted above. The sensors would need to be calibrated separately for each unique set of characteristics on a job by job basis.

Sun Chemicals’ Jonathan Sexton – appointed as the liaison between Finat and the UVFoodSafe group – notes: ‘In-line dose measurement can give guidance as part of a quality assurance system but cannot give an absolute value as to required dose.’

Using Extended Color Gamut (ECG) ink systems will cut down the variables, since the same anilox, inks and color management systems are used for all jobs. This is the approach being pursued by the Revo group of companies, for example.

UV LED is a promising technology in terms of enhancing process control. Compared to conventional UV it gives more consistent cure across the web and does not degrade over time. But once again, care is required as LED still cures progressively (from the base of the material up), so is not a simple ‘pass-fail’ cure given a set amount of energy.

A suggestion going forward is to get flexible packaging and film label materials suppliers more closely involved with the UVFoodSafe group. ‘UVFoodSafe partners could print different substrates in a controlled way, and publish the migration results as general guidance,’ notes Jonathan Sexton.

Looking forward to this year, confirmed UVFoodSafe events include a brand owner-focused seminar at Labelexpo Americas in Chicago in September looking at the whole area of short run flexible packaging and filmic labels produced on narrow and mid web presses by label converters.