- What is inertisation?
The atmospheric oxygen is removed from the reaction space by the addition of an inert gas.
- How do we do inertisation?
The radical polymerization when curing with UV is sensitive to oxygen. Inertisation replaces the disturbing atmospheric oxygen with nitrogen (= N2). A tight-fitting chamber encloses the UV lamp and the substrate to be printed. The chamber is flooded with nitrogen. The atmospheric oxygen around the web is displaced by nitrogen, which would otherwise inhibit the polymerisation and curing.
- Advantages of inertisation
When oxygen is excluded from curing, the process is faster and with a higher bonding rates.
Significantly more double bonds are created in the ink - in shorter time. And the curing of the ink is almost complete.
The improved curing is achieved with fewer photo initiators. That reduces migration.
LOW MIGRATION is becoming more and more important, especially in the field of food packaging.
- Why is inertisation done with nitrogen?
Nitrogen is non-toxic. Breathing air consists of 78 percent nitrogen.
Nitrogen is sterile and is used in the food industry as a protective gas for preservation.
Nitrogen is not flammable and enables safe handling.
- Can I completely remove atmospheric oxygen from a web?
Not complete ... but almost! The PrintConcept technology allows the exclusion of atmospheric oxygen up to approx. 100 - 200 ppm at speeds of up to 450 m/min! Keep in mind what this means at the extremely low oxygen concentrations in ppm (= parts per million!).
At lower speeds, values < 30 ppm residual oxygen are possible.