UV curing of paints and varnishes is an established, fast and energy-efficient method for cross-linking reactive paint and varnish systems. It has proven itself in various sectors such as wood processing, surface coating and the printing industry. Traditionally, photoinitiators are used to absorb UV light, generate radicals and thus start the curing process by converting the C=C double bond. This technology enables the production of highly resistant surfaces that meet the highest customer requirements in terms of both appearance and durability - while at the same time optimizing cost efficiency and compliance with important environmental regulations.

UV direct cross-linking is an innovative curing process that does not require photoinitiators. It uses the energy of short-wave UVC light to directly cross-link the C=C double bonds in coating and ink systems. The result: highly resistant surfaces with minimal energy consumption – without any additional chemicals.

Oxygen inhibition reduces efficiency

In classic UV systems, oxygen can inhibit radical formation and thus slow down the curing process. Common countermeasures such as inerting or the use of additional photoinitiators lead to higher costs, odour development and potential emissions.

Restrictions due to photoinitiators

Photoinitiators are increasingly subject to regulatory restrictions (e.g. REACH) and supply bottlenecks. They can also cause migration and odour formation – a particular problem for sensitive applications such as packaging or kitchen surfaces.

Our UV experts at IST METZ have developed a process that enables UV curing without photoinitiators. To achieve this, the light spectrum is specifically shifted to the energy-intensive UVC range. Key adjustments include:

• Optimisation of plasma technology in the UV lamp
• Use of special materials for reflectors and filters
• Precise electronic control of the UV modules

This combination enables efficient and stable direct cross-linking of reactive systems – without inertisation and without additives.

• Environmentally friendly: No use of photoinitiators
• Low odour: Low migration potential
• Energy efficient: Shortest curing times and reduced energy consumption
• Simple process: No inertisation required
• Economical: Faster production and fewer UV units required