LED cured OPV

Yellowing of clear coats and surface cure are perceived issues in the rapidly growing UV LED curing market. Currently, commercially available clear coats (OPV’s), cured in air with 385 and 395nm LED systems, show higher yellowing index compared to standard OPV’s cured with mercury vapor UV lamps.

Better results can be achieved, but still showing higher yellowing values, with specific formulations for curing in inert atmosphere (i.e. nitrogen) with 385 and 395nm LED systems adding however complexity to the UV curing installation.

Hereafter a brief description of you the results of an innovative, specifically formulated OPV (commercially viable) cured in air with high power 365nm LED systems, showing very similar yellowing and white index values and surface cure properties in comparison with standard OPV’s cured with mercury vapor UV lamps.

OPV formulation specs

• Formulation F1; Commercially available OPV coating with standard photoinitiator package, cured with conventional mercury vapor UV lamps
• Formulation F2; Experimental OPV 100% solid coating with LED specific photoinitiator (Esacure family), cured with High power 365nm LED.

Application, curing and measuring specs

• Manual Bar Coating: Bar Number 0 (White)
• DFT: 4 microns
• Substrate:  Leneta Plain White Charts
• UV Curing Systems used: High power 365nm LED and mercury vapor lamp
• Color Index equipment: BYK Color – Guide 45/0