Formulation and Property Differences of Waterborne UV Polyurethane Dispersions Cured by Mercury and UV LED Lamps
Tong Wang, Technical Specialist, Allnex
Waterborne UV polyurethane dispersions (UV PUDs) offer advantages of no VOC, low viscosity, hard but flexible and improved adhesion. UV PUDs have applications in packaging, industrial coatings and consumer electronic devices coatings. UV LED is becoming popular because it is environmentally friendly, generates less heat and has a longer life. However, LED curing presents disadvantages of the limited photo initiator selection, poor surface cure and demanding for more reactive resins. In this presentation, various UV PUD formulations were prepared and cured under mercury or LED lamps to compare their cure response and performance. The surface and through cures were determined by graphite and acetone double rub methods, respectively. The double bond conversion of the cured surface was analyzed by an FTIR-ATR. Other properties such as chemical resistance and adhesion to plastic substrates were also evaluated. The influences of photoinitiator type, photoinitiator level and cure temperature on coating properties were studied.