UV hardening involves radiation-induced polymerisation of the binding agent leading to a highly cross-linked lacquer film. This process takes a matter of seconds according to a specific mechanism.
The UV radiation sources generate light beams in a wavelength range of some 280 to 450 nm (nanometres) that are concentrated on the coated item by reflectors and mirrors.
The number of UV lamps to be used depends on:
- the reactivity of the coating system
- the amount of wet film applied
- the feed rate of the equipment
When working with pigmented UV lacquers, complete hardening is achieved with combinations of UV lamps in the wavelength ranges of 400 to 450 nm and 280 to 360 nm. The combination of UV lamps must be directed at the object to be coated. (lacktuell no. 5/II 95)