Unlike gas discharge lamps, LED light sources have a monochromatic light spectrum. LED devices used for curing adhesive are available with different wavelengths matched to the curing requirements of the particular adhesive used. LEDs are available with wavelengths in the UV range from 365 to 395 nm and in the visible-light range from 405 to 460 nm.
When exposed to UV or visible light, photoinitiators release free radicals (in acrylate-based systems) or cations (in epoxide systems), which trigger polymerization and thereby curing of the adhesive. As a general rule, the greater the light intensity the shorter the curing time.
Advantages of LED Technology are:
- LEDs have high energy efficiency
- Less maintenance and significant reductions in energy costs
- LEDs have a long operating life (typical lifetime of LED > 20,000 hrs)
- LEDs emit less thermal radiation and thus lower thermal stress on heat-sensitive substrates
- No stand-by times for LEDs needed
- No warm up or cool down phases needed
Panacol’s LED adhesives have been optimized for the LED devices from Hönle. In particular the photoinitiators are chosen to match the wavelengths of Hönle’s LED light sources. With the Vitralit® series Panacol offers a range of specially formulated LED and UV-LED curing adhesive.