How do photoinitiators for UV curing work?
Photoinitiators absorb light in the ultraviolet-visible spectral range, generally 250–450 nm, and convert this light energy into chemical energy in the form of reactive intermediates, such as free radicals and reactive cations, which subsequently initiate polymerization.
Which UV wavelength are products with photoinitiators sensitive to?
Curing. The polymerization process begins when photoinitiators, most commonly camphoroquinone, absorb energy from blue light with a wavelength in the region of 470 nanometers.
What wavelength is used for UV curing?
The wavelength for UVA spans 320 nm to 395 nm, making it the longest UV wavelength. UVA is used for general UV curing and is responsible for most of the adhesion properties for the UV formulations. Common uses for UVA include: Curing inks, coatings and adhesives.
What is nm in UV wavelength?
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays.
What is the purpose of photoinitiator?
A photoinitiator is a molecule that creates reactive species (free radicals, cations or anions) when exposed to radiation (UV or visible). Synthetic photoinitiators are key components in photopolymers (i.e., photo-curable coatings, adhesives and dental restoratives).
What is a peroxide initiator?
The by far most important organic peroxide initiator is benzoyl peroxide (BPO). It consists of two benzoyl groups bridged by a peroxide link. BPO readily undergoes symmetrical fission (homolysis), forming two benzoyloxy radicals: 2-4. The two fragments with unpaired electrons are called free radical initiators.
What are polymer initiators?
initiator, a source of any chemical species that reacts with a monomer (single molecule that can form chemical bonds) to form an intermediate compound capable of linking successively with a large number of other monomers into a polymeric compound.