Photoinitiator, also known as photosensitizer or photocuring agent, is a compound that can produce reactive species after absorbing a certain wavelength energy. These reactive species are capable of initiating or catalyzing chemical reactions, which then trigger the monomers or oligomers to undergo polymerization. This process is called photopolymerization or radiation curing or photocuring, the light used as the energy provider is most often Ultraviolet, that’s why photoinitiator often refers to UV photoinitiator.
UV Photoinitiator is the essential composition of all UV curable resin systems, it transforms a soluble liquid formulation into a hard and insoluble crosslinked polymer network. The cured coating is chemically and physically resistant and is used both to protect and decorate substrates such as plastics, wood and metal.
Photocuring technology is a new energy-saving and environment-friendly technology. The light source (most commonly is Ultraviolet, sometimes visible light), used in radiation curing is fully in line with the “5E” characteristics: Efficient, Enabling, Economical, Energy Saving, Environmental Friendly. Therefore, it is known as “green technology’, and widely used in UV-curable paints, coatings, inks, adhesives industries.
Photoinitiators can be classified into two categories, according to the initiation mechanism. There are free radical initiators and cation initiators. About the details for photoinitiator types, please check this post for more information.
A photoinitiator should exhibit several properties, from which the most important are:
- High absorption at the exposure wavelength and high molar extinction coefficient.
- High quantum yield of formation of initiating species.
- High reactivity of the radical towards the monomer.
Photoinitiators tend to make up a few percentage of the formulation, but the cost represents a much higher proportion of the formulation. The photoinitiator type is chosen for the absorption to be maximized to match the output of the UV source being used.
The most commonly used photoinitiators include: Irgacure 1173, Photoinitiator TPO, Irgacure 369, Irgacure 2959, Photoinitiator 819, Photoinitiator TPO-L, Irgacure 651, photoinitiator 907, Irgacure 184, 2-Isopropylthioxanthone, etc,. BoldChem supplies above photoinitiators and other chemical materials at a high quality but a competitive price, please contact us for the price.