In the UV curing systems, such as UV gel, UV coating, UV ink, after accepting or absorbing energy, they themselves have a chemical change, decomposed into free radical or cationic, then polymerization.
Photoinitiators, also known as photosensitizer or photocuring agent. It can absorb certain wavelengths of energy in ultraviolet light (250~420nm) or visible light (400~800nm), it produces free radicals and cations, etc, triggering monomer polymerization crosslinking curing compounds.
Ideal photoinitiators should have the following advantages:
1 cheap and simple synthesis
2 photoinitiator and light products should be nontoxic and odorless
3 good stability, easy to store for a long time
4 the absorption spectra of photo initiator must match with the emission spectrum of the radiation source, and has a higher molar extinction coefficient
5 higher efficiency jump between initiator channeling of photoinitiation
6 the higher efficiency
The developing trend of photoinitiators focuses on hybrid, visible light type, water base, macromolecules, and the use of dual-cure.
Radiation curing technology is an energy-saving environmental technology. Purple outside light (UV), electron beam (EB), infrared light, visible light, laser, chemical fluorescent and other radiation light irradiation curing completely meet "5E" features: efficient, practical, economical, energy-saving and environment friendly. Therefore, it is called green technology. Photoinitiator is one of the important components of UV-curable adhesives. It plays a decisive role in curing speed. After UV exposure and absorb light energy, photoinitiators divided into 2 active free radicals, initiated photosensitive resin and has chain polymerization with active diluent makes adhesive crosslinking curing, which is characterized by fast, environmental protection and energy saving.
1 According to oligomers and monomers type select suitable activity photoinitiator.
2 Has good solubility and reactivity, low consumption, high raise efficiency.
3 Has a certain degree of thermal stability. It don't breaking up under 85℃, there should be stored for a long time stability.
4 It's better composite using of several photoinitiators, it can cause curing in different wavelength ranges. The curing speed is higher than single photo-initiators.
5 The photoinitiator used with the EDAB amine accelerator.
6 Small odor, non-toxic and pollution-free environment.
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