Free Radical Photoinitiator

Free Radical Photoinitiators are a class of chemicals that initiate free radical polymerization reactions under ultraviolet (UV) or visible light. Free radical photoinitiators can be roughly divided into carbonyl compounds, dyes, metal-organic compounds, halogen-containing compounds, azo compounds and peroxy compounds according to their structural characteristics. Free radical photoinitiators mainly include benzoin and its derivatives, benzoyl derivatives, dialkoxyacetophenones, α-hydroxyalkylphenones, α-aminealkylphenones, and acylphosphine oxides. Benzophenone and its derivatives, thioxanthones, anthraquinones. They undergo chemical reactions when exposed to light, producing free radicals that initiate the polymerization process of monomers or prepolymers. This polymerization process is used in coatings, inks, adhesives, 3D printing, glues, printing inks and a variety of other applications.

Free radical photoinitiators have a wide range of applications and are used in a variety of industries, including coatings, inks, printing, adhesives, polymer preparation, medical devices, electronics, woodworking, etc. Their efficiency, speed, and low volatile organic compound (VOC) emissions make them a key component in many photocuring and photochemical reactions. Selection of an appropriate free-radical photoinitiator generally depends on the desired curing conditions, reaction rate and materials used.

F: What are some suggestions for free radical initiators?

Q: The free radical-initiated system has a fast curing speed, but the shrinkage is large. However, during cationic light curing, the volume shrinkage is small, the bonding force is strong, and it is not easy to be inhibited by oxygen, but the curing speed is slow. Therefore, it is recommended to combine free radical and cationic light curing. The initiators are formulated into a mixed system to complement each other's strengths and have a synergistic effect.