At present, ultraviolet UV LED light curing is a type of radiation curing. Radiation curing is realized by electromagnetic radiation, such as ultraviolet (UV) or electron beam (EB) irradiating the coating to produce radiation polymerization, radiation cross-linking and radiation bonding. Wait for the response. A chemical reaction process that quickly converts low-molecular-weight substances into high-molecular-weight products, and the curing is carried out directly on the substrate without heating. The system does not contain solvents or contains a very small amount of solvents, and the liquid film is almost 100% cured after irradiation. As a result, VOC (Volatile Organic Compound) emissions are very low. Since the project has been rapidly developed in various fields, its products have now been widely used and promoted in various fields.
UV LED light curing mechanism:
UV LED light curing system is divided into two major systems: cationic system and free radical system, and the curing mechanism components of the two are different. The cationic system is that the cationic photoinitiator is irradiated to generate a strong proton acid, which catalyzes the addition polymerization and cures the resin, while the free radical system is that the photoinitiator is excited by UV LED irradiation to generate free radicals to initiate the polymerization of monomers and prepolymers. Cross-linking; the following takes the UV radical system as an example:
UV LED radical curing goes through the following steps:
1. Chain termination: In chemical reactions, since free radicals contain uncoupled electrons, they are very active and tend to be coupled with other free radicals or undergo acidification to terminate the chain reaction.
2. After being irradiated by the UV LED, the free radical photoinitiator is excited and decomposed to generate free radicals.
3. Chain growth: the free radicals generated by the resin and monomer can continue to cause the unsaturated double bonds in the resin and monomer molecules to generate free radicals, and carry out a free radical chain reaction.
4. Initiation: The free radicals generated by the initiator initiate the unsaturated double bonds of the resin and monomer molecules to generate new free radicals.
