UV LED lamp as a common light source, its curing principle refers to UV inks after UV irradiation is triggered by the photoinitiator, thus generating free radicals or ions. These free radicals or ions and pre-polymers or unsaturated monomers in the double bond cross-linking reaction, the formation of monomer genes, these monomer genes begin to chain reaction to generate polymer solids away from the molecule.
There are several important factors that influence UV LED curing:
Curing material characteristics
The curing speed and effectiveness of UV LED curing equipment is largely dependent on the difficulty of the light to trigger the molecules in the curing materials. UV curing is determined by the collision between photons and molecules. The light causes the molecules to diffuse uniformly through the material. In addition to the characteristics of the curing equipment, the optical and thermodynamic properties of the curing materials and their interaction with the radiant energy have a significant impact on the curing process.
Spectral Absorption Rate
The amount of light energy absorbed by UV coatings as they increase in thickness is called the spectral absorption rate. The more energy absorbed near the surface, the less energy is retained in the deeper layers. However, this situation varies for different wavelengths. The total spectral absorption rate includes the effects of light triggers, monomolecular substances, oligomers, additives and pigments.
Reflection and scatter
Rather than absorption, light energy is affected by the change in direction of the ink, resulting in reflection and scattering. This is generally caused by the matrix materials or pigments in the curable material. These factors reduce the amount of UV energy reaching the deeper layers, but improve the curing efficiency at the reaction site.
Infrared absorption rate and appropriate UV wavelength
Temperature has a significant effect on the speed of the curing reaction, and the temperature rise during the reaction also plays a role. Different UV inks require different UV wavelengths for curing. When selecting a curing unit, it is important to select one that matches the wavelength required by the UV coatings. Using a UV LED curing unit with the correct wavelength will give better curing results.
Post time: Jan-17-2024