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Hello everyone, we all know that ink thickness has an impact on LED UV curing efficiency. For thin transparent LED UV coatings or ultra-thin colored coatings, most of the LED UV light penetrating the ink layer reaches the substrate. After reflection, the light travels back to the surface layer, and then reflects off the surface to the substrate again. This process repeats countless times. The higher the LED UV light emissivity of the substrate, the greater the impact on curing and the more favorable it is for the curing process. Aluminum-plated paper, in particular, yields excellent results. Its surface layer receives a large amount of LED UV light reflected repeatedly from the substrate, which significantly accelerates the surface curing rate.

The curing principle of thicker LED UV ink layers differs from the aforementioned mechanism. The Beer-Lambert Law can accurately predict the curing rate at any depth below the surface. As indicated by the Beer-Lambert Law, the light intensity on the surface decays exponentially with increasing depth. The concentration C of light-absorbing substances mainly refers to the concentration of resin: the higher the ink concentration, the more difficult it is to cure; conversely, the lower the concentration, the easier the curing process. The LED UV light absorption coefficient R of liquid materials is primarily determined by the absorption of LED UV light by pigments and photoinitiators. High pigment content and large pigment particles will cause strong absorption of LED UV light, leading to intense attenuation of the light.