Modified Kubelka?Munk Optical Treatment of Photon Flux in a Coating and Its Relationship to UV Curing as Measured with a UV N101 Cure Tester
The Kubelka-Munk two flux model predicted significantly different magnitudes of photon flux within the layers of a coating than a model based on the Lambert-Beer law. Equations and calculation methods are described and results are given that illustrate the effect of substrate reflectance, layer thickness and the absorption and scattering of the layer components on the photon flux and the light absorbed at various levels within the coating. The predicted absorbance of a coating that gave the maximum light absorbtion in the layer adjacent to the substrate, increased as the substrate reflectance increased. Reasonable agreement was found between the predicted curing rate behaviour of pigmented printing ink layers and transparent coatings and that measured by a UV N101 cure tester (Swan Instruments, Consett, England).