The Effect Of Dose Delivery On The Cure Response Of Uv Curable Coatings

Introduction

There are two distinct cross-sectional regions to
consider when irradiating an acrylate functional coating with
UV. energy: the thin layer;of coating at the'air-coating
interface, commonly called the surface; and all the remaining
depth of the coating. In order to obtain a commercially
acceptable level of overall cure, both the surface and body
of a coating must be well cured at high processing speeds.

In order to reach acceptable levels of overall cure, it
is required that the photoinitiator absorb light and produce
radicals efficiently throughout the entire thickness of the
coating. The efficiency of absorbance at a particular
wavelength of light is described by the Beer's law
relationship A= abc, where A is the absorbance, a is the
absorptivity, b is the path length (or depth) of the
radiation, and C is the concentration of the photoinitiator.

The absorptivity, a, is a measure of the probability of
light absorption at each: wavelength (1). The greater the
absorptivity at a certain wavelength, the more efficiently
the photoinitiator will absorb this wavelength.