Direct evaluation method of UV curing process on the basis of conductivity change of photopolymerization materials

摘要

A novel evaluation methods is proposed for UV curing of photopolymerization materials. The method is based on the measurement of photodecease of the conductivity, which is caused by the photopolymerization of acrylate monomer during the curing process of the ink film. The current changing rate by UV irradiation is in proportion to relative hardness of ink lyer in the surface type cell. The evaluation of sensitivity and curing mechanism of UV curable materials is possible by the measurement of photochange of sample current in either surface or sandwich type cell. The information for non-cured ink layer thickness in the surface type cell can be get from the relationship between the initial thickness and the resistivity of ink layer before UV irradiation. In the case of the sandwich type cell, the curing rate of UV curable resin is in proportion to square root of UV intensity and photoinitiator concentration, respectively. These results satisfy the theoretical equation of the photopolymerization.