Photoyellowing and discolouration of UV cured acrylated clear coatings systems: influence of photoinitiator type

The discolouration and yellowing of acrylated coating films after photocuri ng with a broad range of photoinitiators have been measured by colorimetry with the CMC (CIELab) system. The yellowing of the photoinitiators was eval uated and related to the chemical structure of the photoinitiator fragments and to the unreacted photoinitiator itself. The total colour difference wa s related to the type of chromophoric substitutent in the basic structure o f the photoinitiator. The implications of these results are discussed in re lation to clear coats. (C) 1999 Elsevier Science Ltd. All rights reserved.