Characterization of unreacted residues in UV and EB varnishes

Purity and the possibility of making UV and EB coatings with very low levels of extractables is becoming more and more important. The influence of the photoinitiator systems and the structure of the products on the purity of the UV— coatings was studied. It was shown that very low levels of unreacted materials can be obtained. In EB, the influence of the cure dose on the quantity of extractables was investigated. Using the right materials and the correct dose, coatings with very low levels of extractables were achieved. In both UV and EB it was possible to make coatings giving no acrylated materials in the extractables.