PHTHALOCYANINE BASED INKS WITH ABSORPTION MAXIMA IN THE NEAR INFRA RED AND VISIBLE SPECTRUM

摘要

The invention provides an ink composition comprising a charge generating material and a medium wherein the charge generating material absorbs radiation in both the near infra-red and visible regions of the electromagnetic spectrum. Also provided is an electrophotographic toner composition comprising a binder resin and the charge generating material. The compositions are useful in, for example, security marking wherein the composition is printed on an article or substrate. Methods of establishing the authenticity of an article or substrate are also provided which comprise detecting an absorption of infra-red radiation by the charge generating material.