Patent ID: 8362130

Claim:
IR-absorbing ink for an engraved steel die printing process, comprising: a polymeric organic binder and an IR-absorbing material, said ink having a pasty consistency with a viscosity value at 40° C. of at least 3 Pa·s, wherein said IR-absorbing material comprises a transition element compound, and wherein infrared absorption of the IR-absorbing material is a consequence of electronic transitions within the d-shell of transition element atoms or ions, said IR-absorbing material is present in a concentration from 10% to 50% by weight of the ink, and contains IR-absorbing transition element atoms or ions at a concentration of at least 10% by weight, and absorbs in the near infrared range (700 to 1100 nm), and has a CIE (1976) diffuse reflectance lightness (L*) value greater than 70 as measured on the neat powder, and is transparent in some range between 1100 and 2500 nm.