Patent ID: 8002192

Claim:
A printing module for an analog printer, said printing module comprising an ink supply, a printing plate and means for disposing ink from said ink supply onto said plate, wherein said ink comprises an IR-absorbing phthalocyanine dye formulated in a solvent-based or oil-based ink vehicle, said phthalocyanine dye comprising one or more sulfonate groups, wherein a counterion of at least one sulfonate group is a phosphonium cation, and wherein: the or each phosphonium cation is of formula: P + (R m )(R n )(R s )(R t ); each of R m , R n , R s and R t is independently selected from the group consisting of: C 1-30 alkyl, C 5-12 aryl and C 5-30 arylalkyl; and at least one of R m , R n , R s and R t comprises more than 4 carbon atoms.