Addition of copper salts and copper complexes to thermal inkjet inks for kogation reduction

In combination, (a) a low drop volume thermal inkjet pen for jetting ink drops having a volume of 10 picoliters or less and (b) a thermal inkjet ink for inkjet printing comprising at least one colorant and a vehicle, said inkjet ink provided with a copper ion concentration within a range of about 50 to 200 ppm, based on the total ink composition, wherein said copper ion is copper(II).

In combination, (a) a prolonged resistor life thermal inkjet pen for jetting ink drops, said thermal inkjet pen supplied with ink from a separate off-axis reservoir, and (b) a thermal inkjet ink for inkjet printing comprising at least one colorant and a vehicle, said inkjet ink provided with a copper ion concentration within a range of about 50 to 200 ppm, based on the total ink composition, wherein said copper ion is copper(II).

A method of reducing kogation in a thermal inkjet ink for inkjet printing comprising at least one colorant and a vehicle, said method comprising adding to said inkjet ink at least one copper-containing species to provide said inkjet ink with a copper ion concentration within a range of about 50 to 200 ppm, based on the total ink composition, wherein said copper ion is copper(II).