IMPROVEMENTS IN INK JET INKS

摘要

An ink for an electrostatic printer of the drop on demand type adapted to be operated at a selected frequency of droplet formation. The ink comprises a non conductive liquid, insoluble chargeable marking particles, and a mobility modifier for the particles. The mobility modifier is a compound which is adapted to interact with or be adsorbed onto the chargeable particles whereby to vary the chargeability of the particles and hence a charge to mass ratio of the particles. The invention also includes a method of matching a characteristic frequency of droplet formation of an ink from an electrostatic ink jet apparatus with a required frequency of droplet formation and a method of matching the rate of droplet formation for each point of a multi-ejection point electrostatic printer wherein different colours of inks are adapted to be ejected from selected points and each ink has a different characteristic frequency of droplet formation depending on the characteristics of an insoluble marking particle of the ink and the rheology of a liquid portion of each ink.