Patent ID: 6074466
Filing Date: 2000-06-13
Classification: C09D

Abstract:
A method of manufacturing a water base disperse ink for ink-jet recording, containing a water insoluble or slow soluble colorant, a water soluble dispersant, and a water base dispersive vehicle as essential constituents thereof;said method comprising the following steps (1) through (4):(1) a step of purifying by washing pressed cakes composed of the water insoluble or slow soluble colorant;(2) a step of preparing a dispersion liquid with the colorant in high concentration by mixing the colorant obtained through purification by washing, and various additives for ink, as necessary, with an aqueous solution of the dispersant obtained by dissolving the water soluble dispersant in the water base dispersive vehicle;(3) a step of preparing separately a diluent composed of constituents of the dispersion liquid with the colorant in high concentration, excluding the colorant, and preparing an ink-like disperse liquid through dispersion after mixing the diluent with the dispersion liquid with the colorant in high concentration; and(4) a step of obtaining the water base disperse ink, in an evenly dispersed and stable condition, by subjecting the ink-like disperse liquid to ultrasonic irradiation treatment such that secondary aggregations of particles of the colorant contained in the ink-like disperse liquid are reduced to primary particles as much as possible.