METHOD FOR MANUFACTURING INK COMPOSITION FOR OFFSET PRINTING AND INK COMPOSITION FOR OFFSET PRINTING OBTAINED BY THE MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing an ink composition for offset printing with which productivity can be greatly increased compared to a conventional method while using neutral carbon black, and the increase in manufacturing cost can be suppressed while a printed product obtained by printing has almost the same printing quality as that of an ink composition using acidic carbon black.

SOLUTION: The method for manufacturing an ink composition for offset printing includes: a process of stirring a mixture of neutral carbon black and an aqueous solution of oxoacid of the concentration of at least 0.3 mol/L at a temperature equal to or above 25°C to prepare acid treated carbon black by acid treating the neutral carbon black; a process of stirring by adding an oil resin varnish to the acid treated mixture to transfer the acid treated carbon black from a water phase to an oil resin varnish phase in order to prepare a base composition for an ink for offset printing; and a process of dehydrating after removing oxoacid by washing the base composition of the ink for offset printing with water.

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