Patent ID: 7893152

Claim:
A method comprising: reacting a pigment having attached a first chemical group with a second chemical group to form a pigment having attached a third chemical group; providing an acylating agent; and reacting the pigment having attached the third chemical group with the acylating agent, wherein i) the second chemical group reacts with the first chemical group to form the third chemical group, wherein said first chemical group comprises an organic group which comprises at least one electrophile and said second chemical group comprises at least one nucleophile, or vice versa, and the nucleophile reacts with the electrophile, ii) said pigment having attached a first chemical group is prepared by reacting a diazonium salt having the first chemical group with at least one type of pigment to form said pigment having attached a first chemical group, iii) the first chemical group, the second chemical group, and the third chemical group each comprises at least one organic group selected from the group consisting of: acyl azides, isocyanates, ketones, aldehydes, anhydrides, amides, imides, imines, α,β-unsaturated ketones and aldehydes, alkyl halides, epoxides, alkyl sulfates, amines, hydrazines, thiols, hydrazides, oximes, carbanions, and salts thereof, and iv.) the acylating agent is selected from the group consisting of an anhydride of a carboxylic acid and polyacrylic acid.