| 摘要 |
PROBLEM TO BE SOLVED: To improve flashing property during the preparation of a lithography ink, and to obtain an azo lake pigment capable of providing a lithography ink having excellent emulsion fitness, that is, the quantity of emulsion of the ink is reduced, and the ink hardly becomes overemulsification on a printer. SOLUTION: A coupling reaction is carried out by allowing an aqueous suspension containing a polyvalent metal salt of a rosin, and a phenol or a naphthol to directly contact with a suspension containing a diazonium salt of an aromatic amine, or by adding both the suspensions to water. The reaction mixture is subsequently converted into a lake. This process enables the production of an azo lake pigment having higher hydrophobicity in its surface compared with a conventional rosin treating process. The using of an aqueous paste of the pigment obtained by this process can provide a lithography printing ink whose flashing property during the preparation is greatly improved, and which has excellent emulsion fitness, that is, the quantity of emulsion of the ink is reduced, and the ink hardly becomes overemulsification on a printer.
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