Sumitomo Chemical Company, Limited

Hiroshi Okayasu

Taira Fujita

Yoshiaki Hayashi

Toshiaki Kishimoto

Dioxazine violet pigment clear in color hue, high in tinting strength and good in dispersibility, which is suitable for ink, is prepared by treating a crude dioxazine violet with sulfuric acid (to finer it) and then treating an aqueous suspension of the resulting dioxazine violet in coexistence of an alcohol and an inorganic salt.

Process for producing dioxazine violet pigment

Copper phthalocyanine pigment which is a coloring material for ink or paint is prepared by allowing, for example, phthalate, urea, and cuprous chloride to react in a hydrophilic solvent in the presence of a catalyst and at least one element selected from the group consisting of aliphatic tetracarboxylic acids, benzophenone 3,3',4,4'-tetracarboxylic acid or anhydride thereof, pyromellitic acid or anhydride thereof, copper phthalocyanine sulfonic acids, copper phthalocyanine carbonyl imide, tetrahydrophthalic acid or derivative thereof, pyromellitic imide or derivative thereof, sulfophthalic acid, derivative thereof or the salt thereof and benzene carboxylic acid.

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Osaka, Japan

Hiroshi Okayasu