摘要 |
<p>PIGMENTATION OF CRUDE METAL PHTHALOCYANINES A process for the conversion of crude metal phthalocyanines produced by fusion syntheses into pigments having improved tinctorial strength and transparency is described. The process involves mixing the dry crude metal phthalocyanine with 2 to 5 parts of 82 to 86% sulfuric acid per part of pigment in the crude in the absence of shear to form a paste-like mass and then hydrolyzing the mass under certain conditions using a hot aqueous diluent containing 2 to 15% by weight of pigment in the crude of ammonium hydroxide, tetramethyl ammonium hydroxide or certain amines.</p> |