NOVEL AZO LAKE PIGMENT, PRODUCTION THEREOF AND PRINTING INK CONTAINING SAME

摘要

NEW MATERIAL:A novel polymorphic crystal of 3-(2-hydroxy-1-naphthylazo)-6- methylbenzenesulfonic acid strontium salt giving an X-ray diffraction pattern exhibiting strong lines at Bragg angles (2theta+ or -0.2 deg.) of 9.5, 18.8 and 28.8 deg.. USE:A red colorant for indelible printing ink for the printing of various instruments. The content of the compound in the ink composition is usually about 5-50wt%. PREPARATION:The crystal can be produced by stirring strontium salt of 3-(2- hydroxy-1-naphthylazo)-6-methylbenzenesulfonic acid in a polar organic solvent (preferably acetone, etc.) at a temperature between normal temperature and the boiling point of the solvent and subjecting the mixture to filtration, drying and pulverization.