abstract |
Process for the preparation of a 4,4 ', 7,7'-tetrachlorothioindigo pigment, characterized in that a finely divided, 4,4', 7,7'-tetrachlorothioindigo crude pigment in anhydrous form with a nitroaromatic which is volatile in water vapor and has a melting point of 50 ° C or below under normal conditions, treated at temperatures of 50 to 180 ° C. |