Patent ID: 6053972
Filing Date: 2000-04-25
Classification: C01P,C08K,C09C,C09D

Abstract:
A process for preparing iron oxide yellow pigments in the .alpha.-FeOOH modification which comprisesa) producing .alpha.-FeOOH seeds by precipitation from an Fe(II)-containing solution using an alkaline precipitating agent in the presence of soluble aluminum salts in an amount of 3 to 9 wt. % calculated as Al.sub.2 O.sub.3, with respect to precipitated .alpha.-FeOOH, with subsequent oxidation to give .alpha.-FeOOH; andb) producing pigment by precipitating further iron with simultaneous oxidation, wherein the seed/time yield is less than 0.3 h.sup.-1 and the pH over the entire period of pigment growth is less than 3.9; andc) terminating pigment growth at a reproduction factor between 3 and 20.