NON-SILKING YELLOW IRON OXIDE PIGMENT HAVING HIGH COLOR CONCENTRATION

摘要

PROBLEM TO BE SOLVED: To obtain a non-silking yellow iron oxide pigment having a low silking index and a high color concentration. SOLUTION: This yellow iron oxide pigment having <5 silking index in anα-FeOOH transformation is obtained by (a) producing theα-FeOOH by precipitation from a Fe(II)-containing solution using an alkali precipitant in the presence of 3-9 wt.% calculated as Al2 O3 based on theα-FeOOH to be precipitated of a soluble aluminum salt, followed by oxidation to anα-FeOOH species, (b) further precipitating iron with simultaneously oxidizing to grow a pigment in which a species/time yield is 0.3-1 hour and the pigment is grown in the whole period at pH <3.9. and (c) stopping the pigment growth at 3-20 reproduction factor.