RED IRON OXIDE PIGMENTS WITH IMPROVED COLOR PARAMETERS Russian patent published in 2019 - IPC C01G49/06 C09C1/24 C08K3/22 C08K3/13 C09D7/61 B82B3/00 B82Y30/00 

FIELD: chemistry.

SUBSTANCE: invention can be used in paint industry, in production of construction materials, polymers, paper. Hematite pigment is characterized by that sum of values of a* in lacquer testing in pure colour tone and in the bleach ranges from 58.0 to 61.0 CIELAB units, pigment particle size ranges from 0.1 to 0.3 mcm, and water content in pigment 1.0 wt. % and more. Method of producing hematite pigments involves reacting iron, a suspension of hematite nucleation nuclei, and a solution of iron (II) nitrate in the presence of at least one oxygen-containing gas at temperatures of 70 to 99 °C. Hematite crystallisation nuclei are characterized by particle size of 100 nm or less and measured according to DIN 66131 specific BET surface area of 40 to 150 m²/g. Interaction is carried out during saturation with oxygen-containing gas at pH in range from 2.2 to 4.0.

EFFECT: invention increases intensity of colour tone of red iron oxide pigment.

14 cl, 4 dwg, 3 tbl, 2 ex