PARTICULATE MAGNETIC HEXAFERRITE PIGMENTS CONTAINING POTASSIUM FROM PRECIPITATED MAGNETITE, PROCESS FOR THEIR PRODUCTION AND THEIR USE

摘要

The present invention relates to finely divided magnetic hexaferrite pigments of the general composition: M(I)1-xKxM(II)yM(III)zFe12-(y+z)O19, in which 0< = x< = 3, 0< = (y+z)< = 3, (x+y+z)> = 1.0 0< = y< = 3; 0< = z< = 3, M(I) is Ba, Sr, Ca, Eu, Pb or a combination of RE and monovalent cations of the group Li, Na, Rb, Cs, Ag, Tl and RE is La, Y, Sc, Bi or other rare earth metals and M(II) denotes Fe(II), Mn, Co, Ni, Zn, Cu, Cd, Mg or Sn(II) and M(III) denotes Ti, Zr, Hf, Ga, Sn(IV), Ge, In, Sc, Nb, Ta, V, As, Sb, Bi, Al, Cr(III), Mo or W, processes for the preparation of these hexaferrite pigments and their use in magnetic recording media.