Magnetic ink for ink-jet printers, comprises highly anisotropic ferrite particle coated with water-soluble organic compounds such as acids and electrolyte that are soluble in organic compounds miscible with water

摘要

A magnetic ink (I) for ink-jet printers, comprising a carrier fluid containing water and water miscible organic solvent, dispersed magnetic solid particles (II) and other known components is characterized in that the magnetic particles comprise highly anisotropic ferrite with a particle size of 5-30 nm coated with water-soluble organic compounds such as acids and electrolyte (III) that are soluble in organic compounds miscible with water. An independent claim is included for a process for the production of magnetic particles (II) comprising mixing and dissolution of Me(II) salts and Fe(III) salts in a molar ratio of 1:1-1:2.5 where Me is Co, Ni or Mn, adjustment of the pH to 9-11 and temperature to 80-110 [deg]C and stirring of the mixture for 1.5-2.5 hours, sedimentation of the resulting Me(II)-ferrite particles and decanting, washing of the sediment, addition of an organic acid or organic electrolyte (III) and stirring for one hour at 50-80 [deg]C, washing of the particles, adjustment of the pH to 6-8, mixing of the resulting dispersion with other known components for ink-jet ink and evaporation of water and solvent to a particle concentration of 3-12 vol. %.