FIELD: dyes and pigments.
SUBSTANCE: invention relates to a method for preparing an aqueous dispersion wherein water-insoluble dye is dispersed stable in an aqueous medium containing water and that is used as ink, respectively. Invention describes an aqueous dispersion comprising particles including water-insoluble dye and a polymeric compound or surface-active substance wherein its hydrophilic moiety is formed by at least one group taken among the group consisting of carboxyl, sulfonic, phosphorus, hydroxyl and alkylene oxide group. Particles are dispersed in water-containing medium and dispersion shows intensity of light scattering 30000 imp/s, not above, when it comprises sufficient amount of particles and to provides value of absorption peak with respect to visible light = 1 and particles give the same color as a water-insoluble dye in crystalline state. Also, invention relates to a method for its preparing involving the following stages: (1) preparing a solution containing water-insoluble dye and a dispersing agent dissolved in aprotonic water-soluble organic solvent in the presence of alkali; (2) mixing the solution with water and preparing the dispersion containing particles comprising water-insoluble dye and dispersing agent. Also, invention describes particles comprising water-insoluble dye and polymeric compound or surface-active substance wherein its hydrophilic moiety is formed by at least one group taken among the group consisting of carboxyl, sulfonic, phosphorus, hydroxyl and alkylene oxide group provides the same color as water-insoluble dye in crystalline state and having colored moiety with water-insoluble dye and non-colored moiety wherein non-colored moiety exists in the round region with radius 40 nm and wherein its center is the required point in a particle. Also, invention relates to a method for their preparing that involves the following stages: (A) preparing an aqueous dispersion; (B) formation of aggregate consisting of dispersion particles and isolation of aggregate from the dispersion; (C) conferring to particles in aggregate the capacity for repeated dispersing and wherein the stage (B) involves sub-stage of addition of acid to the dispersion to form aggregate, and the stage (C) involves sub-stage of treatment of aggregate with alkali to confer particle in aggregate the capacity for repeated dispersing, and ink containing particles described above. Proposed ink provides printing with excellent quality by color and clearness that are resistant to water and light.
EFFECT: improved preparing method, improved and valuable properties of dispersion and ink.
19 cl, 16 tbl, 1 dwg, 24 ex
