METHOD OF PREPARING MICROCAPSULES WITH ORGANIC PHOTOCHROMIC COMPOUND IN POLYMER MATRIX Russian patent published in 1997 - IPC

FIELD: photochromic materials. SUBSTANCE: invention relates to materials with reversible light-influenced changes in spectral characteristics. Liquid photochromic composition is prepared by dissolving photochromic compound in mixture of multifunctional acrylic acid ester oligomers with initiator which mixture is emulsified in aqueous solution of butylacrylate-metacrylic acid copolymer ammonium salt. Emulsion is supplemented by melamine- formaldehyde resin and polyvinyl alcohol and then, simultaneously with formation of cross-linked polymer shells on surface of photochromic composition, two-step radical polymerization of microcapsule nuclei is performed at 68 ± 2 C for 3.5 to 4 h and at 80 ± 2 C for 6 to 6.5 h. EFFECT: improved procedure.