| abstract |
A microencapsulated photochromic material, a process for its preparation, and a water-base ink composition prepared therefrom are disclosed. The microencapsulated photochromic material comprises a solution of a spirooxaz- ne compound enclosed in microcapsules. The process for preparing the microencapsulated photochromic material comprises dissolving the spirooxazine compound in a solvent having a boiling point of 40 to 160°C and a solubility in water (at 20°C) of up to 15 wt %, microencapsulating the solution, and evaporating most of the solvent during or after the microencapsulating step, thus leaving only a minute amount of the solvent. The water-base ink composition comprises an aqueous medium, a colorant and a vehicle as major components, said colorant being the microcapsules containing the solution of a photochromic compound, said vehicle being an aqueous emulsion resin, and said composition having a pH of 5 or more. |