MICROENCAPSULATED PHOTOCHROMIC MATERIAL, PROCESS FOR ITS PREPARATION, AND WATER-BASE INK COMPOSITION PREPARED THEREFROM.

摘要

Improved microencapsulated photochromic material comprises a soln. (1) of a spinooxazine cpd. enclosed in microcapsules. (1) specifically contains a solvent having a b.pt. of 40-160 deg.C and a solubility in water (at 20 deg.C) of up to 15 wt.%. The microcapsules are made of a bridge gelatine-gp. membrane-forming agent. A uv absorbing agent, which absorbs light of wavelength 300 nm or less, is in (1). An antioxidising agent and/or a hindered amine gp. light stabiliser are in (1). The microencapsulated photochromic material is produced by the following process; i) dissolving the spinnooxaine cpd. in a solvent, ii) microencapsulating the soln. and iii) evaporating most of the solvent during or after (ii), to leave only a minute amt. of the solvent. UV absorbing- and/or antioxidising agents are added during (i). The uv absorbing agent can also be added by mixing it in fine particulate form into the microcapsule wall or by dropping it dissolved in a soln. onto the wall. The water-based ink compsn. comprises an aq. medium, a colourant and a vehicle as major components. The colourant comprises microcapsules contg. a soln. of the photochromic cpd. The vehicle is an aq. emulsion. The compsn. has a pH of 5 or more.