| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a microcapsule wrapping a diazonium salt therein and exhibiting sharp particle distribution, and a thermal recording material having excellent raw stock preservability using the microcapsule and high color development density at thermal recording. <P>SOLUTION: The microcapsule is obtained by wrapping at least one type of a diazonium salt and having a span value δ of not larger than 0.6 represented by formula; span value δ=¾<SP>90</SP>Dp-<SP>10</SP>Dp¾/<SP>50</SP>Dp (wherein<SP>90</SP>Dp,<SP>50</SP>Dp and<SP>10</SP>Dp each represent a particle diameter when the integrated amount each occupies 90%, 50% and 10% in a cumulative particle size distribution curve). Alternatively, the microcapsule is obtained by film-emulsifying a dispersion phase containing at least one type of a diazonium salt, a poly-functional isocyanate compound and an organic solvent in a continuous phase containing a protective colloid-containing aqueous solution and polymerizing the polyfunctional isocyanate compound, the water solvent degree to the dispersion phase being not larger than 1% at 25°C. The interfacial tension at the interface between the dispersion phase and the continuous phase is preferably not less than 4 dyn/cm. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
