| 摘要 |
PROBLEM TO BE SOLVED: To obtain a solid fine particle dispersion of a leuco compd. that properly forms a color at the time of development and is excellent also in suitability to processing by making the dispersion as a dispersion of a leuco compd. forming a blue dye or coloring material by development and making the dispersion spherical. SOLUTION: The solid fine particle dispersion is a dispersion of a leuco compd. forming a blue dye or coloring material by development and the shape is substantially spherical. The substantially spherical particles mean that particles having a circularity of 1.00-1.08 defined by L2/4πS (S is the projection area of each particle observed with a transmission type electron microscope and L is the peripheral length) account for >=70%, preferably >=80%, further preferably >=90% of the total projection area of all particles. The solid fine particles are observed on a fluorescent screen in positive contrast to the background in a TEM clear visual field image, that is, in a dark state with low electron beam transmittance and can easily be distinguished from liq. fine particles.
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