| 摘要 |
PROBLEM TO BE SOLVED: To obtain a pigment composition hardly causing the shortage of print density or the turbulence of dot shape and capable of excellently dispersing pigment in a toner by kneading a pigment and a resin and dissolving, then freeze-pulverizing them and dispersing in a non-aqueous solvent. SOLUTION: This pigment composition is produced by freeze-pulverizing after kneading the pigment and the resin and dissolving and dispersing in the nonaqueous solvent. First, the pigment and the resin are kneaded. At this time, it is preferable that the resin is pulverized and the coarse particles are removed previously. For example, the resultant kneaded material is sufficiently cooled with solid carbon dioxide or liquid nitrogen, then is freeze-pulverized into <=1000μm, preferably <=500μm by a pulverizer. Next, the pulverized material is dissolved and dispersed in the nonaqueous solvent. The purpose of the pulverization is to crack and pulverize the hardened granule of the resin or the undispersed lump of the pigment produced in kneading and to facilitate the dissolution and the dispersion in the nonaqueous solvent by finely powdering the whole kneaded material.
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