| 摘要 |
PROBLEM TO BE SOLVED: To produce the pigment appropriately used for coating a base material for printing by preparing pigment grains each consisting of a calcium carbonate porous crystal which is provided with a single crystal frame surrounding open spaces formed as pores and has a specified specific surface area. SOLUTION: In this production, the preparation of pigment grains comprises subjecting solid calcium oxalate maintained at about 0 to 40 deg.C beforehand to heat treatment for about 1 to 10 hr to heat the solid calcium oxalate to a target temp. (about 580 deg.C) and then, gradually cooling the heated solid material to prepare porous calcium carbonate grains, wherein: water of crystallization of the solid calcium oxalate beings to be separated from the solid material at about 100 deg.C and is released as water vapor and the water of crystallization is removed from the solid material at about 160 deg.C; when temp. of the solid material is raised to about 440 deg.C, carbon monoxide is released from the solid material; and further, carbon dioxide is released from the resulting solid material at about 580 deg.C. Thus, the objective calcium carbonate pigment composed of porous crystal grains each consisting of a calcium carbonate porous crystal which is provided with a single crystal frame surrounding open spaces formed as pores and has a >=5 m2/g specific surface area, can be produced. |
