| 摘要 |
PURPOSE:To produce columnar CaCO3 having calcite type crystal structure advantageously in industrial scale by adding a specified compd. when gaseous CO2 is allowed to react with Ca(OH)2 by a contact reaction of gas with liquid and aging obtd. CaCO3 slurry. CONSTITUTION:In a gas/liquid reaction of CO2 with Ca(OH)2 to form CaCO3, at least one among Mg salts (e.g. MgCl2, MgCO3, etc.) and chlorine compds. (e.g. NaCl, ZnCl2, etc.) is (are) added before completion of the carbonating reaction, and obtd. CaCO3 slurry is then aged. Thus, calcite type columnar CaCO3 is produced advantageously in an industrial scale. When the obtd. CaCO3 is used as coating pigment for white printing paper, the gloss of the coated paper before and after printing, the ink receptivity, and the viscosity of the coating material at high speed shear plane are all satisfied at the same time. When the CaCO3 is used for filler for tissue paper, expensive TiO2 is saved because the CaCO3 has superior opacity and whiteness as compared to conven tional spindle-shaped CaCO3.
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