| 摘要 |
PROBLEM TO BE SOLVED: To provide a solid drawing material which uses porous powder comprising particles prepared by tubularly coagulating flaky basic magnesium carbonate fine crystals, has a practical strength, has a color-developing property, when written, can stably be stored without maldistributing an adhesive with the passage of time, when used as solid drawing material together using the adhesive, and has a good masking property, when written. SOLUTION: This solid drawing material comprises porous particles prepared by tubularly coagulating flaky basic magnesium carbonate fine crystals. The porous particles preferably have an outer diameter of 1 to 20μm, a length of 5 to 200μm, a length/outer diameter ratio of 2 to 50, an inner diameter of 0.5 to 5μm, a specific surface area of 70 to 200 m<SP>2</SP>/g by a BET method, Mohs hardness of 2 to 4, a fine pore volume of 5,000 to 12,000 mm<SP>3</SP>/g at fine pore diameters of 0.01 to 100μm in a fine pore distribution measured by a mercury penetration method, and a fine pore volume of 2,250 to 10,200 mm<SP>3</SP>/g at fine pore diameters of 0.5 to 5μm. COPYRIGHT: (C)2005,JPO&NCIPI
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