| 摘要 |
PROBLEM TO BE SOLVED: To provide a retractable ball-point pen which does not leak ink from the tip of a ball-point pen tip, even when the ball-point pen tip is held downwardly and also is free from an ink swallow which causes the ink to flow back from the interior of the ball-point pen tip to an ink storage barrel side during ejecting the ball-point pen tip or by an impact generated when the pen falls and ensure the reliable writing performance, in the retractable ball-point pen of such a type that the ink storage barrel is directly filled with the aqueous ink. SOLUTION: A ball-point pen tip 7 is arranged on the tip of an ink storage barrel 8. Behind the ball-point pen tip 7, an ink passageway 12 for limiting an ink flow rate is linearly provided. The ink passageway 12 is formed in such a way that the sectional area of the smallest sectional area part of the ink passageway 12 is at least 0.4-0.8 mm2. The ink storage barrel 8 is directly filled with an aqueous ink whose viscosity at 1.9 sec-1 shear rate under measurement environments at 20 deg.C is 900-2,500 mPa.s.
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