| 摘要 |
PURPOSE: To provide a water-base ink ballpoint pen capable of smoothly writing with a light touch and stably allowing flowing-out of an ink to its last without bringing about an omission even in fast writing of twice or faster than a normal speed, not liable to bring about a dribble or a linear crack and without bringing about a backflow at all even by leaving to stand for with a pen point directed upward in a cap OFF state. CONSTITUTION: The water-base ink ballpoint pen comprises a ballpoint pen tip using a metal fine tube, an ink housing tube, a joint having an ink backflow preventing mechanism for coupling the tip to the housing tube and including a metal ball and a receiving seat, a pseudoplastic water base ink having a viscosity of a shearing speed of 38.4 sec¬-1 of 20 to 600 mPa.sec and viscosity of 384 sec¬-1 of 10 to 120 mPa.sec (at 25°C), and an ink follower having a value of an elastic modulus tanδ of 0.2 to 2.0 (at 25°C) in an overall frequency range of an angular frequency of 0.1 to 650 rad/s filled in the rear part of the ink of the housing tube.
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