| CPC B43K 7/10 (2013.01) [B43K 7/02 (2013.01); C09D 11/18 (2013.01); B43K 7/12 (2013.01)] | 7 Claims |
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1. A ballpoint pen comprising a ballpoint pen refill, the ballpoint pen refill including an ink reservoir cylinder and a ballpoint pen tip, an inside of the ink reservoir cylinder being filled with an oil-based ballpoint pen ink composition, the ballpoint pen tip being attached to a distal end portion of the ink reservoir cylinder, wherein
a tip main body of the ballpoint pen tip includes:
a ball holding chamber that holds a ball in a manner of allowing the ball to rotate while causing a part of the ball to protrude from a tip distal end portion;
a ball socket provided on a bottom wall of the ball holding chamber, the ball being placed on the ball socket, the ball socket having a circular-arc surface conforming to an outer shape of the ball;
an ink distribution hole formed in a center of the bottom wall of the ball holding chamber; and
a plurality of ink distribution channels radially extending from the ink distribution hole,
the oil-based ballpoint pen ink composition has an ink viscosity with a range of 500 mPa·s to 15000 mPa·s inclusive at 20° C. and a shear rate of 500 sec−1,
the ball has a ball diameter of 0.5 mm or less,
a sealing surface with a circular-arc shape is formed on an inner wall of the tip distal end portion,
the tip distal end portion includes
a first swaged portion having an inclination angle with a range of 90 degrees to 100 degrees inclusive, and
a second swaged portion provided closer to a distal end side of the ballpoint pen tip than the first swaged portion, the second swaged portion having an inclination angle with a range of 110 degrees to 130 degrees inclusive, and
an angle of the bottom wall of the ball holding chamber is the same as the inclination angle of the second swaged portion.
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