Ballpoint pen
AssigneeKabushiki Kaisha Pilot Corporation
InventorsYusuke Sanada, Hidenori Kudou, Takeshi Fujii
Life of this patent
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Abstract
A ballpoint pen. In the ballpoint pen, an 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. A ball has a ball diameter of 0.5 mm or less. A tip distal end portion includes a first swaged portion and a second swaged portion. The first swaged portion has an inclination angle with a range of 90 degrees to 100 degrees inclusive. The second swaged portion is provided closer to a distal end side of a ballpoint pen tip than the first swaged portion and has an inclination angle with a range of 110 degrees to 130 degrees inclusive. An angle of a bottom wall of a ball holding chamber is the same as the inclination angle of the second swaged portion.
Claims7
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.
Dependencies are inferred from the claim text.