| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a ballpoint pen containing an oil-based ink for the ballpoint pen which maintains lubricative properties even under high writing pressure, reduces the abrasion of a ball seat, brings about an excellent writing trace, and has excellent stability with time. <P>SOLUTION: The ballpoint pen has a constitution that a ballpoint pen tip 3 holding a ball 4 rotatably is attached directly or by the medium of a tip holder to the tip of an ink containing cylinder 2. The oil-based ink 7 for the ballpoint pen which contains at least a colorant, an organic solvent, a lubricant composed of an organic acid and phosphoric ester, and organic amine, and shows an ink viscosity of 500-6,000 mPa s (20°C) at a shear rate of 6.8 sec<SP>-1</SP>is held contained in the ink containing cylinder. The ink satisfies 2.5×10<SP>-3</SP>≥Z≥1.0×10<SP>-3</SP>when the writing trace width of the ballpoint pen is denoted by X mm, the consumption amount of the ink per 100 m by Y mg and the quantity of the ink per 1 mm<SP>2</SP>by Z mg/mm<SP>2</SP>, and when a relation of Y=X×10<SP>-5</SP>×Z is established. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
