Image Number 4 for United States Patent #5929135.
This invention provides a ball-point pen suited to low-viscosity aqueous ink. This ball-point pen includes a ball-point pen refill in which an ink reservoir communicates with a tip for holding a tip ball via a joint, wherein the ink reservoir is filled with water type ball-point pen ink containing at least one type of a solvent selected from the group consisting of ethyleneglycol, diethyleneglycol, propyleneglycol, and glycerin in an amount of 5 to 40 wt % of the total ink amount, a crosslinking acrylic acid polymer in an amount of 0.1 to 1.0 wt % of the total ink amount, a pigment in an amount of 5 to 10 wt % of the total ink amount, and the balance primarily consisting of water, and the tip has a spring which in a normal state urges and brings the tip ball into intimate contact with the inner edge of a ball holding portion at the front end of the tip and releases the intimate contact when writing is performed.
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