Abstract: An oil-based ballpoint pen includes: an ink container configured to accommodate an ink composition for the oil-based ballpoint pen, the ink composition containing colorant, alkylene glycol alkyl ether, and polyacrylic resin; and a ballpoint pen tip configured to rotatably hold a ball at one end thereof in an extending direction of the ink container. A ratio of an ink consumption (mg) per writing distance of 100 m to a diameter (mm) of the ball is 30 or more.

Abstract: An oil-based ball-point pen refill includes a ball-point pen tip in which a ball is held, in which the ball-point pen tip is mounted on a leading end of an ink housing cylinder, an ink composition including a coloring agent consisting of a dye, an organic solvent, and polyvinyl butyral resin is housed in the ink housing cylinder, the arithmetic mean roughness of a surface of the ball is 0.1 to 15 nm, the content of the polyvinyl butyral resin is 50 mass % or more based on the total mass of the whole resin, and an ink viscosity is 5000 to 50000 mPa·s. In an oil-based ball-point pen, the refill is disposed in a barrel cylinder. An oil-based ball-point pen ink composition including a specific salt-forming dye, polyvinyl butyral resin, and an aromatic alcohol can be utilized in the refill.

Abstract: [Problem to be Solved] Provided are: an oil-based ball-point pen refill having the excellent concentration of a written trace, excellent performance against ink dripping, and an excellent feeling of writing; an oil-based ball-point pen using the oil-based ball-point pen refill; and an ink composition that is preferably used in the oil-based ball-point pen refill and the oil-based ball-point pen. [Solution] An oil-based ball-point pen refill includes a ball-point pen tip in which a ball is held, in which the ball-point pen tip is mounted on a leading end of an ink housing cylinder, an ink composition including a coloring agent consisting of a dye, an organic solvent, and polyvinyl butyral resin is housed in the ink housing cylinder, the arithmetic mean roughness of a surface of the ball is 0.1 to 15 nm, the content of the polyvinyl butyral resin is 50 mass % or more based on the total mass of the whole resin, and an ink viscosity is 5000 to 50000 mPa·s.

Abstract: A reversal magnetic display panel where the numbers of writes/erases repeated until the micro magnets in a dispersion liquid sealed in multiple small cells formed between substrates sediment in the lower part of the small cells by repeated writes/erases when the reversal magnetic display panel is used in a vertical position are increased and a favorable display/erase performance is achieved. Between substrates, a dispersion liquid containing a dispersion medium and a thickening agent as main components and further containing micro magnets the both sides of each of which are differently colored are sealed in. Writing is constituted by difference in contrast between the color of the reversed micro magnets and the color of the non-reversed ones. Hollow particles are mixed with the micro magnets so as to reduce the ratio of the specific gravity of the micro magnets to that of the liquid. The residual magnetization per unit mass of the micro magnets is 1.0 to 23.