Abstract: In a magnetic display panel that changes the display using a magnet, a polychrome display panel is obtained that magnetically displays two colors in addition to the background, thus, specifically, magnetically displays three colors. The magnetic migration and reversal display panel encloses a dispersion liquid obtained by dispersing micro-magnets with differently colored magnetic poles in a dispersion medium containing a colorant. After writing representing two display colors is obtained by selecting a specified magnetic pole, causing from the front surface side the migration or migration/reversal of the micro-magnets in the dispersion liquid, and displaying the color tone of the specified surface of the micro-magnets, the color tone of writing is changed without changing the state of writing by causing the magnetic field of the opposite magnetic pole to act from the same surface side on the micro-magnets configuring the writing where the color tone is displayed.

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.

Abstract: In a magnetic display panel that changes the display using a magnet, a polychrom display panel is obtained that can magnetically display two colors in addition to the background, specifically, that can magnetically display three colors. The magnetic migration and reversal display panel encloses at least a dispersion liquid obtained by dispersing micro-magnets with differently colored magnetic poles in a dispersion medium containing a colorant.

Abstract: A ballpoint pen contains an aqueous ink composition into which ink is directly filled. The pen is free from ink dripping and has improved writing performance. The aqueous ink composition is directly filled into an ink reservoir tube equipped with a ballpoint pen tip. The aqueous ink composition includes (a) an aqueous medium, (b) a pigment and (c) a carboxyl group-containing crosslinked hydrophilic polymer. The hydrophilic polymer swells and disperses in a gel state in the form of particles having a particle diameter of 0.5 to 10 .mu.m. The polymer is crosslinked with a crosslinkable monomer having at least two polymerizable unsaturated groups in an amount of 0.5 mol % or more based on the total of a carboxyl group-containing monomer and a copolymerizable monoethylenic monomer used together, if desired. The ink reservoir tube tip has a clearance between a ball and a ball receiver in the range of 10 to 40 .mu.m.