PURPOSE: To eliminate the weak points such as aging stability, dry-up resistance, drooling properties, etc., and improve writing performance by incorporating specific intermediate viscosity in an ink cartridge in a barrel and supplying the ink directly to a writing end of the cartridge. ;CONSTITUTION: Thixotropic ink G having a medium viscosity of 500-5000 centipoises at a shear rate of 1.9sec-1 is contained in a cartridge 2 of a capless ballpoint pen in which a writing end 11 of an ink cartridge 2 is telescoped from a front end opening 1a of a barrel by an operation of a writing element telescoping mechanism, and supplied directly to a writing end 11 of the cartridge 2. Thus, when the ink G is steady in the cartridge 2, its fluidity is extremely low. The fluidity of the ink G is obtained by a vibration due to rotation of a ball B at the end 11 in a writing state, thereby embodying a writing state similar to that of normal low viscosity aqueous ink.;COPYRIGHT: (C)1994,JPO
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