Patent ID: 7208036

Claim:
A central core type marking pen comprising an ink storage portion of a central core and a pen tip connected thereto, wherein said central core comprises a fiber bundle defining a porous capillary structure, and a metallic ink is contained in said capillary structure within said fiber bundle, said metallic ink comprising: a pigment, said pigment comprising an aluminum pigment whose median diameter is not greater than 7 μm, and a thixotropic agent; comprising at least one selected from the group consisting of polyacrylic acid, polyacrylic acid alkali metal salt, polyacrylic acid organic amine salt and polyol, the pigment settling with time when standing, said metallic ink having a viscosity not less than 45 mPa*s when a stress is 0.01 Pa and a viscosity of not greater than 12 mPa*s when a stress is 10 Pa at a temperature of 20° C.