Abstract: The present invention provides: a highly practical and safe oil-based ink composition for a writing board, said composition being capable of imparting high mark-erasability and having excellent resistance to drying up; and a marking pen incorporating the same. Specifically, the present invention provides: an oil-based ink composition for a writing board, said composition containing a pigment, an organic solvent, a resin, and at least one compound selected from compounds represented by general formula (1) or (2); and a marking pen obtained by incorporating the oil-based ink composition for a writing board. (In the formulae, R1-R4 each represent a C6-18 alkyl group or a C2-18 and O2-10 alkoxypolyglycol group.

Abstract: An ink composition useful in an oil-based ballpoint pen capable of drawing a satisfactory line on the surfaces of various materials to be written which are not only papers but also non-permeable materials such as glasses and plastics as well as fibrous materials such as fabrics is provided. Such a ink composition comprises a colorant, an organic solvent having a vapor pressure of 5.0 to 50 mmHg (20° C.) as a main solvent, such as n-propyl alcohol, isopropyl alcohol and propylene glycol monomethyl ether and a shear-viscosity reducing agent.

Abstract: An ink composition useful in an oil-based ballpoint pen capable of drawing a satisfactory line on the surfaces of various materials to be written which are not only papers but also non-permeable materials such as glasses and plastics as well as fibrous materials such as fabrics is provided. Such a ink composition comprises a colorant, an organic solvent having a vapor pressure of 5.0 to 50 mmHg (20° C.) as a main solvent, such as n-propyl alcohol, isopropyl alcohol and propylene glycol monomethyl ether and a shear-viscosity reducing agent.