Patent ID: 7279512

Claim:
A water-based ink composition for a ballpoint pen characterized by comprising at least colored resin particles which have an average particle diameter of 2 to 20 μm and which are non-thermoplastic in a proportion of 5 to 30% by weight based on the total amount of the ink composition, non-colored particles having a glass transition point of lower than −10° C. and an average particle diameter of 0.01 to 2 μm in a proportion of 0.1 to 10% by weight based on the total amount of the ink composition and at least one selected from the group consisting of ethylene oxide or propylene oxide adducts of glycerin and ethylene oxide or propylene oxide adducts of diglycerin in a proportion of 1 to 30% by weight based on the total amount of the ink composition, wherein a viscosity value at 1 rpm which is measured under the condition of 25° C. by means of an EMD viscometer falls in a range of 100 to 1500 mPa·s.