PROBLEM TO BE SOLVED: To provide an aqueous ink composition for writing materials having no odor, having antibacterial effect also against a drug resistant bacterium, so that microbes hardly proliferate, having low irritancy or low toxicity, so that the composition can be safely used, having a wide application range such that the composition is applicable to writing materials having many opportunities to be exposed to open air, and having excellent preservation stability.SOLUTION: This aqueous ink composition for writing materials is for writing materials comprising a colorant, an antibacterial substance, and water in which as the antibacterial substance, 1,2-benzisothiazoline-3-one and 2-methyl-4-isothiazoline-3-one are used in combination and the total of additive amounts of these antibacterial substances is 200 to 700 ppm.COPYRIGHT: (C)2011,JPO&INPIT【課題】臭気がなく、微生物が繁殖しにくく、耐性菌に対しても抗菌効果があり、刺激性や毒性が少なく安全に使用が可能で、外気に触れる機会の多い筆記具にも使用可能な、適用範囲が広い、保存安定性に優れた筆記具用水性インキ組成物を提供する。【解決手段】着色剤と抗菌性物質と水からなる筆記具用水性インキ組成物において、抗菌性物質として、1,2-ベンズイソチアゾリン-3-オンと2-メチル-4-イソチアゾリン-3-オンを併用し、該抗菌性物質の添加量が併せて200ppm~700ppmであることを特徴とする筆記具用水性インキ組成物。【選択図】なし
