Water based ink composition for writing instrument

摘要

Provided is a water-based ink composition for a writing instrument comprising at least a colorant and water, wherein a nonionic high molecular surfactant having an alkylene oxide chain as a hydrophilic group and having an average molecular weight of 3000 to 200,000 is added to the ink composition in a range of 0.1 to 30% by weight. The above nonionic high molecular surfactant has preferably an HLB of 8 or more or a cloud point of 50° C. or higher and includes N-polyoxyalkylene-polyalkylenepolyamine and a polyoxyethylene-polyoxypropylene block polymer.