| 摘要 |
<p>PROBLEM TO BE SOLVED: To solve the problem that, conventional aqueous ink which is disappeared handwriting with time is unstable since a phthalein indicator is hardly soluble in water or a solvent and hence is deposited with time. SOLUTION: The water-base erasable ink comprises water, a humectant, a phthalein indicator, a propylene glycol monoalkyl ether, and a pH adjustment agent.</p> |
