| 摘要 |
<p>PURPOSE:To obtain a marking ink compsn. for a writing board which compsn. is excellent in pigment storage stability, particularlly little in a decrease in concn. even when stored in a marking penholder set upward, and excellent in erasability not only at the initial stage but also after the lapse of time. CONSTITUTION:A polyvinyl butyral resin and a pigment are used in combination with a lower aliph. alcohol, a fatty acid ester, and particularly a polyoxyethylene-polyoxypropylene-castor oil in the form of a block polymer added thereto as a surfactant additive to prepare a marking ink for a writing board.</p> |
