| 摘要 |
<p>An initially erasable ink composition for a ball point writing instrument which ink is characterized by its initial erasability by ordinary pencil erasers when applied by a ball point writing instrument to an absorbent paper-like writing surface and which thereafter develops permanence. The ink composition comprises an elastomer selected from the group consisting of natural rubbers, synthetic rubbers and mixtures thereof, pigment, and a solvent system for said elastomer and pigment. The elastomer is present in the range of about 18-28% by weight of the ink and the pigment is present in the range of about 10-22% by weight of the ink. The solvent system comprises a volatile component present in the range of about 8-30% by weight of the ink and having a boiling point less than about 180 DEG C. and an essentially non-volatile component which is predominantly a low viscosity hydrocarbon oil, essential oil, petroleum derivative, plasticizer or mixtures thereof having a boiling point less than about 300 DEG C. and greater than about 180 DEG C. being present in the range of about 21 to 50.5% by weight of the ink. The solvent system may also include up to 15% by weight of the ink composition of a non-volatile high viscosity material having a boiling point greater than about 300 DEG C.</p> |
