| 摘要 |
PURPOSE:To obtain a glas lens which is colorless and transparent during ordinary use, having a hidden mark capable or being easily seen independently of time and place by baking water glass on a part of the surface of a lens. CONSTITUTION:The surface of a glas lens is marked with a 0.1-20wt% aqueous soln. of water glass consisting of 1mol Na2O and 1-5mol SiO2, and is backed at a temp. 100 deg.C below the glass transition temp. The resulting hidden mark on the lens undergoes no change in the mark performance even if covered with a reflection preventing film, it is not made unclear even after long-time use under severe conditions, and it can be recognized by expiration or reflected light. |
