Writing liquid for use with an opaque recording material for forming transparencies for overhead projection and the like
US4252601A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 5, 1978 |
| Grant date | Feb 24, 1981 |
| Priority date | — |
| Expiry date | Jun 5, 1998 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41M5/0029
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Transparencies for overhead projection are formed in which the information to be displayed is in the form of transparent lines, or other geometric patterns, on an opaque background. The transparent lines are formed on an opaque layer of a recording material formed from a clear or colored transparency on which the opaque layer is firmly adhered. The opaque layer is formed from finely divided organic styrene resin pigment uniformly distributed in a film-forming binder resin. The writing liquid is formed from a solvent for the organic styrene resin pigment. When the writing liquid is applied to the opaque layer using a suitable writing instrument, such as a pen, the opaque layer immediately becomes transparent where it is contacted with the solvent. The potential toxicity of the solvent (or solvent vapors) is eliminated and writing speeds may be increased by mixing a chlorofluoroalkane of from 1 to 3 carbon atoms with the solvent.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.