Water developable lithographic printing plate having dual photosensitive layering
US4104072A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 1977 |
| Grant date | Aug 1, 1978 |
| Priority date | — |
| Expiry date | May 19, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/095
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method for producing a water developable lithographic printing plate which comprises treating at least one surface of a metal sheet substrate with a layer of a lithographically suitable, light sensitive, water soluble substance and subsequently coating the thus treated base sheet with an upper layer of a water insoluble, ink receptive, lithographically suitable photosensitive composition. Said photosensitive layers must be either both positive working or both negative working. Upon imagewise exposure through a mask by standard methods the exposed areas of said upper photosensitive composition are alternatively characterized as either water permeable or water impermeable and the unexposed areas are alternatively water impermeable or water permeable as opposed to the exposed areas. Upon said imagewise exposure, the exposed lower level areas in a negative system are rendered water insoluble whereas the exposed lower level areas in a positive system are rendered more water soluble than the unexposed areas.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.