Concentrated dampening solution with an improved anti-staining activity for printing with a lithographic printing plate obtained according to the silver salt diffusion transfer process
US6436176B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1996 |
| Grant date | Aug 20, 2002 |
| Priority date | — |
| Expiry date | Mar 20, 2019 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41N3/08
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
The present invention provides a concentrated dampening solution for use in a lithographic printing process having a pH between 3 and 6 and comprising a water-soluble organic solvent, a phosphate salt and a transparent pigment, characterized in that said transparent pigment is a modified silica in which the silica particles have a number average size of 0.003 to 0.100 &mgr;m and in which the silica particles are coated with chemically combined atoms of an amphoteric metal which forms an insoluble silicate at a pH between 5 and 12, said metal atoms being chemically bound through oxygen atoms to silicon atoms in the surface of said particles, and the amount of said metal being such that: Gram atoms M/Gram atoms Si=A/1250 to A/250000 where M is the metal and A is the surface area of the particles of the silica sol expressed in m2/g.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.