Agfa Gevaert Nv

Agfa-gevaert

Paul A Mortelmans

Johan Hubert Van Hunsel

Raphael K Van Poucke

Freddy Carolus Baeyens

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&equals;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 m /g.

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

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 in an amount between 1 g/l and 30 g/l, characterized in that said concentrated dampening solution further contains a total concentration of citrate anions between 0.5 mmole and 25 mmole/l.

Concentrated dampening solution with citrate anions for printing with a

A method is described for preparing an .alpha.-substituted-.alpha.-acylacetamide wherein an .alpha.-acyl-.alpha.-halo-acetamide is allowed to react with an organic compound with pKa between 7 and 12 in a medium of an aprotic solvent and in the presence of a tetraalkylguanidine as basic condensing agent.

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Wilrijk, Belgium

Paul A Mortelmans