Agfa-gevaert

Andreas Els&auml;sser

Michael D&ouml;rr

Peter Lehmann

Steffen Denzinger

Joan T Vermeersch

Marc Irene Van Damme

Paul J Coppens

Fritz-Feo Grabley

Inge Claes

Cornelia Alba

G&uuml;nther Hultzsch

Klaus J&ouml;rg

The invention relates to a radiation-sensitive recording material for the production of offset printing plates having a dimensionally stable support, a radiation-sensitive layer located on the front of the support, and a layer which comprises an organic polymeric material having a glass transition temperature of 35&deg; C. or above and in which pigment particles are embedded and which is resistant to processing chemicals and is located on the back of the support. The pigment particles are preferably silica gel particles having a mean diameter of from 0.1 to 50 &mgr;m or organic particles having a mean diameter of from 3 to 10 &mgr;m. The image layer on the front may be matted or pigmented. The back coating enables the recording material to be stacked without separating paper. The image layer located on the front is not scratched by the pigmented back coating during storage and transport and during removal from the stack.

Presensitized printing plate with pigmented back coating

The invention relates to a recording material having a substrate and a negative-working, radiation-sensitive layer which contains a diazonium salt, at least one film-forming, polymeric binder and organic colored pigments, on the surface of which an organic polymeric dispersant has been adsorbed and which are additionally dispersed in an organic polymeric binder which does not permanently combine with the pigments chemically or physically. The dispersant generally has groups, in particular primary, secondary or tertiary amino groups or derivatives thereof, which act as anchor groups on the colored pigment particles. The pigments themselves are preferably phthalocyanine pigments. As a result of the predispersing, aggregation of the pigment particles is effectively prevented so that uniform coloration of the radiation-sensitive layer is achieved. During development of the imagewise exposed recording materials, the colored pigment particles form virtually no insoluble precipitates. In the prepared printing plates, the printing parts are distinguished from the substrate material through being clearly visible and having high contrast.

Recording material having a pigment-coloured radiation-sensitive layer

The invention relates to a process for the production of a photosensitive recording material for the production of offset printing plates which comprises a dimensionally stable, two-dimensional support of a metal or metal alloy and a silver halide-containing, photosensitive layer on the front of the support and a layer which essentially consists of an organic polymeric material and is resistant to processing chemicals on the back of the support. The layer on the back of the support is applied before the photosensitive coating on the front. The invention furthermore relates to a corresponding recording material in which the layer on the back comprises at least one organic polymer having a glass transition temperature T of 50&deg; C. or above. Due to the back coating, the formation of local elements between the metallic support and the silver-containing layer is reliably prevented when the recording materials are stacked. Coating flaws during application of the photosensitive coating have been virtually eliminated.

Process for the production of back-coating recording material for the production of offset printing plates

Method for making positive working printing plates from a heat mode sensitive imaging element

A dummy plate is provided for offset printing which essentially consists of a plate-, sheet- or band-form, mechanically and/or electro-chemically roughened, anodically oxidized and optionally hydrophilized aluminium support and a non-photosensitive, water-soluble protective layer applied thereto, characterized in that the layer contains a water-soluble organic compound which contains at least one OH- or NH-acidic group having a pKa value of &lE;8 as acid or salt, and has a layer thickness which is smaller than the average roughness ra of the support material, determined by optical means. Even after extended storage at elevated temperature, the dummy plate can easily be used without an additional development step and exhibits no tendency to stick.

Coated dummy plates

Growing community of inventors

Idstein, Germany

Andreas Elsässer

Growing community of inventors

Idstein, Germany

Andreas Els&auml;sser

Andreas Elsässer