Agfa Gevaert Nv

Agfa-gevaert

Vickers, Inc.

Other

Dupont (uk) Limited

John Michael Kitteridge

Philip John Watkiss

Allen Peter Gates

Simon John Blanchard

Roland Robinson

Robert J Armstrong

Andrew E Matthews

Stephen Bernard Doyle

Jonathan William Goodin

Malcolm James Mallison

Heat sensitive printing plate precursors

An apparatus is provided for processing a lithographic printing plate precursor comprising an aluminium support, an image-receiving layer and a silver halide emulsion layer. The apparatus comprises a tank for holding a processing liquid, at least one set of driving rollers, at least one guide roller or guide plate and means for providing direct electrical contact between the lithographic printing plate precursor and other electrically conducting surfaces in the apparatus which are in contact with the processing liquid. A method of processing a lithographic printing plate precursor using the apparatus is also disclosed. Undesirable electrochemical cell formation during processing, and the consequent deleterious effects on silver image formation, are prevented and subsequent problems with poor plate run length can therefore be avoided.

Processing method and apparatus for production of lithographic printing plates

The invention provides a lithographic printing plate precursor comprising a grained and anodized aluminium substrate having coated thereon a silver halide emulsion layer, the back surface of said substrate being coated with an inert coating which does not chemically or physically interact with an adjacent silver halide layer when two plates are placed in front to back contact. Fogging of the silver halide layer is avoided and the use of the back coating eliminates the requirement for the use of tissue interleaving when wrapping and packing the lithographic printing plate precursors.

Presensitized printing plates

A wash liquor for use in the decoating of a silver halide diffusion transfer printing plate comprises an aqueous solution containing at least one organic or inorganic acid salt, such as the silicate, metasilicate, tartrate, citrate, hydroxycarboxylate, borate, hexametaphosphate, tripolyphosphate or pyrophosphate of sodium or potassium. The liquor preferably also contains at least one of a non-ionic surfactant, an enzyme and a biocide. A process for the decoating of the said printing plate is also disclosed.

Processing of lithographic printing plate precursors

A wash liquor for use in the decoating of a silver halide diffusion transfer printing plate comprises an aqueous solution containing at least one non-ionic surfactant, such as an alcohol ethoxylate, an alkylphenol ethoxylate or an alkylamine ethoxylate. The liquor preferably also contains at least one organic or inorganic acid salt, and at least one of an enzyme, a biocide and an anti-foam. A process for the decoating of the said printing plate is also disclosed.

Laminates of aluminum and plastic form the substrate of printing plate precursors that are suitable for imaging in conventional roll-fed imagesetters or phototypesetters.

Image formation

A hydrophobic synthetic resin is used to partially or completely replace the hydrophilic colloid conventionally used in silver halide emulsions to obtain a radiation sensitive composition useful in the manufacture of radiation sensitive plates for use in printing plate production by image-wise exposure, tanning development, and washing. The synthetic resin includes a plurality of primary amino groups and optionally acidic groups and is soluble in aqueous or semi-aqueous alkaline solution.

Improvements in or relating to printing plates

A radiation sensitive composition comprises a quaternary ammonium salt and a chemical sensitizer of the formula ##STR1## wherein R.sup.21 is aryl, arylalkenyl or arylalkyl, R.sup.22 is aryl, alkyl, arylalkenyl, arylalkyl, carboxylic acid or salt, or hydrogen and X is carboxylic acid or salt. The quaternary ammonium salt is of the type which will accept at least one electron on exposure to radiation to form a substance capable of causing metal to be deposited onto said substance from an electroless plating solution in contact with said substance and comprising a salt of said metal and a reducing agent. A radiation sensitive plate comprises a metallic substrate coated with a radiation sensitive layer comprising a quaternary ammonium salt. The layer may be formed of the above composition. A lithographic printing plate is produced by image-wise exposing the plate, contacting the plate with an electroless plating solution and, if necessary, rendering the resultant image areas more oleophilic and the resultant non-image areas more hydrophilic.

Lithoplates of quaternary ammonium salt compositions

A radiation sensitive composition comprises a quaternary ammonium salt and a chemical sensitiser of the formula ##STR1## wherein R.sup.21 is aryl, arylakenyl or arylalkyl, R.sup.22 is aryl, alkyl, arylalkenyl, arylalkyl, carboxylic acid or salt, or hydrogen and X is carboxylic acid or salt. The quaternary ammonium salt is of the type which will accept at least one electron on exposure to radiation to form a substance capable of causing metal to be deposited onto said substance from an electroless plating solution in contact with said substance and comprising a salt of said metal and a reducing agent. A radiation sensitive plate comprises a metallic substrate coated with a radiation sensitive layer comprising a quaternary ammonium salt. The layer may be formed of the above composition. A lithographic printing plate is produced by image-wise exposing the plate, contacting the plate with an electroless plating solution and, if necessary, rendering the resultant image areas more oleophilic and the resultant non-image areas more hydrophilic.

Growing community of inventors

Leeds, United Kingdom

John Michael Kitteridge