Hoechst Aktiengesellschaft

Agfa-gevaert Ag

Agfa Gevaert Nv

Agfa-gevaert

Agfa-gervert

Klaus Joerg

Rudolf Zertani

Andreas Elsaesser

Werner Frass

Hermann Idstein

Otfried Gaschler

Uwe Gartmann

G&uuml;nter Hultzsch

Georg Haby

J&ouml;rg Kaden

Joan T Vermeersch

Dieter Mohr

Dirk Franky Kokkelenberg

Franz Durst

Peter Lehmann

Guenter Hultzsch

Philip John Watkiss

Raimund Haas

Klaus Rode

Hans W Frass

Rudolf Neubauer

Ernst-August Hackmann

Dietmar Koenneke

Guenter Hutzsch

Guenter Brenn

A negative-working lithographic printing plate precursor is disclosed which comprises a grained and anodized aluminum support having a hydrophilic surface and a heat-sensitive coating provided on the hydrophilic surface, the coating comprising hydrophobic thermoplastic polymer particles which are capable of forming a hydrophobic phase in the coating by heat-induced coalescence of the polymer particles. The support is characterized by a surface roughness, expressed as arithmetical mean center-line roughness Ra, which is less than 0.45 &#x3bc;m. The smooth surface enables to prepare a lithographic printing plate from the mentioned precursor, which is characterized by a high run length during printing.

Negative-working thermal lithographic printing plate precursor comprising a smooth aluminum support

To avoid or minimize the occurrence of cross streaks or current streaks on a substrate that is transported through an electrolytic bath and roughened electrochemically in it, the current density is regulated in the electrolyte between a first alternating or three-phase current electrode and the substrate in such a way that at the beginning of a roughening zone, the current density has a lesser value than within the roughening zone, in the transport direction of the substrate. Downstream of the first alternating or three-phase current electrode, either a further alternating current electrode or a further three-phase current electrode acts on the substrate. In a preferred embodiment, the first alternating or three-phase current electrode has a rounded outline, which is composed of a curved portion and adjoining it a straight portion.

Method for electrochemical roughening of a substrate

A method and apparatus for electrochemically roughening a support is disclosed to minimize the occurrence of surface discharges or electrical discharges on the support. A DC voltage acts on the support at the start of the movement of the support through the electrolyte bath. Subsequently, a three-phase or single-phase current acts on the support in the roughening zone. Three-phase electrodes are arranged in the electrolyte bath and are connected to the secondary of a three-phase transformer. The primary of the three-phase transformer is connected, via control transformers to a three-phase power transformer. A DC electrode is located upstream of the three-phase electrodes in the direction in which the support is transported through the bath. The DC electrode may be connected to the positive pole of a DC source while the negative pole of this DC source makes contact with the support.

Method and apparatus for roughening a support for radiation-sensitive coatings

The invention relates to a sheet-like radiation-sensitive recording material whose surface is a discontinuous dulling layer comprising monodisperse particles is present. The dulling layer can be produced by spraying on a dulling liquid. An apparatus comprising an oscillation generator, which can transmit oscillations to the liquid in the apparatus, and has an orifice plate which has at least one hole with a diameter of from 5 to 250 .mu.m and from which the liquid emerges in the form of at least one laminar free jet which disintegrates into monodisperse drops is suitable for this purpose. The oscillation generator is preferably a piezoelectric ceramic.

Dulled radiation-sensitive recording material and process for its

A dummy plate for offset printing comprising essentially a mechanically and/or electrochemically roughened, anodically oxidized and hydrophilized aluminium support in the form of a plate, sheet or band and a non light-sensitive, water-soluble layer coated thereon, and characterized in that the layer contains at least one organic polymer with a water-solubility of at least 2 g/L at room temperature and at least one inorganic compound reacting as an acid.

Dummy plate for offset printing

The invention relates to a non-continuous matte layer that can be used with a recording material having a substrate and a radiation-sensitive layer which contains a 1,2-naphthoquinone-2-diazide and an organic, polymeric binder which is insoluble in water but soluble in aqueous alkaline solutions. This matte layer comprises 100 to 10,000 particles per square centimeter which have a mean diameter of less than 40 .mu.m and a maximum diameter of less than 80 .mu.m and a mean height of 2 to 6 .mu.m and a maximum height of 10 .mu.m, and contains a resin which has up to 0.80 mmol of acid groups and/or salt groups per gram. The matte layer is obtained by spraying on and drying an aqueous, anionically or anionically/nonionically stabilized dispersion of the resin.

Matted, radiation-sensitive recording material and printing plate

A radiation-sensitive recording material, in particular for producing planographic printing plates, is disclosed. The material is composed of a layer support and a positive-working, radiation-sensitive layer having a rough surface containing at least one 1,2-quinonediazide as a radiation-sensitive compound, a polycondensate or polymer as a binder insoluble in water and soluble or swellable in aqueous-alkaline solutions, a dye and a filler. At a layer weight of 3 g/m.sup.2 or less, the radiation-sensitive layer comprises a silicic acid product having a mean grain size in the range from 3 to 5 .mu.m with an exclusion limit of 15 .mu.m as a filler in such a quantity that it exhibits a Bekk smoothness in the range from 20 to 100 seconds (determined according to DIN 53 107, Method A). The layer additionally comprises a surfactant having polysiloxane units. The recording material shows good copying properties and technical printing properties, such as an advantageous evacuation time, screen evenness, low susceptibility to air occlusions, good resolving power and a good coating structure. The invention also relates to a process for producing a planographic printing plated, using the recording material according to the invention.

Radiation-sensitive recording material with a positive-working,

A developer concentrate is described which is used by diluting with tap water to give a read-to-use developer for negative-working exposed reproduction layers on a base. The developer concentrate is a mixture which includes water, an organic solvent, an alkali agent, an anionic surfactant, an n-alkanoic acid and/or its salts, an emulsifier, an alkali-metal salt of an oligomeric phosphate and/or of N-(2-hydroxyethyl)ethylenediaminetriacetic acid as complexing agent and also a tris(hydroxyalkyl) aminomethane as buffering substance. The developer concentrate according to the present invention exhibits, in particular, the advantage that it is stable as a concentrate, i.e., exhibits no phase separations, precipitates or turbidities, etc. . . . , and can be diluted without difficulties to produce the ready-to-use developer. The latter is also stable and exhibits optimum developer properties, in particular for reproduction layers with overcoat.

Developer concentrate and developer prepared therefrom for exposed

A developer concentrate is described which is used by diluting with tap water to give a ready-to-use developer for negative-working exposed reproduction layers on a base. The developer concentrate is a mixture which includes water, an organic solvent, an alkali agent, an anionic surfactant, an n-alkanoic acid and/or its salts, an emulsifier, a buffering substance and, as a complexing agent, an alkali-metal salt of an oligomeric phosphate and/or of N-(2-hydroxyethyl)ethylenediamino-triacetic acid. The developer concentrate according to the present invention exhibits, in particular, the advantage that it is stable as a concentrate, i.e, exhibits no phase separations, precipitates or turbidities, etc., and can be diluted without difficulties to produce the ready-to-use developer. The latter is also stable and exhibits optimum developer properties.

A light-sensitive mixture is described which contains a diazonium salt polycondensation product, a free-radical polymerizable compound having at least one terminal ethylenically unsaturated group and a boiling point at atmospheric pressure above 100.degree. C., a polymerization initiator which forms free radicals under the action of actinic radiation, and, as a first binder, a water-insoluble reaction product which is soluble in organic solvents and in aqueous alkaline solutions, which is a reaction product of an intramolecular anhydride of an organic polycarboxylic acid with a hydroxyl-containing synthetic polymer, and which has no further functional groups capable of reacting with acid anhydrides, and, as a further binder, an acid organic polymer having an acid number above 70, preferably a (meth)acrylic acid copolymer. The mixture is useful for producing planographic printing plates which give long print runs, and is notable for a long shelf life at elevated temperature.

Light-sensitive photopolymerizable and diazonium salt polycondensation

A photopolymerizable mixture is described, which contains a polymeric binder; an acrylate or alkacrylate of a polyhydric alcohol possessing at least one photooxidizable group; a compound or a combination of compounds being capable of initiating the polymerization of the ester under the action of light in the spectral region of 450 nm to 650 nm; and at least one compound which absorbs light in the region below 450 nm or which upon exposure forms a compound absorbing light in said region, whereby the optical density of the exposed mixture in this region is at least 2.0 at a layer thickness of 2 .mu.m. The mixture is useful for the production of masters or intermediate masters for reprographic layers being sensitive to light in the UV region, exposure of the mixture itself being performed with visible light.

Photopolymerizable mixture and recording material prepared therefrom,

A radiation-polymerizable mixture is described which comprises

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Ingelheim, Germany

Klaus Joerg