Agfa Gevaert Nv

Agfa-gevaert

Johan Hubert Van Hunsel

Joan T Vermeersch

Jacobus Herman Bosschaerts

Marc Irene Van Damme

Paul A Delabastita

Robert Theodoor Overmeer

Paul A Mortelmans

Jan Van Cauwenberge

Bart J Verlinden

Guido I Hauquier

Dirk Franky Kokkelenberg

Jos A Vaes

Peter Hendrikx

Marc P Stevens

Franciscus Heugebaert

Katrien Daels

Johan Vermeersch

Fred William Marland

Fred Marland

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

According to the present invention there is provided a method for lithographic printing comprising the following steps:

Method for lithographic printing by use of a lithographic printing plate

A printing master 12 is described which includes a printing element and a base 33, characterized in that base 33 is provided with one or more strain gauges 31 and electric connections for measuring electric resistance. In a preferred embodiment, the printing element is a plate having a printing surface 35, of which the back side 37 is laminated to base 33. The printing master 12 may have an optional adhesive layer 36 and/or protective layer 32. The registration of the printing master can be adjusted conveniently and accurately by measuring the resistance of the strain gauges.

Printing master comprising strain gauges

A visual control strip for imageable media such as a printing plate, a photographic film or a printable substrate is described wherein the visual control strip is to be applied to the imageable medium. The control strip includes a plurality of first control fields having differing grey tone values which are relatively insensitive to the processing variables which influence the size of the spots or dots produced on the imaged medium. The control strip also includes at least one second control field which is relatively sensitive to these process variables. The second control field is located immediately adjacent to the first insensitive control fields for ease of comparison. The second sensitive control field has a target grey tone value which may typically be 25%, 50% or 75%. To improve assessment of exposure parameters, the insensitive fields are completely surrounded by a sensitive field or vice versa. Methods of using the strip are also described for both traditional or photomechanical and digital reproduction methods.

Visual control strip for imageable media

According to the present invention there is provided a method for making a lithographic printing plate comprising the image-wise exposure of a heat-sensitive imaging element with a laser and developing said imaging element by rinsing it with plain water or an aqueous solution. To improve ink-uptake the imaging element is exposed on an external drum recorder whereby the pixel dwell time of the laser is above 0.1 .mu.s

Method for making an lithographic printing plate with improved ink-uptake

A method for generating on a lithographic printing plate a screened reproduction of a contone image, comprising the steps of: (1) transporting a thermo-sensitive imaging element through an exposure area; (2) scanwise exposing the thermo-sensitive imaging element according to screened data representative for tones of a contone image with a set (s) of radiation beams (b) as the thermo-sensitive imaging element is transported through the exposure area, characterized in that at any given moment (ta+.DELTA.t) during the exposure at least two radiation beams (bi,bj) of the set of radiation beams impinge on different microdots (ma, ma+.DELTA.m) of a scanline (1a) on the imaging element, so that by completion of the exposure step each effective microdot of the scanline has been impinged by all effective radiation beams of the set.

Producing a lithographic printing plate by sequentially exposing a

According to the present invention there is provided a method for making a lithographic printing plate comprising the steps of:

On the press development of a diazo based printing plate

A method for generating a screened reproduction of a contone image comprises the steps of screening the contone image to obtain screened data representative for tones of the contone image and suitable for driving exposure of microdots on a radiation sensitive imaging element; exposing the microdots according to the screened data by at least one set or plurality (p) of radiation beams (b), characterized in that at a point in time (t) at least two radiation beams of the set of radiation beams impinge on a particular microdot (m) of a scanline (l). In particular is described a method for making a lithographic printing plate comprising the abovementioned steps.

Halftone reproduction by single spot multibeam laser recording

In order to improve the printability of a periodic halftone screen, the amount of growth of the halftone dots in a halftone screen is modulated as a function of tone in a tone selective way that is different for at least two halftone dots.

Halftone screen and methods for making and using the same

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

There is provided a method for making a lithographic printing plate according to the DTR-process from a printing plate precursor comprising on a hydrophilic surface of a support in the order given a layer of physical development nuclei and a silver halide emulsion layer from an original containing continuous tones comprising the steps of:

Method for making a lithographic printing plate with frequency modulated

A modulated writing light beam (18) having a wavelength to which an imaging element (33) is sensitive and a reference light beam (46) having a wavelength to which the imaging element (33) is insensitive are generated and simultaneously directed to a moving optical device (22) to cause the writing light beam (18) to scan across the surface of the imaging element (33) in a first scanning direction (C) and the reference light beam (46) to scan across the surface of a light detecting element (50) in the first scanning direction (C) to generate signals indicative of the position of the writing light beam (18) on the surface of the imaging element (33). The writing light beam (18) is modulated and the imaging element (33) is moved in a second scanning direction (B) in response to the signals generated by the light detecting element (50). Thereafter the exposed imaging element (33) is processed to prepare a lithographic printing plate. The invention is applicable to both positive and negative imaging working systems.

Method for preparing a lithographic printing plate

There is provided an imaging element having a flexible support and comprising on said support a photosensitive layer comprising a silver halide emulsion and an image-receiving layer comprising physical development nuclei, said layers being in water permeable contact with each other, characterized in that said flexible support is a polyester film having a thickness between 0.15 and 0.35 mm and consisting of polyethylene 2,6-naphthalenedicarboxylate. There is also provided a method for making a lithographic printing plate comprising the steps of image-wise exposing an imaging element as defined above and subsequently developing a thus obtained imaging element by an alkaline processing liquid in the presence of developing agent(s) and silver halide solvent(s).

Imaging element with a flexible support and method for making a

The present invention provides a method for lithographic printing comprising the following steps: preparing a lithographic printing plate according to the silver salt diffusion transfer process by (1) image-wise exposing an imaging element comprising on a support a photosensitive layer comprising a silver halide emulsion and an image receiving layer containing physical development nuclei in water permeable relationship with said emulsion layer, (2) developing said imaging element in the presence of developing agent(s) and silver halide solvent(s) using an alkaline processing liquid and (3), if said emulsion layer is overlying said image receiving layer, removing the layers overlying said image receiving layer, mounting said lithographic printing plate to a lithographic printing press, and printing while supplying to said lithographic printing plate a dampening solution and a printing ink characterized in that the dampening solution as used on the printing plate contains less than 1.0 g/l of a transparent pigment with an average grain diameter of less than 0.1 .mu.m and at least 0.35 g/l of a clay incorporating an inorganic polyphosphate peptiser.

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Hasselt, Belgium

Johan Hubert Van Hunsel