EP1354700B1 - Process for handling renewable imageable printing plates or cylinders in printing machines - Google Patents

Description

The invention relates to a method for treating reimageable printing plates or printing forme cylinders in printing presses, wherein the surface of the printing forme / Printing forme cylinder is hydrophilic, on this by means of a jet printer a hydrophobic, imageable layer is applied and then the imaging takes place by means of a Bebilderungseinrichtung or the surface of the printing form / Printing form cylinder is hydrophobic, on this by means of a jet printer a hydrophilic, imageable layer is applied and then by means of a Bebilderungseinrichtung the picture is taken.

From DE 100 39 822 A1 is a method for treating reimageable Printing forms or printing forme cylinders known in printing presses, in which to treating surface is applied an imageable coating and this Coating for generating image information by a laser equipped Bebilderungseinrichtung is energized. In one embodiment According to the invention, this ablatable coating is applied with a jet printer.

This solution has the disadvantage that for the creation of the image motif by the application a laser's energy consumption is high. Removing the residue from The burning process is very complicated.

In order to eliminate these disadvantages, the document DE 43 39 493 A1 discloses a method for producing a printing form proposed by a hydrophilic plate surface emanates. Data is provided which is one to a carrier Define a printing graphic and / or a text. The data is in a computer converted into machine data suitable for the operation of a machine. The selected portions of the plate surface containing an image-forming material to be coated are defined. For this purpose, a jet printing device with a Beam printhead provided on the selected portions of the disk surface applying the image-forming material and the other portions of the plate surface leaves free. In the jet printing device is a supply of photosensitive, liquid imaging material used to create hydrophobic areas is curable on the plate surface. Thereafter, the imaging material is included Radiation energy exposed to produce a hardened image.

Although this method can be used to save coating material, the requirements to the print quality of the printing form or printing form cylinder surface thus produced are not enough.

The object of the invention is a method for treating reimageable To develop printing plates or printing forme cylinders in printing presses, by maintaining a minimum of coating material while maintaining high quality criteria is consumed and almost no combustion residues are generated.

According to the invention the object is achieved by the features of the first and the second claim solved.

The invention has the advantage that the energy consumption in an optimal range brought and a significant amount of material is saved. Furthermore, both Time saved when applying the coating material as well as during imaging.

Figur 1

Schematische Darstellung eines Druckwerks einer Bogenoffsetdruckmaschine mit einer nach dem erfindungsgemäßen Verfahren arbeitenden Einrichtung

Figur 2

Stark vereinfachte Darstellung der Oberfläche einer Druckform oder der Oberfläche eines Druckformzylinders mit einer Beschichtung nach dem erfindungsgemäßen Verfahren

The invention will be explained in more detail using an exemplary embodiment. The corresponding drawings have the following meaning:

FIG. 1

Schematic representation of a printing unit of a sheet-fed offset printing machine with a device operating according to the inventive method

FIG. 2

Highly simplified representation of the surface of a printing form or the surface of a printing form cylinder with a coating according to the inventive method

FIG. 1 shows a printing unit 1 of a multicolour sheet-fed rotary printing press. Each printing unit 1 contains, as a sheet-guiding cylinder, a printing cylinder 2 and a transfer cylinder 3 and, as a printing image transfer cylinder, a printing form cylinder 4 and a blanket cylinder 5 .

Each printing form cylinder 4 is assigned an inking unit 6 and a dampening unit 7 . On the printing form cylinder 4 and a printing plate 12 can be spanned.

The printing form cylinder 4 is a designed as an inkjet printer coating device 8, a Bebilderungseinrichtung 9 and possibly a developer unit 10 assigned. The imaging device 9 for imaging the printing form cylinder 4 is embodied as a laser-based ablation device.

The process according to the invention is realized as follows:

With the pressure off and the inking and dampening unit 6 off; 7 and turned off rubber cylinder 5 , a medium is applied to the surface of the printing form cylinder 4 by the coating device 8 or, if this is done with a printing plate 12 , this medium is applied to the surface of the printing plate 12 . As a result, a layer 11 is formed. This is applied by a jet printer, which works according to the ink-jet principle.

To realize the method according to the invention, only the areas of the surface of the printing form cylinder 4 or the printing plate 12 are coated, which motifs 13, 14 (see Figure 2 ) are assigned. This applies to both image motifs 13 and text motifs 14. In this case, the position and the areas occupied by the motifs 13, 14 are determined on the basis of the scanned print originals or from the precursor data.

As can be seen from FIG. 2, the areas occupied by the motifs 13, 14 become including its edge regions 16 coated. Under edge area 16 is the Understood area that encloses the motifs 13, 14 on all sides. In any case, the Size of the border area chosen so that sufficient for the subsequent imaging Ablatierbares material is available.

The applied layer 11 can now, depending on the printing process, have hydrophobic or hydrophilic properties.

In one case, the layer 11 is hydrophobic and the surface of the printing form cylinder 4 or the printing plate 12 is hydrophilic. As a medium, a color or a color-like product can be used. To carry out the method, the areas to which the motifs 13, 14 are assigned are determined. Once this can be done during the current print job, so that these values are introduced into the current printing process. In another case, data may be used that has been determined from the scanned print templates or from the prepress data before the start of the print process. The imageable layer is then applied so that only these areas, including a minimum edge area 16 beyond the motifs 13, 14 , are coated.

In another case, the medium is hydrophilic and the surface of the printing form cylinder 4 and the printing plate 12 is hydrophobic. Here, the areas are determined to which no motifs 13, 14 are assigned. The imageable layer is applied so that only these areas, including a minimum edge area 16 entering the motifs 13, 14 , are coated.

The medium for the layer 11 is usually self-curing. If the curing of the medium is not possible automatically, the curing can take place parallel to the coating via UV light (polymerization) or via laser beam drying and baking.

The printing form cylinder 4 or the printing form 12 prepared after application of the medium can now be imaged by the imaging device 9 . The imaging device 9 is a laser-based imagesetter.

In this case, data for the printing process are processed in a generally known manner in a computer, not shown, and fed to the device for printing plate cylinder imaging. The rotational speed of the plate cylinder 4 is synchronized with the line-controlled speed of the imaging device 9 . In the case where the motif-forming areas are made hydrophobic, the material is ablated in the areas that are not covered with motifs 13, 14 . This means that the material of the edge region 16 is completely removed. If the motif-forming regions are made hydrophilic, the material is ablated in the regions which are covered with the motifs 13, 14 . The edge region 16, which extends into the motifs 13, 14, is removed.

The imaging is optionally followed by a development process in order to fix the image information on the surface of the plate cylinder 4 or the printing plate 12 .

List of used reference numbers

1

printing unit

2

pressure cylinder

3

Transfer cylinder

4

Plate cylinder

5

rubber cylinder

6

inking

7

dampening

8th

jet printers

9

imaging

10

Developer unit

11

layer

12

printing form

13

motif

14

text motive

15

areas covered with motifs

16

Border area of the motifs

Claims (6)

1. Method of treating printing formes or printing forme cylinders, to which an image is to be reapplied, in printing machines, wherein the surface of the printing forme (12) or of the printing forme cylinder (4) is hydrophilic, a hydrophobic layer, to which an image can be applied, is coated thereon by a jet printer (8) and subsequently the imaging is carried out by means of an imaging device (9), characterised in that the regions of the surface of the printing forme (12) or of the printing forme cylinder (4), to which motifs (13, 14) are assigned, are ascertained and the layer to which an image can be applied is coated on in such a manner that only these regions inclusive of a minimum edge region (16) going out beyond the motifs (13, 14) are coated.
2. Method of treating printing formes or printing forme cylinders, to which an image is to be re-applied, in printing machines, wherein the surface of the printing forme (12) or of the printing forme cylinder (4) is hydrophilic, a hydrophobic layer, to which an image can be applied, is coated thereon by a jet printer (8) and subsequently the imaging is carried out by means of an imaging device (9), characterised in that the regions of the surface of the printing forme (12) or of the printing forme cylinder (4), to which no motifs (13, 14) are assigned are ascertained and the layer to which an image can be applied is coated on in such a manner that only these regions inclusive of a minimum edge region (16) going into the motifs (13, 14) are coated.
3. Method according to claim 1 or 2, characterised in that the edge region (16) is so selected that this encloses the corresponding motif (13, 14) all round.
4. Method according to claim 1 or 2, characterised in that the size of the edge region (16) is so selected that in the case of imaging sufficient material able to ablated is available.
5. Method according to claim 1 or 2, characterised in that the determination of the regions, which are concemed with the printing application and occupied by the motifs (13, 14), takes place from preliminary data or on the basis of scanned printing models.
6. Method according to claim 1 or 2, characterised in that the imaging device (9) is an illuminating means on a laser basis.

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