EP1456030B1 - Method for producing rotogravure forms, rotogravure forms and the use thereof - Google Patents

Abstract

The intaglio printing plate has a ceramic substrate (1) with recesses (2) defined by webs (3) of equal height, to give a regular and unified screen pattern. The screen is formed by a laser, with removal of molten matter from the shaped structure. The screen recesses are filled selectively by ink jets, according to the images to be printed, using a low viscose printing medium, which is hardened within the screen by polymerization using ultra violet light. The ink jet system delivers droplets of 20-40 mum diameter into the screen, by digital scanning of the original material to determine the screen filling according to tonal qualities. The substrate is covered by a protective layer to prevent leakages through its porosity. After use, the ink material is removed for the plate to be used again.

Description

State of the art

The invention relates to a method for producing erasable and reproducible rotogravure molds, in which a substrate provided with a grid of defined depressions and uniformly high webs is provided and in the depressions for forming a grid of wells which are tuned to the tonal values of the printing master , Structures are formed from at least one repositionable imaging material, gravure forms from a substrate having a grid of pits, and structures of removable imaging material incorporated into the pits in accordance with tone and the use of such gravure forms. A method of this kind is known from DE 38 37 941 C2 known.

Gravure printing forms are characterized by imaging wells, which are placed lower than the non-imaging printing form surfaces and thus absorb ink and this, after removing excess ink by means of a doctor blade from the non-imaging, uniformly high printing form surfaces, upon contact with the substrate by color splitting on this transfer. In order to reproduce the print template in a tone-value-corresponding manner, it is usually resolved into a grid of lines and raster elements, and the cells of the gravure printing form are formed in the substrate in accordance with these raster elements. Different tonal values are depth-variable in conventional intaglio, by different Well depths at uniformly large cell openings (depth-modulated), or variable area, by uniform well depths at different sized cell openings (amplitude modulated), or depth and area variable, by different Well depths at different sized cell openings (depth and amplitude modulated). The larger the well opening and the deeper the well, the larger the well volume and the amount of transferred color. In this case, rasters are usually used with geometrically regularly shaped raster elements whose center and area centers always have the same distances and are called in the following grid with matrix arrangement. Even grids with usually constant grid points and arbitrary point distances, which may be stochastically distributed, are described for use in area-variable intaglio printing.

Substrates in gravure printing are printing plates, printing cylinders or printing cylinder sleeves, which consist of metal, ceramic or plastic. In the conventional manufacturing processes, the image-forming wells are removed by removal of material in the form of etching or engraving processes such as engraving, laser or electron beam engraving. The technical, financial and time required in the manufacture and regeneration of such gravure forms is considerable, but since a large number of identical prints can be produced with high quality and productivity, they are mainly used for large print runs.

In the known, in the DE 38 37 941 C2 described method, it is about the production of a gravure printing form, which receives different amounts of ink during the dyeing before the printing process in wells of different size and / or depth, wherein a Tiefdruckrohform prepared with at least on the maximum amount of ink to be transferred Näpfchengrundraster and a solid, by energy In a pixel transfer unit liquefiable substance in an inversely proportional to the amount of ink to be transferred amount imagewise introduced into each of the wells. The pixel transfer unit has a print head provided with at least one nozzle through which the liquefiable substance is injected imagewise in a melt-injection process under pressure. It is guided in a guide bar and transmits the substance line by line with individual addressing each cup directly or indirectly, and apparently preferred, via a transfer belt to the Tiefdruckrohform. The substance is applied to a transfer film and is transferred by the thermal transfer process. As a liquefiable substance, which cures very quickly in contact with the cold surface of the printing forme cylinder, a thermoplastic or a wax can be used. The gravure mold is erased by its internal or external heating leads to liquefaction or sublimation of the substance and this is removed by a, designed as a wiping and / or blowing or suction, extinguishing device.

However, the imagewise material application may cause problems with the positional accuracy of the imaging. It is not readily possible with the method used to bring deposited on the webs material completely in the wells. However, complete incorporation is necessary so that the entire transferred material also contributes in a desired manner to reducing the scoop volume.

To avoid these problems and to improve the positional accuracy of the imaging, the owner of this method has the well-known in the DE 195 03 951 A1 developed method for producing a erasable and reusable rotogravure mold, in which the wells of the basic grid of Tiefdruckrohform are evenly filled by means of a liquefiable substance by a request device, then imagewise material removed by a pixel transfer device from the wells is inked, the imagewise screened gravure form by means of a Einärbesystems and then printed in gravure printing and the Tiefdruckrohform is regenerated after the printing process and the wells are filled again evenly. The liquefiable substance, for which thermoplastics, photopolymers or paints are used, is introduced into the depressions in the liquid state by hydrodynamic forces, in particular by capillary action. The image-wise ablation preferably takes place by thermal energy action, for example laser beams. The regeneration of the gravure form after the printing process provides that the liquefiable substance is completely removed by ultrasonic cleaning or high-pressure water from the wells of the basic grid and this is filled again with liquefiable substance. Alternatively, only the removed by the imagewise ablation material of the liquefiable substance can be replenished.

However, since three different process media, namely water, printing ink and liquefiable substance are involved in this process, there is a certain risk of process media mixing during production.

From another pre-publication DE 196 24 441 C1 a method is known in which the process concept is simplified and solvent-based inks are avoided. In this case, in turn, starting from a Tiefdruckrohform with basic grid for printing forme making a filling made in which the wells of the basic grid of Tiefdruckrohform evenly by a UV ink are filled by a request device and the UV ink (filler) then by means of a Tiefdruckrohform positioned dryer is cured to form a highly cross-linked and thus sparingly soluble and infusible material. In the subsequent imaging process, UV-cured UV ink is removed from the wells by thermal ablation by means of a pixel transfer device using a laser. Then the imagewise screened gravure form is inked by means of a UV inking system and the printing process is performed. For conversion, the gravure form undergoes a deletion process using UV ink, preferably by refilling the ablated image locations. Alternatively, the filler may first be completely removed by laser ablation from the wells of the Tiefdruckrohform and then refilled.

Another development Ink-jet of common media for the production of printing plates is directed to other liquid and polymerizable materials, which are solidified in addition to the UV curing by various processes. That's how it describes EP 0 776 763 A1 a process for making lithographic printing plates using the ink-jet technique and liquid ink-jet drops containing resin-forming reactants and after application to polymerize the plate. According to digital image data, a resin image is thereby formed on the plate, and the printing plate thus prepared can be used in offset printing. Such reactants include, as also in the EP 0 776 763 A1 described, polymerizable resin-forming monomers - including low molecular weight polymers, copolymers, terpolymerformende chemicals and further polymerizable prepolymers such as oligomers - and initiators that cause polymerization and may be, inter alia, chemical catalysts, air or oxygen or electromagnetic radiation.

It is the object of the present invention to provide a simple and reproducible method and apparatus for producing erasable and reproducible rotogravure printing forms.

This object is achieved by the features of independent claims 1 and 7 and of claim 11 and with respect to the use according to the features of claim 13.

In the method according to the invention, in which imaging material is imagewise introduced into the depressions of a substrate with the aid of the inkjet technique and then solidified, it is not necessary to liquefy the imaging material before introduction, since liquid substances are used as imaging material be solidified the introduction into the wells. Non-solidified imaging materials are hereinafter referred to as precursors, which are defined as liquid, low-viscosity and non-pigmented substances that can be introduced using the ink-jet technique in the wells and must not be changed in their state of aggregation prior to introduction, and which are physically solidified by solvent removal and / or chemically by polymerization to imaging material. As a result, neither an elaborate device for metered energy supply upstream of the introduction device nor any other process steps for liquefying the imaging material prior to introduction into the recesses are required. The solidification of the precursor can be advantageously controlled so that this significantly takes place only when the precursor is introduced into the wells

In the method according to the invention can be used common devices and common process steps to bring the at least one precursor with relatively little effort positionally accurate and reproducible In the wells, which from the substrate with depressions depth-variable or area variable or depth-and area-variable gravure forms with the tonal values Print template corresponding wells arise. In the following, this process step is also called imagewise introduction and in the Wells solidified imaging material referred to as Bebilderungsstruktur. The imaging of the substrate can be done outside or advantageously within the printing press. The intaglio printing plates produced in this way can be colored with the techniques and machines used for gravure printing and used for the printing process.

The ink-jet technique can be used particularly well for the introduction of the precursors, since the prerequisite for defined individual points is optimally fulfilled and also image resolution (dots per inch) and the ink drop volumes (picoliter) are variable. In addition, ink droplets of the same volume as well as multiple ink droplet volumes can be used, the tonal values being generated in binary fashion by means of dot density modulation of equal dots (dots) and / or by modulation of the individual droplet volume and thus of the individual print dot. Advantageously, these variables can be adapted to the requirements of the method according to the invention, e.g. Resolution and drop volume of the ink-jet device and groove pattern are adapted to each other so that each well is addressable and can be filled with one or more droplets completely. Special rasterizing techniques may also be used with relatively low resolution ink-jet printers, e.g. 386 dpi, images with sufficient print quality can be generated. Another advantage is the process consistency in the production of gravure printing - and thus the finished printed product - and the creation of the print samples (proofs), since both are done by means of the ink-jet technique. Both methods are based on the same data set and pigment-identical ink-jet inks and gravure inks can be selected.

For the method according to the invention, the precursor can thus be defined in the form of uniformly or variably large drops in accordance with a logged digital dataset, which was created by scanning a print original or processing digital image information, with pinpointed single-layer or multilayered and imagewise into the recesses. As a result of the variably adjustable ink drop volume, the cup filling level can be adjusted so that, according to the invention, a defined overfilling of a recess with precursor can counteract any material shrinkage during its hardening.

It is particularly advantageous if the data set used in the generation of the pit pattern for the calculation of the exact addressing of the droplets is included in the dataset. In order to optimize the addressing and to take into account possible manufacturing-related deviations in the substrate or to allow an accurate addressing without taking into account the basis used in the generation of the wells data set, it is advantageous if the surface of the substrate is optically scanned and detected by a printhead upstream of the printhead and the data obtained thereby for data synchronization are forwarded to the ink-jet device.

The intaglio printing plates according to the invention can also be produced cost-effectively and with significantly less effort than conventional intaglio printing plates, in particular with the method according to the invention, which increases the data variability, although the techniques and machines used in conventional intaglio printing can be used in the printing process. They extend the use of gravure printing to medium and small print runs and offer for this segment, but also for large runs, a market-driven and cost-effective solution that meets the usual low-pressure high quality requirements for the print result and includes wide substrates.

Preferably, in the method according to the invention, at least a portion of the depressions are filled with the precursor imagewise in one or more layers, so that the printing material-side surfaces of the imaging structures formed thereby, hereinafter referred to as web surfaces or web structures, with the uniformly high webs of the substrate in lie a plane and form part of the non-imaging, uniformly high pressure surface form and surface variable or, if the remaining wells are filled with Bebilderungsstrukturen different heights, deep and surface variable gravure forms arise. In this case, each well of a substrate provided with uniformly deep and large depressions in a matrix arrangement is particularly preferably filled completely or not at all, whereby all the wells reproduce printing dots with the same tone value, but these are reproduced by image resolution by means of a conventional binary inkjet raster, e.g. Error diffusion, are distributed so that the image is still reproduced tonwertwertsprechend. Soil depth and size of the well openings are always the same and correspond to those of the wells remained unchanged, which is why the wells of this gravure form neither depth nor surface variable in the sense of conventional gravure forms but binary-surface variable, since the printed image also by the ratio of printed to non-printed areas is reproduced.

It is particularly advantageous to additionally vary the depth of these binary area-variable wells by corresponding screening and image-wise introduction of differently sized droplets or multiple layers, whereby deep and binary area variable wells arise and depending on the number of selected depths a larger Tonwertumfang can be achieved , In a further embodiment of the method according to the invention, the wells with precursor imagewise filled so high that in the wells different high Bebilderungsstrukturen and thus deep variable gravure forms are formed.

It is favorable for the adaptation of the intaglio printing plates according to the invention to the conditions during their production and to the printing conditions that the imaging structures can be constructed in one or more layers, wherein the individual layers are hardened (eg in UV-curing systems) or hardened and the drops are pinpointed can be sprayed on top of each other. Advantageously, relatively high imaging structures can thus be built up in layers, which on the one hand can produce many different well depths and therefore tonal values and on the other can also be used by adapted well depths and printing inks with volatile solvents in the printing process. Another advantage is the thereby extended range of useful precursors, e.g. Two-component systems can be used, which mix by pinpoint spraying of the drops one above the other by means of the ink-jet device on the substrate and solidify in the wells. Cured imaging materials, which may be deposited in smaller quantities on the webs, can also be advantageously doctored off easily before curing, which can be repeated before each layer job.

With the method according to the invention, in particular area-variable gravure forms, which can also be binary in area, can advantageously be produced by two different approaches. In one approach, the precursor is incorporated directly into the recesses imagewise and so made the gravure form with imaging wells. The wells of the intaglio printing plate are therefore primarily formed by imagewise material build-up and not by material removal, whereby the additional process step of image-wise ablation is eliminated.

In the other approach, which is a two-step reversal process, the recesses with ridge structures are first covered so that the areas of the recesses in the substrate which form imaging cups in the rotogravure to be produced are covered with imaging material and the possible further explained below, protective layer is not attacked. Is introduced into the then still unfilled areas of the wells in temporal - determined by the solidification time of the first material introduced - distance a second precursor, which does not attack when introducing and solidifying the first introduced imaging material and the possible protective layer - so on, off or dissolves - and the first introduced imaging material is then removed, for example by suitable solvents, without the second imaging material and the To attack any protective layer, then created the gravure mold to be produced with imaging wells. The advantage of the two-stage process is that it is relatively uncritical for it if possibly smaller amounts of the imaging materials are deposited on the webs, because the second imaging material deposited thereon is also detached on detachment of the first applied imaging material.

In order to remove imaging materials possibly deposited on the webs, the web surfaces before the imaging process can advantageously also be covered with high-viscosity auxiliary protective layers in a thin layer by rolling, which can be removed together with any imaging materials prior to the printing process by washing with suitable solvents. To remove imaging materials from the lands and / or to remove material traps in the cavities, it is particularly advantageous if the precursors are only quenched, then excess material is removed by means of a doctor blade and further cured, e.g. in UV-curing systems by exact radiation dosage is possible

In the construction of the intaglio printing plates according to the invention and in their use, it is favorable that very many different - in particular organic - materials with very different properties are available, from which the imaging materials and optionally the protective layers and also the printing inks can be selected such that they are chemically and physically compatible with each other to the required extent, as described for example in the two-stage reversal process, and are easily removable again.

Advantageously, the precursor used is a material which can be solidified physically by solvent removal and / or chemically by polymerization to form one of the imaging materials. Particularly preferred are materials with high mechanical resistance, e.g. Abrasion resistance, and adhesion to the substrate, such as radiation-curing liquid polymers, since especially the web structures together with the webs, as explained below, are heavily stressed mechanically in the printing process. In addition, the educational materials and the possible protective layer can be selected so that the gravure forms produced therewith are suitable for various color systems which can be used in gravure printing and are therefore not limited to specific colors.

Substrates may be made of metal, plastic or ceramic, all of which may be in the form of printing cylinders, cylinder sleeves or plates and advantageously have uniformly high ridges and a nearly 100% doctor blade support. To be favoured ceramic substrates, which have a very high mechanical resistance and thus a long service life used. This is necessary because in the inking process in the printing process excess ink is removed by means of a doctor blade from the webs and this and the web structures are characterized significantly mechanically stressed. In addition, due to the pigments incorporated in the printing inks, a strong mechanical stress on the printing form in the doctor blade gap arises. In contrast to metal or plastic surfaces, the production of ceramic substrates, for example by the use of chromium oxide with a particle size of about 2-30 microns, creates a finely porous and therefore absorbent substrate surface. Although this advantageously enhances the adhesion of the imaging materials to the substrate structure, the imaging materials or else the printing inks can deposit in these pores, making them difficult to remove again.

It may therefore be advantageous in the described methods, e.g. in order to facilitate the detachment of the imaging materials and / or printing inks from ceramic substrates but also metal or plastic, to cover the surface of the depressions or else only those areas of the depressions on which imaging structures are to be produced with a thin protective layer. For this purpose, low-viscosity, solvent-based materials having a defined solids content (eg VC copolymers) which accumulates or deposits on these surfaces after solvent removal can be sprayed or rolled in or sheeted in a defined layer thickness of about 1-3 μm or be sprayed with the ink-jet device, wherein the capillary action of the ceramic supports this introduction. Due to the high solvent removal (about 60%), neither the volume of the depressions nor the adhesion of the imaging materials on the substrate is substantially changed and the protective layer remains in the substrate structure during the print job.

In the method according to the invention, the detachment of the imaging structures from the substrate is primarily initiated by chemical processes and not by physical or mechanical measures such as heating, laser erasing, ultrasound or high-pressure water and is merely supported physically or mechanically. By this measure, advantageous imaging materials and inks can be completely removed from the substrate again, even if left after removal by means of suitable solvent and mechanical cleaning remains in the substrate, since these are replaced by the release of the protective layer by means of suitable solvents together with this.

In the process according to the invention dependence and interaction between protective layer, precursors or imaging materials and the solvent groups used with them (eg ketones, alcohols, gasolines, etc.) and the ink systems (eg alcohol / water, UV inks, etc.) used and tuned advantageous.

The precursors are tuned in their viscosity and their rheological properties to the requirements of the method according to the invention and to the use of the inkjet technique and can also contain auxiliaries such as initiators, waxes and wetting agents. In spite of these additives, it is usually possible to dissolve the photosetting materials that cure by solvent removal in common defined solvents. By contrast, polymerization-solidifiable imaging media such as UV-curing systems can be influenced in their solubility so that they are no longer attacked by normal solvents and especially in substrates made of ceramic only by aggressive solvents such as methylene chloride in conjunction with mechanical measures from the wells completely trigger.

In order to be able to work in the process according to the invention nevertheless with ceramic substrates and common, environmentally friendly solvents such as N-methylpyrrolidone, the properties of the ceramic substrate and the aforementioned coordination between protective layer, precursors or imaging materials, solvent groups and printing ink systems can be advantageously combined. Namely, when a N-methylpyrrolidone-soluble protective layer and then a polymerizable solidifying precursor are introduced into the substrate, in the printing process, e.g. be printed with alcohol-based inks. Upon completion of the print job, the printing form is erased and printed e.g. impregnated with N-methylpyrrolidone. This diffuses through the pores under the imaging material where it dissolves the protective layer and thereby detaches the thus unaffected imaging material from the substrate, e.g. ultrasonically assisted almost residue-free from the substrate can be removed. After detachment of all materials described, the cleaned substrate cylinder is reimaged.

For applying various media such as protective layer and precursor, it is advantageous to apply these in separate systems to avoid process media mixing, wherein in each case one or more printing or injection heads can be used, one behind the other parallel to the substrate cylinder on a traverse in the y-direction or and / or in x-direction on several parallel. Trusses are mounted and can move in both directions of the trusses. If different or the same media are sprayed one after the other with pinpoint precision, and if the individual layers are to be hardened or hardened, then the subsequent layers must be applied in suitable media-dependent different time intervals. You can do this alternately in different directions or, with sufficient spatial distance of the different media leading pressure or spray heads are applied in the same direction. Preferably, this spatial distance is selectively adjustable according to the required time interval in the y- and / or x-direction by variably placeable pressure or spray heads and / or traverses. But it is also possible to apply only one medium at each roller revolution.

Further advantageous embodiments of the method according to the invention, the intaglio printing plates according to the invention and the use according to the invention are listed in the subclaims

• Fig. 1 in perspektivischer Darstellung einen vergrößerten Ausschnitt aus einem keramischen Substrat für wiederbeschreibbare Tiefdruckformen, das Vertiefungen aufweist, die einheitlich tief sind, einheitliche Öffnungen aufweisen, und einen Raster in Form einer Matrixanordnung bilden,
• Fig. 2 in Detailansicht den Querschnitt durch das Vertiefungsrasters eines keramischen Substrats mit unspezifischer Rauhigkeit der Stegoberflächen vor dem Polieren
• Fig. 3 in Detailansicht den Querschnitt durch das Vertiefungsrasters eines keramischen Substrats mit spezifischer Rauhigkeit nach dem Polieren,
• Fig. 4 in Aufsicht einen vergrößerten Ausschnitt aus dem in der Fig. 2 gezeigten Substrat,
• Fig. 5 in Aufsicht einen vergrößerten Ausschnitt aus dem in der Fig. 3 gezeigten Substrat,
• Fig. 6a bis 6b in Aufsicht einen vergrößerten und einen stark vergrößerten Ausschnitt aus einem keramischen Substrat ohne Vertiefungsraster und mit poröser Oberflächenstruktur,
• Fig 7 Ink-Jet Einrichtung mit zwei Schreibköpfen, zwei UV-Lichtdioden und einem vorgeschalteten Abtastkopf,
• Fig. 8 das in der Fig. 1 gezeigte Substrat mit binär flächenvariablen Bebilderungsstrukturen
• Fig. 9 das Beispiel einer Reinigungsanlage,
• Fig. 10a bis 10e in schematischer Querschnittsdarstellung verschiedene Stadien der erfindungsgemäßen Herstellung und Verwendung einer lösch- und wiederbebilderbaren binär flächenvariablen Tiefdruckform, wobei von einem Substrat ausgegangen wird, wie es in den Fig. 1 und 3 gezeigt ist.
• Fig. 11a bis 11e in schematischer Querschnittsdarstellung verschiedene Stadien der erfindungsgemäßen Herstellung und Verwendung einer lösch- und wiederbebilderbaren tiefen- und binär flächenvariablen Tiefdruckform, wobei von einem Substrat ausgegangen wird, wie es in den Fig. 1 und 3 gezeigt ist.
• Fig. 12 in schematisierter, stark vergrößerter Aufsicht einen Ausschnitt aus einem nichtkeramischen Substrat für wiederbeschreibbare Tiefdruckformen, das Vertiefungen aufweist, die einheitlich tief sind, einheitliche Öffnungen aufweisen, und einen Raster in Form einer Matrixanordnung bilden,
• Fig. 13 in schematischer Darstellung eine Ausführungsform einer flächenvariablen Tiefdruckform, bei der die Vertiefungen des in der Fig. 12 gezeigten Substrats mit Stegstrukturen belegt sind,
• Fig. 14 in schematischer Darstellung eine Ausführungsform einer flächenvariablen Tiefdruckform, welche dasselbe Muster wie die in der Fig. 13 aufweist, wobei sich jedoch anstelle der Stegstrukturen Näpfchen und anstelle der Näpfchen Stegstrukturen befinden,
• Fig. 15a bis 15e in schematischer Querschnittsdarstellung verschiedene Stadien der Herstellung und Verwendung einer flächenvariablen Tiefdruckform,
• Fig. 16a bis 16e in schematischer Querschnittsdarstellung verschiedene Stadien der Herstellung und Verwendung einer erfindungsgemäßen tiefenvariablen Tiefdruckform.

In the following the invention will be described by means of embodiments. It shows very schematically

• Fig. 1 FIG. 2 is a perspective view of an enlarged detail of a ceramic substrate for rewritable intaglio printing plates having depressions that are uniformly deep, have uniform openings, and form a grid in the form of a matrix arrangement;
• Fig. 2 in detail view the cross section through the depression pattern of a ceramic substrate with nonspecific roughness of the web surfaces before polishing
• Fig. 3 in detail view the cross section through the dimple grid of a ceramic substrate with specific roughness after polishing,
• Fig. 4 in supervision an enlarged section of the in the Fig. 2 shown substrate,
• Fig. 5 in supervision an enlarged section of the in the Fig. 3 shown substrate,
• Fig. 6a to 6b in plan view an enlarged and a greatly enlarged section of a ceramic substrate without recessed grid and with a porous surface structure,
• Fig. 7 Ink-jet device with two write heads, two UV light diodes and an upstream readhead,
• Fig. 8 that in the Fig. 1 shown substrate with binary area-variable Bebilderungsstrukturen
• Fig. 9 the example of a cleaning system,
• 10a to 10e in a schematic cross-sectional view of various stages of the production according to the invention and the use of a erasable and wiederbebilderbaren binary surface variable gravure form, starting from a substrate, as shown in the Fig. 1 and 3 is shown.
• Fig. 11a to 11e in a schematic cross-sectional view of various stages of the production according to the invention and use of a erasable and wiederbebilderbaren deep and binary variable-area gravure form, starting from a substrate, as in the Fig. 1 and 3 is shown.
• Fig. 12 in schematic, greatly enlarged plan view of a portion of a non-ceramic substrate for rewritable intaglio printing forms, having recesses which are uniformly deep, have uniform openings, and form a grid in the form of a matrix array,
• Fig. 13 a schematic representation of an embodiment of a variable area gravure form, wherein the wells of the in Fig. 12 shown substrates are covered with web structures,
• Fig. 14 a schematic representation of an embodiment of a variable area intaglio printing die, the same pattern as that in the Fig. 13 but instead of the web structures there are wells and web structures instead of the wells,
• Fig. 15a to 15e in a schematic cross-sectional representation different stages of the production and use of a variable area gravure form,
• Fig. 16a to 16e in a schematic cross-sectional representation of various stages of the production and use of a depth-variable intaglio printing form according to the invention.

The FIG. 1 shows an enlarged section of a ceramic substrate 1 with uniformly deep, approximately identical depressions 2 in matrix arrangement and uniformly high webs 3, which is preferably used in the inventive method. As a result of the laser ablation, a melt charge is generated due to the manufacturing process FIG. 2 shown causes a nonspecific surface roughness 4 on the ceramic surface. This is abpoliert for the use of the substrate in the process according to the invention, as in FIG. 3 shown to obtain uniformly high webs 3 with a defined roughness of the web surface with a nearly 100% doctor blade support. By this measure, the in FIG. 4 shown characteristic, production-related honeycomb structure of the ceramic recess openings changed approximately to the round point, which in FIG. 5 is illustrated. Due to the uniformly high webs 3, the percentage web portion increases, so that the lifetime is further increased without further compensation of the substrate surface. The production-related porous and therefore absorbent substrate surface 5 is in FIG. 6a and enlarged in FIG. 6b shown.

In the production of the substrates line number / cm, screen angle, depth and volume of the wells and the percentage web portion can be determined. The introduction of the runners is advantageously facilitated if the webs 3 of the substrate are kept as narrow as possible and form between about 15% and about 30% of the substrate surface. Preferably, the recesses 2 in the substrate are uniformly deep and have approximately identical dimensions and the webs 3 are uniformly high. The depth of the recesses 2 may be greater than or equal to the depth of the deepest wells and the well openings may be greater than or equal to the well openings. It is advantageous if the depressions 2 in the substrate are positioned so as to form a grid with a matrix arrangement and particularly advantageous if they are also produced with identical dimensions. Preferably about 40 to about 300 lines / cm are used, but they can Also smaller and larger numbers of lines can be used. It is also possible to use stochastically distributed grids with constantly large grid points and arbitrary point distances or variations of these grids or other grids. In the following, the entirety of the depressions formed according to a grid in a substrate is also called a depression grid.

When in the FIG. 7 shown ink-jet device move one or more, connected to the media supply and control electronics, printheads 6 or spray heads with 1 + x printheads 7 in both directions 8 at a distance of 1-2 mm to the substrate substrate 9 on a parallel to this attached traverse 10 (Y-axis) and / or, successively or offset, on several parallel traverses. In another version, the print or spray heads are fixed over the entire width of the substrate in the y-direction. The X-axis 11 is given by the rotation of the substrate cylinder and the droplets are applied line by line, whereby the exact control of the coordinates on the substrate cylinder is possible. The precise addressing that can be achieved and the individual droplets being sprayed on top of each other can be optimized by one or more upstream scanning heads 12. The hardening or curing of, for example, photopolymeric substances can also be done according to the prior art on the Y-axis with the aid of a energy-dosable light guide and one or more UV diodes 13 are made with pinpoint accuracy.

Preferably, at least one material from the group of polymer solution, such as e.g. liquid solvent debinding-physically setting adhesives or polymerizable monomers, prepolymers and polymers such as e.g. UV-curable liquid polymers, chemically setting adhesives and one- or multi-component reaction adhesives and their chemical catalysts or initiators for the polymerization and, correspondingly, as solidified imaging material at least one material from the groups of plastics from which the solvent has been removed, hardened, polymerized polymers such as radiation-cured polymers, cold-hardened one-component systems and fully reacted two-component systems selected In addition to the chemical catalysts or initiators and the UV rays, such as other electromagnetic radiation, oxygen or air or oxygen deprivation may include Act. In order to make general precursors ink-jet common, the addition of defined additives is usually necessary. A precursor of a UV-curable liquid polymer is then e.g. about 80% of prepolymerized acrylates, monomers, prepolymers and oligomers and about 20% of photoinitiators, waxes, wetting agents and auxiliaries. As already described, such additives can considerably influence the dissolution behavior of the imaging materials.

The precursors can be introduced into the wells with pinpoint precision in a single-layered or multilayered manner and imagewise in accordance with a logged digital dataset, wherein the solidification can be controlled so that it does not take place significantly until the precursor has been introduced into the depressions. In the case of polymer solutions, this is achieved by adapted solvents having suitable evaporation numbers and in the case of polymerizable monomers and polymers, e.g. achieved by exposure to radiation after introduction or precise over-molding with chemical catalysts or initiators. The drops are jetted out of the print head and mix together by pinpoint superimposing.

In the method according to the invention, the at least one precursor is imagewise introduced into the selectable, different pit patterns of the substrate such that either deep-variable or area-variable or area-variable and preferably binary area-variable and deep-area and binary area-variable gravure forms are formed. Fig. 8 shows that in the Fig. 1 shown substrate 1 with wells 2 in matrix arrangement and with binary variable-area imaging structures 14, wherein resolution and drop volume of the ink-jet device adapted to the well grid and thus each well addressable has been. As an example, a printer resolution of 386 dpi corresponds to a substrate line width of 152 lines / cm. The image resolution was frequency modulated, eg by means of error diffusion. However, in the process according to the invention, both the raster types used in intaglio printing, for example depth or amplitude modulated rasters, and the digital raster types of the inkjet device, eg dither matrix or error diffusion or variations and mixtures of both or other rasters, can be used as the imaging raster become. In addition, it is possible for all manufacturable intaglio printing plates to choose different, also stochastically distributed, dimple screens. In this case, for example, the number of lines per cm of Bebilderungsrasters be greater than, equal to or smaller than the number of lines of the pit pattern and the volume of variably or uniformly large precursor droplets greater than, equal to or less than the volume of the individual wells.

It is advantageous to use in printing with the intaglio printing forms, also for environmental reasons printing inks containing as a solvent substantially water or water / alcohol mixtures. The use of such inks considerably expands the range of organic materials that can be used according to the invention as imaging materials and for the protective layer, since these materials can be used preferably in solvents for organic substances such as hydrocarbons , in particular fluorohydrocarbons, tetrahydrofuran, Dimethylformamide and N-methylpyrrolidone are soluble. However, it is also possible to use other printing ink systems tailored to these materials according to the method with different, more volatile solvents or without solvents.

After the printing process, the gravure printing form is cleaned by the printing inks and then erased. Ink residues remaining on the substrate are removed with the protective layer and the imaging material in this erasing operation Fig. 9 shown used closed cleaning equipment in which gravure printing plates 15 using solvent 16, such as N-methylpyrrolidone, ultrasonically assisted 17 of imaging material and protective layer are released. Advantageously, the porous substrate surface of the ceramic can be used in conjunction with the protective layer and its solubility, since the solvent by diffusion, the protective layer and removes and thus ensures a virtually residue-free detachment of protective layer, imaging material and ink. In the second cleaning cell 18, the remaining dirt particles are removed in a water bath 19 and evaporating solvent 20 of a recovery fed, after which again in the FIG. 1 shown substrate 1, which then imaged again can be. The protective layer according to the invention must be renewed before each imaging.

The production of a preferred, binary area variable erasable and wiederbebilderbaren rotogravure mold with the method according to the invention and the use of the gravure mold produced thereby is based on the 10a to 10e to be discribed. The starting point is one in the Fig. 1 shown substrate 1 with uniformly deep, approximately identical wells 2 in matrix arrangement and with uniformly high webs 3. The grid line width is preferably about 60 - 300 lines / cm.

The Fig. 10a shows a cross section through the in the Fig. 1 shown substrate 1. In the wells 2, a non-illustrated protective layer is first introduced in the form of a polymer solution. In the wells 2, a precursor by means of the ink-jet technique is preferably imagewise introduced according to a logged digital data in one or more layers and solidified into web structure 21 An example of a binary surface variable intaglio printing form is formed, wherein the recesses filled either completely with web structure 21 or not to be filled, whereby the wells 14 correspond to the wells of approximately identical dimensions and do not vary in depth and size of the well opening. So the cups 14 all have the same volume and the tonal values are created solely by the distribution of these cups 14 in the substrate. The imaging material must be removable after use, have a high mechanical resistance and must not be attacked by the printing ink systems used. As precursors are polymerizable monomers, prepolymers and their chemical catalysts or initiators in question, which are not soluble after solidification in water or water / alcohol mixtures.

The in the Fig. 10b shown structure is filled with printing inks 22, for example, as the solvent water or water / alcohol mixtures, the supernatant ink is stripped with a doctor blade according to Fig. 10c , Then the gravure mold is brought into contact with the print carrier, for example a paper web

From then present, in the Fig. 10d shown, only color remains having structure, which is practically in the Fig. 10b is shown, then - optionally after cleaning with the solvent for the printing inks - the imaging material is removed by, dissolving or dissolving with the imaging material solvent or solvent mixtures, and / or removed with a chemical with which the imaging material reacts, or the imaging material is formed by dissolving the protective layer from the substrate replaced. These processes can be assisted by mechanical means, such as brushing or the use of an ultrasonic device. What remains in the Fig. 10e shown shape, which with the in the Fig. 10a shown is identical. It can therefore be re-imaged with precursor.

The method can also be used to produce particularly advantageous Tiefvariable- and binary area variable gravure forms that can be deleted and re-imaged. In this case, the depth of binary area-variable wells is additionally varied by appropriate screening, whereby deep and binary area variable wells with different volumes arise and depending on the number of selected depths a larger Tonwertumfang can be achieved. It is based on the Figure 11a-11e described. The starting point is again one in the Fig. 1 shown substrate 1 with uniformly deep, approximately identical wells 2 in matrix arrangement and with uniformly high webs 3. The grid line width is preferably about 60 - 300 lines / cm.

The Fig. 11 a shows a cross section through that in the Fig. 1 shown substrate 1. In the wells 2, a non-illustrated protective layer is first introduced in the form of a polymer solution. In the wells 2 then a precursor by means of the ink-jet technique is preferred according to a logged digital dataset depth and binary area variable imagewise introduced in one or more layers and solidified to imaging material. In addition to the web structures 21, the depth of the binarized, variable-area cells is varied by means of imaging structures 23 of different heights, which in turn produce cups 14 which correspond to the wells of approximately identical dimensions and do not vary in depth and size of the well opening, and additional wells 24 arise whose depth is different. The imaging material has the same properties as the Fig. 10b - 10d and is formed from the same precursors.

The in the Fig. 11b shown structure is filled with printing inks 22, for example, as the solvent water or water / alcohol mixtures, the supernatant ink is stripped with a doctor blade according to Fig. 11c , Then the gravure mold is brought into contact with the print carrier, for example a paper web.

From then present, in the Fig. 11d shown, only color remains having structure, which is practically in the Fig. 11b shown, is then using the same method as based on the Fig. 10d deleted remains in the FIG. 11e shown shape, which with the in the Fig. 11a is identical so it can be re-imaged with precursor.

The method can also be used to create area-variable intaglio forms that can be erased and re-imaged. The size of the well openings is varied while the depth of the wells remains the same. They will be described with reference to Figures 15a -15e and 13 and 14.

The production of a gravure form, as used in the Fig. 13 is shown and their use is based on the Fig. 15a to 15e be explained. As a basis for the area-variable gravure form can in the Fig. 12 serve shown substrate 25 with uniformly deep, approximately identical wells 2 in a matrix arrangement and with uniformly high webs 3, which is a non-ceramic substrate. The raster line width is preferably about 60-300 lines / cm.

The Fig. 15a shows a cross section through the in the Fig. 12 substrate shown 25 in the wells 2, a precursor by means of the ink-jet technique preferably according to a recorded digital data is imagewise introduced in one or more layers and solidified to web structure 21. An example of a surface-variable intaglio printing plate is formed, wherein the depressions are filled with web structure 21 in such a way that wells 26 of different size of the well opening arise at the same depth, whereby the volume of the wells 26 can be varied and different tone values can be generated. The imaging material has the same properties as the Fig. 10b - 10d and is formed from the same precursors.

The in the Fig. 15b shown structure is filled with printing inks 22, for example, as the solvent water or water / alcohol mixtures, the supernatant ink is stripped with a doctor blade according to Fig. 15c , Then the gravure mold is brought into contact with the print carrier, for example a paper web.

From then present, in the Fig. 15d shown, only color remains having structure, which is practically in the Fig. 15b is subsequently shown with the same method as the one of Fig. 10d deleted deleted, with no protective layer must be removed. What remains in the Fig. 15e shown shape, which with the in the Fig. 15a shown is identical. It can therefore be re-imaged with precursor.

The FIG. 13 give the Fig. 15b bzw.15d in supervision again. The depressions of the variable-area intaglio printing plate are filled in image form with web structure 21 in such a way that wells 26 of different size of the well opening arise at the same depth, whereby the volume of the wells 26 can be varied and different tone values can be generated.

The in the Fig. 14 shown gravure form shows the same pattern as the Fig. 13 , however, are in the places in the Fig. 14 Cup 26, in which in the Fig. 13 Web structures 21 are located and vice versa, ie the web structures in the FIGS. 13 and 14 are in this respect complementary to each other, as they taken together the depression grid of Fig. 12 completely fill. The in the Fig. 14 shown gravure form can be produced by the precursor introduced directly into the recesses imagewise and thus the gravure mold is made with imaging wells. Alternatively, the in the FIG. 13 shown gravure mold with the two-stage reversal process in the in the FIG. 14 convert shown.

For this purpose, the depressions 2 are first covered with web structures 21 such that the regions of the depressions in the substrate which form imaging cups in the low-pressure mold to be produced are covered with web structures 21 and a possible protective layer is not attacked. In the then still unfilled areas of the wells in time - determined by the solidification time of the first material introduced - distance introduced a second precursor, which does not attack when introducing and solidifying the first introduced imaging material and the possible protective layer - so on, off or dissolves - and the first introduced imaging material is then removed, for example by suitable solvents, without attacking the second imaging material and the possible protective layer, then arises in the Fig. 14 shown intaglio printing form with web structures 21 imaging wells 26. Also binary-variable area gravure forms can be produced with this reversal process.

The second imaging material may, for example, be selected from among the materials used as the first introduced imaging material provided that it is ensured that the first introduced imaging material is not attacked when the second is applied and it is not attacked when the first inserted or removed ,

The method can also be used to create depth-variable intaglio forms that can be erased and re-imaged and in which tone values are produced only by different well depths and not additionally by the distribution of the wells become. It is based on the FIGS. 16a-16e described. The starting point is again one in the Fig. 1 shown substrate 1 with uniformly deep, approximately identical wells 2 in matrix arrangement and with uniformly high webs 3. The grid line width is preferably about 60 - 300 lines / cm.

The Fig. 16a shows a cross section through the in the Fig. 1 shown substrate 1. In the wells 2, a non-illustrated protective layer is first introduced in the form of a polymer solution. In the wells 2, a precursor by means of the ink-jet technique is preferably introduced according to a recorded digital database depth variable imagewise in one or more layers and solidified to imaging material. An example of a surface-variable intaglio printing plate is formed, wherein the depressions are filled with imaging structures 27 such that wells 28 with different depths are created with the same size of the well opening, whereby the volume of the wells 28 can be varied and different tonal values can be generated. The imaging material has the same properties as the Fig. 10b -10d and is formed from the same precursors.

The in the Fig. 16b shown structure is filled with printing inks 22, for example, as the solvent water or water / alcohol mixtures, the supernatant ink is stripped with a doctor blade according to Fig. 16c , Then the gravure mold is brought into contact with the print carrier, for example a paper web

From then present, in the Fig. 16d shown, only color remains having structure, which is practically in the Fig. 16b shown, is then using the same method as based on the Fig. 10d described deleted. What remains in the Fig. 16e shown shape, which with the in the Fig. 16a shown is identical. It can therefore be re-imaged with precursor.

In the following, the method and the use will be explained in more detail with reference to four specific examples.

Example 1:

On a substrate (see Fig. 10a), a solution of polyvinyl chloride in tetrahydrofuran is applied over the entire surface. After evaporation of the tetrahydrofuran, a protective layer of polyvinyl chloride remains. In the wells of the substrate coated therewith, a precursor consisting of a two-component adhesive having an alpha-cyanoacrylic ester-based adhesive component and a binder component is formed by means of an ink-jet Facility, as based on the Fig. 7 described, imagewise introduced, wherein successively first the filler component of the adhesive and then the binder component set point by point superimposed injected and layer by layer web structures are produced. After reactive curing of the adhesive, which takes about three minutes, the imaging material is present (s. Fig. 10b ), which has a Shore hardness of about D87 and framing the cups of the gravure form. The applied imaging material is not significantly attacked by a printing ink containing as solvent a water / alcohol mixture or no solvents (UV-curing inks). After the printing process (s. Fig. 10d ), the imaging material and the protective layer are replaced with N-methylpyrrolidone (s. Fig. 10e ).

Alternatively, the polyvinyl chloride solution may also be selective, i. are applied only on the substrate areas, which are then covered with the precursor. In this case, the polyvinyl chloride solution with the ink-jet device from a spray head, which is upstream of the spray head for the binder component, applied with pinpoint accuracy and time in front of the components of the adhesive

Example 2:

On the in the Fig. 1 shown substrate is applied over the entire surface of a solution of polyvinyl chloride in tetrahydrofuran, from which a protective layer of polyvinyl chloride is formed. In the wells is then as a first precursor, a solution of nitrocellulose in ethanol by means of an ink-jet device, as shown by the Fig. 7 described, by precise superimposing a plurality of droplets, which are on or hardened between introduced, the recesses are first occupied with web structures so that the areas of the recesses in the substrate, forming in the produced gravure form imaging wells are covered with web structures. The areas of the recesses which are not covered by the first imaging material are subsequently separated in the temporal distance determined by the solidification time of the material introduced first with a second imaging material or its precursor by means of an ink-jet device, as described with reference to FIGS Fig. 7 described, filled. As a precursor of the second imaging material, the two-component adhesive used in Example 1 as described therein or a UV-curing liquid polymer can be used. After detachment of the nitrocellulose with ethanol, the intaglio printing plate to be produced with imaging cells is present in accordance with the tonal values of the original. The gravure form is used as described in Example 1 and deleted.

Alternatively, and valid for each reversal process, the second imaging material may be painted, then cured, e.g. when using UV-curable liquid polymers by means of UV rays, and then the substrate are doctored off, whereby the deposited by the excess application and deposited on the webs material is completely removed and the web surfaces of the imaging material with the surfaces of the webs lie in a plane.

Example 3:

On the in the Fig. 1 shown substrate is applied over the entire surface of a solution of vinyl chloride copolymer in N-methylpyrrolidone, from which after the evaporation of N-methylpyrrolidone a protective layer of vinyl chloride copolymer is formed. In the wells is then introduced as the first precursor, a solution of an alkyd resin in acetone, which cures very quickly by means of an ink-jet device as described in Example 2 for forming the web structures described in Example 2, wherein additionally precursors targeted to the surfaces of Webs injected. The areas not covered by the first imaging material are then filled as described in Example 2 with a second imaging material or its precursor, which may consist of the same materials as those listed in Example 2. When the alkyd resin is removed with acetone or alcohol, the layer formed on the webs and with it the possibly deposited second imaging material are also removed. After that, the gravure form to be produced with imaging cells is present corresponding to the tonal values of the artwork. The gravure form is used as described in Example 1 and deleted.

Example 4:

On the in the Fig. 1 shown substrate is applied over the entire surface of a solution of vinyl chloride copolymer in N-methylpyrrolidone, from which a protective layer of vinyl chloride copolymer is formed. Before the imaging process, the surfaces of the webs are then covered with a high-viscous auxiliary protective layer of a plasticizer-based aluminum paste thin layer by means of an elastic inking roller by rolling. A solution of an alkyd resin in acetone by means of an ink-jet device as described in Example 2 is then introduced into the depressions as the first precursor to form the web structures described in Example 2. The areas not covered by the first imaging material are then filled as described in Example 2 with a second imaging material or its precursor, which may consist of the same materials as those listed in Example 2. When removing the alkyd resin with acetone or Alcohol is also formed on the webs, also alcohol-soluble auxiliary protective layer of aluminum paste and with her possibly deposited thereon first and / or second imaging material then the produced gravure form with imaging wells according to the tonal values of the artwork. The gravure form is used as described in Example 1 and deleted.

All gravure forms produced by the described method can be used for both direct and indirect gravure printing. According to the current state of the art, the exchange of printing forms between the print jobs is largely automated, which is why the imaging and erasing of the produced gravure forms can be done advantageously in the printing press or outside this in a separate device. Both in Bebildem as well as deleting the intaglio printing forms, the areas of the substrate surface to be processed to facilitate the application of material and the removal of material can be selectively heated and thereby evolved vapors are sucked. During the deletion process, in addition, the respective solvent can additionally be heated in order to assist the dissolution of the various materials from the substrate. The closed cleaning system which is preferred during the deletion process can be located outside the printing press or can be integrated particularly advantageously into the printing press, by e.g. the paint application system is extended to a closed system, which then, for example, instead of the color, the respective solvents are applied to the gravure mold and the various materials are supported by a supersonic integrated ultrasonic device.

Claims (13)

1. A method for producing rotogravure forms in which a substrate provided with a screen of sufficiently deep recesses is prepared and structures consisting of at least one re-removable illustration material are produced in the recesses for the formation of a screen of ink cells which are matched to the tone values of the print copy, characterised in that at least one precursor of the illustration material (precursor being defined as a liquid, low viscosity and unpigmented substance which can be introduced into the recesses using inkjet technology and whose aggregate condition must not be changed before introduction) is introduced as an image into the recesses by means of an inkjet device, and is consolidated into illustration material, and in that a material that can be consolidated physically as a precursor by solvent extraction and/or a material that can be consolidated chemically by polymerisation into illustration material.
2. The method according to Claim 1,
   characterised in that
   the precursor contains at least one organic material, in particular a material from the group of polymer solutions, e.g. liquid adhesives physically setting by means of solvent extraction or polymerisable monomers, preolymers and polymers, e.g. UV-hardening liquid polymers, chemically setting adhesives and single or multi-component reaction adhesives and their chemical catalysts or initiators for the polymerisation.
3. The method according to Claim 1 or 2,
   characterised in that
   at least some of the recesses are filled with the precursor of the illustration material so that depth-variable, surface-variable, in particular binarily surface-variable or depth- and surface-variable rotogravure forms with ink cells are formed according to the tone values of the print copy.
4. The method according to Claims 1 to 3,
   characterised in that
   the illustration structures are single- or multilayer.
5. The method according to one of Claims 1 to 4,
   characterised in that
   the individual layers are composed of spray points set next to and if necessary above each other.
6. The method according to one of Claims 1 to 5,
   characterised in that
   at least some of the recesses are filled with the at least one precursor up to the established heights, but not fully, and the recesses are then occupied with bridge structures up to their upper edge, wherein the filling and occupying take place in such a manner that the ink cells formed correspond to the tone value of the print copy.
7. A method for producing rotogravure forms, in which a substrate provided with a screen of sufficiently deep recesses is prepared and structures consisting of at least one re-removable illustration material are produced in the recesses for the formation of a screen of ink cells which are matched to the tone values of the print copy, characterised in that at least one precursor of the illustration material (precursor being defined as a liquid, low viscosity and unpigmented substance which can be introduced into the recesses using inkjet technology and whose aggregate condition must not be changed before introduction) is introduced as an image into the recesses by means of an inkjet device, and is then consolidated into illustration material, in that the regions of the recesses not yet filled are filled with a second illustration material which does not attack, or whose precursors do not attack, the illustration material first applied, and in that the illustration material first applied is then removed without substantially attacking the second illustration material, whereby the rotogravure form to be produced is formed with a screen of ink cells corresponding to the tone values of the print copy.
8. The method according to Claim 7,
   characterised in that
   the illustration material applied is physically removed by dissolving or is chemically removed.
9. The method according to one of Claims 1 to 8,
   characterised in that
   at least one protective layer, which seals the porosity of the substrate, is applied before the introduction of the precursor, which protective layer is soluble in a suitable solvent since the solvent releases and removes the protective layer by diffusion, thus providing a removal of the protective layer, illustration material and printing ink almost without residue.
10. The method according to Claim 9,
    characterised in that the protective layer is applied from a material which is not substantially attached by the materials used in illustrating the rotogravure from and by the printing inks used.
11. A rotogravure form, produced by a method according to one of Claims 1 to 10, from a substrate (1) with a screen of sufficiently deep recesses (2) and a screen of structures consisting of a removable illustration material matched to the tone values of the print copy.
12. The rotogravure form according to Claim 11,
    characterised in that
    the substrate (1) consists of ceramic.
13. Use of a rotogravure form according to Claim 11 or 12,
    characterised in that
    it is provided with a printing ink (8) which does not attack the illustration material in the finished rotogravure from and the protective layer, in that printing is carried out and in that, after completion of the printing process, the illustration material, the material of the protective layer and any printing ink residues remaining on these materials are chemically removed.

Images