DE102008035203A1 - A method of making a rotary printing form for use in a web-fed rotary printing process - Google Patents

Abstract

A method for producing a rotary printing form for use in a web-fed rotary printing process initially provides a cylindrical mold base body onto which a non-metallic coating material is applied either directly or directly through a ballard skin. As soon as the coating material has cured, imaging or inscription can take place by introducing a cup structure into the coating material. In order to ensure a residue-free laser engraving of the non-metallic coating material, the coating material is a nanocomposite of an acrylate-based monomer, oligomer or polymer with nanoparticles contained therein.

Description

The The invention relates to a method for producing a rotary Printing form for use in a web-fed rotary printing process the method steps of claim 1. Furthermore relates the invention is a gravure form suitable for use in the process is suitable according to claim 1 and the use a composite as a coating material of a gravure form with cylindrical mold base body, thus in a web-fed rotary printing process can be used.

State of the art

Of the Rotogravure is unlike other printing methods like Flat, high, digital or screen printing for the production predominantly high-performance products suitable. Characteristic of rotogravure is that the individual points of the printed image deepened lie in the surface of the printing forme cylinder. you will be referred to as wells and result from the print image transfer means Engraving or etching. When printing, they take, depending of their volume, the appropriate amount of ink on and Give them punctiform to the substrate.

At the Printing magazines and catalogs (illustration gravure) is coming aggravating that the time between file input and Completion of the printing forme and finally the delivery of the Printed product plays a crucial role. The paper web speed is very high with> 15 m / s and the quantities of paint transferred at web widths up to 4.32 m very large. To dry them fast enough, solvent-based paint is used.

In In practice, different methods are used for this Production of these wells and different materials, in which the wells are introduced, for use.

When The basic state of the art has been gravure printing for many years known, consisting of a steel cylinder with a copper base coat consist. On this copper base coating is another copper layer galvanized as an engraving copper layer, which has a layer thickness of about 0.5 mm. This engraved copper layer is surface-treated and then engraved to print or typeface in the form of cups.

to Improving the wear resistance will be the already engraved engraved copper layer additionally with a hard chrome plating for which galvanic application methods are used.

Such "classic" rotary Printing forms with metal coating can after printing through Remove the thin copper coating down to the surface the steel cylinder can be used again.

adversely on these classic metal-coated rotary printing plates in particular, that on the one hand a plurality of process steps with high time and cost and on the other polluting galvanic coating steps are required.

As a further prior art, processes for the production of erasable and reusable intaglio printing plates are already known, which are represented in the patent literature as follows:
For example, describes WO 02/40272 a method for the production of screening cups in preferably rotationally symmetrical basic body by means of time-modulated, in particular pulsed laser radiation. An ablation support layer is applied over the upper layer area provided for the information embossing, through which sieve cups are introduced by means of laser radiation into the upper layer areas by material ablation. Subsequently, this erosion assist layer is removed with the aim of obtaining burr-free screen wells.

An in EP 1568490 described, high-resolution direct laser process of chrome or copper cylinders achieved in comparison to conventional electromechanical or laser engraving significantly higher cell resolutions and thus finer contours in the printed image. However, a disadvantage is the significantly extended engraving time at not reduced manufacturing costs of the cylinder.

Out DE 10 2005 052 156 A1 For example, a method and apparatus for gravure printing by means of a erasable and reusable gravure printing form are known. The gravure printing forms shown there are formed as a solid cylinder, as a tubular or thin-walled sleeve on which a basic grid is engraved analogously to a conventional gravure mold in copper. To increase the durability is on the engraved with the basic layer first a layer of chromium and then a hard coating such. As diamond-like carbon, titanium nitrite or tungsten carbide applied.

Furthermore are described anilox rolls, the thermally sprayed ceramic coatings into which laser engraved a gravure grid becomes.

From this document it is known that in order to increase the abrasion resistance of the filling material hard material powder having a particle size of less than 1 micron, is to be added.

The Imaging is done by thermal ablation by means of a pixel transfer device, by imagewise filling material from the wells is removed.

To the printing process passes through the known gravure printing a deletion process in which the filler material as well Remaining ink from the printing process completely or partially by means of laser be removed. Subsequently, the basic grid of the Rotogravure mold can be refilled, making it suitable for the Imaging is prepared with a new print job.

Out DE 10 2005 052 157 A1 For example, an apparatus and method for imaging a erasable and reusable gravure printing form is known, using a plurality of laser beams that may be derived from one or more lasers.

Out EP 1 410 924 a manufacturing method for a gravure printing is known in which only a wear-resistant layer is applied according to the desired application to the cylindrical printing plate. This wear-resistant layer forms the engraving surface of the printing form and may consist of a hard material, composite material or metal. Different coating methods are mentioned. Cups for receiving the ink are formed by mechanical engraving, laser engraving or etching. For reuse, it is intended to remove the imaged wear-resistant layer chemically, electrochemically or mechanically after the printing process.

Out DE 101 26 264 A1 are known a gravure cylinder, a method for producing a gravure cylinder and method for recycling a gravure cylinder, wherein a gravure cylinder is described in detail, wherein on a provided with an auxiliary layer steel cylinder, a ceramic coating is applied by means of a plasma spraying. To "delete" the gravure cylinder after the printing process, a recycling treatment is provided, in which the imaged cylinder is abraded. This creates a used reusable cylinder blank.

From the generic EP 584 857 A2 is a gravure cylinder consisting of a steel cylinder with a the engraving image bearing coating known. To increase the service life of the coating consists of polyamide, the service life can be increased by the addition of pigments in the sub-micron range.

As a general rule is to be determined from the aforementioned sources in the prior art, that the polymer materials proposed there, thermoplastics, Resins, waxes, etc. the essential requirements of a rotary Gravure printing process is not enough. In particular, they are not sufficiently resistant to toluene and not sufficient verschleißresitent. In terms of quality The laser engraving is to determine that it is in the focus of severe laser beam to flow phenomena of the material in the cup and thus contour blurs comes.

outgoing From this prior art, the invention is based on the object a manufacturing method of a rotary printing form or a gravure cylinder or a gravure form indicating a cup production laser at high speed, with the laser engraving result significantly improved compared to the known methods, already engraved Rotative rotogravure molds for a re-imaging can be "deleted" again, wherein the deletion process can be carried out in a simple manner should be and complicated and environmentally harmful procedures within a printing company to produce and prepare the rotary Printing forms are avoided or greatly simplified.

These The object is achieved by the features of method claim 1 and the device claim 26 solved. Advantageous developments The invention will become apparent from the dependent claims 2-25 or 27-44.

When At the heart of the invention it is considered that as coating material a post-coating curing by polymerization Composite material comprising at least one organic binder is applied with nano and / or microparticles contained therein.

Thereby is it possible to enter in a single technology sequence Radiation-curable composite material on the cylinder surface of the mold base body to be cured there can, the picture information-bearing cell structure over Laser engraving can be generated and after the printing process the Cup structure via a re-coating process with the said composite is leveled and thus for a renewed Imaging is available.

It has been found that the combination of an acrylate-based matrix and nanoparticles contained therein significantly improves the laser engravability of the surface formed. With known non-metallic coating materials, laser engraving regularly involves considerable difficulties; the incident laser beam leads to thermally induced flow processes in the order of magnitude field of the beam, so that no sufficiently sharp cell structures can be formed by the laser beam. The resulting in the prior art cups are usually surrounded by a crater rim, which leads to a significant deterioration of the image quality of the printed product. The formulated in claim 1 combination of micro- or nanoparticles embedded in a composite material, such as a polymer matrix, for. B a polyacrylate avoids such negative flow phenomena. The wells formed with laser beams are significantly contour sharper than in the prior art and thus suitable to ensure a much better, print result. In addition, the material is sufficiently hard, tensile and compressive strength, elongation at break, modulus of elasticity and wear resistance are suitable to withstand the high mechanical stresses associated with a high speed web-fed rotary printing process. The heat resistance is sufficient for such loads. In thermal terms, the claimed composite layer advantageously has a low coefficient of expansion, which has an advantageous effect on its bonding to the substrate. In addition, the radiation-curable micro- or nanoparticles have an advantageous effect in terms of abrasion resistance of the composite material.

The optical and thermal absorption, dissipation and / or emission properties of such a layer can be achieved by embedding micro- or nanoparticles are favorably affected, d. H. the aforementioned flow processes and smearing effects, the laser engraving of other plastic layers usually arise, are so greatly reduced that the lasered cell structure is made far sharper than this with other known Plastic coatings is possible. additionally It is possible in principle, the UV absorption the hardened layer on the wavelength of Engraving laser to optimize energy consumption to further refine the engraving result.

The However, said composite layers are not only advantageous in terms of on the cup formation by means of laser, further advantages they have with regard to a deletion of the cell structure to offer. The layers are easy to recoat, d. H. an erase operation can be performed without a composite layer completely detached from its base. By "over-lasers" existing Structures are deleted and the surface newly coated in the required layer thickness with composite material become.

Also this can fill in the cells of the structuring Composite material exposed by laser radiation and then be completely refilled. This will "delete" the structure and provides after refilling for a new structuring. Both the "over-lasing" of existing structures, as well as the uncovering and subsequent refilling can also be done only on sections of the molding, This makes it possible, even a section of pressure cylinder delete or provide with new image information.

in principle it is also possible to use the composite material with a non-metallic To coat the barrier layer after the imaging, the a greater hardness and / or a larger one Solvent resistance as the coating material itself has. Advantageously, it has been shown that the Durability of the barrier layer on the surface of the Composite layer is improved by the micro and nanoparticles. The barrier layer comprises silasane or SiOx compounds. The provision of carbon and / or nitrogen atoms in The barrier layer has proven to be advantageous.

claim 2 deals with radiation curing of the composite layer. To the adhesion of the composite layer on the cylinder surface of the mold base can increase, the cylinder jacket surface provided in a conventional manner with a basic structure be. But it is also possible to use the composite material to apply a ballard skin. Such a ballard skin can come together with the composite layer applied to it from the base cylinder be detached, without the structure of the basic cylinder negative to impair. A ballard skin is generated by that on so-called ground copper plated on a copper skin about 0.1 mm thick which is provided with a surface structure can. After the print run, the ballard skin can be removed from the impression cylinder subtracted from. Alternatively to the ballard skin can also be a nonmetallic Intermediate layer, z. B. a primer fulfill the detachment function.

advantageously, For example, the layer thickness of the composite layer can be between 15 and 150 μm be. Further advantageous compounds and / or elements of Composite layer can be found in claims 27-35.

The laser engraving, ie the embossing of wells by means of laser radiation, which is mentioned in claims 2 and 8 and in more detail in claims 21-25, can be carried out particularly well with pulsed laser. The depth and shape of the wells in the composite layer can be adjusted by the number of pulses per spot and the energy deposited by the laser beam. Since the composite layer has far more favorable optical and thermal absorption properties than other plastic coatings, any desired cell shapes can be engraved by laser insertion ren, for example, square, triangular, round. Also different depth profiles on a basic shaped body can be generated, for. B. in step shape, in the form of a Gaussian curve or wedge-shaped. The Bebilderungsablauf the layer can be done either locally individually or by a raster method. In the usual way, the laser beams can be directed via scanners or multiple axis systems onto the composite layer to be imaged.

The Cup shape can advantageously via a Beam shaping of the laser beam done. Such a beam shaping can be through apertures, masks and / or others realize optical elements.

A so laser-registered structuring can by laser ablation be deleted and the composite layer, which then in the thinned out areas, re-coated become, whereby coating material can be saved. there performs the refilling of the partially worn Wells to a closed composite surface layer. The achievable time savings represents a significant Advantage of the method according to the invention.

It But it is also possible, one provided with a picture Composite surface layer completely from the Cylinder surface of the mold body through Radiation or mechanically ablate or detach and a substantially complete recoating of the cylinder surface of the mold base body by a composite material.

In front Laser engraved imaging can be a coated composite layer be smoothed mechanically or by laser action, which leads to a further improvement of the printing result.

Claims 21-44 relate to a gravure form which can be made by the method of claims 1-20. The imageable surface formed by a composite layer has, as a first component, the following compounds: acrylates of radically UV-curing systems, cycloaliphatic epoxides, aliphatic epoxides and compounds of cationically UV-curing systems. Such compounds for the composite layer lead to particularly advantageous laser engraving results with highly definable cup shape. The composite layer comprises several multifunctional radiation-curable monomers, oligomers or polymers which may comprise orthogonal functional groups. The particles of the nanocomposite layer are micro- or nanoscale metal or semimetal oxides or oxides of transition metals or mixed oxides in powder form or organometallic particles. Compounds of Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO _{2 have} proved to be particularly advantageous for the nanocomposite layer.

The Compound layer compounds can be organophilic Be provided with serving. Further advantages regarding different compounds in different proportions give the Claims 30-33.

The layer thickness of the composite layer can be between one nanometer as the theoretical lower limit and one millimeter. The hardness of the composite layer should be greater than 200 N / mm ² (Marten hardness). The cup structure of the composite layer should be chosen so that the depth of the wells is less than the thickness of the composite layer. In order to erase an imaged composite layer, the composite layer may carry a quenching layer that completely overlaps the wells.

The Connection is based on an advantageous embodiment explained in more detail in the drawing figures. These demonstrate

1 a schematic section through a provided with a ballard skin rotary printing form for use in a web-fed rotary printing process;

2 a schematic detail section according to I in 1 ;

3 a schematic sectional view of an alternative rotary printing plate;

4 a schematic detail section according to III in 3 ,

In the 1 illustrated rotary printing form 1 consists essentially of a cylindrical mold base with structuring 2 and a non-metallic coating material applied to the surface, ie, the cylinder surface 4 of the mold body 2 can be applied. The coating material is according to 2 from a composite material 3 and thus forms a composite layer 33 out. The composite material 3 comprises an acrylate-based matrix 5 and substantially equally distributed nanoparticles therein 6 that - as in 2 shown schematically - can have different shapes and sizes.

On the surface 7 of the composite material 3 becomes a non-metallic barrier layer 8th applied, which has a greater hardness than the composite material 3 having. Um in the coating material 3 a cup structure 9 For the purpose of imaging, a laser engraving process is used. The cell structure 9 is in drawing figure 2 to se hen. Overall, it should be noted to the drawing figures that, of course, the sizes of the particles 6 , the thickness of the layers shown 33 . 8th . 21 , Overall, the size ratios of the cylindrical shaped body 2 with the layer thicknesses and particle sizes do not correspond to reality. For reasons of illustrative clarity, the layer thicknesses and particle sizes are widely coated and not shown to scale relative to each other.

As further in drawing figure 2 can be seen, the surface can be 4 of the mold body 2 with a basic structure 20 on a ballard skin 21 is applied, be provided, which ultimately the composite layer 33 wearing. In this regard, it should be noted that the application of a ballard skin 21 before applying the composite layer 33 is merely an option, the complete detachment of a coating from the mold body 2 should facilitate.

In addition, the on the mold body 2 applied ballard skin 21 be provided with a structuring.

In the drawing figures 3 and 4 an alternative embodiment is shown. Here is the composite layer 33 without ballard skin directly on the mold body 2 arranged. To the adhesion between the cylinder surface 4 and the composite layer 33 to increase, is the cylinder surface 4 with a z. B. web-like basic structure 20 provided, which increases the contact area.

The cell structure 9 can have different shapes, depths and / or dimensions.

From the introduction, it is also apparent that the composite layer 33 from a coating material 3 can be formed, which can include a wide variety of chemical compositions. The compositions may be selected by those skilled in the art within the ranges indicated to form a scratch / abrasion resistant and solvent resistant coating which, in the spirit of the invention, ensures almost residue free laser engravability.

1

printing form

2

Form body

3

composite

4

Cylinder surface v. 2

5

matrix on acrylate basis

6

particle

7

Surface v. 3

8th

barrier layer

9

cup structure

20

Basic structuring v. 4

21

Ballard

22

Surface structuring v. 21

33

composite

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 02/40272 [0009]
• - EP 1568490 [0010]
• - DE 102005052156 A1 [0011]
• DE 102005052157 A1 [0016]
• - EP 1410924 [0017]
• - DE 10126264 A1 [0018]
• - EP 584857 A2 [0019]

Claims (44)

Method for producing a rotary printing plate ( 1 ) for use in a web-fed rotary printing process, comprising the following process steps: - providing a cylindrical molding base body ( 2 ); - Providing a non-metallic coating material; - Application of the coating material on the cylinder jacket surface ( 4 ) of the molding base body ( 2 ); - curing the applied coating material; - imaging by entry of a cell structure ( 9 ) in the coating material, characterized in that - as a coating material, a polymerizable by polymerization after the coating process composite material ( 3 ) comprising at least one organic binder with nano- and / or microparticles ( 6 ) is applied. Process according to claim 1, characterized in that the composite material ( 3 ) is cured by exposure to radiation. Method according to claim 1 or 2, characterized in that on the surface ( 7 ) of the composite material ( 3 ) after the entry of the cell structure ( 9 ) a non-metallic barrier layer ( 8th ) is applied. Process according to claim 3, characterized in that the solidified composite material ( 3 ) a composite layer ( 33 ) and the barrier layer ( 8th ) a greater hardness and / or a greater solvent resistance than the composite layer ( 33 ) having. Method according to one of the preceding claims, characterized in that the composite material ( 3 ) on the cylinder surface ( 4 ) is applied by spraying, spraying, atomizing, knife application, roller application, its coating or dip coating. Method according to one of the preceding claims, characterized in that the applied composite material ( 3 ) is cured by VUV, UV, electron, gamma radiation and / or a plasma. Method according to one of the preceding claims, characterized in that the curing of the composite material ( 3 ) is thermally caused and / or supported. Method according to one of the preceding claims, characterized in that the composite material ( 3 ) is structured and / or removed by laser ablation. Method according to one of the preceding claims, characterized in that the solidified composite material ( 3 ) a composite layer ( 33 ) and for the purpose of forming the well structure ( 9 ) is subjected to a laser engraving process. Method according to one of the preceding claims, characterized in that the cylinder jacket surface ( 4 ) of the molding base body ( 2 ) with a basic structure ( 20 ). Method according to one of the preceding claims, characterized in that the cell structure ( 9 ) has a variable cup shape. Method according to one of claims 10 or 11, characterized in that the composite material ( 3 ) Deepening of the basic structure ( 20 ). Method according to one of the preceding claims, characterized in that the composite material ( 3 ) on a ballard skin ( 21 ) is applied. Method according to claim 13, characterized in that the ballard skin ( 21 ) a surface structuring ( 22 ) having. Method according to one of the preceding claims, characterized in that an imaged rotary printing plate ( 1 ) in the area of existing engraved wells ( 9 ) in the composite layer ( 33 ) for the purpose of deletion and re-imaging with composite material ( 3 ) is refilled. Method according to one of Claims 10-15, characterized in that the basic structure ( 20 ) of the molding base body ( 2 ) for the purpose of deletion by laser ablation of the basic structure ( 20 ) filling composite material ( 3 ) is uncovered and completely refilled. Process according to Claim 15 or 16, characterized in that the refilling or refilling of the well structure ( 9 ) to a closed surface of the composite layer ( 33 ) leads. Method according to one of claims 15-17, characterized in that the deletion and / or re-imaging only on subsections of the molding base body ( 2 ) and / or the composite material ( 3 ) he follows. Method according to one of the preceding claims, characterized in that a with an imaging composite layer ( 33 ) from the cylindrical surface ( 4 ) of the molding base body ( 2 ) is ablated or detached by radiation or mechanical action and a substantially complete recoating of the cylinder surface ( 4 ) of the molding base body ( 2 ) by a composite material ( 3 ) he follows. Method according to one of the preceding claims, characterized in that on the cylinder jacket surface ( 4 ) applied composite layer ( 33 ) is mechanically smoothed before the laser engraving. Method according to one of Claims 8-20, characterized in that the imaging of the composite material ( 3 ) is done with a pulsed laser. Method according to claim 21, characterized that the pulse duration between a femtosecond and a hundred Milliseconds, the wavelength of the laser between 157 nm and 10.6 μm and the pulse repetition frequency between 1 Hz and 10 MHz varies. Method according to one of claims 8-22, characterized characterized in that one or more laser beams simultaneously be used for imaging, with the use of multiple laser beams this by splitting a laser beam or by using several Lasers are realized. Method according to one of claims 8-23, characterized characterized in that for setting defined Well forms a beam shaping of the laser beam takes place. Method according to one of the preceding claims, characterized in that the Bebilderungsablauf per place individually or by screening. Gravure printing form, in particular rotary printing form ( 1 ) for use in a rotary gravure gravure printing process which has a surface engravable with wells for imaging (US Pat. 7 ), characterized in that the surface is a composite material ( 3 ) which, after the coating process by polymerization, forms a cured composite layer ( 33 ) which contains at least one organic binder with nano- and / or microparticles ( 6 ). Thermoforming mold according to claim 26, characterized in that the composite layer ( 33 ) comprises as a first component the following compounds: polymerized acrylates based on radically UV-curing systems and / or polymerized cycloaliphatic and / or aliphatic epoxides based on cationically UV-curing systems. Thermoforming mold according to one of claims 26 or 27, characterized in that the composite layer ( 33 ) comprises micro- or nanoscale metal and / or semi-metal oxides or oxides of transition metals or mixed oxides in powder form or organometallic particles. Thermoforming mold according to any one of claims 26-28, characterized in that the particles contained therein ( 6 ) Comprises compounds of Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO ₂ and / or carbon-based nanotubes and / or organoaluminum particles. Thermoforming mold according to one of claims 26-29, characterized in that the particles ( 6 ) or particles are at least partially provided with a compatible with the surrounding binder organophilic envelope. Thermoforming mold according to one of Claims 26-30, characterized in that the composite layer ( 33 ) comprises the following compounds in different proportions: organosilanes such as alkyltrialkoxysilanes and / or dialkyldialkoxysilanes and / or trialkylalkoxysilanes, and their completely or partially hydrosilated and condensed forms, wherein the alkyl component is linear, branched or cyclic. Thermoforming mold according to claim 31, characterized that the compounds have one or more of the following functional Units carry: fluoroalkyl, chloroalkyl, isocyanoalkyl, cyanoalkyl, aryl, acylalkyl, acryloyloxyalkyl, methacryloyloxyalkyl, polysulfanealkyl, mercaptoalkyl, thracyamidoalkyl, glycidyloxyalkyl, aminoalkyl, diaminoalkyl, triaminoalkyl, carbonatoalkyl and ureidoalkyl. Thermoforming mold according to one of claims 26-32, characterized in that the composite layer ( 33 ) contains one or more polymerization initiators (photoinitiators) and / or polymerization inhibitors. Thermoforming mold according to one of Claims 26 to 33, characterized in that the layer thickness of the composite layer ( 33 ) is between 1 nm and 1 mm. Thermoforming mold according to one of claims 26-34, characterized in that the hardness of the composite layer ( 33 ) is greater than 200 N / mm ² (Marten hardness). Thermoforming mold according to one of claims 26-35, characterized in that the composite layer ( 33 ) with a well structure ( 9 ), wherein the depth of the wells is less than the thickness of the composite layer ( 33 ). Thermoforming mold according to one of claims 26-36, characterized in that the composite layer ( 33 ) is provided with a Nachfüllmaterial a Nachfüllstruktur that fills the wells and forms an overarching erase layer. Thermoforming mold according to one of claims 26-37, characterized in that the composite layer ( 33 ) is connected to a metallic surface carrying it. Gravure printing form according to one of Claims 26 to 38, characterized in that the composite layer ( 33 ) on the surface of a ballard skin ( 21 ) is arranged. Thermoforming mold according to one of claims 26-37, characterized in that the composite layer ( 33 ) is arranged on a non-metallic intermediate layer. Thermoforming mold according to one of claims 26-40, characterized in that on the composite layer ( 33 ) at least one subsequent coating arranged thereon ( 8th ) is arranged. Thermoforming mold according to claim 41, characterized in that as a post-coating ( 8th ) on the composite layer ( 33 ) a barrier layer ( 8th ) is arranged. Thermoforming mold according to claim 42, characterized in that the barrier layer ( 8th ) is an SiO layer or silasane layer. Thermoforming mold according to one of claims 42-43, characterized in that the barrier layer ( 8th ) Comprises carbon and / or nitrogen atoms.