EP2314386B1 - Coating method and device - Google Patents

Description

The invention relates to a method and associated apparatus for producing optically visible or invisible effects in a coating.

This involves the use of paints containing ferromagnetic pigments for the production of printed products and their refinement. This method is basically known and the effects are used in various applications.

• DE 101 14 445 A1 betreffend Weicheisenpigmente,
• EP 0 641 461 A1 betreffend verkapselte magnetische Teilchen, Pigmente und Russ, Verbindungen und damit verbundene Verfahren,
• DE 36 17 430 A1 betreffend Perlglanzpigmente,
• DE 43 40 141 A1 betreffend magnetisierbare Glanzpigmente,
• DE 40 41 467 A1 betreffend magnetische Druckfarben,
• EP 2 024 451 B1 betreffend eine Beschichtungszusammensetzung zur Erzeugung magnetisch induzierter Bilder,
• DE 44 38 743 A1 betreffend eine Offsetdruckmaschine,
• DE 10 2004 035 866 A1 betreffend eine Einrichtung und ein Verfahren zum Beschichten,
• EP 1 641 624 B1 betreffend ein Verfahren und Mittel zur Herstellung eines magnetischen Musters in einer Beschichtung mit magnetischen Partikeln und
• EP 0 556 449 B1 betreffend eine Lackierung mit magnetisch hergestelltem Muster und lackiertes Produkt mit magnetisch hergestelltem Muster.

Reference is made to the state of the art in the context of the following documents:

• DE 101 14 445 A1 concerning soft iron pigments,
• EP 0 641 461 A1 concerning encapsulated magnetic particles, pigments and carbon black, compounds and related processes,
• DE 36 17 430 A1 concerning pearlescent pigments,
• DE 43 40 141 A1 concerning magnetizable luster pigments,
• DE 40 41 467 A1 concerning magnetic printing inks,
• EP 2 024 451 B1 concerning a coating composition for producing magnetically induced images,
• DE 44 38 743 A1 concerning an offset printing machine,
• DE 10 2004 035 866 A1 concerning a device and a method for coating,
• EP 1 641 624 B1 concerning a method and means for producing a magnetic pattern in a magnetic particle coating and
• EP 0 556 449 B1 concerning a magnetically produced pattern and a magnetically produced patterned product.

An applied in offset, flexo, gravure or screen printing or inkjet coating (dispersion or UV) is before complete drying or curing exposed to a magnetic field, so that the pigments contained are individually aligned. In this way, optical effects are achieved and / or transmitted information. The above-mentioned methods can be combined in any order with the known printing methods, for example by offset printing and flexo lacquer coating, both inline and offline. The method can be applied to sheetfed and web presses.

In the DE 101 14 445 soft iron pigments are disclosed which can orient themselves by the action of a magnetic field in a medium. The application in printing inks and lacquers is listed as a possible field of application. In the DE 101 14 446 Another embodiment of magnetizable iron effect pigments is described, which are suitable for use in paints and printing inks. In the EP 0 641 461 encapsulated magnetic particles, pigments and blacks are shown for use in lithographic printing inks. In the DE 36 17 430 colored, pearlescent pearlescent pigments are described which have magnetic properties. In the DE 43 40 141 describes magnetizable luster pigments for printing ink and lacquers based on coated non-ferromagnetic, metallic substances with a ferromagnetic layer. The application of printing inks with magnetic properties are in the DE 44 38 743 demonstrated. In this patent, the control of the color transfer of a magnetic ink by means of applied magnetic fields. In the DE 40 41 467 For example, magnetic printing inks are used to create magnetic imprints on, for example, check forms, tickets and similar printed products that are legible with special equipment.

Printing inks and coatings containing magnetizable pigments and / or magnetizable particles and the use in offset printing press and other rotary printing presses are therefore well known.

Furthermore, from the EP 1 641 624 B1 a device for magnetically transferring characters such as a design or an image onto a wet coating applied to a sheet or web. The coating includes at least one type of magnetic or magnetizable particles, and the device includes a body of permanent magnetic material. The magnetic material is permanently magnetized in a direction substantially perpendicular to the surface of the body. The surface of the body carries signs in the form of indentations, causing disturbances of its magnetic field. The body is mounted either as a flat or cylindrically curved plate and on a rotatable cylinder on a printing machine.

1. a) Aufbringen einer Schicht aus einer Druckfarbe oder einer Beschichtung auf eine Oberfläche eines Blattes oder einer Bahn, wobei Druckfarbe oder Beschichtung magnetischen oder magnetisierbare Partikel umfasst;
2. b) Die Druckfarbe oder Beschichtung nach Schritt a) wird nass dem Magnetfeld an der Oberfläche eines Körpers aus permanentmagnetischem Material auf einem Zylinder auf einer Druckmaschine ausgesetzt, wobei dort vorbestimmbare Zeichen in Form von Einkerbungen vorhanden sind, so dass sich die magnetischen oder magnetisierbaren Partikel in dem Magnetfeld orientieren können; und
3. c) Härten der Druckfarbe oder Beschichtung, so dass die Orientierung der orientierten magnetischen Partikel von Schritt b) irreversibel fixiert wird.

A method of magnetically transferring predeterminable characters, such as a design or an image, to a printed document using the device should comprise the steps of:

1. a) applying a layer of a printing ink or a coating on a surface of a sheet or a web, wherein printing ink or coating comprises magnetic or magnetizable particles;
2. b) The printing ink or coating after step a) is wet exposed to the magnetic field on the surface of a body of permanent magnetic material on a cylinder on a printing machine, where predeterminable characters are present in the form of notches, so that the magnetic or magnetizable particles in can orient the magnetic field; and
3. c) curing the printing ink or coating, so that the orientation of the oriented magnetic particles of step b) is irreversibly fixed.

Furthermore, from the EP 0 556 449 B1 a painted product having a desired pattern formed thereon. This contains a body; a lacquer layer, which lies on a surface of the body, wherein the lacquer layer consists of a transparent lacquer medium. The medium is mixed with magnetic non-spherical particles and fixed therein. A pattern is defined by a portion of the lacquer layer in which the particles have a predetermined orientation that alters the transparency. The particles in the lacquer layer are present in an amount and are oriented so that a maximum cross-sectional area of the particles is arranged substantially parallel to the surface of the lacquer layer or inclined or perpendicular to the surface. This variation results in a pattern with three-dimensional appearance and is stably visible on the surface of the body.

1. (a) Bilden einer Lackschicht in flüssigem Zustand auf der Oberflache des Produkts, wobei das Lackmedium transparent ist und eine Vielzahl von magnetischen Partikeln enthält;
2. (b) Anlegen eines Magnetfelds an die Lackschicht im Bereich des Musters, um dort eine bevorzugte Orientierung der Partikel zu bewirken, die die Transparenz der Lackschicht verändert,
3. (c) Verfestigen der Lackschicht, um so die Partikel in der Lackschicht zu fixieren,
4. (d) Einbringen der Partikel und Anlegen eines Magnetfelds, dessen Feldlinien in dem Bereich von einer Orientierung im Wesentlichen parallel zu einer Oberflache der Lackschicht zu einer Orientierung geneigt oder senkecht zu der Oberflache der Lackschicht variieren.

A process for painting the product shows the process steps:

1. (a) forming a paint layer in a liquid state on the surface of the product, wherein the paint medium is transparent and contains a plurality of magnetic particles;
2. (b) applying a magnetic field to the lacquer layer in the region of the pattern in order to effect a preferred orientation of the particles which alters the transparency of the lacquer layer,
3. (c) solidifying the lacquer layer so as to fix the particles in the lacquer layer,
4. (D) introducing the particles and applying a magnetic field whose field lines in the range of an orientation substantially parallel to a surface of the lacquer layer to an orientation inclined or senkecht vary to the surface of the lacquer layer.

Furthermore, from the DE 10 2004 035 866 A1 a device and a method for coating known. Described is the generation of optically visible or invisible effects in a coating containing magnetic or magnetizable pigments and / or particles. The process takes place under the influence of a magnetic field. Characteristic of these effects is that the effect is caused by magnetic field generating devices during the machine pass through a rotary printing machine directly on the substrate on the substrate or indirectly in the layer before application to the substrate. These effects can be used for decorative purposes, but also to ensure high security against counterfeiting.

Finally, out of the EP 2 024 451 B1 a coating composition for producing a magnetically induced image, which is defined by a ratio of an ink content to magnetically orientable interference pigments of greater than 3 to 5. The inks are called flexographic, gravure, screen or inks.

• Aufbringen der Beschichtung auf ein Substrat, Orientieren der Pigmentpartikel durch Anlegen eines Magnetfeldes und Härten bzw. Trocknen der orientierten Beschichtung, um die Partikel in den orientierten Positionen zu fixieren.
• Der Schritt zur Orientierung der Pigmentpartikel kann gleichzeitig mit der Beschichtung oder danach ausgeführt werden.
• Die Härtung oder Trocknung kann durch physikalische Verdampfung, UV-Härtung, oxidative oder chemischer Vernetzung, Elektronenstrahlhärtung oder eine Kombination davon ausgeführt werden.
• Die magnetisch orientierbaren und optisch variablen Pigmentpartikel werden mit einer Druckfarbe gedruckt, die als Flexodruck-, Tiefdruck-, Siebdruck- und Walzenbeschichtungsfarbe charakterisiert wird.
• Eine solche Bildbeschichtung wird auf Banknoten, Kreditkarten, Zugangskarten, Sicherheitsabzeichen, Dokumenten von Wert, Rechten oder Identität, Transporttickets, Lotterietickets, Eventtickets, Steuerbanderolen, Sicherheitsfäden, - etiketten, -folien, -streifen oder Produktsicherheitsapplikationen oder in dort verwendeten Sicherheitselementen Produktsicherheitsapplikationen eingesetzt. Als Markierungsmittel werden Infrarot-, Fluoreszenz-, UV-, Phosphoreszenz-, magnetische oder forensische Marker verwendet.

The production of a magnetically induced image includes that from the EP 1 641 624 B1 known steps:

• Applying the coating to a substrate, orienting the pigment particles by applying a magnetic field, and curing or drying the oriented coating to fix the particles in the oriented positions.
• The step of orienting the pigment particles may be carried out simultaneously with the coating or thereafter.
• The curing or drying can be carried out by physical evaporation, UV curing, oxidative or chemical crosslinking, electron beam curing, or a combination thereof.
• The magnetically orientable and optically variable pigment particles are printed with a printing ink characterized as flexographic, gravure, screen and roller coating.
• Such image coating is used on banknotes, credit cards, access cards, security badges, documents of value, rights or identity, transport tickets, lottery tickets, event tickets, tax stamps, security threads, labels, films, strips or product safety applications or security products used in product safety applications. As a marker, infrared, fluorescent, UV, phosphorescence, magnetic or forensic markers are used.

Furthermore, from the DE 10 2005 019 919 A1 a method of producing color effect images is known, wherein color effect images are produced on a carrier substrate. On a magnetizable printing plate to a latent magnetic image of magnetic pixels and non-magnetic pixels is generated. At the magnetizable printing form, a carrier substrate with a decorative layer applied thereon is then guided past non-spherical, preferably acicular or platelet-shaped magnetic, color effect pigments. This color effect pigments of the decorative layer changed by the generated by the magnetic pixels of the magnetizable printing form field line image in its orientation to the carrier substrate.

The color effect pigments are in a changed by the field line image of the printing form alignment in the

Decorative layer fixed. An apparatus for carrying out the method produces a multilayer body that can be produced thereby.

Furthermore, from the WO 2004/007095 A2 a method and apparatus for orienting magnetic flakes to produce optical effects in a substrate such as ink. In this case, a magnetized cylinder with permanently installed magnetic elements is associated with a coated substrate. The magnetic elements act from the magnetization cylinder in the arrangement specified there from the rear side of the substrate to the magnetically influenceable coating of the substrate.

Furthermore, from the EP 1 990 208 A1 an apparatus and method for magnetically transferring features into a coating on a substrate. For magnetic imagewise influencing of a coating, a further intermediate layer is provided in addition to a magnetizable plate, which has a cutout pattern corresponding to the image to be generated.

The above-described methods of the above-referenced documents generally use, for the production of patterns, the application of permanent magnets which are to be attached to a cylinder surface during the production of the patterns. Also, the use of electromagnets for direct imaging is called. All procedures are either inflexible or very expensive.

The object of the invention is to improve an economical method and associated devices according to the preamble of claim 1 for economical use within printing presses.

The object is achieved with the method features of claim 1 and the device features of claim 4.

The present invention utilizes a writable magnetic printing form to produce an image in a coating of lacquer enriched with ferromagnetic pigments.

The basis here are elements with ferromagnetic properties that can be aligned by an external magnetic field.

These action elements can be imaged outside a printing press in a suitable device under the influence of suitable magnetic fields. According to the invention, the action elements within the printing machine are imaged under the influence of suitable magnetic fields.

According to the invention, the action elements are designed as controllable magnetic devices arranged in the printing machine of the coated surface to be influenced.

As a result, the printed product is influenced by the magnetic field for the time of transport in the region of the magnetic field. When using a stationary mounted electromagnets result in significantly shorter exposure times.

If the action element is a compressible foil, the imaging can take place as in a conventional pressure plate. The film is clamped on a rubber or printing cylinder for imaging. When the print job is completed, the magnetic image is deleted again and it can be a new orientation or imprinting of a magnetic field.

Also, a magnetically writable endless belt can be passed through the printing unit similar to the film transfer arrangement, wherein the endless belt is individually imaged on a clear and write head.

Furthermore, an active element is also conceivable, wherein in a carrier film, a grid of magnetic elements is embedded, which are used for individual image design. For this purpose, the imaging can be linked with the workflow of the prepress to the printing press to match the image information.

As a further procedure, in combination with a device for magnetically supporting working elements on a printing cylinder by partially attaching ferromagnetic cover elements, a targeted disturbance of the induced magnetic field may be possible. When using a homogeneous (machine side) magnetic field image information is generated by redirecting or disturbing the magnetic field lines in the overlying paint coating by the cover.

As a further procedure, in combination with a film transfer device by partial application of ferromagnetic film regions to the substrate, a targeted disruption of the magnetic field induced by the substrate may be possible. When using a homogeneous from the machine side magnetic field is due to the application of foil on the substrate a Image information generated by diversion or disturbance of the magnetic field lines in the overlying paint coating.

These optical three-dimensional effects are not only decorative, but create a unique structure that is adjustable only at great expense. As a result, a counterfeit protection is achieved, which is inexpensive and at the same decorative nature.

In the following, the invention is illustrated in more detail with reference to drawings.

Figur 1

eine prinzipielle schematisierte Darstellung einer erfindungsgemäßen Anordnung,

Figur 2

eine erste alternative Anordnung,

Figur 3

eine zweite alternative Anordnung,

Figur 4

eine Inline-Anordnung mit Magnetisierungsköpfen, und

Figuren 5 und 6

zwei Beispiele für optische Ausprägungen in Lackschichten mittels Magnetbeeinflussung.

Show here

FIG. 1

a schematic diagram of an inventive arrangement,

FIG. 2

a first alternative arrangement,

FIG. 3

a second alternative arrangement,

FIG. 4

an inline arrangement with magnetizing heads, and

FIGS. 5 and 6

two examples of optical manifestations in lacquer layers by means of magnetic influence.

The state of the art after the DE 10 2004 0355 866 A1 is reproduced in detail below. This is the working principle of the method in FIG. 1 shown schematically and explained.

The effect presupposes that the particles or pigments are still freely movable in the medium, therefore it makes sense to have the pigment and / or particle distribution influenced by the magnetic field as directly as possible after application of the printing ink or varnish. Preferably, the application is carried out with a coating unit, since with this higher layer thicknesses than with an offset printing unit can be transferred to the substrate. In a thicker coating, the magnetizable pigments and / or particles can move and orient much easier in the rule. Another aspect that speaks for the application of paints containing therein magnetizable pigments and particles is that with an offset printing unit only relatively small pigments and / or particles can be printed. The range of processable pigment and / or particle sizes are significantly greater in a coating unit, which is preferably equipped with a chamber doctor blade and an anilox roller, compared to the application via an offset printing unit.

The selection of the medium in which the magnetizable pigments and / or particles are embedded also influences the expression of the effect. While in the conventional, oil-based printing inks, a substantial proportion of the drying process takes place via the removal of binder components in the printing substrate, the curing of so-called UV inks or other radiation-curing inks or varnishes takes place only after passing through a curing device. The removal of conventional printing inks usually occurs spontaneously after the application of the printing ink to an absorbent substrate. This is disadvantageous for the method described here for producing optically effective effects, since the path-impacting process reduces the layer thickness and, associated therewith, the mobility of the magnetic pigments and / or particles. Similar Wegschlageffekte can also be observed in aqueous emulsion paints, the applied layer thickness is indeed generally higher than the typical transmitted in an offset printing layer thickness, but on the other hand, these aqueous coatings containing a large proportion of water as a solvent that particularly easy and fast in an absorbent Can reject printing material. Again, UV paints or other radiation-curing paints offer a good alternative, since the paint layer on at least for the most part the printing material rests and thus the mobility of the magnetic particles and / or pigments is optimally given. Another advantage of the radiation-curing inks and varnishes is that once a distribution pattern of the magnetic particles and / or magnetic pigments radiation exposure in a curing device, for example by a UV dryer, can be frozen relatively spontaneously.

Basis for the invention are active elements such as films, sheets, plates or strips, which are provided with ferromagnetic properties. These properties can be formed over the full surface or partially via an active element. The ferromagnetic property can be formed offline and inline by an external magnetic field and aligned specifically, so that virtually a caption of the magnetizable active element takes place.

1. a.) außerhalb der Druckmaschine in einer geeigneten Vorrichtung oder
2. b.) innerhalb der Druckmaschine unter Einfluss geeigneter Magnetfelder (siehe hierzu Figur 4)

magnetisiert bzw. magnetisch bebildert werden.These action elements can thereby

1. a.) outside the printing press in a suitable device or
2. b.) within the printing press under the influence of suitable magnetic fields (see FIG. 4 )

magnetized or magnetically imaged.

Essential for efficient action to align the magnetizable pigments or particles in the paint is that the magnetic field lines close in the region of the coating on the printed sheet. This is best given by the chosen performance as a magnetized thin plate or foil (see FIG. 1 ). In this arrangement, the magnetizable pigments or particles are deflected to a very great extent from the normal orientation and thus give the desired optical effect in a particularly favorable manner.

By use in the printing unit or coating unit, the printed product is exposed to a magnetic influence in the range of its magnetic field for the time of transport to the contact element. For example, on a sheet leading cylinder surface of a conventional sheet-fed offset printing machine for the duration of half a revolution of a counter-pressure cylinder, the magnetic field of a clamping element spanned on the impression cylinder influence the paint layer of the printing sheet resting there.

When using one or more stationary mounted electromagnets to influence the effect of the paint coating, on the other hand, significantly shorter exposure times and thus weaker effects result.

If the action element is, for example, a magnetic film which is clamped, the imaging can also take place outside the machine, such as, for example, in a printing plate conventionally used in printing presses. The magnetic film is clamped for imaging on form, plate, rubber or impression cylinder. Advantageously, the application on sheet leading impression cylinder, since there the exposure time is the longest. When the print job is completed, the magnetic image on the magnetic film can be erased again and it can be a new orientation or an imprint of a differently structured magnetic field.

In addition, a magnetically writable tape can be passed through the printing unit. For this purpose, a device in the manner of a film transfer arrangement can be used in a sheet-fed press. Here, instead of a transfer film web, an endless belt with magnetic properties is used. This endless belt can be guided past a delete and write head, which inline and running the individual imaging with magnetic effects in the desired patterning - possibly designed to be variable - executes. Here comes a device similar to the one in FIG. 4 shown magnetizing heads in question.

As an alternative embodiment, an active element is also conceivable: In a carrier film, a grid of magnetic elements is inserted, which can be used for individual image design - depending on the control, this can be done in relation to individual sheets or on print jobs.

In addition, the imaging can be linked with the workflow of a preliminary stage or the printing press in order to match the image information of the printed images and the coating patterns to be produced.

In a reversal of the principle of action, a targeted disturbance of the induced magnetic field is possible by a combination with a film transfer device in the printing press by partially applying ferromagnetic film regions from a transfer film. This image information is generated in the paint in combination with the use of a homogeneous and fixed in the printing machine magnetic field by the transfer film order. This results from a diversion or disturbance of the magnetic field lines on the film pattern.

As devices for generating a magnetic field, all types of known magnetizable elements can be used. One possible embodiment could be plates similar to printing plates or blankets, trays as curved plates or films that can be taken in the printing or coating units in holding devices All conceivable designs are possible, which are suitable for producing an effect structure. The magnetizable elements must be taken in a holding device so that the main direction of the magnetic field is directed against the substrate.

As an alternative to the previously mentioned approach, the magnetic elements could be clamped or glued onto the impression cylinder in a printing unit or in a transfer module, ie the magnetic force would act on the layer located thereon through the back of the sheet. This approach can be realized by, for example, mounting a plate on the impression cylinder, which has magnetized and non-magnetized regions. On the other hand argues that the plates are clamped at a double-sized cylinder on both halves of the cylinder and the two patterns would have to be made to fit. As a result, an increased set-up time is expected. The maximum magnetic force is limited because the height of the magnet is limited by the often low undercut of the impression cylinder. Also, the air gap between the site of action of the magnet and the layer to be influenced in the carton printing is very high large, as the substrate is between the magnet and the sighting. Nevertheless, this method would be quite suitable for thin substrate, for example for label printing, since the long wrap angle, the exposure time is very long and thus the low magnetic force could be compensated quite.

As a further embodiment, the impression cylinder or a plate located thereon could consist of a magnetizable material. This would have the advantage that the cylinder or an optionally located thereon plate could be partially magnetized. This could be done by a magnetizer during the period in which the cylinder is not covered by a print sheet. This period of time is relatively long, so that a very high magnetic force could be achieved by a skillful power selection or by a series connection of multiple angle-controlled magnetization, which has a good effect through the substrate on the layer thereon with the embedded therein magnetic or magnetizable pigments and / or would allow particles. The advantage of the long contact time due to the long wrap angle could well be realized without the fact that superstructures on the impression cylinder would interfere with the sheet travel due to magnets. The magnetization of the impression cylinder or on a counter-pressure cylinder plate could be done by electromagnets, permanent magnets or by another device that can generate a magnetic field.

In addition to the direct production of the optical effect of the invention by the action of a magnetic field on magnetized or magnetizable pigments and / or particles in a coating on the substrate, the effect of the invention can also be generated indirectly by the magnetizable elements against the printing plate in a coating unit or the Blanket or printing plate of an offset printing unit to be addressed. The orientation of the pigments and / or the particles in this case takes place on the printing form or the blanket before the lacquer or printing ink layer comes into contact with the printing material. On the substrate thus a layer is applied by the magnetic or magnetizable pigments and / or particles are already structured in a structured by the action of a magnetic field.

The magnetic influence of the layer could also allow the transmission of data information. In this case, the effect of the ordered magnetizable or magnetic pigments or particles would not even have to be visible, i. the particles or pigments could be embedded in a printing ink and be there after exposure to a magnetic field in an ordered structure containing information. In the simplest case, for example, these could be line information of different complexity, but also letters or other information-bearing codes. This would allow a complete tracking of a package, because ultimately each package could be provided with a different code. At least every edition could be given an individual code. The code could later, even if it is not visually visible, read with appropriate readers. In contrast to the known methods for transmitting information to magnetic strips, which can also be made with magnetizable ink, the information-carrying code is introduced by means of a magnetic head or other type of magnetic device in the fresh, undried ink or paint by the magnetizable or magnetic particles be arranged by a magnetic field according to the information code and the paint or the paint then dried by physical and / or chemical means, with or without the action of a drying device. This method has the advantage that once a code introduced by the drying process fixed and can not be changed later by manipulation.

Another advantage for the indirect production of structures and patterns in the present ink or varnish film is that the ink or varnish film is available in a higher thickness than on the substrate and thus gives better mobility of the pigments and / or particles is. Of the printing form, only a portion of the layer present there is transferred to the substrate during the nip process. Another advantage of the indirect method is also due to the fact that still no strike-breaking process has taken place in the direct method (action of the magnetic field on the substrate located on the substrate) begins almost suddenly in aqueous systems and printing inks. The consequent reduction of the layer thickness limits the mobility of the pigments and / or particles. On the printing form or the blanket no components of the printing ink or varnish can knock off, so that there is always the full layer thickness and thus maximum mobility is guaranteed.

The exemplary embodiments will now be explained with reference to the drawings.

In FIG. 1 is the principle for the action of a static magnetic field for the alignment of magnetizable pigments 2 or particles in a freshly applied paint layer L shown on a substrate. A magnetic image 1 is embedded as a permanent magnet or electromagnet 3 in a magnetizable plate 4 and here shows a magnetic polarity with a north pole N and a south pole S. Between the magnetic poles, closed magnetic field lines 5 propagate. Furthermore, a substrate B is placed on the magnetizable plate 4. On the printing substrate B, in turn, a layer L of a lacquer equipped with magnetizable pigments 2 and / or particles is applied. The arrangement is chosen such that the magnetic field lines 5 close in the region of the layer L which is applied to the printing substrate B. Due to the shape of the magnetization in the magnetizable plate 4, the displacement of pigments 2 or particles shown in the layer L is generated. This results in the layer L of the desired optical effect. The magnetizable plate 4 may be a thin plate or so may be formed as a film.

By use in a printing unit or coating unit of a sheet-fed printing machine, the printing substrate 4 is exposed in the manner shown above for the time of transport to the magnetized plate 4 the action of the magnetic field and the pigments 2 or particles in the paint can align along the field lines 5 ,

In FIG. 2 the principle is extended to a static imagewise magnetization. A magnetic image 1 is embedded as a permanent magnet or electromagnet 3 in a magnetizable plate 4 and here shows a more detailed magnetic polarity with several alternately arranged north N and south poles S. Between the alternating magnetic poles now many each closed magnetic field lines 5 from. A layer L of a ferromagnetic lacquer coated with pigments 2 and / or particles is again applied to the printing material B applied to the magnetizable plate 4. The arrangement is also chosen so that the magnetic field lines 5 close in the region of the layer L on the substrate B. The shape of the magnetized image in the plate 4 shown here produces the displacement of pigments 2 or particles shown in the layer L, which shows more details here than in the arrangement in FIG Fig. 1 , Thus, in the layer L optical effects can be achieved, which contain images, graphic elements, data or codes. The magnetizable plate 4 may also be designed as a thin plate or film for this purpose.

For the generation of the magnetic imaging after Fig. 1 and Fig. 2 First, a magnetization outside the printing press as a preparatory measure for the coating process in question. However, it is also possible within the printing press to assign a magnetization device to the respective cylinder carrying the magnetizable plate 4 (for example, correspondingly executable as in FIG Fig. 4 ). Then the magnetization can take place as an automatic setup measure during the setup of the printing press. Likewise, the magnetization can be refreshed during the printing process or during print interruptions.

In FIG. 3 the principle of imagewise magnetization is extended as an indirectly executable process. The magnetization of permanent or electromagnets 3 in the magnetizable plate 4, referred to as magnetic image 1, is to be understood here as a statically present and areally homogeneous magnetization. Therefore, here shows a small-scale magnetic polarity with many alternately arranged north N and south poles S, which extends over the entire plate 4 in a uniform distribution. Spread between the alternating magnetic poles There are many magnetic field lines 5.1, each closed by a short path. In addition, an intermediate layer 6 of ferromagnetic material is now placed on the magnetizable plate 4. In this intermediate layer 6, a magnetization is again induced, which is oriented at its outer edges. Magnetic field lines 5, which penetrate a printing substrate B on which a layer L of a ferromagnetic paint having pigments 2 and / or particles coated paint is applied, are thus again produced. The arrangement is also chosen so that the magnetic field lines 5 close in the region of the layer L on the substrate B. As a result of the form of the magnetized image derived from the shape of the intermediate layer 6 from the magnetized plate 4, the displacement of pigments 2 or particles shown in the layer L is produced, which now shows exactly the details given by the intermediate layer 6. The magnetizable plate 4 may also be designed as a thin plate or film for this purpose. Likewise, the intermediate layer 6 may be formed of magnetizable material as a thin plate or foil.

The arrangement after Fig. 3 allows a comparatively easy handling. On the respective cylinder of the printing press, which leads the freshly coated printing material B, a permanent and flat, homogeneously magnetized plate 4 is clamped here. For imaging now only one with respect to the desired expression of the magnetic image prefabricated intermediate layer 6, which should consist of magnetizable material, are placed on the plate 4, where it then adheres independently. The transfer of the magnetically induced image into the lacquer layer L then takes place without further support measures. The liners are easy to prepare and easy to install on the plate 4 and position.

When using a pad of non-magnetizable material on the one hand, the need for attachment other than magnetic type, so for example by gluing. On the other hand, it is thus also possible to effect a pictorial influence on the lacquer layer L by means of a corresponding weakening of the magnetic field from the plate 4 with possibly more cost-effective materials.

Another very interesting production variant with regard to the achievement of optical effect in the combination of coating media can in connection with the arrangement according to Fig. 3 be carried out with the process of so-called cold foil transfer.

In cold foil transfer, metallic layers are applied in image form from a transfer film to a printing material printed with an adhesive image. The adhesive printing takes place in a first printing unit in any mass printing process. In a subordinate coating unit (sheet-fed printing unit, coating unit, coating module), the metallized image is transferred to the adhesive area by applying the transfer film to the printing material under pressure. Of the transfer film only the necessary parts of the metal layer are removed in the area of the adhesive image. For example, a metallic picture was created on the substrate.

If, after the cold foil transfer, the printing material is still printed on the printing material and then coated with a ferromagnetically doped lacquer, a plate 4 homogeneously magnetized as mentioned above can also be used here in order to introduce magnetically induced image effects. Here, the magnetic field is then transformed into a magnetic image by means of the metal layers applied to the printing substrate so that the pigments 2 or particles are deflected directly in the overlying lacquer layer L and cause optical effects corresponding to the metal image. Thus, the optical effects of the metal image complement those of the pigment deflection in the paint layer L on the substrate B.

According to this embodiment, therefore, to generate a magnetically induced image instead of an intermediate layer 6, which after Fig. 3 between the plate 4 and the substrate B carrying the paint layer L is used, a metallic layer used, which has been applied before the paint application to the substrate B below the paint layer L.

The arrangements of FIGS. 1 to 3 are provided on bow-leading cylinders or devices with fixed cylindrical surfaces associated with one or more gripper assemblies. By means of grippers, printed sheets are held and transported in a sheet transport direction.

On the one hand, such cylinders can be used for the arrangement in a coating module for a simultaneous application of the lacquer layer L upstream of the magnetization. Or such cylinders are arranged in a treatment module which is directly downstream of a printing unit or paint module producing the paint layer L.

In FIG. 4 The principle of imagewise magnetization is shown again as a directly executable process, which, however, is characterized by a dynamic - ie not static - magnetization, extended. Here is a bow leading cylinder Z indicated by drawing, as it is known by default in sheetfed presses. Sheet leading cylinders Z in sheetfed presses are provided with fixed cylindrical surfaces associated with one or more gripper assemblies. These can be impression cylinders or bow guide drums. By means of the grippers, printing sheets of the printing material B to be processed are held on the cylinder surface and transported in the sheet transport direction R. The cylinder Z indicated here is provided for the arrangement in a coating module for the application of varnish or in a module downstream of the coating module.

The magnetization representing a magnetic image is generated here completely with electromagnets 3 which are arranged in magnetization heads 7. The magnetizing heads 7 are arranged equidistantly above the surface of the cylinder 7 in a raster arranged over the entire width and over parts or the entire circumference of the cylinder Z, in accordance with the need for imaging. On the cylinder Z itself, a magnetizable pad can be provided as a plate 4.1. Between the cylinder surface and the magnetizing heads 7, the printing material B is guided with the lacquer layer L and the pigments 2 and / or particles contained therein. Between magnetic poles controllably controllable in the magnetization heads 7, many closed magnetic field lines now spread, which now directly penetrate the layer L of a paint material equipped with magnetizable pigments 2 and / or particles without the interposition of a printing material B there. The arrangement is also chosen here so that the magnetic field lines close in the region of the layer L on the substrate B. By the here shown magnetization, a shift of magnetizable pigments or particles is generated in the layer L, which now shows exactly the details that are given by the magnetic control of the magnetizing heads 7 before.

Since the magnetization when passing through the printing substrate B at a magnetization head 7 lasts only for a very short time, the corresponding magnetization effect is repeated at corresponding downstream magnetizing heads 7 for each image area. A corresponding magnetizing pulse is controlled in accordance with the curve 8 by all magnetizing heads 7 synchronously with the movement of the printing material B.

Thus, fine or coarse optical patterns or areal displacements of the pigments 2 and / or particles can be produced in the lacquer layer L.

A magnetizable thin plate 4.1 or foil on the cylinder Z can support the magnetization effect by the dynamic magnetization is reflected there and enhances the dynamic effect.

In Fig. 4 the assignment of a dryer T after the treatment station is represented by the magnetization. With the dryer T, the previously prepared displacement of the pigments 2 and / or particles in the lacquer layer (L) can be frozen by rapid curing of the lacquer layer (L). Thus, he desired optical effect in the lacquer layer (L) is recorded.

An arrangement of magnetizing heads 7 accordingly Fig. 4 is also suitable for erasing and rewriting a magnetization image on a plate 4, if this according to the arrangement Fig. 2 is used to form a static magnetization image.

Furthermore, it is conceivable that the optically visible or invisible effect in the lacquer layer L is due to an action of the magnetic field generated by the magnetizing heads 7 or a magnetizable plate 4 on magnetically or magnetizable formed pigments 2 and / or particles within a printing ink or a lacquer before these are applied as a layer L on the substrate B. Then the magnetization heads 7 or a magnetizable Plate 4 may be arranged on or opposite to a surface of a cylinder carrying the coating medium. This arrangement requires a very rapid curing, since the displacement of the pigments 2 and / or particles can be disturbed in the coating. The arrangement has the advantage that the dryer is arranged very close to the coating position and thus also positioned very quickly acting.

For this purpose, a magnetizable plate 4 or a plate 4 with an intermediate layer 6 or an array of magnetizing 7 or arranged opposite to a forme cylinder of a high-pressure, flexographic printing or coating unit, arranged on a blanket cylinder of an offset printing unit or on a printing plate carrying printing form cylinder of an offset printing unit , Thus, the optical effect or the image pattern can be generated on the corresponding cylinder before the layer L present on the corresponding cylinder is applied directly or indirectly to the printing material B.

Finally, there is the possibility that the working position of the magnetization of the lacquer layer L and the dryer are combined with each other. In this case, it must be ensured that the hardening can take place only after the reorientation of the pigments 2 and / or particles in the lacquer layer L.

LIST OF REFERENCE NUMBERS

• Magnetic picture 1
• Pigments 2
• Permanent or electromagnet 3
• magnetizable plate 4
• magnetized plate 4.1
• magnetic field lines 5
• magnetic field lines 5.1
• Liner 6
• Magnetization head 7

• Lacquer layer L
• North Pole N
• South Pole S.
• Substrate B
• Cylinder Z
• Transport direction R

Claims (5)

1. A method for creating an optically visible or invisible effect or pattern in a coating (L), which contains magnetic and/or magnetisable pigments (2) and/or particles in approximately uniform distribution, and which was applied with a rotary printing press having a letter press, rotogravure or offset printing couple onto a substrate (B), wherein the optically visible or invisible effect or the pattern is achieved through an action of a magnetic field on the magnetic or magnetisable pigments (2) and/or particles in the coating (L), which was applied onto the substrate (B) where it is present in a largely undried or unhardened state during the machine passage and in that the pattern or the effect after the action of the magnetic field is fixed in the coating through drying or irradiation, wherein the magnetic field is created through at least one variably magnetisable element (3; 6; 7),
   characterized in that
   on the substrate (B), which is optionally provided with a pictorial coating, a varnish layer (L) with magnetisable pigments (2) and/or particles is applied, and in that the substrate (B) is guided on a sheet-guiding cylinder (Z) in the region of at least one controllably magnetisable element (3, 7) in such a manner that the magnetic force emanating from the magnetisable element (3, 7) in a controlled manner directly acts on the coating (L) overlying the substrate (B) during the transport of the coated substrate (B).
2. The method according to Claim 1, characterized in that
   at least one further passively magnetisable element (4.1) is mounted onto the sheet-guiding cylinder (Z), such as a single-size or double-size sheet guiding, transfer or impression cylinder of a printing couple or varnish unit so that the magnetic force emanating from the controllably magnetisable element through the substrate and the coating (L) acts on the passively magnetisable element.
3. The method according to Claim 1 or 2,
   characterized in that
   the pattern carries visual information or information detectable through a suitable reading device, which is formed as an image or pattern or logo or barcode or text, consisting of characters and/or numbers.
4. A device for carrying out the method according to Claim 1 in a printing press processing sheets with one or multiple printing couples, with impression cylinder, blanket cylinder and plate cylinder, and at least one varnish module with impression cylinder and forme cylinder, wherein at least one magnetisable element in the form of a plate (4.1) or film with a specifically applied magnetisation representing a pattern or for applying a magnetisation representing a pattern is arranged on a sheet guiding cylinder (Z), which is an impression cylinder or blanket cylinder or plate cylinder of a printing couple or an impression cylinder or forme cylinder of a varnish module, wherein the magnetisation of the plate (4.1) acts on the substrate (B) to be coated in such a manner that a layer (L) provided with magnetic or magnetisable pigments (2) and/or particles of a coating substance on the substrate (B) is influenced according to the magnetisation of the plate (4) representing the pattern,
   characterized in that
   at least one actively controllably magnetisable element for generating a magnetisation representing a pattern is assigned located opposite a sheet guiding cylinder (Z), which is an impression cylinder or blanket cylinder or plate cylinder of a printing couple or an impression cylinder or forme cylinder of a varnish module.
5. The device according to Claim 4,
   characterized in that
   the cylinder (Z) is assigned one or multiple magnetising heads (3, 7) located opposite the sheet guiding surface, wherein the magnetising heads (3, 7) are preferably arranged grid-like over the width and over the circumference corresponding to the area to be magnetised and are provided with a control in such a manner that they can be activated synchronously to the movement of the substrate on the cylinder (Z) in a sheet transport direction (R).

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