EP1737662A2 - Production of image elements - Google Patents

Abstract

The device has a coating module transferring imaging layers of a bearing foil on a printing paper. The module contains an impression cylinder (4) and a pressing roller (3), which together form a combined transfer crack (6). A transfer foil (5), provided in the area of a foil routing device for guiding the transfer foil to a transfer crack, is attached with a device for application of the layers and/or information containing imprints. An independent claim is also included for method for coating of printed sheets in a sheet of paper processing machine.

Description

 Generation of picture elements

The invention relates to a method and apparatus for transferring imaging layers from a carrier foil to printed sheets according to the preamble of patent claims 1, and 9 to 11.

It is known to produce metallic layers on printed sheets by means of a film transfer process. Thus, EP 0 569 520 B1 describes a printing material and a printing device using this material. In this case, a sheet-processing machine is shown, which has a feeder and a boom, wherein printing units and a coating module are arranged between the two units. In at least one of the printing units, an adhesive pattern is applied by means of the planographic printing process. This adhesive pattern is applied in a cold printing process and has a specific imaging subject. In the printing unit following the coating module with a counter-pressure cylinder and a press roller, a film guide is provided. This is designed in such a way that a film strip or a transfer film is guided through the transfer nip of the coating module between the impression cylinder and the press roll from a film supply roll. The film strip is rewound on the outlet side after leaving the coating module. The transfer film has a carrier layer on which imaging layers such as metallic layers, for example of aluminum, can be applied. Between the metallic layer and the carrier film, a separating layer is provided, which ensures that the metallic layer can be removed from the carrier layer.

When printing sheets are transported through the printing unit, each sheet is given an adhesive pattern. Thereafter, the sheet is passed through the coating module, being brought by means of the press roller on the impression cylinder resting sheet with the film material in combination. At the same time, the downwards lying metallic layer is closing in on 12.04.2005 Connect to the adhesive areas on the sheet. After further transporting the printing sheet, the metallic layer adheres only in the area provided with the adhesive pattern. The carrier film is thus removed from the metallic layer in the region of the adhesive pattern. The used in this way transfer film is wound up again. The print sheet is laid out in the coated state.

It is known to use such coating modules, for example in printing units of printing presses. A disadvantage of the known devices is that they can not be used flexibly.

The object of the invention is therefore to provide a device by means of which the transfer of an imaging layer or imaging elements on a sheet can be done safely, economically and accurately, the device should be manageable for an extended range of applications.

The solution to this problem results in a method according to the features of claim 1 and devices according to the features of the claims 9 to 11 ..

Advantageously, the transfer film is coated with separate pixels and the pixels are transferred as or within the coating on the substrate.

In this case, an article security device can advantageously be secured by means of securing elements mounted on the transfer film, such as e.g. Holograms are made.

The device can also be advantageously used in order to improve the use of the film by dividing the transfer film into one or more partial film webs of lesser width. In combination with the above-mentioned method, it is thus also possible to use different types of film side by side. Furthermore, the division of the transfer film into partial films can be used for the use of strips with picture elements for the separate order.

To ensure the cost-effectiveness of the coating process, it may be provided to control the film advance so that the transfer film is stopped when there is no transfer of the imaging or metallization layer but in particular of no image element.

Advantageously, a control of the transfer film can be carried out such that when passing through a gripper of the sheet-guiding impression cylinder receiving cylinder channel of the film feed is stopped, wherein the pressure roller then passes under the transfer film sliding.

Advantageously, it is also possible to provide a plurality of coating modules behind one another within a sheet-processing machine. Thus, the application of different imaging coatings or metallization layers within a subject can take place one after the other. In this case, it is possible to transmit the imaging layers next to one another using a single adhesive pattern with all image-pattern elements. It is also possible to provide a first adhesive pattern in a first coating module with a first image-forming coating or metallization layer and, in the following, superimpose another, the first enclosing adhesive pattern and to provide it with another imaging coating or metallization layer.

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

Showing:

Figure 1 is a basic illustration of a printing machine with a film transfer device and

Figure 2 shows the structure of a coating module with a film transfer device and 3 shows a press roller of a coating module and

Figure 4 shows a variant for the construction of a commissioned work.

FIG. 1 shows a sheet-processing machine, here a printing press, which consists of at least two printing units. The two printing units are used for the following purposes:

- A sheet to be coated is provided in a first step with an adhesive imaging pattern. The application of the adhesive takes place in a device configured as applicator 1, e.g. a conventional printing unit of an offset printing press via existing dyeing and dampening units 11, a printing plate on a plate cylinder 12, a blanket or blanket cylinder 13 and a counter-pressure cylinder 4. Likewise applicators in the form of flexographic printing units or lacquering plants can be used here.

- Thereafter, in a second step, together with a printing sheet, a transfer sheet 5 is passed through a transfer nip 6, wherein the transfer sheet 5 is pressed in the transfer nip 6 against the sheet. For this purpose, a coating module 2 is used which can correspond to a printing unit or a lacquer module or a base unit or another type of processing station of a sheet-fed offset printing press.

The transfer nip 6 in the coating module 2 is formed by a press roll 3 and an impression cylinder 4. In this case, the press roller 3 can correspond to a blanket cylinder and the counterpressure cylinder 4 to a countercurrent cylinder of a known offset printing unit. Furthermore, the press roll 3 can be a forme cylinder and the counterpressure cylinder 4 a counterpressure cylinder of a paint module of a sheet-fed printing machine. correspond to the machine.

- Furthermore, the coating module 2 downstream of a so-called calendering be provided when the coated sheet to increase the adhesion of the coating or to increase the smoothness and gloss of the sheet is to be rolled under increased pressure.

Within the coating module 2 used for the film transfer, a web guide for transfer films 5 is shown. For processing in question transfer sheets 5 are constructed in multiple layers. They have a carrier layer on which an imaging layer is applied by means of a release layer. The separating layer serves to facilitate lifting of the imaging layer from the carrier layer. The imaging layer may be e.g. a metallized layer or a glossy layer or a texture layer or a colored layer or a layer containing one or more image patterns.

The film supply roll 8 is assigned to the coating module 2 on the side of the sheet feed. The film supply roll 8 has a rotary drive 7. The rotary drive 7 is required for the continuous controlled feeding of the transfer film 5 to the coating module 2 and is therefore controllable. Furthermore, in the field of film feed and removal guide devices 14, such as deflection or tensioning rollers, pneumatically actuated conducting means, baffles o. Ä. Provided. In this way, the film web of the transfer film 5 can always be guided flat without distortions and held in the same tension against the press roll 3. The guide devices 14 may also contain aids for introducing the transfer film 5. In this case, automatic retraction aids for the film web of the transfer film 5 can be used. In this way, the film feed in the area of the protective unit 15 surrounding the coating unit 2 is simplified. The protective function of the shields 15 is at the same time completely maintained. In this case, the transfer film 5 can be guided around the press roll 3, wherein the transfer film 5 can advantageously be fed and discharged from the press nip 6 only from one side of the coating module 2 (see dashed representation). 1 and depending on the space conditions on the one side of the coating module 2, the film web can be guided in an advantageous manner in the feeding strand and in the discharging strand closely parallel to one another.

In a further embodiment, the transfer film 5 can also be fed in and out substantially tangentially on the press roll 3 or wrap it around the press nip 6 only in a small peripheral angle. For this purpose, the transfer film 5 is supplied from one side of the coating module 2 and discharged to the opposite side of the coating module 2.

On the outlet side of the printing unit, a film collecting roller 9 is shown. On the film collecting roll 9, the used film material is wound up again. Again, a rotary drive 7 is provided for the optimized production, which is controllable. In essence, the transfer film 5 could also be moved by the rotary drive 7 on the outlet side and kept taut on the inlet side by means of a brake.

For the transfer process of imaging e.g. Wear layer of the transfer film 5 on the sheet in the transfer nip 6 between the press roll 3 and the impression cylinder 4 is essential that the surface of the press roll 3 so the blanket cylinder or forme cylinder is equipped by means of a compressible, damping element.

The press roll 3 is therefore provided with a press fabric 10 or as a roll with a corresponding coating (see Fig. 3). The press fabric 10 or press coating can be performed, for example, as a plastic coating, comparable to a blanket or blanket. The surface of the press fabric 10 or press coating is preferably made very smooth in a press surface 20. It can also be formed from antiadhesive substances or structures. Here comes, for example, a relatively hard structure in the form of very fine spherical caps in question. A press fabric 10 is held on the press roll 3 in a cylinder channel 19 on jigs. The press fabric 10 may be equipped to improve the transmission properties in the transfer nip 6 with a targeted elasticity. If necessary, this can act in a compressible intermediate layer. This compressibility is preferably similar or less than in conventional blankets or blankets, which can also be used at this point. The mentioned compressibility can be produced by means of a conventional compressible printing blanket. Furthermore, combined fabrics made of a hard blanket and a soft pad can be used.

Furthermore, a limited pressing surface can be provided directly on the press roll 3 or on the press fabric 10. This can be worked out of the surface of the press fabric 10 or it can be additionally attached as a partial surface of the material of the press fabric 10 on the press roller 3.

To improve the efficiency of the coating process, it is provided that the film advance of the transfer film 5 from the film supply roll 8 to the transfer nip 6 and the film collection roll 9 is controllable so that as far as possible the transfer film 5 is stopped when no transfer of the imaging layer should take place :

For this purpose, a control of the transfer film 5 can be made such that the film feed is stopped when passing through a gripper of the sheet-guiding impression cylinder 4 receiving cylinder channel. The grippers hold the printed sheet on the impression cylinder 4. The press roll 3 has a corresponding cylinder channel 19 (see Fig. 3), in which a press fabric 10 is supported. In the region of the corresponding cylinder channels, there is no pressing of the transfer film 5 between the press roll 3 (blanket cylinder) and the impression cylinder 4. The press roll 3 then continues to slide on the transfer film 5, while the transfer film 5 is stretched freely between the press roll 3 and impression cylinder 4. This state continues until at the so-called pressure beginning of the cylinder channel 19 ends and the transfer film 5 is again clamped between the press roller 3 and the counter-pressure cylinder 4 including a printed sheet. Then, the transfer sheet 5 continues transported. The timing of the film feed can begin or suspend slightly earlier than pretend the channel edges of the cylinder channel according to a necessary acceleration or braking of the film supply roll 8 or film collecting 9. In reaction-fast timing systems via so-called dancer rollers 18, as are shown by way of example in FIG. 1, the control of the rotary drives 7 of the film supply rolls 8 or film collection roll 9 may not be necessary. By means of the dancer rollers 18, the necessary film tension is also maintained.

A further improvement of the film utilization of the type described results from the fact that the transfer film 5 is divided into one or more Teilfolienbahnen lesser width. Thus, with appropriate control by means of the device or devices for timing the film feed each of the sub-film webs, the utilization of the transfer film 5 can be improved even in zonal different Lie long coating areas within an arc. For this purpose, each partial film web is conveyed only exactly in the area where the imaging surface layer is to be applied. In the areas not to be coated, each partial film web can be stopped independently of the other partial film webs, whereby no unnecessary film consumption arises.

Furthermore, to improve the coating process provided in the area of the adhesive application and in the area of the film order dryer 16 provided. Thus, in particular by means of UV drying, the imagewise applied adhesive layer can be predried by means of a first dryer 16 (intermediate dryer I), so that the wear layer of the transfer film 5 adheres better. Furthermore, the adhesive effect of the applied wear layer on the printed sheet can be improved by the action of a second dryer 16 (intermediate dryer II) by additionally accelerating the drying of the adhesive.

Finally, the quality of the coating can be controlled by means of an inspection or monitoring device 17 after the foil application. For this purpose, the inspection device 17 is mounted on a sheet-guiding surface of the coating module 2 after the transfer nip 6 and optionally sealed off from the track ner 16 or be directed to a sheet-guiding surface of the coating module 2 downstream further sheet leading module. The coated sheet passing there can thus be checked for completeness and quality of the coating. As poorly recognized printed sheets can be marked or rejected in a sorter as waste.

According to FIG. 2, the coating module can be provided with means for conditioning the transfer film in order to improve the layer transfer and the coating result. In this case, the film web 5 can be influenced by means of the film guiding device 14.

To improve the adhesion and gloss effect, the image-forming layer can be applied by means of an adhesive which reacts to ultraviolet radiation. Here, so-called UV negative pressure paint can be applied. As described, UV-reactive adhesives require UV drying equipment. This results in improved smoothness and thus gloss effect of resting on the sheet imaging layer. In particular, however, the secure attachment of special picture elements, such as holograms or partial images is possible. For this purpose, a UV dryer 15 after the applicator 1 for predrying the adhesive application and / or after the transfer of the imaging layer in the coating unit 2 a UV dryer 15 penetrating the imaging layer is to be arranged, for example, on the impression cylinder 4 of the coating unit 2.

In order to increase the quality of the printed product, it is possible by means of the described device to carry out processes for applying reliefs or embossings, holograms or prefabricated image motifs, which likewise may have surface structures, on the printed sheet.

Embossments or reliefs are advantageously applied to the already coated surface. This can be done, for example, in a coating plant 2 downstream embossing. In this case, the printed sheet is guided, for example, over a profiled surface and under pressure against a soft counter surface. Conversely, embossing from the upper side, ie the coated side of the printed sheet, against an elastic base can also be carried out. be guided. The required device can be arranged in a printing unit or a coating module. There, the embossing or relief shape on a blanket or form cylinder or on the impression cylinder 4 is arranged. The soft or elastic mating surface is correspondingly arranged on the respective other cylinder of the printing unit or coating module. By means of such an embossing device, the imaging coating can also be used for the transmission of special picture elements.

FIG. 4 schematically shows the attachment or generation of picture elements 21 or holograms introduced into the imaging layer from a transfer film 5. This process requires a particularly precise control of the film guide of the transfer film 5 in the transfer nip 6 between the press roller 3 and counter-pressure cylinder 4 relative to the printing sheet on the impression cylinder 4. For this purpose, the position of the control sheet to be coated sheet 22 are provided, but also from the Derive control of the sheet processing machine.

Furthermore, control devices 23 are provided for detecting position marks which define the position of the picture elements 21 or holograms and which are additionally mounted on the transfer film 5 in addition to the picture elements 21. By means of these control devices 23, it is possible, upon appropriate detection of the relative position of the printing sheet via the control device 22 in the transfer nip 6 and in conjunction with the film control to detect the positioning of the hologram and perform the positioning of the picture elements 21 on the sheet exactly.

If special prefabricated picture elements are to be applied, for example, from multicolored motifs or with a profiled surface, said method can also be used in the device described. For this purpose, the picture elements are applied to a transfer film 5 in the same way as described above for the imaging layer. The application of the image elements is carried out in the manner already described by appropriate adhesive application and subsequent transfer of the respective Bildele- Mentes in the transfer nip 6 between the press roller 3 and impression cylinder 4 of the coating module. 2

Here, a distinction can be made between the following processes: application of continuous elements

- Application of individual elements in a marking area

- Application of Einzeleiementen in defined positions

In the case of continuous picture elements, a control of the position of the picture elements 21 transversely to the transport direction T is required. The relative position of image patterns in the direction of transmittance T results from their arrangement on the transfer film 5. In the case of relatively coarse positioning of image elements 21 in an identification area, the positioning within this area can be achieved by means of the normal film control by means of clocking. The positioning in defined layers for marking requires accurate measurement and control of transfer sheet 5 and printed sheet, as indicated in Fig. 4.

Advantageously, within the press fabric 10, as described above, a press surface 20 in the form of a cut-out blanket or a high-pressure plate can be tailored to image elements 21 or regions of image elements 21. Advantageously, the pressing surface 20 in this case is flexible or yielding or elastic, in particular if a prefabricated picture element 21 has a structured surface. Furthermore, advantageously, a position control of the picture elements can be carried out with the aid of these position marks also assigned to the transfer film 5, as has been described for the processing of holograms.

In particular, in the last application example, the actual advantage of the method described becomes clear. The application of picture elements in the cold foil stamping process is particularly gentle. In contrast to the hot foil stamping process, the picture elements are not exposed to strong heating. This conditionally special Materiaieigenschaften and possibly manufacturing process to protect the picture elements 21 against damage during the embossing process. Simple picture elements 21 are not transferable in the hot foil stamping method, since they are destroyed there, unless a particularly high-quality, and thus also expensive, transfer foil 5 is used. Thus, the inventive method is particularly simple and particularly inexpensive to handle.

LIST OF REFERENCE NUMBERS

commissioned

coating module

press roll

Impression cylinder

Transfer foil / foil web

transfer nip

roller drive

Film supply roll

Foil composite role

Press covering

Inking / dampening unit

plate cylinder

Blanket / blanket cylinder

Folienleiteinrichtung

Printing plant security

dryer

Inspection device / monitoring system

dancer roll

cylinder gap

Press area

Picture element, hologram

control device

control device

Claims

claims Anspruch [en] A process for coating printed sheets in a sheet-processing machine, in particular a sheet-fed rotary printing press using a transfer film (5) formed from imaging layers and a carrier film for transferring image-forming layers from the carrier film to the printed sheets, characterized in that - at least one Coating unit (1) an imagewise coating of a printed sheet with an adhesive takes place, and - that in a coating module (2) a transfer film (5) is used, in whose imaging layers on the support film picture elements (21) are arranged such that their image side the carrier film is adhesively arranged, that the image-forming layers or image elements (21) are transferred from the carrier film to the printed sheet by means of a coating module (2), wherein in the coating module (2) an impression cylinder (4) and a press roll (3) form a common transfer nip (6), - the Tran Sferfolie (5) through the transfer nip (6) is feasible, such that it is placed with the coated side on the guided on the impression cylinder (4) sheet and fed under pressure together with the sheet through the transfer nip (6), - the image-forming layer (s) or image elements 821) adheres to the printing sheet after the sheet has emerged from the transfer nip (6) in the region of the adhesive image-forming areas in a surface-conforming manner and is lifted off the carrier film, and Positioning of the picture elements (21) is controlled on the sheet. 2. The method according to claim, characterized in that the picture elements (21) by means of control means (22, 23) by detecting the position of the transfer sheet (5), detecting the position of the sheet and positioning the transfer sheet (5) before or during the Einlau- fen in the transfer nip (6) against the sheet on the sheet to be positioned. 3. The method according to claim 1 or 2, characterized in that the transfer film (5) for detecting its position before the coating process is provided with a detectable by the control device (23) marker. 4. The method according to claim 1 to 3, characterized in that the picture elements (21) are holograms. 5. The method according to claim 1 to 3, characterized in that the picture elements (21) are plastic embossing elements. 6. The method according to claim 1 to 3, characterized in that the picture elements (21) are colored picture elements. 7. The method according to claim 1 to 3, characterized in that the printed sheet is provided during or after the coating by means of the transfer film (5) with a plastic embossing. 8. The method according to claim 1 to 7, characterized in that the printed sheet is provided in one or more printing units after the coating by means of the transfer film (5) with a single- or multi-color printed image. 9. A device for transferring image-forming layers from a carrier film to printed sheets at least with an applicator (1) for image-wise coating the printed sheets with an adhesive and with a coating module (2) for transferring the imaging layers from the carrier film to the printed sheet a transfer nip between a counterpressure cylinder and a press cylinder, wherein the carrier film with the coated side can be guided in contact with the printed sheet together with the latter through the transfer nip and the image forming layers can be transferred imagewise to the printed sheet, characterized in that a transfer film (5 ) is provided in the imaging layer of pixels (21), such as holograms, are introduced, that a control device (22) for detecting the position of the sheet before or in the transfer nip (6) is provided, and that for the attachment of in the image-forming layer introduced picture elements (21), such as hologram me, a separate control device (23) of the film guide is provided with respect to the position of the sheet to be coated. 10. An apparatus for transferring image-forming layers from a carrier foil to printing sheets at least with an applicator (1) for an imagewise coating of the printed sheets with an adhesive and with a coating unit (2) for transferring the image-forming layers from the carrier foil to the printed sheet a transfer nip between a counterpressure and a press cylinder, wherein the carrier film with the coated side in engagement with the printed sheet is feasible together with this through the transfer nip and while the image forming layers are imagewise transferable to the printed sheet, characterized in that pixels of multi-colored motifs or can be applied with a profiled surface when the picture elements are removably mounted on a transfer film (5), wherein applied in a applicator (1) surface adhesive pattern according to the contours of the applied pixels and the picture elements in a coating unit (2) insgesa from the Transfer film (5) are transferred to the sheet. 11. A device for transferring image-forming layers from a carrier film to printing sheets at least with an applicator (1) for image-wise coating the printed sheets with an adhesive and with a coating unit (2) for transferring the image-forming layers from the carrier film to the printed sheet a transfer gap between a counterpressure cylinder and a press cylinder, wherein the carrier film with the coated side can be guided in contact with the printed sheet together with the latter through the transfer nip and the image-forming layers can be transferred imagewise to the printed sheet, characterized in that in a coating module ( 2) or one of the coating module (2) downstream embossing reliefs or imprints can be applied as picture elements (21) in the imagewise coating of the printing sheet. 12. Device according to claims 9, 10 or 11, characterized in that a pressing surface (20) of a pressing roller (3) is limited to the picture element (21) to be transmitted and that the pressing surface (20) is flexible or elastic. 13. Device according to claims 9, 10 or 11, characterized in that a pressing surface (20) of a pressing roller (3) is limited to the picture element (21) to be transmitted and that the pressing surface (20) is profiled.