EP1676702B1 - Foil supplying for cold foil embossing - Google Patents

Abstract

The foil supply transfers layers on a printed sheet transparency according to a work order with a coating printed with an adhesive and a coating work (2). The coating work (2) contains an impression cylinder (4) and a press roll (3), which forms a common transfer gap (6). The transparency is conductible around the press roll (3), in such a manner that together with the coated side presented on the printed sheet with the impression cylinder (4) and under pressure with the printed sheet a transfer gap (6) is provided between the press roll and the impression cylinder (4). The layers after removal of the printed sheet and removal from the transfer gap (6) are removed from the transparency. The press roll has a smooth cover (10) and a mechanism is provided to reduce or abolition the adhesion of the surface of the cover opposite the transparency (5). An air film is provided to the transfer gap (6) for the production of an air layer between transfer foil (5) and surface of the printed sheet. An independent claim is included for a method.

Description

The invention relates to a method and a device for transferring imaging layers from a carrier foil to printed sheets according to the preamble of patent claims 1, 7 and 10.

It is known to produce metallic layers on printed sheets by means of a film transfer process. So is in the EP 0 569 520 B1 a printing material and a printing apparatus using this material are described. In this case, a sheet-processing machine is shown, which has a feeder and a boom, between two units printing units and a coating unit are arranged. 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 unit 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 passed through the transfer nip of the coating unit between the impression cylinder and the press roll from a film supply roll. The foil strip is rewound on the outlet side after leaving the coating unit. 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 unit, being brought by means of the press roller on the impression cylinder resting sheet with the film material in combination. The metal layer lying downwards is in close contact with 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 units, for example in printing units of printing presses. A disadvantage of the known devices is that they are not flexible and that the consumption of transfer film is expensive.

The object of the invention is therefore to provide a device by means of which the transfer of an imaging layer, e.g. a metallization can be done safely, economically and accurately, the device should be easy to handle.

The solution to this problem results in devices according to the features of claims 1 and 7, as well as in a method according to the features of claim 10.

Advantageously, a timing method is used to guide the transfer film, wherein the transfer sheet is separated during a clocking step by pneumatic means of the press roll.

To ensure the efficiency of the coating process can be provided to control the film feed such that the transfer film is then stopped when no transmission of the imaging or metallization takes place.

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

Furthermore, the film transport can be stopped when auxiliary functions such as washing or setting operations are carried out on the press.

In a further embodiment, the surface of the press roll may be provided with an elevated pressing surface contoured in outline, which is limited to the area to be coated. For this, a cut-out blanket, a plastic printing form or a stick-on press-on segment is suitable. As a result, the feed of the transfer film can be stopped in a very advantageous manner even if the area to be coated lies within the image area of the printed sheet.

A further improvement of the film utilization results from the fact that the transfer film is divided into one or more Teilfolienbahnen smaller width. In combination with the above-mentioned method, it is thus also possible to use different types of film side by side.

Within the sheet-processing machine receiving the coating unit, the coating unit can advantageously be placed anywhere on the machine. In this way, in the case of a printing press having a plurality of printing units, it is possible for imaging coatings or metallization layers to be applied both before, as well as after and also between the application of printing ink layers.

Advantageously, it is also possible to provide several coating units 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 the following the invention is illustrated in more detail with reference to figures.

Figur 1

eine grundsätzliche Darstellung einer Druckmaschine mit einer Folientransfereinrichtung,

Figur 2

den Aufbau Druckwerkes mit einer Folientransfereinrichtung und einer Folientaktung,

Figur 3

den Aufbau eines Druckwerkes mit einer vereinfachten Folientransfereinrichtung und Folientaktung, und.

Figur 4

den Aufbau eine Presswalze.

Showing:

FIG. 1

a basic representation of a printing press with a film transfer device,

FIG. 2

the structure of printing unit with a film transfer device and a film timing,

FIG. 3

the construction of a printing unit with a simplified film transfer device and film timing, and.

FIG. 4

the structure of a press roll.

• Ein Druckbogen wird zunächst mit einem bildgebenden Klebstoffmuster versehen (Auftragwerk 1).
• Danach wird im Folgedruckwerk gemeinsam mit einem Druckbogen eine Transferfolie 5 durch einen Transferspalt 6 geführt, wobei die Transferfolie 5 im Transferspalt 6 gegen den Druckbogen gepresst wird (Beschichtungswerk 2).
  Der Transferspalt 6 im Beschichtungswerk 2 wird durch eine Presswalze 3 und einen Gegendruckzylinder 4 gebildet. Diese können dem Drucktuchzylinder und dem Gegendruckzylinder eines Offsetdruckwerkes entsprechen.
  Weiterhin kann nachgeschaltet ein so genanntes Kalandrierwerk vorgesehen werden. Innerhalb des für den Folientransfer genutzten Beschichtungswerkes 2 ist eine Bahnführung für Transferfolien dargestellt.
  Die Transferfolien 5 sind mehrschichtig aufgebaut. Sie weisen eine Trägerschicht auf, auf der mittels einer Trennschicht eine bildgebende Schicht aufgebracht ist. Die Trennschicht dient dem erleichterten Abheben der bildgebenden Schicht von der Trägerschicht. Die bildgebende Schicht kann z.B. eine metallisierte Schicht oder eine Glanzschicht oder eine Texturschicht oder eine eingefärbte Schicht oder eine ein oder mehrere Bildmuster enthaltende Schicht sein.
  Die Folienvorratsrolle 8 ist dem Beschichtungswerk 2 auf der Seite der Bogenzuführung zugeordnet. Die Folienvorratsrolle 8 weist einen Drehantrieb 7 auf. Der Drehantrieb 7 wird zur kontinuierlichen geregelten Zuführung der Transferfolie zum Beschichtungswerk 2 benötigt und ist daher steuerbar. Weiterhin ist im Bereich der Folienzuführung eine Umlenk- bzw. Spannwalze vorgesehen. Damit wird die Folienbahn der Transferfolie immer in gleicher Spannung gegenüber der Presswalze 3 gehalten. Auf der ablaufseitigen Seite des Druckwerkes ist eine Foliensammelrolle 9 dargestellt. Auf der Foliensammelrolle 9 wird das verbrauchte Folienmaterial wieder aufgewickelt. Auch hier ist für die optimierte Produktion ein Drehantrieb 7 vorzusehen, der steuerbar ist. Im Wesentlichen könnte die Transferfolie 5 auch durch den Drehantrieb 7 auf der Ablaufseite bewegt und auf der Zulaufseite mittels einer Bremse straff gehalten werden.
  Der Transfervorgang der bildgebenden z.B. metallisierten Schicht auf das Druckpapier erfolgt in dem Transferspalt 6 zwischen der Presswalze 3 und dem Gegendruckzylinder. Die Presswalze 3 kann ein Drucktuchzylinder eines Offsetdruckwerkes sein. Die Presswalze 3 kann auch der Formzylinder eines Lackmodules sein. Wesentlich ist, dass die Oberfläche der Presswalze 3 also des Drucktuchzylinders bzw. Formzylinders mittels eines kompressiblen, dämpfenden Elementes ausgerüstet ist.

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

• A printed sheet is first provided with an imaging adhesive pattern (applicator 1).
• Thereafter, a transfer sheet 5 is passed through a transfer nip 6 in the following printing unit together with a printing sheet, wherein the transfer sheet 5 is pressed in the transfer nip 6 against the sheet (coating unit 2).
  The transfer nip 6 in the coating unit 2 is formed by a press roll 3 and an impression cylinder 4. These may correspond to the blanket cylinder and the impression cylinder of an offset printing unit.
  Furthermore, downstream of a so-called calendering be provided. Within the used for the film transfer coating 2 a web guide for transfer films is shown.
  The transfer films 5 have a multilayer structure. 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 image-forming layer may be, for example, 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 unit 2 on the sheet feed side. 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 to the coating unit 2 and is therefore controllable. Furthermore, a deflecting or tensioning roller is provided in the region of the film feed. This will be the film web of the transfer film is always held in the same tension against the press roller 3. On the downstream side of the printing unit, a film collection 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 discharge side and kept taut on the inlet side by means of a brake.
  The transfer process of the imaging eg metallized layer on the printing paper takes place in the transfer nip 6 between the press roller 3 and the impression cylinder. The press roll 3 may be a blanket cylinder of an offset printing unit. The press roll 3 can also be the forme cylinder of a paint module. It 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 can be provided with a press fabric, for example as a plastic coating, comparable to a blanket or blanket. The press fabric 10 is held in a cylinder channel 11 to tensioning devices, as in FIG. 4 is shown. Here, the press roller 3 is formed as a rubber cylinder 13.

The press fabric 10 is equipped to improve the transmission properties in the transfer nip 6 with a targeted elasticity. This may optionally 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 may be from the surface of the Pressing fabric 10 be worked out or it can be additionally attached as a partial surface of the material of the press fabric 10 on the press roller 3.

To ensure the economic efficiency of the coating process, it is provided that the film advance of the transfer film from the film supply roll 8 to the transfer nip 6 and the film collection roll 9 is controllable so that the transfer film 5 is stopped as far as possible if no transfer of the image-forming layer is to 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 counter-pressure cylinder 4 receiving cylinder channel. The grippers hold the printed sheet on the impression cylinder 4. The press roll 3 has a cylinder channel 11. In the region of the cylinder channel, there is no pressing of the transfer film 5 between the press roller 3 (blanket cylinder) and the impression cylinder 4, since both cylinders have this cylinder channel 11. The press roll 3 then slidably passes under the transfer sheet 5, while the transfer sheet 5 between the press roll 3 and impression cylinder 4 is freely stretched. This state continues until at the so-called pressure beginning of the cylinder channel 11 ends and the transfer sheet 5 is again clamped between the press roller 3 and the impression cylinder 4, including a sheet. Then, the transfer sheet 5 is further transported. The timing of the film feed can begin or suspend a little earlier than predetermine the channel edges of the cylinder channel 11 corresponding 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 exemplified in FIG. 1 are shown, the control of the rotary actuators 7 of the film supply rolls 8 and film collecting roll 9 may not be necessary.
However, the associated device fundamentally includes a corresponding feed control for the transfer film 5, which ensures that at least the foil piece lying between the press roll 3 and the impression cylinder 4 is stationary as long as the cylinder channel 11 passes through.
In a further embodiment, a contoured pressing surface can be provided as the surface of the press roll 3. This is done instead of a full-surface plastic layer a press surface limited to the area to be coated is set on the press roller 3. For this purpose, for example, a cut-out printing blanket, an imageable plastic printing form or a pressure pad which can preferably be releasably fastened to a smooth base, possibly stickable or magnetically attachable, can be used to support the limited pressing surface.
The function of this limited pressing surface is that as in the passage of the cylinder channel 11, the entrapment of the transfer film 5 is only given when the pressing surface, the transfer film 5 touching the transfer nip 6 passes.

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 zonally different lengths 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.

In order to improve the coating process, it is provided to bring the film to a standstill in areas where there is no stripping, such that the press roll 3 passes empty under the film web 5. This can take place, for example, when the so-called cylinder channel passes through or when a non-pressing region passes through when using a press segment. To stop the film, it is necessary to release the film from the surface of the blanket cylinder 4 or the press roller 5.

A corresponding device is in FIG. 2 shown. For this purpose, an arrangement of blowing devices is provided in the coating unit 2. In each case at the inlet of the film web 5, possibly in front of a deflection roller, and at the outlet of the film web 5, possibly after a further deflection roller, a Blasluftleiste 17 is provided. When stopping the film web 5 is first a blast of air at both Blasluftleisten 17 introduced into the gap of the inlet or outlet of the film web 5 relative to the press roller 3. The compressed air surge causes a - possibly thin - air layer between the film web 5 and the surface of the press roll 3 forms. As a result, the film web 5 can slip or float on the press roller 5. Thus, the press roller 3 can continue to rotate without the risk of damaging the film web 5 while the film web 5 is stationary.

In the arrangement of the coating unit 2 it is shown that so-called dancer rollers 18 are provided. Dancer rolls 18 can be used in the region of the film supply roll 8 and / or the film collection roll 9. They allow, in addition to a web tension control, that the film web 5 can be continuously unwound from the film supply roll 8 while it is stationary at the coating location. Thus, the film material required for the further transport of the film web 5 can be fed back very quickly.

In a simplified form of the coating device according to FIG. 3 the film web 5 is pressed onto the printing cylinder 4 via an additional pressure roller 14, wherein the pressure point as the transfer nip 6 'is arranged downstream of the coating gap for the adhesive between a blanket cylinder 13 and the printing cylinder 4. The pressure roller 14 is switched on and off by means known per se with respect to the impression cylinder 4.

The representation after FIG. 3 also shows an integrated embodiment of a film applicator, wherein applicator 1 and coating unit 2 are arranged within a single printing unit. The applicator 1 is formed here by the existing printing unit, while the coating unit 2 is formed by the assignment of the pressure roller 14 to the impression cylinder 4 of the printing unit.

The thus formed pressure roller 14 can be lifted in a simple manner by means of their means for turning on and off during the time of a continuous cylinder channel or in the range of uncoated parts of the sheet from the printing cylinder 4. At the same time, the film web 5 as described earlier for this case already be shut down. In this case, ventilation of the film web 5 on the pressure roller 14 is not required.

Foil consumption is minimized especially when auxiliary functions on the printing machine, e.g. a washing function, must be performed. This can be the case with blanket washing or inking unit washing.

1.

Die Foliensammelrolle 9 und die Folienvorratsrolle 8 werden über den jeweiligen Rollenantrieb 7 mittels einer Lageregelung in Stillstand gebracht. Es erfolgt keine Folienaufrollung oder -abrollung.

2.

Die Tänzerwalzen 18 werden festgesetzt, d.h. es erfolgt keine Bahnspannungsregelung.

3.

Die Folienvorratsrolle 8 oder die Foliensammelrolle 9 wird über die Lageregelung freigeschaltet, um einen bestimmten Bereich der Folienbahn z.B. von 10 mm freizugeben. Der entsprechende Rollenantrieb 7 wird wieder festgesetzt.
Damit wird die Folienbahn um die Presswalze 3 bzw. den Drucktuchzylinder herum frei und kann auf dessen Oberfläche schweben.

4.

Zeitgleich wird Luft über die beiden Blasstangen am Folienein- und -auslauf zum Drucktuchzylinder bzw. zur Presswalze eingeblasen und die Bahn wird zum Schweben gebracht.

To do this, proceed as follows:

1.

The film collecting roller 9 and the film supply roll 8 are brought to a standstill via the respective roller drive 7 by means of a position control. There is no Folienaufrollung or -abrollung.

Second

The dancer rollers 18 are fixed, ie there is no web tension control.

Third

The film supply roll 8 or the film collection roller 9 is released via the position control to release a certain area of the film web, for example, of 10 mm. The corresponding roller drive 7 is set again.
Thus, the film web around the press roller 3 and the blanket cylinder around freely and can float on the surface.

4th

At the same time, air is blown in via the two blower rods at the film inlet and outlet to the blanket cylinder or to the press roller and the web is levitated.

This type of shutdown of the film transport is used in particular for auxiliary functions of the printing press. Ink washing, rubber cylinder washing, printing cylinder washing or paper transport work are possible here.

On the basis of the present embodiments, it is possible to transfer different types of coatings in the transfer process from a transfer film 5 to different substrate materials. The detailed embodiments of the invention are not limited to the possibilities given here, but can be interpreted within the scope of expert knowledge beyond that.

LIST OF REFERENCE NUMBERS

1

commissioned

2

coating plant

3

press roll

4

Impression cylinder

5

Transfer foil / foil web

6

transfer nip

7

roller drive

8th

Film supply roll

9

Foil composite role

10

Press covering

11

cylinder gap

12

plate cylinder

13

Blanket cylinder

14

pressure roller

15

UV dryer

16

monitoring system

17

Blasluftleiste

18

dancer roll

6 '

transfer nip

Claims (13)

1. Device for transferring image donating layers from a carrier foil (5) to printed sheets with a least one applicator unit (1) for an imagewise coating of a printed sheet with an adhesive and with a coating unit (2) for transferring the image donating layers from the carrier foil (5) on to the printed sheets, wherein the coating unit (2) contains an impression cylinder (4) and a press roller (3), which form a common transfer nip (6), and whereby furthermore the carrier foil can be guided around the press roller (3), in such a fashion that it can be laid with the coated side on to the printed sheet guided on the impression cylinder (4) and guided under pressure together with the printed sheet through the transfer nip (6) between press roller (3) and impression cylinder (4) and wherein the image donating layers after the emergence of the printed sheet from the transfer nip (6) adhere to the printed sheet in the region of the imagewise regions provided with the adhesive and is lifted away from the carrier foil (5), characterised in that the press roller (3) is provided with a smooth cover (10) and has a device for reducing or removing the adhesion of the surface of the cover relative to the carrier foil (5).
2. Device according to claim 1 characterised in that fitted to the transfer nip (6) are pneumatic means to generate an air layer between transfer foil (5) and the surface of the press roller (3).
3. Device according to claim 1 and 2 characterised in that the foil advance can be controlled by means of a device for foil guidance, that the transfer foil (5) is then held back when no transfer of an image donating layer on to a printed sheet takes place in the transfer nip (6) of the coating unit (2) and that the pneumatic means subject the transfer nip between transfer foil (5) and the surface of the press roller (3) to blown air.
4. Device according to claim 3 characterised in that a control is provided in connection with the rotating drive (7) of the transfer foil (5) in such a way that on the passage of a cylinder channel (11) receiving a gripper of the sheet guiding impression cylinder (4) the foil feed is restrained, while the press roller (3) continues to runs smoothly under further contact of the transfer foil (5).
5. Device according to claim 3 characterised in that provided as the surface of the pressing roller (3) is a raised pressing surface (13) contoured about its periphery, whereby the pressing surface (13) is limited to the maximum region to be coated.
6. Device according to claims 1 to 5 characterised in that the transfer foil (5) is divided into one or several partial foil webs of narrower width and that the partial foil webs are fed adjacent one another to the transfer nip (6).
7. Device for transferring image donating layers from a carrier foil (5) on to printed sheets with at least one applicator unit (1) for an imagewise coating of the printed sheets with an adhesive and with a coating unit (2) for transferring the image donating layers from the carrier foil (5) on to the printed sheets in a transfer nip between an impression (4) and a press roller, wherein the carrier foil (5) can be guided with the coated side lying against the printed sheet together with this through the transfer nip and thereby the image donating layers are imagewise transferable on to the printed sheets, and with a unit for feeding the transfer foil (5) to the coating unit (2) and for feeding it away from the coating unit (2) with a drive for moving the transfer foil in the working direction, characterised in that the transfer foil (5) is guided around a pressing on roller (14) fitted to the surface of the impression cylinder (4) and arranged downstream of a pressure nip between blanket cylinder (13) and impression cylinder (4), which with the impression cylinder forms the transfer nip (6'), while the adhesive application on to the printed sheet takes place in the pressure nip between blanket cylinder (13) and impression cylinder (4).
8. Device according to claim 7 characterised in that the pressing on roller (14) can be set on and off relative to the impression cylinder (4).
9. Device according to claim 8 characterised in that the pressing on roller (14) can be set on and off the impression cylinder (4) in the working rhythm of the sheet treatment machine.
10. Method for foil saving in a device for the transfer of image donating layers from a carrier foil (5) on to printed sheets with at least one applicator unit (1) for an imagewise or area coating of a printed sheet with an adhesive and with a coating unit (2) for transfer of the image donating layers from the carrier foil (5) on to the printed sheets, wherein the coating unit (2) contains an impression cylinder (4) and a press roller (3), which form a common transfer nip (6), and wherein furthermore the carrier foil can be guided around the press roller (3) in such a fashion that it is laid with the coated side on to the printed sheet guided on the impression cylinder (4) and is guided under pressure together with the printed sheet through the transfer nip (6) between press roller (3) and impression cylinder (4) and wherein the image donating layers after the exit of the printed sheet from the transfer nip (6) in the region of the regions provided with adhesive adhering on to the printed sheets is lifted away from the carrier foil (5), characterised in that, with reduction of the web tension of the carrier foil (5) between the surface of the press roller (3) guiding the foil web (5) and the carrier foil (5) an air layer is introduced and that the transport of the carrier foil (5) is rendered stationary with simultaneously rotating press roller (3).
11. Method according to claim 10 characterised in that during the carrying out of auxiliary functions on the printing press the transport of the carrier foil (5) is rendered stationary.
12. Method according to claim 11 characterised in that during the carrying out of washing processes for an inking unit or a blanket cylinder or an impression cylinder of the printing press the transport of the carrier foil (5) is rendered stationary.
13. Method according to claim 11 characterised in that during the carrying out of adjustment processes for the paper transport on the printing press the transport of the carrier foil (5) is rendered stationary.

Images