EP1884362B1 - Film transfer device with material application device - Google Patents

Description

The present invention relates to an apparatus for transferring a transfer layer from the front side of a carrier film, which together form a transfer film, onto a printing material comprising at least one transfer unit for transferring the transfer layer to the printing substrate, the transfer unit comprising at least one transfer cylinder for transferring the transfer layer.

Furthermore, the invention relates to a method for transferring a transfer layer from the front side of a carrier film, which together form a transfer film, onto a printing material, wherein the transfer film is transferred to a transfer cylinder for transfer, and the transfer layer is transferred to the printing material by moving away from the area Carrier film is detached.

Preferably, the invention relates to a device and a method which is suitable for the so-called cold foil stamping.

In cold foil stamping, a transfer layer is transferred from a substrate to a substrate.

The carrier material used is a carrier film. On this carrier film, a lacquer layer is applied, which is responsible in particular for the coloring of the transfer layer. Connected to the paint layer is an aluminum layer, which is the metallic gloss of the transfer layer causes. Furthermore, a further adhesive layer can be provided on the aluminum layer, which improves the adhesive properties of the transfer layer with the adhesive on the printing substrate. The layers transferred from the substrate are collectively referred to as the transfer layer.

In order to transfer the transfer layer to a printing substrate, the transfer film is passed through a transfer nip together with the printing substrate. The transfer nip is formed by a transfer cylinder and an impression cylinder, which abut each other. Transfer cylinder and impression cylinder are rotated together with a force to each other, that in the transfer nip, the transfer layer is transferred to the substrate.

So that an areawise transfer of the transfer layer to the print substrate can take place, for example, the print substrate is provided with an adhesive layer before the film transfer which corresponds to the area in which the film is transferred.

The adhesive used may be a colorless adhesive, an adhesive with a certain intrinsic color, or a glue colored according to the film. Already from the Bronzierungstechnik it is already known to transfer metal particles to use a particularly sticky color whose color corresponds to the desired metallization. In this respect, of course, a sticky color can also be used as an alternative to a colored adhesive.

The transfer layer can essentially be a metal layer but also other layers. For example, an aluminum layer can be provided, which is applied as needed on a yellow / golden lacquer layer or a silver-colored lacquer layer.

Furthermore, as the transfer layer, a colorless layer e.g. be used from PE film, which is transferred to the substrate so that it forms a protective layer there.

The use of a conductive layer as a transfer layer is possible, thereby electrically and / or thermally conductive area can be transferred to the substrate. The transfer of prepared delimited layer regions as a transfer layer is also possible, which may be, for example, RFID chips or their antennas. It is also possible to transfer suitable ceramics. In this way, it is conceivable that superconducting structures can be transferred to a printing substrate.

A device for cold foil stamping is in the EP 0 578 706 B1 presented.

Here, the cold foil stamping takes place within a multi-color printing machine. The printing material is transported along a predetermined transport path in the printing press. The printing material may be, for example, paper sheets, cardboard or even rolls.

In a first printing unit of the printing press, an adhesive is transferred to the substrate instead of a paint. For application of the adhesive in regions a correspondingly imaged printing plate is clamped in this printing unit and the adhesive is transferred onto the printing substrate like a conventional offset printing ink. Such an adhesive-applying printing unit is referred to as a commissioned work.

The printing material is then transported further into a second printing unit. In this second printing unit, the impression cylinder and the blanket cylinder are designed as a transfer unit.

In the area of this second printing unit there is a film module with a transfer film supply shaft and a transfer film collecting shaft. Via intermediate rollers of a film guiding device, the film is guided as a transfer film web from the transfer film supply shaft to the transfer nip and on to the transfer film collecting shaft.

In order to transfer the transfer layer to the printing substrate, the transfer film web and the printing material with the area-wise adhesive layer are passed together along their respective transport paths through the transfer nip so that the transfer layer rests on the adhesive layer. The transfer layer is then transferred onto the substrate by printing in the transfer nip. The adhesive removes the transfer layer cleanly from the transfer film.

For a clean transfer of the transfer layer to the printing substrate, the film and the printing material in the region of the transfer nip are driven at the same speed during the transfer.

In a subsequent press shop, the transferred transfer layer is then essentially acted upon, so that a durability of the film support is achieved.

As a particularly sensitive step in the transfer of the transfer layer to the substrate here is the moment to see, in which the transfer layer is detached from the carrier film. This detachment and also the further transport of the carrier film can be at least disturbed by adhesion of the carrier film on the transfer cylinder. Therefore it is in the EP 0 578 706 B1 also intended to use as a transfer cylinder a smooth-surface possibly elastic pressure roller. However, adhesion forces still still act between the transfer cylinder and the transfer film.

To reduce this adhesive force between the carrier film and the transfer cylinder, it is in the WO 2005/100025 A1 has been proposed to provide the transfer cylinder with a low-friction cover, which has a spherical cap-like structure as a known glass bead cloth. By using such a glass bead cloth as a transfer cylinder or as the surface of the transfer cylinder, the frictional force between transfer cylinder and carrier film can be at least reduced.

The problem with the solution described here is that this surface structure of the transfer cylinder is also impressed on the substrate to be coated. This is not always desirable. If a conventional printing unit of a printing press is used as a transfer unit for transferring the transfer layer to the printing substrate, then the transfer cylinder z. B. set up a blanket cylinder of the printing unit. During a printing process, however, no glass bead cloth can be used as the surface of this blanket cylinder. It is therefore necessary to replace the surface of the blanket cylinder for the previously known solution for reducing the friction. For this purpose, the rubber blanket of the blanket cylinder used in offset operation is exchanged for a corresponding glass bead cloth.

The object of the present invention is to propose a device, a method and a transfer film of the type mentioned, which at least reduces the described problem of friction between the transfer cylinder and carrier film without further restricting the flexibility of the transfer unit and at the same time the best possible quality of the resulting printed product.

The object of the invention is achieved by a device according to claim 1. Particular embodiments of this device are described in the subclaims 2 to 13.

Furthermore, the object of the invention is achieved by a method according to claim 14. Further embodiments of the method according to the invention are described in the dependent claims 15 to 27 and embodiments of the transfer film in the subclaims 29 and 31.

To reduce the friction between the carrier film and the transfer cylinder, i. In order to reduce the adhesion of the carrier film to the transfer cylinder, it is provided that the transfer unit comprises at least one material application device for applying friction-reducing material to the transfer cylinder and / or the carrier film back side. By means of this Materialaufbringeinrichtung can then the corresponding material on the surface of the transfer cylinder d. H. be applied to the transfer cylinder surface or the back of the carrier film. Likewise, the adhesion of the carrier film to the transfer cylinder can be at least reduced by a transfer film having a backside coating of a corresponding friction reducing material.

As friction-reducing material on the back of the carrier film can, for. EFTA, i. Teflon or a powder coating, be provided.

According to the invention, the material application device can be provided in the region of the transfer cylinder in order to apply the friction-reducing material directly to the surface of the transfer cylinder. In an alternative embodiment, it can be provided that the material application device is provided in the region of the transport path of the transfer film, in which case the friction-reducing material is applied directly to the rear side of the transfer film becomes. This is particularly useful in a position where the transfer layer of the transfer film has not yet been transferred to the substrate by the transfer cylinder. This transfer can for example take place in a transfer nip formed by the transfer cylinder and an impression cylinder.

In order to increase the flexibility of a corresponding transfer station and to enable retrofitting of existing transfer stations, it is provided according to the invention in a particularly advantageous embodiment that the material application device is arranged in the manner of a removable from the transfer unit cassette.

In one embodiment of the invention, it is provided that the friction-reducing material is applied either by brushing, spraying, rolling, knife-coating or with a cloth on the transfer cylinder surface and / or carrier film backside. For this purpose, according to the invention, it is accordingly provided that the material application device has either a brush, a cloth, an inflator for inflating the material, a doctor blade or a corresponding roller. But it can also be provided in particular that the material is applied by means of a combination of these elements on the backing sheet back and / or the transfer cylinder surface.

In order to prevent the friction-reducing material from reaching other positions within a printing machine or a corresponding transfer station, where damage may be caused or the quality of a printed product may suffer from this material, it is provided in an advantageous embodiment that the air contaminated with friction-reducing material is sucked out of the area of application of this material. For this purpose, a corresponding suction is provided.

As a particularly preferred provision, it is provided that the transfer unit is an already existing printing unit of a printing press and a corresponding blanket cylinder of a printing unit is used as a transfer cylinder. As a result, the most flexible use of the printing unit and the transfer unit is achieved. It can then be used, for example, instead of a use for transferring the transfer layer to a substrate for printing the substrate by means of color. In particular, it is therefore provided that the transfer unit can be a printing unit, a coating unit or a modular work of a printing press.

To provide the transfer cylinder with a largely intact surface, and to increase the flexibility of the transfer cylinder, so that after a transfer operation for other methods, such. B. the printing of substrates can be used according to the invention advantageously provided a washing device for washing the transfer cylinder surface. By means of this, the transfer cylinder surface can be cleaned of residues of the friction-reducing material. This washing device may in particular be a blanket washing device. This can then advantageously be an already provided blanket washing device in the region of the transfer cylinder or the blanket cylinder.

In order to be able to use this blanket washing device as flexibly as possible, ie both for cleaning the transfer cylinder surface of residues of the friction-reducing material and ink residues during an offset printing process, it is advantageously provided that the blanket washing device at least two detergent cycles for at least a first detergent for cleaning the transfer cylinder surface of residues of the friction-reducing material and for a second detergent for cleaning the transfer cylinder surface of ink residues of an offset printing process. Procedurally, it is accordingly provided that the Transfer cylinder surface is cleaned by means of the first detergent from the corresponding residues of the friction-reducing material by means of the second detergent of paint residues.

In further embodiments of the invention, it is provided that the transfer cylinder is a blanket cylinder and a plate cylinder, which is set for a possible offset printing on the blanket cylinder, pressure plate free or provided by the blanket cylinder is provided. This advantageously achieves that there is a gap between the blanket cylinder and the plate cylinder. Then the friction-reducing material can not pass from the surface of the transfer cylinder or the blanket cylinder on the plate cylinder and above in a possibly existing inking unit. The same applies to other roles or cylinders that are employed on a transfer cylinder of the transfer station, such. B. rolls in a coating unit, which prevents the friction-reducing material enters an appropriate circuit in which it is undesirable.

In this case, it can advantageously be provided, in particular in terms of the method, that the plate cylinder is set up such that it is provided without contact to the blanket cylinder, at least during the process for transferring the transfer layer to the printing material. This can advantageously be done so that the plate cylinder is actively parked from the blanket cylinder or vice versa, the blanket cylinder is moved away from the plate cylinder. In general, it is advantageously sufficient to provide the plate cylinder without plates, i. without attached pressure plate. Even so, a correspondingly sufficient gap between plate cylinder and blanket cylinder can already be achieved.

In particularly advantageous embodiments of the device, it is provided that the friction-reducing material is a material of the group fluids and powders.

Accordingly, it can be provided that silicone oil is provided as a fluid or a mineral or organic powder or talc as friction-reducing material. If powder is used as friction-reducing material, it can be provided, in particular, that the material application device is a powder device of a printing press. This can then be used on existing technologies.

It has proven to be particularly favorable that powder having a particle size between 10 and 90 μm is used in order to reduce the friction between the carrier film and the transfer cylinder. As a particularly preferred here a grain size of 15 to 35 microns has been found.

In a further development of the transfer film, it is provided that on the transfer layer, the z. B. may consist of a metal layer, an additional layer of a bonding agent is applied. This adhesion promoter can then produce a contacting compound with the adhesive layer on the printing substrate, and thus support the transfer of the transfer layer even better on the printing substrate.

The advantages of the device, of the method and of the transfer film described here also apply to combinations of the individual features which are not listed here but are conceivable by a person skilled in the art in the area of the possible embodiments.

Embodiments to which the invention is not intended to be limited and from which further features according to the invention may result are shown in the figures.

Fig. 1

ein Transferwerk mit Materialaufbringeinrichtung am Transferzylinder

Fig. 2

ein Transferwerk mit Materialaufbringeinrichtung am Transportpfad der Transferfolie und

Fig. 3

den Aufbau einer Transferfolie mit Anti-Adhäsionsschicht

Show it:

Fig. 1

a transfer unit with material applicator on the transfer cylinder

Fig. 2

a transfer unit with material applicator on the transport path of the transfer film and

Fig. 3

the construction of a transfer film with anti-adhesion layer

The Fig. 1 shows a transfer unit for transferring a transfer layer on an arc 6. This transfer unit, as it should be shown here, may be a printing unit of a printing press.

A transfer film 1 is unwound from a film supply roll, not shown, and guided around deflection rollers 2 along a transport path to a transfer nip 3. This transfer nip 3 is formed by a blanket cylinder 4, which serves here as a transfer cylinder, and a counter-pressure cylinder 5. After passing through the transfer nip 3, the transfer film 1 is fed again via a deflection roller 2 of a film collecting roll, which is likewise not shown here.

Along a separate transport path, a sheet 6 is also passed through the transfer nip 3. On the sheet 6 is not shown here partially adhesive layer, which was applied to the sheet 6 in a commissioned work also not shown here. The sheet 6 is then passed together with the transfer film 1 through the transfer nip 3, and by the contact pressure between blanket cylinder 4 and impression cylinder 5, the transfer layer 12 of the transfer film 1 is transferred to the adhesive-coated portion of the sheet 6. This transfer layer 12 is removed in the transfer nip 3 from the transfer sheet 1.

In order to avoid adhesion of the transfer film 1 to the blanket cylinder 4, is on the blanket cylinder 4, ie on its surface, a friction-reducing Material applied via a material applicator 7. This friction-reducing material may be, for example, talcum powder. It may also be a liquid such as silicone oil or, as is preferred, a powder. This can be z. B. a mineral powder with a type designation KSL-K2 or an organic powder with the type designation KSL-S5 KSL-Staubtechnik GmbH act. Overall, it is desirable that the powder in this case has particle sizes between 10 and 90 microns, with particular grain sizes in the section between 15 and 35 microns are preferred.

As a material applying device 7 in this case a powder device can be used, as they are for. B. in the DE 197 51 383 B4 for the powder application on a sheet was described.

Since it is in the case described here is a printing unit, which is used as a transfer unit, there is a plate cylinder 9 in the vicinity of the blanket cylinder 4. This plate cylinder 9 is either turned off by the blanket cylinder 4 or by not using a printing plate, ie it will not That is, the powder or generally the friction-reducing material, which is applied via the material application device 7, can not from the blanket cylinder 4 on the plate cylinder 9 are transmitted. It can therefore not get into a dampening or inking unit of the printing unit. Therefore, it is also possible to provide the material application device 7 in the circumferential direction of the blanket cylinder 4 either before or after the gap 10. A corresponding position of the material applying device 7 in front of the intermediate space 10 is shown in dashed lines.

The printing unit shown here can also be used as a normal printing unit and not as a transfer unit in a further method. For this purpose, on the one hand it is necessary that no transfer film 1 is passed through the transfer nip 3. This can be achieved by removing the transfer film 1 from the transfer station. So that no powder or friction-reducing material can get into the inking units or dampening units of the printing unit, it is necessary that the blanket cylinder is freed from residues of the friction-reducing material before the printing unit is put into operation. This can be done via a washing device. In this case, a blanket washing device 8 is provided, which is provided at a Belibigen point of the blanket cylinder 4. This blanket washing device 8 can act, for example, via brushes or compressed air or via a cloth acting on the surface of the blanket cylinder. Corresponding blanket washing devices are in the patents and applications EP 715 956 B1 . EP 291 745 B and DE 102 44 218 A1 for example disclosed. The content of these applications or patents relating to the embodiments of blanket washing devices is fully incorporated by reference.

In order to further prevent a corresponding friction-reducing material or powder from reaching other areas of the printing press or the printing unit, a suction device 17 is additionally provided around the material-applying device 7. This suction device 17 is shown only for a material application device 7, but can in principle and should also preferably be provided for every possible positioning of the material application device 7.

The Fig. 2 shows an alternative positioning of the material applicator 7, wherein the remaining elements with those of Fig. 1 essentially match. Identical elements are referred to here with the same reference numbers.

In the case shown here, the carrier film 1 is guided for passage through the transfer nip 3 via two deflection rollers 2. This is of course also for the in Fig. 1 possible case shown. Overall, a wide variety of guides for the carrier film 1 are possible.

In the in the Fig. 2 In this case, the material application device, which should preferably also be a powder device, is not provided in the vicinity of the blanket cylinder 4, but rather in the region of the transfer film 1, ie in the region of the transport path of the transfer film 1, namely the material application device 7 here attached so that it applies the friction-reducing material to the back of the transfer film before it is passed through the transfer nip 3. Although the material applicator 7 is shown here without suction device 17, it is of course possible and can also be provided that it is enclosed by a suction device 17, to avoid that friction-reducing material from the area of the material applicator in the air space within the Druckwerkes arrives.

In an alternative embodiment, not shown here, it is of course also possible for material application devices 7 to be provided both in the region of the transport path of the transfer film 1 and in the region of the blanket cylinder 4.

In the event that the friction-reducing materials are applied to the back of the transfer sheet 1, this is passed through the transfer gap 3 with these materials. Here then lies the powder or the friction-reducing material between the back of the transfer sheet 1 and the blanket cylinder 4 and thus reduces the friction between the blanket cylinder 4 and the transfer sheet 1. This may happen that friction-reducing material reaches the blanket cylinder 4 and here accumulates. In order to avoid, in a subsequent offset printing process, residues of the friction reducing material on the printing plate cylinder 9 is also here, as in Fig. 1 already described, a blanket washing device 8 is provided.

The Fig. 3 shows the structure of a transfer film according to the invention 1. The transfer film 1 is composed of a carrier film 11, on which on the front first a transfer layer 12 is applied, which may also have a bonding agent 15 on its surface. The transfer layer 12 can generally have a different structure, it is used to be applied to a printing material and to highlight a region. This is the usual cold foil stamping process. In this case, the transfer film 1 can be embodied such that it has a separating layer 13 and a metal layer 14 as transfer layer 12, as here in the illustrated example. The metal layer 14 may in particular also comprise a lacquer which dyes the metal or the metal of this layer leads to a metallic luster of a lacquer layer.

In order to reduce the friction between a blanket cylinder 4 and the transfer sheet 1, it is provided that on the back of the transfer sheet 1, i. on the back of the carrier film 11, an anti-adhesion layer is provided. This anti-adhesion layer consists of friction-reducing material and provides for the previously described reduction of the friction between transfer film 1 and blanket cylinder 4. This anti-adhesion layer 16 may be, for example, a powder coating which is also particularly within a printing unit or a transfer unit is applied directly to the back of the transfer sheet 1. It can also be provided that the transfer film 1 is already produced in such a way that it has a backside anti-adhesion layer 16. This may then be, for example, EFTA or another friction-reducing layer.

By the embodiments of the transfer units or the transfer film shown here, it is possible, the transfer film 1 directly or a Transfer cylinder surface, ie the surface of the blanket cylinder 4 with a friction-reducing material, such. As powder, so as to reduce the friction between the transfer cylinder, ie the blanket cylinder 4 and the transfer sheet 1. Adhesion between the blanket cylinder 4 and the transfer sheet 1 is thereby reduced. The adhesion can no longer take place as in the known state of the art. Due to the smooth surface of the applied material layer, no impressions of structures in the transfer film 1 or the sheet 6 will occur.

In particular, it is provided here that a conventional blanket is used. This blanket is mounted on the surface of the blanket cylinder 4 and should have a substantially smooth surface. In particular, it can also be elastic. It may also be that a smooth surface is preferred as the surface of the blanket cylinder 4, but that this surface should be as inelastic and hard as possible. This can be z. B. can be achieved by a metal plate. For example, can be used as a standard blanket a blanket from IMC GmbH Munich with the trade name Perfect Dot® MX. This has a preferred smooth surface structure and leads to no adverse effects, ie no impressions in the sheet 6. It can thus be carried out a high-quality coating of the printing sheet 6, wherein due to the reduced frictional force between the blanket cylinder 4 and transfer sheet 1, the detachment of the transfer layer 12 of the transfer film 1 is better supported and a smooth structure of the transfer layer on the sheet 6 is achieved.

reference numeral

1

transfer film

2

guide rollers

3

transfer nip

4

Blanket cylinder

5

Impression cylinder

6

bow

7

Material application device

8th

Blanket wash

9

plate cylinder

10

gap

11

support film

12

transfer layer

13

Interface

14

metal layer

15

bonding agent

16

Anti-adhesion layer

17

suction

Claims (27)

1. Device for transferring a transfer layer (12) from the front of a carrier foil, which, together with the transfer layer (12), forms a transfer foil (1), to a printing material (6) comprising

   - at least one transfer unit for transferring the transfer layer (12) to the printing material (6),

   - the transfer unit comprising at least one transfer cylinder for transferring the transfer
   layer (12),
   characterized in
   that the transfer unit comprises at least one material application device for applying a friction-reducing material to the transfer cylinder and/or to the back of the carrier foil.
2. Device according to Claim 1,
   characterized in
   that the material application device (7) is provided in the region of the transfer cylinder to apply the friction-reducing material to the surface of the transfer cylinder.
3. Device according to Claim 1,
   characterized in
   that the transfer foil is moved to the transfer cylinder along a transport path and that the material application device (7) is provided upstream of the transfer cylinder in the region of the said transport path of the transfer foil (1) to apply the friction-reducing material to the back of the transfer foil (1).
4. Device according to any one of Claims 1 to 3,
   characterized in
   that the material application device (7) is designed as a cassette removable from the transfer unit.
5. Device according to any one of Claims 1 to 4,
   characterized in
   that the material application device (7) includes at least one elements of the following group comprising brush, cloth, blowing element to apply the friction-reducing material to the surface of the transfer cylinder and/or to the back of the carrier foil.
6. Device according to Claim 5,
   characterized in
   that the material application device (7) includes a suction device (17) for withdrawing residues of the friction-reducing material by suction or is comprised by the suction device (17).
7. Device according to Claim 1,
   characterized in
   that a washing device for washing the transfer cylinder surface is provided.
8. Device according to Claim 7,
   characterized in
   that the washing device is a blanket-washing device (8).
9. Device according to Claim 6,
   characterized in
   that the blanket-washing device (8) includes at least two detergent circuits at least for a first detergent for washing residues of the friction-reducing material off the surface of the transfer cylinder and for a second detergent for washing ink residues of an offset printing ink off the surface of the transfer cylinder.
10. Device according to Claim 1,
    characterized in
    that the transfer unit is one of the group comprising printing unit, varnishing unit and modular unit of a printing press.
11. Device according to Claim 10,
    characterized in
    that the transfer cylinder is a blanket cylinder (4) and that a plate cylinder (9) that is engaged with the blanket cylinder (4) for an offset printing process is provided without a printing plate or disengaged from the blanket cylinder (4).
12. Device according to any one of Claims 1 to 11,
    characterized in
    that the friction-reducing material is a material of the group comprising fluids and powder.
13. Device according to Claims 1 and 12,
    characterized in
    that the material application device (7) is a powdering device of a printing press.
14. Device according to Claim 12 or 13,
    characterized in
    that a powder of a grain size of between 10 µm and 90 µm, preferably between 15 µm and 35 µm is used as the friction-reducing material.
15. Method for transferring a transfer layer (12) from the front of a carrier foil, which, together with the transfer layer (12), forms a transfer foil, to a printing material, wherein

    - the transfer foil is supplied to a transfer cylinder to be transferred and

    - the transfer layer (12) is transferred to the printing material (6) by being released
    from regions of the carrier foil (11),
    characterized in
    that a friction-reducing material is applied to the back of the carrier foil (11) and/or to the surface of the transfer cylinder at least to reduce adhesion between the carrier foil (11) and the surface of the transfer cylinder, the friction-reducing material being applied using one method of the group comprising brushing on, spraying on, rolling on, scraping on, and applying by means of a cloth.
16. Method according to Claim,
    characterized in
    that air polluted with friction-reducing material is removed by suction from the application region.
17. Method according to Claim 15,
    characterized in
    that a blanket cylinder (4) of a printing unit is used as the transfer cylinder.
18. Method according to Claim 17,
    characterized in
    that a plate cylinder (9) associated with the blanket cylinder (4) is set up in such a way that at least during the method, it is provided wtihout contact with the blanket cylinder (4).
19. Method according to Claim 18,
    characterized in
    that the plate cylinder (9) is disengaged from the blanket cylinder (4) and/or is provided without a plate.
20. Method according to Claim 15,
    characterized in
    that a washing device washes residues of the friction-reducing material off the transfer cylinder surface.
21. Method according to Claim 20,
    characterized in
    that a blanket-washing device (8) is used as the washing device.
22. Method according to any one of Claims 15, 20 or 21,
    characterized in
    that residues of the friction-reducing material are washed off the surface of the transfer cylinder using a detergent from a first detergent circuit and ink residues of an offset printing process are washed off the surface of the transfer cylinder using a second detergent from a second detergent circuit.
23. Method according to any one of Claims 15 to 21,
    characterized in
    that a fluid or a powder is used as the friction-reducing material.
24. Method according to any one of Claims 15 and 23,
    characterized in
    that a powdering device of a printing press is used to apply the friction-reducing material.
25. Method according to Claim 23,
    characterized in
    that silicone oil is used as the fluid.
26. Method according to Claim 23,
    characterized in
    that one of the group comprising talcum, mineral powder and organic powder is used as the powder.
27. Method according to Claim 23 or 26,
    characterized in
    that a powder of a grain size of between 10 µm and 90 µm, preferably between 15 µm and 35 µm is used.

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