EP2163394A1 - Printing blanket for a cold film transfer method - Google Patents

Abstract

The blanket (32') has a carrier layer, a compressible layer and a covering layer i.e. foil, where the covering layer is formed from polyester, polyolefin, polyvinyl, polyimide or acrylonitrile butadiene styrene. The carrier layer is made of fabric i.e. cotton fabric, and the compressible layer is formed from rubber. The blanket has a thickness in a range of 1.8 to 2 millimeters preferably 1.95 millimeters, and adhesion of the covering layer opposite to a carrier foil (42) of a transfer foil (40) is equal to zero. An independent claim is also included for a cold foil transfer process.

Description

The invention relates to a blanket for use in a cold foil transfer method and to such a cold foil transfer method.

In the case of cold foil transfer, a transfer film, consisting of a carrier film, optionally a release layer, and a transfer layer detachable from the carrier film, is usually combined with a substrate which has previously been provided with a full-area or patterned cold adhesive layer on its surface facing the transfer film in an adhesive applicator. In the regions of the substrate coated with the adhesive layer, the transfer layer of the transfer film is fixed to the substrate and detached from the carrier film. The used transfer film, comprising the carrier film and possibly not transferred to the substrate residues of the transfer layer is wound while the transfer layer coated substrate is transported further to optionally subsequently further processing steps, coating or printing operations, Umwendevorgänge, punching or cutting operations and the like , A unit for film application is usually formed from a smooth roller and a likewise smooth counter-pressure roller, which press the substrate and the transfer sheet against each other, wherein the coming into contact with the transfer sheet roller is covered in particular with a compressible blanket or blanket.

The EP 0 578 706 A describes a film-printing method and a film-transfer machine which are used for the cold-embossing of surfaces of substrates by means of transfer films. An adhesive applicator is for pattern-wise application of an adhesive to a substrate, a unit for film application and a pressing unit for fixing the applied transfer layer areas provided on the substrate under application of high pressure.

The EP 1 880 848 A2 discloses an apparatus and a method for transferring layers of a transfer film to a substrate or a substrate by means of a cold embossing device, wherein a film application module is used in a sheet-fed rotary printing machine. A turning device allows the reversal of the substrate and a double-sided printing and / or embossing of the substrate. In particular, further coating or printing units are connected upstream and / or downstream of the film application module.

From the DE 103 49 963 A1 It is known to carry out a cold foil stamping process using a radiation-crosslinking adhesive. In this case, an adhesive which crosslinks under UV irradiation is used in particular, so that neither heat nor increased pressure is required for fixing the transfer layer to adhesive-coated regions of a substrate.

The UV exposure of the adhesive is usually carried out in practice after a merger of transfer film and substrate. It is necessary that either the transfer film or even the transfer layer, or the substrate to be coated for the UV radiation used to crosslink the adhesive is at least partially permeable. In order to be able to use a transfer film flexibly in combination with a wide variety of substrates, it is customary to provide the transfer film or the transfer layer with a permeability to the UV radiation.

As a cold adhesive, however, it is known to also use conventional adhesives that cure without pressure and irradiation, or adhesives that cure under the action of pressure in a cold-film transfer process.

A roll for film application is, as stated above, usually covered with a blanket or blanket, which has a certain Compressibility and allows a uniform pressing of the transfer film to the substrate.

The printing blankets or blankets previously used in cold foil transfer usually have a hardness of <60 Shore A, an adhesion of> 0 and a rough surface, often made of ground rubber, which comes into contact with the transfer film.

The following examples of printed or rubber blankets have hitherto been used as a covering for transfer cylinders or rolls in cold foil transfer processes. These are usually swelling resistant to all solvents and printing inks used.

The Vulcan ^® IRIO ^™ multilayer blanket, which is particularly recommended for use in sheet-fed offset printing, is compressible, has a thickness of 1.96 mm (± an internationally tolerated tolerance) and a surface roughness in the range of 0.3 to 0.5 on. In addition to a number of fabric layers and elastomeric layers, it has a compressible layer, a carrier layer and a plastic cover plate surface. The rubber blanket Vulcan ^® IRIO ^™ is often used in Heidelberger printing presses.

The SUPER-PRESS multi-layered glass bead blanket, which is recommended as a cylinder cover on high-speed newspaper presses or for hot stamping, has a rubber surface with approximately 7000 smallest glass spheres per cm ² rubber surface and a hardness in the range of 88 to 95 Shore A. on. It is often used in printing presses from manroland.

Both mentioned printing blankets are used, for example, by the company Streb AG, DE-63303 Dreieich, expelled.

However, it has been found that an optical appearance of a cold transfer layer on a substrate is often poor using conventional process parameters and blankets. There is a cracking and the formation of defects in the applied to the substrate transfer layer areas.

In addition, the surface quality of a transfer layer transferred to a substrate in a cold foil transfer process is highly dependent on the surface condition of a roller for film application and in particular on its blanket covering.

It is therefore an object of the invention to provide a printing blanket or blanket with which the surface quality of a transfer layer of a transfer film applied to a substrate in a cold foil transfer process can be improved and a suitable cold foil transfer method can be specified.

The object is achieved for the printing blanket by comprising at least three layers comprising a carrier layer, a compressible layer and a cover layer, wherein the cover layer of polyester, polyolefin, polyvinyl, polyimide or ABS, in particular a film of one of these materials is formed.

Such a cover layer has a particularly smooth surface with high hardness, in particular a hardness> 50 Shore A, more preferably a hardness of> 70 Shore A, so that particularly smooth surfaces of transfer layers are formed on substrates so embossed, if one with a such blanket is used to compress a substrate in a cold foil transfer process under pressure with a transfer film.

In fact, it has been recognized that the printing blankets or blankets used hitherto in cold foil transfer have a rough surface which comes into contact with the transfer foil, as a result of which they impair the visual appearance of the regions of the transfer layer applied to the substrate.

Using a printing blanket according to the invention, cracking no longer occurred and it was reliably possible to reliably prevent the formation of defects in the regions of the transfer layer applied to the substrate.

It has proved to be advantageous if the cover layer of the printing blanket of PET, PC, PP, PE, PVC, PS, polyimide or ABS or is formed. Particularly preferred here is PET.

The cover layer of the printing blanket has in particular a thickness in the range of 0.1 to 2 mm.

The printing blanket preferably has, in this order, the carrier layer, the compressible layer, an adhesive layer and the cover layer.

The carrier layer of the blanket is in particular made of a fabric, preferably a cotton fabric.

It has proven useful if the blanket has a thickness in the range of 1.8 to 2 mm, in particular of 1.95 mm.

It is particularly preferred if the blanket comprising the carrier layer of cotton fabric, the compressible layer, the adhesive layer and the cover layer is constructed and has a total hardness in the range of 50 to 85 Shore A, in particular in the range of 75 to 80 Shore A.

Preferably, the cover layer of the blanket has an adhesion to a carrier film of a transfer film of polyester, polyolefin, polyvinyl, polyimide or ABS, which is equal to zero. This results in no adhesion of the transfer film on the blanket.

The blanket of the present invention is optimally suited for use in a cold foil transfer process and is fundamentally different from conventional blankets used in offset printing processes. In offset printing, a printing blanket or blanket has the task of, on the one hand, accepting ink and, on the other hand, transferring it. On the one hand, the printing ink must therefore adhere to the blanket and, on the other hand, be transferable from it (removable). Particularly suitable for this are printing blankets made of rubber-like materials (hence "rubber blanket"), because they are relatively soft and one for rubber materials have typical surface roughness, ie are not too smooth on the surface. The Shore hardness of such blankets suitable for offset printing is <60 Shore A. The invention now claims a blanket having a surface that is substantially harder and smoother compared to rubber. Because in the cold film transfer process, no ink must be transferred, but it must be a transfer film pressed against a substrate. The basic requirements of the cold foil transfer process thus differ essentially from offset printing. The printing blanket according to the invention would be substantially too hard for an offset printing process and above all essentially too smooth. Offset ink would adhere very poorly to the blanket of the invention.

Preferably, the carrier film of the transfer film is formed from a material which is formed from the same class of material, in particular the same material, as the cover layer of the printing blanket.

The object is for the cold foil transfer method, in which a substrate by means of a cold adhesive, in particular a crosslinking under UV irradiation adhesive, at least partially connected to a transfer layer of a transfer film, wherein the transfer film comprises a carrier film and the removable from the carrier film transfer layer, and wherein the transfer film and the substrate are brought together by means of a roller and a counter-pressure roller, by covering the roller with a blanket according to the invention and the cover layer of the blanket being arranged in the direction of the carrier foil of the transfer foil on the roller.

A cold foil transfer method is much cheaper and faster to perform than a hot stamping process due to the low demands on the transfer device used, the low preparation and setup times and the high transfer speeds achievable and therefore enjoys a steadily increasing popularity. The cold foil transfer process according to the invention results in a substrate which is completely or only partially coated with a transfer layer and which has a particularly smooth surface of high quality, above all because of the special printing blanket described in detail above. The visual appearance of the transferred transfer layer is impeccable and very appealing.

The roller covered with the blanket is in particular provided with two bearer rings. The function and operation of Schmitzringen will be explained in more detail below. Preferably, the blanket is placed on the roll in the range of 0 to 0.3 over Schmitz, in particular in the range of 0.05 to 0.2 over Schmitz.

The cold adhesive is applied in particular to the substrate and / or the transfer layer of the transfer film before the transfer film is brought together with the substrate.

The cold glue is preferably applied by means of a pressure cylinder covered with a conventional blanket.

It has proven useful if the cold adhesive, in particular the adhesive which crosslinks under UV irradiation, is applied to the substrate in an application amount in the range from 1 to 3 g / m ² . Depending on the absorbency of the substrate used, the amount of adhesive should be varied, with less absorbent and / or open-pore-free substrates, in particular with adhesive amounts in the range of 1 to 2 g / m ² and more absorbent and / or open-pored substrates, in particular with adhesive amounts be coated or printed in the range of 2 to 3 g / m ² .

In principle, all commercially available cold adhesives, in particular UV adhesives, are suitable for use in the method according to the invention.

The cold adhesive is preferably cured after the substrate and transfer film have been brought together, in particular the adhesive which crosslinks under UV irradiation is irradiated with UV radiation in an exposure station and crosslinked, an adhesive bond being formed with the transfer layer of the transfer film.

In general, the cold adhesive can be applied over the entire surface or only partially to the substrate and / or the transfer film. A pattern-shaped formation of transfer layer on the substrate is possible in both cases, since in a full-surface application of cold adhesive only partial activation of the Cold glue can be done. If, for example, a UV adhesive is used as the cold adhesive, which is applied, for example, to the substrate on the whole surface, then this can be partially exposed after the substrate and transfer film have been brought together, for example via a shadow mask. The UV adhesive is only cured in the exposed areas and only there fixes the transfer layer on the substrate, while in unexposed areas the transfer layer remains on the carrier film and can be pulled off with it again from the substrate. The cold adhesive applied over the entire surface to, for example, the substrate can furthermore be exposed in pattern form for the first time so that it already partially cured and no longer be able to develop adhesion if, after being brought into contact with the transfer film, the entire surface is exposed a second time is hardened and the previously uncured adhesive areas and connected to the transfer layer. After peeling off the carrier film from the substrate, the areas which were exposed in a patterned manner the first time now remain without transfer layer.

In the case of a pattern-like application of cold glue to the substrate and / or the transfer film, after a combination of substrate and transfer film, the carrier film can be removed from the transfer layer at different times. Thus, the carrier film can be removed immediately after the combination of substrate and transfer film and before curing of the cold adhesive. For this purpose, it is necessary that the adhesion of the transfer layer to the not yet or not yet completely cured cold adhesive is higher than the force for detaching transfer layer areas from the transfer layer and for overcoming the adhesion of the transfer layer to the carrier film. If an adhesive crosslinking under UV irradiation is used, then a UV permeability of the transfer layer is sufficient here. Frequently in sheetfed offset presses this method is used.

Alternatively, the carrier film can be removed after the combination of substrate and transfer film and only after curing of the cold adhesive. It is not necessary that the adhesion of the transfer layer to the not yet or not yet fully cured cold adhesive is higher than the force to dissolve transfer layer areas from the transfer layer and to overcome the adhesion of the transfer layer to the carrier film. Only the adhesion of the transfer layer to the fully cured cold adhesive and furthermore to the substrate when removing the carrier film must be higher than the force for detaching transfer layer regions from the transfer layer and overcoming the adhesion of the transfer layer to the carrier film.

It is possible to use a single composition for the cold adhesive or to use a plurality of different cold adhesives side by side on the substrate which differ in terms of their chemical and / or physical properties. This often requires a separate printing unit per adhesive. A locally different adhesion of the transfer layer to the substrate can be achieved so that any manipulative detachment attempts to change or exchange the substrate are made more difficult and the security against counterfeiting is increased.

It is particularly preferred if radiation having a wavelength in the range from 250 to 400 nm is used as the UV radiation for irradiating the adhesive crosslinking under UV irradiation, or the radiation used has a maximum in this wavelength range.

As cold glue, in particular a UV-crosslinking adhesive having the following first composition is used (in% by weight): 50 - 80 Polyester acrylate (s) 2 - 20 Urethane acrylate (e) 10 - 15 bonding agent 3 - 8 Photoinitiator (s) 3 - 10 Filler (e) 0 - 5 Monomeracrylat (e) 0.1 - 2 organic pigment (s)

This UV adhesive in the first composition is used in particular in combination with a paper or film substrate.

Alternatively, the adhesive used is a UV-crosslinking adhesive having the following second composition (in% by weight): 40 - 80 Epoxy acrylate (e) 10 - 30 Polyester acrylate (s) 3 - 10 Photoinitiator (s) 10 - 15 Filler (e) 0 - 5 Monomeracrylat (e) 0.1 - 2 organic pigment (s)

This UV adhesive in the second composition is used in particular in combination with a paper substrate.

A transfer film suitable for cold foil transfer has, in particular, a thickness in the range from 9 to 25 μm, in particular in the range from 13 to 16 μm.

Thus, the transfer film has a carrier film and a transfer layer detachable therefrom, it being possible for the carrier film to be drawn off after a partial or full-surface gluing of the transfer layer with a substrate. The areas of the transfer layer which are not adhesively bonded to the substrate are removed together with the carrier film.

A release layer can be arranged between the carrier film and the transfer layer in order to improve or specifically adjust the detachment behavior between transfer layer and carrier film. Such a release layer preferably has a thickness in the range of 0.01 to 0.4 μm.

The carrier film of the transfer film preferably has a thickness in the range of 7 to 23 μm. An adhesion between the cover layer of the blanket and a carrier foil is preferably equal to zero.

The carrier film is formed in particular from a material which is formed from the same class of material, in particular the same material as the cover layer of the printing blanket. The carrier film is preferably formed from polyester, polyolefin, polyvinyl, polyimide or ABS, in particular from PET, PC, PP, PE, PVC, PS educated. Particularly preferred here is a carrier film made of PET.

It has been shown that in direct contact of a cover layer of the blanket to a carrier film of a transfer film, which are formed of material of the same class of materials, in particular the same material, results in between the top layer of the blanket and the carrier film, an adhesion of zero , This has a positive effect on the uniform transfer of the transfer layer to the substrate.

The use of a transfer film with a carrier film made of PET or PP with simultaneous use of a cover layer of the printing blanket made of PET or PP has proven particularly useful.

It has proven useful if the transfer layer is of multilayer design, in particular if it comprises a transparent protective lacquer layer and at least one decorative layer.

After the cold foil transfer, the protective lacquer layer preferably forms a protection for the at least one decorative layer on the substrate with regard to mechanical and / or chemical stress. A protective lacquer layer with a thickness in the range of 0.8 to 2.0 microns has been proven. The transparent protective lacquer layer can be colorless, clear or even colored or at least partially colored.

The at least one decorative layer is preferably formed by a metallic layer or a dielectric layer. It has proven useful if the at least one decorative layer has a thickness in the range of 8 to 500 nm.

It has proven useful if the substrate is brought together with the transfer film in a transfer nip between the roller for film application and the associated counter-pressure roller, wherein in the transfer nip preferably a pressure in the range of 0.1 to 0.3 mm, in particular in the range of 0, 15 to 0.2 mm, is set. This results in an improved surface transfer, a higher gloss and a more pronounced edge sharpness.

The substrate which is to be partially or completely coated with a transfer layer of a transfer film is preferably formed from paper, cardboard, plastic film, metal foil or a laminate comprising at least two of these materials. Preferably, the substrate is flexibly formed so that it can be processed in a roll-to-roll process, continuously or on a sheetfed offset press. In this case, it is possible to use a band-shaped substrate or a substrate in the form of individual printed sheets, in particular wound up on a roll.

A finished with transfer layer partially or fully covered and optionally further processed and / or printed substrate is preferably used in the form of wet labels, in-mold labels, magazines or as packaging material, such as folding boxes, and the like.

A use of a printing blanket according to the invention in a cold foil transfer process in which a roller is covered by means of the blanket and the cover layer of the blanket is arranged away from the roller and brought into contact with a transfer foil is ideal. This makes it possible to achieve particularly high-quality and perfect transfer-transfer surfaces of excellent smoothness and in particular high gloss on substrates.

In particular, the transfer film used has a carrier film and a transfer layer detachable therefrom, wherein the carrier film is arranged to face the blanket.

Preferably, the carrier film of the transfer film is formed so that it has an adhesion of 0 relative to the cover layer of the printing blanket. In particular, the carrier film is formed from polyester, polyolefin, polyvinyl, polyimide or ABS. Preferably, a carrier film is formed from a material which is formed from the same class of material, in particular from the same material, as the cover layer of the printing blanket. Particularly preferred is the material PET or PP for the carrier film and the cover layer of the blanket.

Figur 1

schematisch den Ablauf eines Kaltfolientransferverfahrens, bei dem das Substrat von Rolle zu Rolle verarbeitet wird;

Figur 2

einen Querschnitt durch ein Druck- bzw. Gummituch;

Figur 3

eine Draufsicht auf eine Druckwalze mit Schmitzringen und einer Bespannung mit einem Druck- bzw. Gummituch;

Figur 4

einen Querschnitt durch eine Transferfolie;

Figur 5

einen Querschnitt durch ein Substrat mit einem partiell darauf aufgebrachten Kaltkleber;

Figur 6

eine schematische Darstellung einer Druckmaschine mit einem Folientransfermodul in der Seitenansicht; und

Figur 7

den Aufbau des Folientransfermoduls gemäß Figur 6 im Detail.

The FIGS. 1 to 7 are intended to exemplify the blanket and various cold foil transfer methods according to the invention. So shows:

FIG. 1

schematically the process of a cold foil transfer process, in which the substrate is processed from roll to roll;

FIG. 2

a cross section through a blanket or blanket;

FIG. 3

a plan view of a pressure roller with Schmitzringen and a covering with a blanket or blanket;

FIG. 4

a cross section through a transfer film;

FIG. 5

a cross-section through a substrate with a partially applied cold adhesive;

FIG. 6

a schematic representation of a printing machine with a film transfer module in the side view; and

FIG. 7

the structure of the film transfer module according to FIG. 6 in detail.

FIG. 1 shows a cold foil transfer unit comprising a printing station 10, an exposure station 20, three rollers 31, 32 and 33 and a deflection roller 34. The printing station 10 is preferably an offset or flexographic printing station. However, it is also possible that the printing station 10 is a gravure printing station.

A flexible substrate 51 is supplied to the printing station 10 continuously and partially printed with a cold adhesive 11, here in the form of a UV-crosslinking adhesive. The printing station 10 has a trough 9, in which the cold adhesive 11 is provided. By means of a plurality of transfer rollers 12, 13, the cold adhesive 11 is applied to a printing cylinder 14. The printing cylinder 14 now prints between the printing cylinder 14 and an associated counter-pressure roller 15th continuous flexible substrate 51 pattern with the cold adhesive 11, preferably in a thickness in the range of 1 to 3 microns.

The arrangement of substrate 51 and cold adhesive 11 is in FIG. 5 enlarged shown in cross section.

FIG. 5 shows a cross section through a flexible substrate 51, on the pattern of a cold adhesive 11 is applied in the form of a crosslinking under UV irradiation adhesive. The flexible substrate 51 may in the simplest case be a paper web, a plastic film or a printed sheet.
A plastic film is preferably made of polyester, polyolefin, polyvinyl, polyimide or ABS, preferably with a film thickness in the range of 6 to 200 .mu.m, in particular from 19 to 38 microns.
For paper sheets or webs, it has proven useful when these are painted, such as in a picture printing material or Chromolux.

Usually, the substrate 51 will have additional layers or applied film areas applied in previous process processes. Such further layers are, for example, printing ink layers, lacquer layers and / or metal layers, etc., while applied film regions can be formed by transfer layer regions of transfer films, labels, etc. Here, it is also possible for these further layers or applied film regions to be present only partially on the substrate 51 or in total cover the substrate 51 superficially.

The application amount of cold adhesive 11 to the substrate 51 is in particular in the range of 1 to 3 g / m ² .

Independent of FIG. 1 For example, the cold adhesive can generally be applied over the entire surface or only partially to the substrate 51 and / or the transfer film 40.
A pattern-shaped formation of transfer layer 41 on the substrate 51 is possible in both cases, since in a full-surface application of cold adhesive only partial activation of the cold adhesive can take place.

If, for example, a UV adhesive is used as the cold adhesive 11, which is applied over the entire surface, for example, to the substrate 51, then this can be partially exposed after the substrate 51 and transfer film 40 have been brought together, for example via a shadow mask. The UV adhesive is cured only in the exposed areas and only there fixes the transfer layer 41 on the substrate 51, while in unexposed areas the transfer layer 41 remains on the carrier film 42 and can be removed from the substrate 40 with this again.
The cold adhesive 11 applied over the entire area, for example to the substrate 51, can be exposed in pattern form for the first time, so that it already partially cured and can no longer develop adhesion if, after being brought into contact with the transfer film 40 second entire surface is exposed and the previously not cured adhesive areas cured and connected to the transfer layer 41. After the carrier foil 42 has been removed from the substrate 51, the regions of the substrate which have been exposed in a pattern-like manner the first time now remain without a transfer layer 41.

As an alternative to printing the substrate 51 with cold adhesive 11, printing of the transfer film 40 with the cold adhesive 11 can thus also be provided or both can be provided printed with cold adhesive 11.

It is possible to use a single composition for the cold adhesive or to use a plurality of different cold adhesives side by side on the substrate 51, which differ in terms of their chemical and / or physical properties. This makes it possible to achieve a locally different adhesion of the transfer layer 41 to the substrate 51, so that any manipulative detachment attempts to change or exchange the substrate 51 are made more difficult and the security against counterfeiting is increased. Optionally, this is a separate printing station required per cold glue type.

• vorzugsweise 120 bis 220 Pas, insbesondere 180 Pas
• Viskosität bei Scherrate 100 1/s:
• vorzugsweise 40 bis 90 Pas, insbesondere 80 Pas

The preferably used UV-crosslinking adhesive has, in particular, the following viscosities, measured with the Rheometer MCR 101 measuring instrument from Physica (measuring cone: CP25-1 / Q1, measuring temperature: 20 ° C.).
Viscosity at shear rate 25 1 / s:

• preferably 120 to 220 Pas, in particular 180 Pas
• Viscosity at shear rate 100 1 / s:
• preferably 40 to 90 Pas, especially 80 Pas

• UV-Klebermenge: 1g
• Walzengeschwindigkeit: 100 m/min
• Messtemperatur: 20 °C
• Messdauer: 2 min

Furthermore, the preferably used UV-crosslinking adhesive preferably has a tack in the range from 18 to 25, in particular from 22 to. The "tack", also called initial tack or tack, is determined by means of the measuring instrument Inkomat 90T / 600 from Prüfbau. The following measurement conditions were chosen:

• UV adhesive quantity: 1g
• Roller speed: 100 m / min
• Measuring temperature: 20 ° C
• Measuring time: 2 min

Depending on the type of cold adhesive 11 used, it is possible that the coated with the cold adhesive substrate 52 passes through a drying channel in which the cold adhesive 11, for example, at a temperature in the range of 100 to 120 ° C, dried.

The substrate 51 processed by the printing station 10 is fed, as a substrate 52 partially printed with the UV-crosslinking adhesive, over the deflection roller 34 to the pair of rollers 31 and 32, which applies a transfer film 40 continuously to the substrate 52 printed with UV adhesive. The transfer film 40 is in FIG. 4 enlarged and shown in cross section.

FIG. 4 shows the cross section through the transfer film 40, which has a carrier film 42 and a detachable from the carrier film 42 transfer layer 41. The transfer film 40 comprises, starting from the carrier film 42 in this order, an optional transparent release layer 43, a transparent protective lacquer layer 44, a decorative layer 45 and optionally an adhesion promoter layer 46. The carrier film 42 is a PET film having a thickness in the range from 4 to 75 μm, in particular 12 μm.

The transfer film 40 is withdrawn from a supply roll (not shown separately) and in contact with the substrate 52 printed with UV-crosslinking adhesive on the side of the transfer layer 41 (cf. FIG. 1 ) brought. This results in a composite 53 of the printed with UV-crosslinking adhesive substrate 52 and the transfer film 40th

The roller 32 of the roller pair 31, 32 for film application is covered on its circumference with a blanket or blanket 32 'according to the invention. The blanket 32 'is composed of several layers, in particular more than three layers, which have different compressibility and elasticity. It is preferred to provide a compressible layer, a non-compressible layer and an elastic layer. The individual layers are glued together over the entire surface or mechanically coupled to each other, in particular by a rail.

In this case, the blanket 32 'in this order comprises a carrier layer, in particular of a textile fabric, in addition a compressible layer, an adhesive layer and the cover layer, which are interconnected. The cover layer of the blanket 32 ', which comes into contact with the transfer film in the cold-foil transfer unit, has an antistatic and detergent-resistant design.

1. 1. Lage: Trägerlage 32a' aus Baumwollgewebe
2. 2. Lage: kompressible Lage 32b' aus Kautschuk
3. 3. Lage: Kleberlage 32c'
4. 4. Lage: Decklage 32d' aus PET-Folie

The blanket 32 'is in FIG. 2 in cross-section and enlarged and constructed as follows:

1. 1st layer: carrier layer 32a 'made of cotton fabric
2. 2nd layer: compressible layer 32b 'of rubber
3. 3rd layer: adhesive layer 32c '
4. 4th layer: cover layer 32d 'made of PET film

The thickness of the carrier layer 32a 'plus the compressible layer 32b' is in particular in the range of 1 to 2 mm. The thickness of the adhesive layer 32c 'is in particular in the range of 0.1 to 0.8 mm. The thickness of the cover layer 32d 'is preferably in the range of 0.1 to 2 mm.

The thickness of the blanket 32 'overall is preferably in the range of 1.8 to 2 mm, in particular 1.95 mm. The hardness of the blanket is preferably 50 to 85 Shore A, in particular 75 to 80 Shore A. An adhesion of the blanket 32 'to the carrier foil 42 of the transfer foil 40 made of PET (see FIG. 4 ) is in particular equal to 0.

The blankets or blankets previously used in cold foil transfer usually had a hardness of <60 Shore A, an adhesion of> 0 and a cover layer of ground rubber, so that the blanket had a rough surface, which came into contact with the transfer film and in Result impaired the visual appearance of the applied to the substrate areas of the transfer layer.

Such is no longer observed when using the above-described blanket 32 'with a cover layer of PET film, especially when it is used in combination with a transfer film having a carrier film of PET.

The blanket 32 'is particularly suitable for a cold foil transfer, since the smoothness and hardness of the cover layer noticeably in an increase of the gloss and the surface quality of the applied to the substrate 51 areas of the transfer layer 41 of the transfer film 40 effects.

The blanket 32 'is placed on the roller 32 (see FIG. 1 ), wherein between roller 32 and blanket 32 'for setting an optimal contact pressure of the roller 32 one or more paper layers can be inserted.

FIG. 3 shows the covered with the blanket 32 'roller 32 in plan view, wherein the cover layer 32d' of the roller 32 is arranged facing away. On both sides of the roller 32 bearer rings 323a, 323b are arranged.

A bearer ring is part of the printing unit construction of modern printing machines. Bearer rings on printing presses are arranged on the sides of the impression cylinders or rollers. The bearer rings are made of hardened steel with high rolling resistance and roll with high preload on each other.

The task of the bearer rings is above all to prevent the torsional vibrations in the oscillatory, mechanically strained system of cylinders and gears. Furthermore, the bearer rings increase the bending stiffness of the cylinder pairing. This shifts the resonant frequency to non-critical areas and reduces flexing vibrations that excite the impact of rolling over channels in the rollers or cylinders. The grading of the bearer ring diameter - slightly smaller on the plate cylinder than on the blanket cylinder - enables the introduction of mechanical stresses in the direction of movement between the bearer rings and the gears. As a result, a clear flank position of the gears can be ensured even with strong torque laps in the channel rollover.

In a bearer ring plate and rubber cylinder based on the bearer rings at both ends of the cylinder from each other. The bearer ring has the same diameter as the pitch circle of the driving gear. Usually, the blanket is underlaid so that it is compressed by the pressure plate by 1/10 mm, thereby to compensate for surface irregularities and build up the required surface pressure. It has proven to be beneficial to mount pressure plates 1/10 mm over Schmitzring and to place blankets at Schmitzringhöhe. The bearer rings also serve as a reference height in order to be able to measure the elevator heights on the cylinders. However, the bearer rings primarily ensure smooth cylinder running due to the pretensioning applied during assembly and the avoidance of quality-reducing and noise-producing effects of load fluctuations as a result of channel overrun. Bearing force fluctuations can produce quality-reducing stripes in homogeneous, larger screen areas by minimally varying dot gain.

When cold foil transfer is usually "worked on Schmitz" in order to apply a sufficient pressure, although it is also possible to work a few hundredths of a millimeter "under Schmitz". Over the selected circumference of the blanket 32 ', the speed of the transfer film and the transfer ribbon tension can be influenced to a small extent.

The carrier film 42 can be removed from the composite 53, consisting of the substrate 51 coated with cold adhesive 11 and the transfer film 40, before or after curing of the cold adhesive 11, depending on the level of adhesion of the transfer layer 41 on not or not yet fully cured cold adhesive 11. According to FIG. 1 For example, the composite 53, including the carrier foil 42, is supplied to an exposure station 20 by way of example and exposed to UV radiation.

The composite 53 is in this case irradiated from the side of the transfer film 40. This is only possible if the transfer film 40 is sufficiently UV-transmissive. If the substrate 51 is designed to be transparent or semi-transparent for the UV radiation required for curing the UV-crosslinking adhesive 11, the composite 53 can alternatively or additionally also be irradiated from the side of the substrate 51.

The exposure station 20 has a UV lamp 21 and a reflector 22, which bundles the UV radiation emitted by the UV lamp 21 onto the composite 53. The power of the UV lamp 21 is in this case selected so that the UV-crosslinking adhesive 11 is irradiated when passing through the exposure station 20 with a sufficient amount of energy that ensures a secure curing of the UV-crosslinking adhesive 11.

The duration of irradiation of the UV adhesive with UV radiation is preferably in the range of less than one second, using, for example, high-pressure mercury lamps, high-pressure mercury doped lamps, carbon arc lamps, xenon arc lamps, metal halide lamps, UV LEDs or suitable UV lasers , Alternatively, an electron beam curing can be performed.

For sheet-fed presses (see FIGS. 6 and 7 ), which process, for example, sheets of 75 cm in length and wherein a range of about 8 to 10 cm of the arc length is irradiated with a UV lamp having a power in the range of 160 to 200 W / cm, can thus approx 10000 sheets per hour are processed.

According to FIG. 1 As a result of the curing of the pattern-shaped UV-crosslinking adhesive, the transfer layer 41 of the transfer film 40 is adhesively bonded to the substrate 51 at the locations where the UV-crosslinking adhesive is present. Subsequently, the exposed composite 54 is fed to the roller 33, where the carrier foil 42 is peeled off the exposed composite 54. If the carrier film 42 is peeled off from the irradiated composite 54, then the transfer layer 41 adheres to the substrate 51 in the regions in which the cold adhesive 11s which has now hardened is present, and is thus removed from the transfer film 40 at these points. In the other places, the adhesion between carrier film 42 and transfer layer 41 predominates, so that here the transfer layer 41 remains on the carrier film 42.

If a conventional or pressure-curing adhesive is used as the cold adhesive in the cold-film transfer process, of course, no exposure station 20 is as for curing the cold adhesive FIG. 1 shown required.

After the removal of the used transfer film 40 ', the substrate 55 partially coated with transfer layer 41 remains, which can now be fed to further printing or film application units, punching or cutting units, etc.

In particular, the substrate 55, which is partially coated with transfer layer 41, is at least partially printed with conventional printing inks, in particular UV-curing printing inks, UV-curing lacquers, hybrid paints or lacquers.

The fixed to the substrate 51 transfer film portions 41 have due to the cured cold adhesive 11s a tesa-firm adhesion to the substrate 51, which can be checked by the Tesatest described below.

The adhesion of transfer layer areas of a transfer film, which were transferred to a substrate by means of cold foil transfers, was determined immediately after the transfer at room temperature:

A test pattern in the form of a substrate with the transfer layer coldly applied thereto was placed on a flat surface. A 13 to 16 cm long strip of Tesafilm 4104 was adhered to it, so that about 5 to 7 cm of the Tesafilms over the edge of the substrate survived. Subsequently, the Tesafilm was pressed with the thumb three to four times and finally subtracted at an angle of> 90 ° from the test pattern. The test was passed if the transfer layer remained completely on the test sample or if the test sample itself ruptures.

FIG. 6 now shows a schematic representation of a printing machine with a film transfer module for the cold foil transfer, wherein a single sheet-processing printing machine is shown, 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 a pattern of cold glue. The cold glue is applied in a device configured as a printing station 100, e.g. B. a conventional printing unit of an offset printing press on there existing inking and dampening 110, a printing plate on a plate cylinder 120, a covered with a conventional blanket cylinder 130 and an impression cylinder 400 '. Likewise, printing units in the form of flexographic printing units or coating units can be used here.

Thereafter, together with a printing sheet, a transfer film 40 is passed through a transfer nip 60, wherein the transfer film 40 is pressed in the transfer nip 60 against the printing sheet. For this purpose, a film transfer module 200 is used which can correspond to a printing unit or a coating module or a base unit or another type of processing station of a sheetfed offset printing press. The transfer nip 60 in the film transfer module 200 is formed by a roller 300 and a counterpressure roller 400. In this case, the roller 300 can correspond to a blanket cylinder and the counterpressure roller 400 to an impression cylinder of a known offset printing unit. Furthermore, the roller 300 can correspond to a forme cylinder and the counterpressure roller 400 can correspond to an impression cylinder of a paint module of a sheet-fed printing press.

Furthermore, the film transfer module 200 downstream of a so-called calendering be provided if 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 film transfer module 200 used for the film transfer, a web guide for transfer films 40 is shown. The sheet supply roll 80 is associated with the sheet transfer module 200 on the page of the sheet feeder. The film supply roll 80 has a rotary drive 70. The rotary drive 70 is required for the continuous controlled feeding of the transfer film 40 to the film transfer module 200 and is therefore controllable.

Furthermore, in the area of the film feed and film removal guide devices 140 (see FIG. 7 ), such as deflection or tensioning rollers, pneumatically actuated conducting means, guide plates and the like provided. In this way, the transfer film 40 can be smoothly guided without distortions and held in constant tension with respect to the roller 300. The guide devices 140 may also include means for introducing the transfer film 40. In this case, automatic feeding aids for the transfer film 40 can be used.

In this case, the transfer film 40 can be guided around the roller 300, wherein the transfer film 40 can be fed and discharged advantageously from only one side of the film transfer module 200 to the transfer nip 60 (see dash-lined illustration). The transfer film 40 can deviate from the illustration here to Fig. 4 and depending on the space conditions on one side of the film transfer module 200 are advantageously performed in the feeding strand and the laxative strand closely parallel to each other.

In a further embodiment, the transfer film 40 can also be fed in and out tangentially on the roller 300 substantially tangentially or around the transfer gap 60 only in a small circumferential angle. For this purpose, the transfer film 40 is supplied from one side of the film transfer module 200 and discharged to the opposite side of the film transfer module 200.

On the outlet side of the printing unit, a film collecting roll 90 is shown. On the film collecting roll 90, the used transfer film material is rewound. Again, a rotary drive 70 is provided, which is controllable. In essence, the transfer film 40 could also be moved by the rotary drive 70 on the outlet side and kept taut on the inlet side by means of a brake.

For the transfer process of the transfer layer 41 of the transfer film 40 to a printing sheet in the transfer nip 60 between the roller 300 and the counter-pressure roller 400, it is essential that the surface of the roller 300, so the blanket cylinder or forme cylinder, is equipped with a compressible, damping element.

The roller 300 is therefore covered with a blanket 320 according to the invention. The blanket 320 is held on the roller 300 in a cylinder channel on jigs.

To improve the economy of the cold foil transfer process, it is provided that the film advance of the transfer film 40 from the film supply roll 80 to the transfer nip 60 and the film collection roll 90 is controlled so that as far as possible the transfer film 40 is stopped when no transfer of the transfer layer 41 take place For this purpose, a control of the transfer film 40 can be carried out such that when passing through grippers of the receiving cylinder channel of the sheet-guiding counter-pressure roller 400 of the film feed is stopped. The grippers hold a signature on the platen roller 400. The roller 300 has a cylinder channel corresponding thereto, in which the blanket 320 is held. In the region of the corresponding cylinder channels, there is no pressing of the transfer film 40 between the roller 300 (blanket cylinder) and the counterpressure roller 400. The roller 300 then slides on the transfer film 40 while the transfer film 40 between the roller 300 and the counterpressure roller 400 is tensioned freely is. This state continues until the cylinder channel ends at the so-called pressure beginning and the transfer film 40 is again clamped between the roller 300 and the platen roller 400 including a sheet.

Then, the transfer film 40 is further transported. The timing of the film feed can begin according to a necessary acceleration or braking of the film supply roll 80 or film collecting roll 90 a little earlier or expose, as pretend the channel edges of the cylinder channel. In response-fast timing systems via so-called dancer rollers 180, as exemplified in FIG. 5 are shown, the control of the rotary actuators 70 of the film supply rolls 80 and film collecting roll 90 may not be necessary. By means of the dancer rollers 180, the necessary transfer ribbon tension is also maintained.

A further improvement of the transfer film utilization results from the fact that the transfer film 40 is divided into one or more sub-film webs of 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 40 can be improved even in zonally different lengths coating areas within a sheet.

For this purpose, each partial film web is conveyed only exactly in the area in which the transfer layer 41 is to be applied. In the areas not to be coated, each partial film web can be shut down independently of the other partial film webs, so that no unnecessary film consumption arises.

Furthermore, in order to improve the cold foil transfer process, provision is made for drying 160 in the area of the cold adhesive application and in the area of the film application. In this way, in particular by means of UV drying, the pattern-applied cold adhesive, in particular UV adhesive, can be pre-dried by means of a first dryer 160, so that the transfer layer 41 better adheres to the transfer film 40 and the carrier film 42 (see FIG. 4 ) can be removed already before curing of the cold adhesive.

The adhesion of the impressed transfer layer 41 on a printed sheet can be improved in succession by means of a second dryer 160 by additionally accelerating the drying and curing of the cold adhesive.

The quality of the coating is controlled by means of an inspection or monitoring device 170 after the foil application. For this purpose, the inspection device 170 is directed onto a sheet-guiding surface of the film transfer module 200 after the transfer nip 60 and possibly sealed off from the dryer 160 or onto a sheet-guiding surface of a further sheet-guiding module downstream of the film transfer module 200. 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 discarded in a sorter.

According to FIG. 7 For example, the film transfer module 200 can be provided with means for conditioning the transfer film 40 in order to improve the layer transfer and the coating result. In this case, the transfer film 40 can be influenced by means of the film guide device 140.

To improve the adhesion and gloss effect, the transfer layer 41 is applied in particular by means of a UV adhesive to a printed sheet. For this purpose, a UV dryer after the printing station 100 for predrying the cold adhesive application and / or after transfer of the transfer layer 41 in the film transfer module 200, a transfer layer 41 penetrating UV dryer, for example, to the platen 400 of the film transfer plant 200 to arrange.

To increase the quality of the printed product, it is possible by means of the device described to carry out processes for applying reliefs or embossings, holograms or prefabricated image motifs, which may likewise 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 one, the film transfer module 200 downstream embossing. Here is the For example, the printed sheet is guided over a profiled surface and under pressure against a soft counter surface. Conversely, the embossing of the top, ie the coated side of the sheet, can be performed against an elastic base. The required device can be arranged in a printing unit or a coating module. There, the embossing or relief shape is arranged on a blanket or form cylinder or on the counter-pressure roller 400. The soft or elastic mating surface is arranged corresponding to the respective other cylinder of the printing unit or coating module. By means of such an embossing device, the transfer layer 41 can also be used for the transmission of special picture elements.

Depending on the type of printing press used, the following machine parameters are selected in particular when merging the printed sheet and the transfer film, with the standard values specified by the respective machine manufacturer being indicated for comparison in square brackets at the end of the line:

Manroland 700 printing machine from manroland

Contact pressure: in the range of -0.1 to 0.1; in particular 0.05 [0] Blanket (over Schmitz): in the range of 0 to 0.3; in particular 0.2 [0,1] Transfer film handling: in the range of 20 to 50%; in particular 30% [50%] Transfer ribbon take-up: in the range of 20 to 50%; in particular 30% [50%]

Printing machines of the type XL105 or CD 102 or CD 74 from Heidelberger

Contact pressure: in the range of -0.1 to 0.1; in particular 0.1 [0,3] Blanket (over Schmitz): in the range of 0 to 0.3; in particular 0.2 [0] Transfer film handling: in the range of 0.2 to 1.5; especially 1.0 [1,5] Transfer ribbon take-up: in the range of 0.2 to 1.5; especially 1.0 [1,5]

Printing machines of the company König & Bauer

Contact pressure: in the range of 0 to 0.3; in particular 0.2 [0,2] Blanket (over Schmitz): in the range of 0 to 0.2; in particular 0.05 [0] Transfer film handling: in the range of 1.5 - 4 bar; especially 2.5 bar [4,0] Transfer ribbon take-up: in the range of 1.5 - 4 bar; especially 2.5 bar [3.9]

For all types of machine, it is preferred if the permanent humidification is set to "off" in the printing unit 100 for applying the cold adhesive to a printed sheet. This means for example with regard to FIG. 6 in that the blanket on the printing cylinder 130, which transfers cold glue to a sheet, is moistened with water at the locations where there is no cold glue only when printing. Thus, a water absorption of the cold adhesive, which leads to emulsification of water and adhesive and further loss of adhesive properties, reliably avoid.

With a transfer layer 41, which by means of the inventive method, in particular by means of a device according to FIG. 1 on a substrate or a printing press according to the FIGS. 6 7 or 7 was fixed on a sheet by means of UV adhesive, an excellent, Tesa-firm adhesion of the transfer layer was achieved.

It is to be noted at this point that the figure representations represent the printing blanket and its use in cold foil transfer processes only by way of example and that there are a multiplicity of further obvious possibilities for a person skilled in the art to construct suitable blankets and cold foil transfer devices with the blanket according to the invention and / or to carry out a potassium transfer, without departing from the invention or having to act inventive.

Claims (15)

Blanket (32 ') comprising at least three layers comprising a carrier layer (32a'), a compressible layer (32b ') and a cover layer (32d'),
characterized,
in that the cover layer (32d ') is formed from polyester, polyolefin, polyvinyl, polyimide or ABS, in particular from a film of one of these materials. Blanket according to claim 1,
characterized,
that the blanket (32 ') in this order, the base sheet (32a' has), the compressible layer (32b '), an adhesive layer (32c') and the cover layer (32d '). Blanket according to one of claims 1 and 2,
characterized,
that the carrier layer (32a ') is formed from a fabric, in particular a cotton fabric. Blanket according to one of claims 1 to 3
characterized,
that the compressible layer (32b ') is formed of rubber, Blanket according to one of claims 1 to 4,
characterized,
that the blanket (32 ') has a thickness in the range of 1.8 to 2 mm, in particular of 1.95 mm. Blanket according to one of claims 1 to 5,
characterized,
that the blanket (32 ') has a hardness in the range of 50 to 85 Shore A, in particular in the range of 75 to 80 Shore A,. Blanket according to one of claims 1 to 6,
characterized,
that adhesion of the cover sheet (32d ') to a carrier foil (42) consists of polyester, polyolefin, polyvinyl, polyimide or ABS is equal to zero. Cold foil transfer method in which a substrate (51) is at least partially joined to a transfer layer (41) of a transfer film (40) by means of a cold adhesive (11), in particular a UV-crosslinking adhesive, the transfer film (40) comprising a carrier film (40). 42) and the carrier film (42) detachable transfer layer (41), and wherein the transfer film (40) and the substrate (51) by means of a roller (32) and a counter-pressure roller (31) are merged,
characterized,
in that the roller (32) is covered with a blanket (32 ') according to one of claims 1 to 8 and in that the cover layer (32d') of the blanket (32 ') faces the carrier foil (42) of the transfer foil (40) on the roller (32) is arranged. Cold foil transfer method according to claim 8,
characterized,
that the blanket (32 ') on the roller (32) in the range from 0 to 0.3 over Schmitz, in particular in the range of 0.05 to 0.2 above Schmitz, is arranged. Cold foil transfer method according to claim 8 or claim 9,
characterized,
that the cold adhesive (11) is applied in a printing station (10) to the substrate (51) and / or the transfer layer (41) of the transfer film (40) before the Transfer film (40) is brought together with the substrate (51). Cold foil transfer process according to one of claims 8 to 10,
characterized,
in that the substrate (51) is brought together with the transfer film (40) in a gap between the roller (32) and the counterpressure roller (31), wherein in the gap a pressure in the range of 0.1 to 0.3 mm, in particular in the range from 0.15 to 0.2 mm. Cold foil transfer method according to one of claims 8 to 11,
characterized,
that a transfer film (40) having a carrier film (42) is used which is formed from the same class of materials, in particular the same material as the liner (32d ') of the blanket (32'). Cold foil transfer method according to one of claims 8 to 12,
characterized,
that a transfer film (40) having a carrier film (42) made of polyester, polyolefin, polyvinyl, polyimide or ABS is used. Use of a printing blanket (32 ') according to one of claims 1 to 7 in a cold foil transfer process, wherein a roller (32) is covered by the blanket (32') and the cover layer (32d ') of the blanket (32') is covered by the roller (32 '). 32) arranged away from and brought into contact with a transfer film (40). Use according to claim 14
characterized,
in that the carrier film (42) of the transfer film (40) is formed from polyester, polyolefin, polyvinyl, polyimide or ABS.

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