EP2911889B1 - Hot stamping machine - Google Patents

Description

The invention relates to a hot embossing device according to the preamble of the subject of claim 1.

Hot embossing devices are used to transfer a transfer layer arranged on a carrier layer of a hot embossing film to a substrate under the action of temperature and pressure. For this purpose, a heated embossing roller is provided, which cooperates with a counter-pressure roller. The support layer is withdrawn downstream of an embossing gap formed between the embossing roller and the counterpressure roller by means of a release device from the transfer layer transferred to the substrate. When using a profiled embossing roll only areas, in particular according to the shape of the profiling on the embossing roller, the transfer layer transferred to the substrate, so that the drawn backing layer also has remnants of the transfer layer, in particular according to the negative shape of the profiling on the embossing roll. From the DE 10159661 C1 a hot stamping device of the type described is known.

In the space between the embossing gap and the detachment device, the transfer layer is still relatively easy to detach from the substrate, at least in the vicinity of the embossing gap, because the composite of substrate and hot stamping film still has a relatively high temperature and no contact force acts more. If the carrier foil dissolves too early, it leads to uncleanness in the embossing, especially in fine and finest structures.

Increasingly, structured transfer layers having the finest structures are used, which can be formed, for example, from a toner applied to the carrier layer in a printing process, as in US Pat EP 0191592 B1 described.

In the EP 0 433 575 A1 discloses a hot stamping device according to the preamble of claim 1, wherein the lateral surface of the impression cylinder serves as a support for the embossed substrate.

The object of the present invention is to provide a hot embossing device which avoids uncleanness in the embossing.

According to the invention, this object is achieved with the subject matter of claim 1. The invention relates to a hot embossing device with an embossing device for transferring a transfer layer arranged on a carrier layer of a hot stamping foil to a flexible substrate, comprising a heatable embossing roller and a counterpressure roller, between which an embossing gap is formed, and a downstream removal device for detaching the carrier layer from the latter the substrate transferred transfer layer, wherein it is provided that between the Embossing gap and the release device under the substrate a flat support element for the embossed substrate immediately adjacent to the embossing gap or from the embossing gap by <1 mm or the embossing gap is arranged across.

The hot embossing device according to the invention has a flat support element, which provides the coated substrate in the section, which is decisive for the quality of the embossing, between the embossing gap and the detaching device, a supporting surface on which the coated substrate rests over its entire surface. The hot stamping device may be a manufacturing station in a production line according to the roll-to-roll principle. The substrate can be processed according to the roll-to-roll principle, i. unwound from a roll endlessly, then processed and then wound up again. The substrate may also be processed in sheets, the individual sheets being fed from a stack and collected on a stack after processing. The hot stamping foil is usually processed according to the roll-to-roll principle, i. unwound from a roll endlessly, then processed and then wound up again.

It can be provided that the support element is formed from a material having a hardness in the range of 60 ° Shore A to 95 ° Shore A, preferably in the range of 80 ° Shore A to 95 ° Shore A and / or a degree of hardness in the range from 450 HV 10 (HV = Vickers hardness) to 520 HV 10, preferably in the range of 465 HV 10 to 500 HV 10. By this hardness range, the support element can be particularly advantageous as a mechanical counter-bearing for the substrate and the hot stamping foil resting thereon serve and premature detachment of the transfer layer and / or the Prevent carrier layer of the substrate, especially in particularly finely resolved structures of the applied transfer layer.

It can further be provided that the support element is a rigid element whose maximum deflection is less than 10 microns at operational load or is in the range of about 1 micron to 10 microns. By such a small deflection, the support element can be particularly advantageous as a mechanical counter-bearing for the substrate and the hot stamping foil resting thereon and prevent premature detachment of the transfer layer and / or the carrier layer of the substrate.

In an advantageous embodiment it can be provided that the support element is made of stainless steel. A support element made of stainless steel can provide in particular the aforementioned properties with respect to hard surface and low deflection and is particularly suitable as a mechanical counter bearing for the substrate and the hot stamping foil resting thereon. A further advantageous feature of a support element made of stainless steel is that due to the high thermal conductivity of stainless steel by means of the belt excess heat can be transported from the embossing gap in an advantageous manner. Particularly in the case of embossing operations that continue for a long time without interruption, it has been found that, in particular, the counterpressure roller, despite additional cooling measures, is becoming increasingly hotter and thereby the staving conditions in the embossing gap change unfavorably in a creeping manner. A supporting element made of stainless steel can now additionally dissipate heat energy from the embossing gap, whereby the embossing conditions in the embossing gap can be better adjustable and controllable.

Alternatively, it can be provided that the support element is made of copper, aluminum, of other steel or stainless steel alloys, titanium, paper, foil or fiber-reinforced material.

In an advantageous embodiment it can be provided that the support element is designed as a support plate. Since relative to a platen a relative movement between the surface of the platen and the underside of the coated substrate occurs, the surface is preferably polished, that is designed for minimal friction, the deviations of the support surface from an ideal level are negligible.

The embossing gap facing the end portion of the support plate may preferably be formed cut-shaped. Due to the blade-shaped design of the required distance <1 mm between the platen and the embossing gap can be adjusted.

In a further advantageous embodiment it can be provided that the support element is designed as a circulating belt. In this case, a relative movement between the surface of the platen and the underside of the coated substrate can be avoided when the tape is mounted on the platen roller. Also in this training, it has been proven that the surface is polished, that is, the deviations of the support surface of an ideal level are negligible.

It can be provided that the band is formed as a seamless band. A seamless tape with no joints provides the same mechanical properties over its entire surface Counter bearing for the substrate and the hot stamping foil resting thereon. According to these thus advantageously constant mechanical properties of the remaining embossing parameters can be adjusted according to accurate and constant.

It can further be provided that the seamless strip has a thickness in the range of 0.2 mm to 0.5 mm, preferably in the range of 0.3 mm to 0.35 mm. A strip of this thickness or strength can in particular provide the abovementioned properties with respect to a hard surface and low deflection, and is particularly suitable as a mechanical abutment for the substrate and the hot stamping foil resting thereon.

In a further embodiment it can be provided that the band is formed as a link belt of plate-shaped members, adjacent members are connected by a hinge so that they form a gap-free, in particular substantially homogeneous support surface in the stretched state. The link belt may have edge-side transport recesses and the guide roller may have corresponding sprockets which engage in the transport recesses.

The embossing roller may have a coating of an elastomer having a thickness in the range of 3 to 10 mm, preferably in the range of 5 mm to 10 mm. When forming an embossing the surface of the coating is deformed so that instead of a line-shaped embossing gap, a sheet-shaped embossing gap is formed. The embossing gap may for example have a width of 5 mm to 20 mm. It has proven useful to set an embossing gap with a width of 5 mm of 10 mm. Of the associated embossing pressure may for example be in the range of 1 bar to 6 bar. It has been proven to choose the embossing pressure in the range of 3 bar to 6 bar.

The elastomer may preferably be silicone rubber.

It can be provided that the coating has a hardness in the range of 60 ° Shore A to 95 ° Shore A, preferably in the range of 70 ° Shore A to 90 ° Shore A.

In a further embodiment it can be provided that the support element is designed as the end face of a sonotrode of an ultrasound bearing device. The ultrasonic bearing device comprises the sonotrode and an ultrasound transducer. Between the sonotrode and the underside of the embossed substrate, an air film is formed by the action of the ultrasound, on which the embossed substrate slides. In the thus constructed bearing gap, a pressure between the end face of the sonotrode and the underside of the embossed substrate is constructed, which is sensitive as well as the thickness of the air film adjustable. It is also possible to form the end face of the sonotrode with suction openings, which are connected via channels with a vacuum pump to suck the substrate against the pressure in the bearing gap and thus make the bearing gap even more precisely adjustable with the equilibrium pressure.

For heating the embossing roller, a heating device arranged outside the embossing roll can be provided. Preferably, an infrared radiation heater can be provided with temperature controller. The embossing temperature may be in the range of 100 ° C to 250 ° C, preferably in the range of 130 ° C to 190 ° C.

It can also be provided within the embossing roll arranged heating device. Such a heating device within the embossing roller can be, for example, an electrical heating element, in particular a heating coil or heating coil. Likewise, a tempered oil circuit can be arranged within the embossing roller, which heats the embossing roller to a desired temperature.

Fig. 1

ein erstes Ausführungsbeispiel der erfindungsgemäßen Heißprägevorrichtung in schematischer Darstellung;

Fig. 2

ein zweites Ausführungsbeispiel der erfindungsgemäßen Heißprägevorrichtung in schematischer Darstellung;

Fig. 3

ein drittes Ausführungsbeispiel der erfindungsgemäßen Heißprägevorrichtung in schematischer Darstellung;

Fig. 4

ein viertes Ausführungsbeispiel der erfindungsgemäßen Heißprägevorrichtung in schematischer Darstellung;

Fig. 5

ein fünftes Ausführungsbeispiel der erfindungsgemäßen Heißprägevorrichtung in schematischer Darstellung;

Fig. 6

eine alternative Heißprägevorrichtung in schematischer Darstellung.

The invention will now be explained in more detail with reference to exemplary embodiments. Show it

Fig. 1

a first embodiment of the hot stamping device according to the invention in a schematic representation;

Fig. 2

a second embodiment of the hot stamping device according to the invention in a schematic representation;

Fig. 3

a third embodiment of the hot stamping device according to the invention in a schematic representation;

Fig. 4

a fourth embodiment of the hot stamping device according to the invention in a schematic representation;

Fig. 5

a fifth embodiment of the hot stamping device according to the invention in a schematic representation;

Fig. 6

an alternative hot stamping device in a schematic representation.

Fig. 1 1 shows a hot embossing device 1 with an embossing device 2 and a detaching device 3. The embossing device 2 comprises an embossing roll 11, a counterpressure roll 12 and a heating device 13.

The embossing roller 11 has on its outer periphery a coating 11 b of an elastomer having a thickness in the range of 3 to 10 mm, preferably in the range of 5 to 10 mm. The elastomer is preferably silicone rubber. In the in Fig. 1 illustrated embodiment, the silicone rubber has a hardness of 80 ° Shore A. The counter-pressure roller 12 is made of steel.

The heater 13 is disposed above the emboss roller 11 and in the in Fig. 1 illustrated embodiment as a regulated by means of a temperature controller infrared radiation heating.

Upstream of the embossing device 2, a substrate 14 to be embossed and a hot stamping film 15 are fed, which are joined together in an embossing gap 16 formed between the embossing roller 11 and the counterpressure roller 12 to form an embossing pressure.

The hot stamping foil 15 has a transfer layer 15u arranged on a carrier layer 15t. The carrier layer 15t may be made of PET, for example, or of polypropylene, polystyrene, PVC, PMMA, ABS, polyamide. The hot stamping foil 15 is arranged so that the transfer layer 15u faces the upper side of the substrate 14 to be embossed. The transfer layer 15u may be coated with a heat-activatable adhesive layer or may be self-adhesive (cold adhesive). Between the transfer layer 15u and the carrier layer 15t may be a release layer be arranged, which facilitates the detachment of the transfer layer 15u of the carrier layer 15t.

The transfer layer of the hot stamping foil generally has several layers, in particular a release layer (for example of wax or wax-containing compounds), a protective lacquer layer, a heat-activatable adhesive layer. In addition, one or more, surface partially or fully applied, decorative layers and / or functional layers may be included. Decorative layers are, for example, colored (opaque or transparent or translucent) lacquer layers, metal layers or relief structures (haptic or optical refractive or optically diffractive effect). Functional layers are, for example, electrically conductive layers (metal, ITO (ITO = Indium Tin Oxide)), electrically semiconductive layers (for example semiconductor polymers) or electrically non-conductive layers (electrically insulating lacquer layers) or optically matting or anti-reflective layers (for example with microscopic matte structures ) or the adhesion and / or the surface tension modifying structures (lotus effect structures or the like). Between the individual layers, additional auxiliary layers, in particular adhesion promoter layers, may be present. The individual layers of the transfer layer are approximately between 1 nm and 50 microns thick.

The substrate 14 to be embossed is a flexible substrate, for example paper having a basis weight of 30 g / m ² to 350 g / m ² , preferably 80 g / m ² to 350 g / m ² , cardboard, plastic or a hybrid material or a laminate ,

By transferring the transfer layer 15u onto the substrate 14, an embossed substrate 17 is formed, which is still connected to the carrier layer 15t.

The width of the embossing gap 16 is essentially determined by the embossing pressure and by the local deformation of the coating 11 b of the embossing roller 11 occurring under the embossing pressure. The embossing gap 16 has a width of 5 to 20 mm, preferably a width of 5 by 10 mm. In the embossing gap 16, an embossing pressure of 1 bar to 6 bar is generated, preferably an embossing pressure of 3 bar to 6 bar generated. The embossing temperature may be in the range of 100 ° C to 250 ° C, preferably in the range of 130 ° C to 190 ° C. The transfer layer 15u is transferred to the substrate 14 at a speed of up to 75 m / min. The values to be set for pressure, temperature and speed depend on numerous parameters, such as the material properties of the hot stamping foil used, the embossing decor and the material properties of the substrate. Because of the multiple dependencies, a mathematical modeling is so complex that the o. G. Values starting from a basic setting of the hot embossing device 1 are preferably determined by tests.

The carrier layer 15t is detached from the embossed substrate 17 in the detachment device 3 arranged downstream of the embossing device 2. The detaching device 3 can be designed, for example, as a bar with a detaching edge, which is arranged above the embossed substrate 17 connected to the carrier layer 15t. The carrier layer 15t is pulled over the release edge and fed to a take-up reel, not shown.

Between the embossing gap 16 and the detachment device 3 is below the embossed substrate 17 a rigid flat support plate 18 with a distance from the embossing gap of <1 mm arranged so that the embossed substrate 16 emerging from the embossed substrate 17 rests on the support plate 18 over its entire surface. The embossing gap 16 facing the end portion of the support plate 18 is cut-shaped, so that between the embossing gap 16 facing end edge of the support plate 18 and the embossing gap 16, a distance of <1 mm is adjustable. The support plate 18 is preferably made of stainless steel, as a plywood board, or a plastic plate with appropriate surface treatment (- coated). The coated substrate 17 facing top of the support plate 18 is preferably formed with a polished surface, that is, with a mean roughness depth <0.1 microns.

In the in the Fig. 1 to 6 Embodiments shown are transport devices and supply and take-up rolls for the substrate 14, 17 and the hot stamping film 15 and the carrier layer 15t not shown. It can be provided that the hot stamping device 1 is a production station in a production plant according to the roll-to-roll principle.

Fig. 2 shows a hot stamping device 1, which, like the in Fig. 1 described hot stamping device is formed, with the difference that a seamless belt 19 is provided as a rigid flat support element between the embossing gap 16 and the detachment device 3. The seamless band 19 forms a stamping gap 16 cross-rigid bearing device. The seamless belt 19 is guided on the platen roller 12 and a guide roller 20, wherein the bearing distance of the platen roller 12 and a guide roller 20 is set so that the belt 19 with such a tensile force is loaded, that it forms a rigid flat support surface for the coated substrate 17.

In a preferred embodiment, the band 19 is made of stainless steel. It can also be provided a material other than stainless steel, for example silicone, coated rubber, paper, foil or fiber-reinforced material. It is essential that the strip material in a stainless steel strip a degree of hardness in the range of 450 HV 10 to 520 HV 10, preferably in the range of 465 HV 10 to 500 HV 10 (HV = Vickers hardness), and silicone or coated rubber a degree of hardness in the range from 60 ° Shore A to 95 ° Shore A, preferably in the range of 80 ° Shore A to 95 ° Shore A.

The aforementioned stainless steel strip is formed with a thickness in the range of 0.2 mm to 0.5 mm, preferably in the range of 0.3 mm to 0.35 mm.

It has proved to be advantageous in the band 19 formed of stainless steel that it prevents overheating in the embossing gap 16, because it dissipates excess heat from the embossing gap because of its good heat conduction.

In a case example, for example, the following embossing parameters have been set: Temperature at the surface of the embossing roller 11: 150 - 155 ° C Temperature control setting: 160 ° C Embossing: 4 bar Feed speed: 15 m / min Material of the hot stamping foil: SHORT Digital Metal DT- H Silver Toner: HP Indigo Electrolnk black Material of the substrate: Digital Silver print material 200 g / m ² Sheet Size: 500 x 320 mm

Fig. 3 shows a hot stamping device 1, which, like the in Fig. 2 described hot stamping device is formed, with the difference that instead of the seamless belt 19, a link belt 21 is provided from plate-shaped members 21g, wherein adjacent members 21g are connected by a hinge so that they form a gap-free planar support surface in the stretched state.

The link belt 21 may have peripheral transport recesses and the guide roller 20 may have corresponding sprockets, which engage in the transport recesses.

Fig. 4 shows a hot stamping device 1, which, like the in Fig. 2 described hot stamping device is formed, with the difference that a further guide roller 20 is provided, and that the counter-pressure roller 12 only fulfills the function to apply the counter-pressure for the embossing. In the in Fig. 4 illustrated embodiment, the platen 12 thus has a smaller diameter than the two guide rollers 20.

Fig. 5 shows a hot stamping device 1, which, like the in Fig. 1 described hot stamping device is formed, with the difference that as a rigid flat support element between the embossing gap 16 and the detaching device 3, an ultrasonic bearing device 22 is provided. The Ultrasonic storage device comprises a sonotrode 22s and an ultrasonic transducer 22w. Between the sonotrode 22s and the underside of the embossed substrate 17, an air film of constant thickness is formed by the action of ultrasound, on which the embossed substrate 17 rests and slides. In the thus constructed bearing gap, a pressure between the end face of the sonotrode 22s and the underside of the embossed substrate 17 is constructed, which is sensitive as well as the thickness of the bearing gap adjustable. It is also possible to form the end face of the sonotrode 22s with suction openings, which are connected via channels with a vacuum pump to suck the substrate 17 against the bearing gap pressure and thus make the bearing gap even more precisely adjustable with the equilibrium pressure.

Fig. 6 shows an alternative, not belonging to the invention, hot embossing device 1, which, like the in Fig. 5 described hot stamping device is formed, with the difference that instead of the counter-pressure roller, a second ultrasonic bearing device 23 is provided which comprises a sonotrode 23s and an ultrasonic transducer 23w. It may also be provided only an ultrasonic bearing device whose sonotrode has a width which is equal to the sum of the widths of the sonotrodes 22s and 23s.

LIST OF REFERENCE NUMBERS

1

Hot stamping device

2

embosser

3

detachment device

11

embossing roller

11b

coating

12

Backing roll

13

heater

14

to be embossed substrate

15

Hot stamping foil

15t

backing

15u

transfer layer

16

embossing gap

17

embossed substrate

18

platen

19

seamless band

20

deflecting

21

link belt

21g

plate-shaped member

22

Ultrasonic storage facility

22s

sonotrode

22w

ultrasound transducer

23

second ultrasonic bearing device

23s

sonotrode

23w

ultrasound transducer

Claims (15)

1. Hot stamping device (1) having a stamping device (2) for transferring a transfer layer (15u) arranged on a carrier layer (15t) of a hot stamping film (15) to a flexible substrate (14), comprising a heatable stamping roller (11) and a counter-pressure roller (12), between which a stamping gap (16) is formed, as well as a detachment device (3) arranged downstream for the detachment of the carrier layer (15t) from the transfer layer (15u) transferred to the substrate (14),
   characterised in that
   a flat support element (18, 19, 21, 22s) for the stamped substrate (17) is arranged between the stamping gap (16) and the detachment device (3) beneath the stamped substrate (17), directly adjoining the stamping gap (16) or at a distance of < 1mm from the stamping gap (16) or overlapping the stamping gap (16).
2. Hot stamping device according to claim 1,
   characterised in that
   the support element (18, 19, 21, 22s) is formed from a material which has a degree of hardness ranging from 60° to 95° Shore A, preferably ranging from 80° to 95° Shore A, and/or a degree of hardness ranging from 450 HV 10 to 520 HV 10, preferably ranging from 465 HV 10 to 500 HV 10.
3. Hot stamping device according to claim 1 or 2,
   characterised in that
   the support element (18, 19, 21, 22s) is a rigid element whose maximum sag under operational stress is less than 10µm.
4. Hot stamping device according to claim 2 or 3,
   characterised in that
   the support element (18, 19, 21, 22s) is formed from stainless steel.
5. Hot stamping device according to claim 2 or 3,
   characterised in that
   the support element (18, 19, 21) is formed from silicon, coated rubber, paper, foil or fibre-reinforced material.
6. Hot stamping device according to one of claims 1 to 5,
   characterised in that
   the support element is formed as a support plate (18).
7. Hot stamping device according to claim 6,
   characterised in that
   the end section of the support plate (18) facing towards the stamping gap (16) is formed to be blade-like.
8. Hot stamping device according to one of claims 1 to 5,
   characterised in that
   the support element is formed as a circulating belt (19, 21).
9. Hot stamping device according to claim 8,
   characterised in that
   the belt is formed as a seamless belt (19).
10. Hot stamping device according to claim 9,
    characterised in that
    the seamless belt (19) has a thickness ranging from 0.2mm to 0.5mm, preferably ranging from 0.3mm to 0.35mm.
11. Hot stamping device according to claim 8,
    characterised in that
    the belt is formed as a link belt (21) made from plate-shaped links (21g), wherein adjacent links (21 g) are connected to each other by a swivel joint in such a way that they form a gap-free support surface in the stretched state.
12. Hot stamping device according to one of claims 1 to 11,
    characterised in that
    the stamping roller (11) has a coating (11b) made from an elastomer having a thickness ranging from 3mm to 10mm, preferably ranging from 5mm to 10mm.
13. Hot stamping device according to claim 12,
    characterised in that
    the elastomer is silicone rubber.
14. Hot stamping device according to claim 12 or 13,
    characterised in that
    the coating (11b) has a degree of hardness ranging from 60° to 95° Shore A, preferably ranging from 70° to 90° Shore A.
15. Hot stamping device according to claim 1,
    characterised in that
    the support element is formed as the front face of a sonotrode (22s) of an ultrasound air bearing device (22).

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