Patent Grant
11155427
This application claims priority based on an International Application filed under the Patent Cooperation Treaty, PCT/EP2017/058291, filed Apr. 6, 2017, which claims priority to DE102016109044.1, filed May 17, 2016.
The invention relates to a device for the surface treatment of a substrate according to the preamble relating to the subject-matter of claim 1.
Devices for the surface treatment of a substrate are used, for example, to print on the surfaces of curved or web-type substrates or to coat them with a transfer layer of a stamping film.
A hot-stamping device of the type described is known from DE 10159661 C1.
The object of the present invention is to specify an improved device for the surface treatment of a substrate.
According to the invention this object is achieved with the subject-matter of claim 1. A device for the surface treatment of a substrate, having a transport device, a vacuum suction device, a corona device and a coating device is proposed, wherein it is provided that the transport device has a conveyor belt, that the conveyor belt is formed as a vacuum suction belt of the vacuum suction device, and that the conveyor belt is formed as a counter electrode of the corona device.
The device according to the invention has the advantage that the transport device has a conveyor belt which fulfills three functions, namely the transport of the substrate, the positional fixing of the substrate on the conveyor belt by vacuum suction and the provision of an electrode for the corona device. The conveyor belt can fulfill these three functions in particular simultaneously, with the result that a very advantageous synergy between these functions arises.
It can be provided that the conveyor belt is mounted on two guide rollers spaced apart from each other, wherein one of the guide rollers is formed as a drive roller.
The conveyor belt can be formed as a rotating belt which rotates in particular around the two guide rollers.
Further it can be provided that the conveyor belt is mounted on a supporting device in the area of the coating device and/or of the corona device. Several supporting devices can be provided, which are arranged, for example, in the area of the coating device and of the corona device.
The supporting device can have one supporting roller or several supporting rollers which are arranged next to each other in the longitudinal direction of the conveyor belt. The supporting rollers can in particular rotate at the same speed as the supported conveyor belt is moving, with the result that as little friction as possible arises between the supporting rollers and the conveyor belt. This means that the supporting rollers have the same speed at their circumference as the supported conveyor belt.
The supporting device can alternatively or additionally have an in particular fixed support body, preferably in the form of a plate.
The conveyor belt can have a thickness in the range of from 0.2 mm to 1 mm, preferably in the range of from 0.3 mm to 0.5 mm.
It can be provided that the conveyor belt is formed from a material which has a degree of hardness in the range of from 450 HV10 to 520 HV10, preferably in the range of from 465 HV10 to 500 HV10.
In an advantageous embodiment, it can be provided that the conveyor belt is formed and/or mounted such that its maximum deflection under normal operating load lies in the range of from 1 μm to 10 μm.
Further it can be provided that the surface of the conveyor belt facing the substrate is polished, i.e. has a surface roughness of less than 0.3 μm.
The conveyor belt can be formed from a steel alloy.
In an advantageous embodiment, it can be provided that the conveyor belt is formed from stainless steel.
Alternatively, it can be provided that the conveyor belt is formed from copper or aluminum or titanium or from an alloy which contains copper and/or aluminum and/or titanium, in particular from an alloy which contains aluminum and/or titanium.
The conveyor belt can be formed as a seamless belt. A seamless conveyor belt without joints provides the same conditions over its whole surface with respect to the property as mechanical counter surface for the substrate.
The conveyor belt can have several partial conveyor belts which are arranged connected to each other in the transport direction, preferably with the smallest possible distance between the partial conveyor belts. These partial conveyor belts can have the same or also different properties, in particular with respect to material and/or hardness and/or thickness and/or bending stiffness. The properties described above for the conveyor belt also apply to the partial conveyor belts.
For example, a first partial conveyor belt can be arranged in the area of the coating device and a second partial conveyor belt can be arranged in the area of the corona device.
In an advantageous embodiment, it can be provided that, between adjacent partial conveyor belts, a supporting element is arranged which bridges the distance between the adjacent partial conveyor belts without leaving a gap.
Alternatively, it can be provided that the conveyor belt is formed as a link conveyor composed of plate-type links, wherein adjacent links are connected to each other by a pivot joint such that they form a gap-free supporting surface in the extended state.
It can be provided that the conveyor belt has transport recesses at the edge, and that the guide rollers have corresponding toothed rims which engage in the transport recesses.
Further it can be provided that the conveyor belt has through-holes, in particular a plurality of through-holes.
The through-holes can be formed as in particular circular drilled holes and/or in particular elliptical elongated holes and/or slits and/or rhombuses.
Further it can be provided that the through-holes are arranged in a grid.
The grid can be formed regular or irregular or random.
It can also be provided that the grid is formed differently in areas.
The through-holes can have a diameter in the range of from 0.2 mm to 5 mm, preferably in a range of from 0.3 mm to 2 mm or can have a surface area corresponding to a circular hole of above-named diameter, in particular when the through-hole is not formed circular.
It can be provided that a sealing element with a circumferential sealing lip is arranged between the side of the conveyor belt facing away from the substrate and a suction head of the vacuum suction device.
In an advantageous embodiment, it can be provided that the vacuum of the vacuum suction device lies in the range of from 0.1 bar to 1 bar, in particular in the range of from 0.1 bar to 0.75 bar.
It can be provided that the corona device has a housing that is open on its underside, in the lower end portion of which an electrode is arranged. The electrode can be formed, for example, as an air-cooled ceramic electrode, and can have a cross-section of 16 mm×16 mm and a length which corresponds to the width of the conveyor belt. The corona device can be arranged with its longitudinal side transverse to the transport direction of the conveyor belt and above the substrate.
It can be provided that the electrode of the corona device forms the cathode and the conveyor belt as counter electrode forms the anode of the corona device, wherein a corona gap is formed between the cathode and the anode. The corona gap can lie, for example, in the range of from 1 mm to 2 mm.
A high electrical voltage is applied to the electrode and the counter electrode, which is generated by a high-frequency generator with a frequency range of from 10 kHz to 60 kHz and develops a field strength of from 20 kV/cm to 30 kV/cm in the air gap. Ions are formed by field ionization and are accelerated in the electric field and attach themselves to the surface of the substrate.
The polar fraction of the surface tension of the substrate can be increased through the formation of polar functional groups. The surface of the substrate is electrically charged; the surface energy of the substrate is increased. For good wetting of the substrate with a liquid, thus e.g. a UV adhesive or a printing ink, the surface tension of the substrate should be approx. 10 mN/m to 15 mN/m higher than the surface tension of the liquid. For example, the surface tension of an ink can be between 20 mN/m and 25 mN/m and the surface tension of a film-type substrate to be printed on can be between 30 mN/m and 35 mN/m. The surface tension of the substrate can be increased to approx. 40 mN/m to 45 mN/m by means of the corona device, whereby this substrate can be printed on.
The corona gap can be formed adjustable. For example, the electrode of the corona device can be formed height-adjustable. A corona gap which is as small as possible can thereby be adjustable, for example depending on the thickness and/or on the material of the substrate, in order to be able to adapt the electric field surrounding and/or penetrating the substrate.
The corona device can have an extraction device for the removal of ozone by suction, connected in a gas-tight manner to the housing. Ozone, which must be removed by suction or destroyed, is generated by the ionization of the air in the corona gap. The ozone-containing extracted air is conducted via an extracted-air tube and discharged outside the production space. The ozone-containing extracted air can optionally be guided through an ozone destroyer, for example an activated carbon filter, before being discharged into the environment. In this way 99.5% of the ozone can be destroyed. The extracted-air tube can have, for example, a length of from 12 m to 15 m. An extraction rate of 4.9 m3/min has proven successful. The extraction device can at the same time form a cooling device for the electrode.
It can be provided that the coating device is formed as a printing device. The printing device can have, for example, a printing roller and an inking device and/or can operate according to the screen printing principle and/or according to the inkjet principle.
It can also be provided that the coating device has a stamping device for transferring a transfer layer arranged on a carrier layer of a transfer film, in particular a hot-stamping film or cold-stamping film, onto the substrate.
A stamping roller of the stamping device can have on its outer circumference a coating of an elastomer with a thickness in the range of from 3 mm to 10 mm, preferably in the range of from 5 mm to 10 mm. The elastomer is preferably silicone rubber. The silicone rubber preferably has a hardness in the range of from 60° Shore A to 95° Shore A, preferably in the range of from 70° Shore A to 90° Shore A. A supporting roller arranged in the area of the stamping device forms an impression cylinder for the stamping roller.
The coating device can preferably be arranged downstream, after the corona device. The coating of the substrate can thereby be effected after the treatment of the substrate surface by means of the corona device.
Downstream, after the corona device, several coating stations can also be arranged downstream one after another, for example several printing devices and/or several stamping device and/or a printing device and a stamping device or other combinations thereof. The printing devices can each operate according to the same printing method and/or according to different printing methods. The stamping devices can each operate according to the same method and/or according to different methods.
Downstream, after the corona device and preferably after the at least one coating device, it is also possible to arrange further processing stations such as sorting stations, punching stations, blind-embossing stations, folding stations or other processing stations for the processing of the substrate.
The transfer film has a transfer layer arranged on a carrier layer. The carrier layer can be made of e.g. PET or polypropylene, polystyrene, PVC, PMMA, ABS, polyamide. The hot-stamping film is arranged such that the transfer layer is facing the upper side of the substrate to be stamped. The transfer layer can be coated with a heat-activatable adhesive layer or can be formed self-adhesive (cold adhesive). A separating layer which facilitates the detachment of the transfer layer from the carrier layer can be arranged between the transfer layer and the carrier layer.
In general, the transfer layer of the transfer film has several layers, in particular a detachment layer (for example made of wax or wax-containing compounds), a protective varnish layer, a heat-activatable adhesive layer. One or more decoration layers and/or functional layers, applied over part of the surface or over the whole surface, can additionally be included. Decoration layers are, for example, colored (opaque or transparent or translucent) varnish layers, metal layers or relief structures (with a haptic or optically refractive or optically diffractive effect). Functional layers are, for example, electrically conductive layers (metal, ITO (ITO=indium tin oxide)), electrically semiconductive layers (e.g. semiconductor polymers) or electrically non-conductive layers (electrically insulating varnish layers) or optically matting or anti-reflective layers (e.g. with microscopic matte structures) or structures that modify the adhesive action and/or the surface tension (lotus effect structures or similar). Additional auxiliary layers, in particular adhesion promoter layers, can be present between the individual layers. The individual layers of the transfer ply are approximately between 1 nm and 50 μm thick.
The substrate is preferably a flexible substrate, for example paper with a weight per unit area of from 30 g/m2 to 350 g/m2, preferably 80 g/m2 to 350 g/m2, or cardboard or plastic or a hybrid material made of several paper and plastic layers or a laminate made of several paper and/or plastic layers.
The invention is now explained in more detail with reference to embodiment examples. There are shown in:
The transport device 3 is formed as a rotating conveyor belt 31, which is mounted on two guide rollers 32 spaced apart from each other, wherein one of the guide rollers 32 is formed as a drive roller 32a. The conveyor belt 31 is formed as a seamless belt made of stainless steel in the embodiment shown in
It can also be provided that the conveyor belt 31 is formed as a link conveyor composed of plate-type links, wherein adjacent links are connected to each other by a pivot joint such that they form a gap-free supporting surface in the extended state. In this embodiment, not represented in the figures, the conveyor belt 31 can advantageously have transport recesses at the edge which interact with corresponding toothed rims, which are connected to the guide rollers 32 in a torsionally rigid manner.
The conveyor belt 31 rotates in a transport direction 31t. The substrate 2 is arranged on the conveyor belt 31 in a transport section of the conveyor belt 31 and is fixed on the conveyor belt 31 by a vacuum. The substrate 2 is moved, corresponding to the transport direction 31t of the conveyor belt 31, in a transport direction 2t which corresponds to the transport direction 31 in the transport section.
The conveyor belt 31 is mounted on a supporting device 7 in the area of the corona device 5 and in the area of the coating device 6. The coating device 6 is arranged downstream, after the corona device 5.
In the embodiment example represented in
The supporting device 7 arranged underneath the coating device 6 has a supporting roller 71, the axis of rotation of which is likewise aligned transverse to the transport direction 31t of the conveyor belt 31.
In the embodiment example represented in
The conveyor belt 31 has a thickness in the range of from 0.2 mm to 1 mm, preferably in the range of from 0.3 mm to 0.5 mm.
The conveyor belt 31 is formed from a material which has a degree of hardness in the range of from 450 HV10 to 520 HV10, preferably in the range of from 465 HV10 to 500 HV10.
The conveyor belt 31 can be formed from a steel alloy, preferably from stainless steel. It can also be provided the conveyor belt is formed from copper, aluminum or titanium.
The surface of the conveyor belt facing the substrate 2 is polished, i.e. it has a surface roughness of less than 0.3 μm.
The conveyor belt 31 is formed as a vacuum suction belt 31v with through-holes 31d (see
The through-holes 31 can be formed as in particular circular drilled holes and/or in particular elliptical elongated holes and/or slits and/or rhombuses.
Via a sealing element 42 arranged on the side of the conveyor belt 31 facing away from the substrate 2, a section of the conveyor belt 31 arranged above the sealing element 42 is connected to a suction head 41 of the vacuum suction device 4 in a gas-tight or almost gas-tight manner. The sealing element 42 is formed as a circumferential sealing lip. In the embodiment example represented in
In the embodiment example represented in
As the embodiment examples described above show, the grid can be formed regular or irregular or random.
The corona device 5 has a housing 51 that is open on the underside, in which an electrode 52 is arranged. The electrode 52 is formed as an air-cooled ceramic electrode and arranged above the substrate 2. The conveyor belt 31 forms a counter electrode 31e, which is in particular earthed. In the embodiment example represented in
A high electrical voltage is applied to the electrode 52 and the counter electrode 31e, which is generated by a high-frequency generator 54 with a frequency range of from 10 kHz to 60 kHz and develops a field strength of from 20 kV/cm to 30 kV/cm in the air gap 5l. Ions are formed by field ionization and are accelerated in the electric field and attach themselves to the surface of the substrate 2.
The polar fraction of the surface tension of the substrate 2 can be increased through the formation of polar functional groups. The surface of the substrate 2 is electrically charged; the surface energy of the substrate 2 is increased. For good wetting of the substrate 2 with a liquid, thus e.g. a UV adhesive or a printing ink, the surface tension of the substrate 2 should be approx. 10 mN/m to 15 mN/m higher than the surface tension of the liquid. For example, the surface tension of an ink can be between 20 mN/m and 25 mN/m and the surface tension of a film-type substrate 2 to be printed on can be between 30 mN/m and 35 mN/m. The surface tension of the substrate 2 can be increased to approx. 40 mN/m to 45 mN/m by means of the corona device 5, whereby this substrate 2 can be printed on.
The corona device 5 has an extraction device 53 for the removal of ozone by suction, connected in a gas-tight manner to the housing 51. Ozone, which must be removed by suction or destroyed, is generated by the ionization of the air in the air gap 5l. The ozone-containing extracted air is conducted via an extracted-air tube and discharged outside the production space. The ozone-containing extracted air can optionally be guided through an ozone destroyer, for example an activated carbon filter, before being discharged into the environment. In this way 99.5% of the ozone can be destroyed. The extracted-air tube can have, for example, a length of from 12 to 15 m. An extraction rate of 4.9 m3/min has proven successful. The extraction device 53 at the same time forms a cooling device for the electrode 52.
The coating device 6 is formed as a stamping device 65 for transferring a transfer layer arranged on a carrier layer of a transfer film 66, in particular a hot-stamping film or cold-stamping film, onto the substrate 2.
A stamping roller 67 of the stamping device 65 has on its outer circumference a coating of an elastomer with a thickness in the range of from 3 mm to 10 mm, preferably in the range of from 5 mm to 10 mm. The elastomer is preferably silicone rubber. In the embodiment example represented in
In the embodiment example represented in
The device 1 represented in
| Number | Date | Country | Kind |
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|---|---|---|---|
| PCT/EP2017/058291 | 4/6/2017 | WO | 00 |
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|---|---|---|---|
| WO2017/198390 | 11/23/2017 | WO | A |
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