Device and method for high-frequency corona pretreatment of substrate surfaces

Abstract

The invention relates to a device and a method for the high-frequency (HF) corona treatment of substrate surfaces using a comb electrode, and the use of a comb electrode for the HF corona pretreatment of substrate surfaces of substrates having a thickness of at least 2.5 mm.

Description

[0001] DESCRIPTION

[0002] Device and method for high-frequency corona pretreatment of substrate surfaces

[0003] The present invention relates to a device and a method for high-frequency (HF) corona treatment of substrate surfaces using a comb electrode, as well as the use of a comb electrode for HF corona pretreatment of substrate surfaces of substrates with a thickness of at least 2.5 mm.

[0004] A common problem when bonding and printing on metals, ceramics, glass, and plastics is that the surfaces of many materials have poor wettability. This poor wettability is due to the material-dependent specific surface tension, which is expressed in mN / m or dyn / cm. Plastics typically have a relatively low surface tension, significantly less than 50 mN / m. To ensure that adhesives, paints, varnishes, or inks don't simply bead up on a surface but instead wet it effectively, it's necessary to increase the surface tension and, consequently, the wettability of the materials with liquids and the adhesion of the liquids to the materials. Without surface pretreatment, liquids would either not adhere to the surface at all or would delaminate after some time.In addition to the classic chemical pretreatment of surfaces with primers (adhesion promoters), physical methods, such as gas flame treatment, or electrochemical methods, such as plasma or corona treatment of the metal or plastic surfaces in question, are often used for this purpose. However, gas flame or plasma treatment is unsuitable for numerous temperature-sensitive materials because the treatment causes heating and damage to the substrates. This problem does not exist with corona treatment, which is why this method is particularly suitable for pretreating the surfaces of plastics and foams.

[0005] Corona surface pretreatment utilizes corona discharges, which are discharges occurring on high-voltage conductors. A high-voltage electrode is positioned close to the surface of the material to be treated, with a grounded counter electrode snugly attached to its rear. A discharge zone forms in the narrow air gap between the electrodes. Within this zone, the corona discharge ionizes gases and generates a high concentration of various activated species, such as ozone. These activated species then react with the surface of the substrate located within the discharge zone.Although the exact mechanism is not yet fully understood, it is assumed that polar functional groups are formed on the surface of the materials, resulting, among other things, from oxidation processes, and that radical cleavage and cross-linking of polymer chains occurs in the surface layer of the substrates. The associated local increase in surface polarity improves the wettability and adhesive properties of the surface. Since the air gap between the electrodes is typically only 1–2 mm, the main application of corona discharge is currently in the pretreatment of relatively flat surfaces and thin substrates, such as those found in packaging films and labels, as well as cups and tubes. In principle, both conductive and non-conductive substrates can be treated with this method.

[0006] A disadvantage of conventional corona treatment methods is the risk that an uneven distribution of the electrical discharge can lead to a so-called "breakthrough" of the discharge through the film, potentially causing burn holes. Another problem is that conventional corona treatment devices are equipped with a continuous, wire-like, high-voltage electrode that is either guided over the surface to be treated or the surface of the substrate is guided past it. These devices can be used to treat substrates with thin walls, such as films or thin containers. However, substrates with thicker walls exceeding 2.5 mm cannot be treated, or not satisfactorily, with these known devices.

[0007] The present invention is therefore based on the objective of overcoming the disadvantages of the previously known devices and methods for pretreating substrate surfaces and in particular of creating a device and a method for high-frequency (HF) corona treatment of substrate surfaces of thick-walled non-conductive substrates.

[0008] The technical problem underlying the invention is solved by the subject matter of the independent claims.The present invention relates in particular to a device for high-frequency (HF) corona treatment of substrate surfaces, comprising: i) at least one high-voltage generator for generating a high-frequency voltage with a voltage of at least 3 kV and a frequency of 30 to 90 kHz, preferably 60 to 70 kHz, ii) at least one comb electrode with at least 6 prongs, iii) at least one grounded counter electrode, wherein a treatment area for receiving a substrate is formed between the at least one comb electrode and the at least one counter electrode, wherein a substrate arranged in the treatment area contacts the counter electrode and a gap with a width of 0.25 to 3 mm, preferably 0.5 to 1 mm, is located between a surface of the substrate to be treated and the distal ends of the prongs of the at least one comb electrode.

[0009] Within the scope of the present invention, it has been found that the use of a comb electrode instead of a continuous wire electrode allows for efficient corona pretreatment at lower voltage. Furthermore, the use of a comb electrode advantageously allows for the provision of recesses or projections across the width of the electrode, depending on the substrate to be treated.

[0010] According to the invention, the at least one high-voltage generator is at least one high-voltage generator for generating a high-frequency voltage with a voltage of at least 3 kV, preferably at least 4 kV, preferably at least 5 kV, preferably at least 6 kV, preferably at least 7 kV, preferably at least 8 kV, preferably at least 9 kV, preferably at least 10 kV.

[0011] In a preferred embodiment of the invention, the at least one high-voltage generator is at least one high-voltage generator for generating a high-frequency voltage with a voltage of at most 25 kV, preferably at most 22.5 kV, preferably at most 20 kV, preferably at most 17.5 kV, preferably at most 15 kV, preferably at most 12.5 kV, preferably at most 10 kV, preferably at most 7.5 kV, preferably at most 5 kV. At voltages above 25 kV, the effectiveness of the at least one counter electrode decreases, and free-radiating discharge increasingly occurs. Preferably, the at least one high-voltage generator is at least one high-voltage generator for generating a high-frequency voltage with a voltage of 3 to 30 kV, preferably 4 to 20 kV, preferably at least 5 to 15 kV, preferably at least 6 to 12 kV, preferably at least 7 to 10 kV.

[0012] According to the invention, the at least one high-voltage generator is at least one high-voltage generator for generating a high-frequency voltage with a frequency of 30 to 90 kHz, preferably 35 to 90 kHz, preferably 40 to 85 kHz, preferably 45 to 85 kHz, preferably 50 to 80 kHz, preferably 55 to 80 kHz, preferably 60 to 75 kHz, particularly preferably 60 to 70 kHz.

[0013] In a preferred embodiment of the present invention, the at least one high-voltage generator is a semiconductor generator.

[0014] In a preferred embodiment of the present invention, the at least one comb electrode comprises at least 8, preferably at least 10, preferably at least 12, preferably at least 14, preferably at least 16, preferably at least 18, preferably at least 20, preferably at least 22, preferably at least 24, preferably at least 26, preferably at least 28, preferably at least 30, preferably at least 32, preferably at least 34, preferably at least 36, preferably at least 38, preferably at least 40, tines.

[0015] According to the invention, it can be provided that all tines of the comb electrode have an identical length and / or an identical diameter. However, it can also be provided that the tines of the comb electrode, for example individual tines of the comb electrode, have a length and / or a diameter that differs from the length and / or diameter of the other tines of the comb electrode.

[0016] Preferably, the individual prongs of the comb electrode, preferably all prongs of the comb electrode, have a length of 1 to 3 cm, preferably 1.25 to 2.75 cm, preferably 1.5 to 2.5 cm.

[0017] According to the invention, the individual tines of the comb electrode, preferably all tines of the comb electrode, can have a length of at least 0.25 cm, preferably at least 0.5 cm, preferably at least 0.75 cm, preferably at least 1 cm, preferably at least 1.25 cm, preferably at least 1.5 cm. In a preferred embodiment of the present invention, the individual tines of the comb electrode, preferably all tines of the comb electrode, have a length of at most 5 cm, preferably at most 4.5 cm, preferably at most 4 cm, preferably at most 3.5 cm, preferably at most 3 cm, preferably at most 2.5 cm, preferably at most 2 cm, preferably at most 1.5 cm.

[0018] In a preferred embodiment of the present invention, it can be provided that the tines of the comb electrode have a non-uniform length.

[0019] According to a preferred embodiment of the invention, the individual tines of the comb electrode, preferably all tines of the comb electrode, have a diameter of 1 to 2 mm, preferably 1.25 to 1.75 mm, particularly preferably 1.5 mm.

[0020] In a further preferred embodiment of the present invention, the individual tines of the comb electrode, preferably all tines of the comb electrode, have a diameter of at least 0.5 mm, preferably at least 0.75 mm, preferably at least 1 mm, preferably at least 1.25 mm, preferably at least 1.5 mm, preferably at least 1.75 mm, preferably at least 2 mm.

[0021] According to the invention, it can also be provided that the individual tines of the comb electrode, preferably all tines of the comb electrode, have a diameter of at most 5 mm, preferably at most 4.5 mm, preferably at most 4 mm, preferably at most 3.5 mm, preferably at most 3 mm, preferably at most 2.5 mm, preferably at most 2 mm, preferably at most 1.75 mm, preferably at most 1.5 mm.

[0022] According to a preferred embodiment of the present invention, adjacent tines of the comb electrode have a distance of at least 2 mm, preferably at least 2.5 mm, preferably at least 3 mm, preferably at least 3.5 mm, preferably at least 4 mm, preferably at least 4.5 mm, preferably at least 5 mm, from each other.

[0023] In a preferred embodiment of the present invention, adjacent tines of the comb electrode have a distance of at most 10 mm, preferably at most 9.5 mm, preferably at most 9 mm, preferably at most 8.5 mm, preferably at most 8 mm, preferably at most 7.5 mm, preferably at most 7 mm, preferably at most 6.5 mm, preferably at most 6 mm, preferably at most 5.5 mm, preferably at most 5 mm. Particularly preferably, adjacent tines of the comb electrode have a distance of 2 to 10 mm, preferably 3 to 8 mm, preferably 4 to 6 mm from each other.

[0024] In a particularly preferred embodiment of the present invention, all adjacent tines of the comb electrode have a uniform distance from one another. However, according to the invention, it is also possible for the individual tines of the comb electrode to have a non-uniform distance from one another. In particular, it is possible for the comb electrode to have one or more recesses across its width, and especially to have one or more areas across its width in which adjacent tines have a greater distance from one another than in other areas of the electrode.

[0025] In a preferred embodiment of the present invention, the tines of the at least one comb electrode are made of an aluminum alloy or stainless steel, preferably of AlMg3 or V2A stainless steel.

[0026] According to the invention, a gap, in particular an air gap, with a width of 0.25 to 3 mm, preferably 0.3 to 2.75 mm, preferably 0.35 to 2.25 mm, preferably 0.4 to 2 mm, preferably 0.45 to 1.5 mm, preferably 0.5 to 1 mm is located between a surface of the substrate to be treated and the distal ends of the tines of the at least one comb electrode.

[0027] In a preferred embodiment of the present invention, a gap, in particular an air gap, with a width of at least 0.1 mm, preferably at least 0.15 mm, preferably at least 0.2 mm, preferably at least 0.25 mm, preferably at least 0.3 mm, preferably at least 0.35 mm, preferably at least 0.4 mm, preferably at least 0.45 mm, preferably at least 0.5 mm is located between a surface of the substrate to be treated and the distal ends of the tines of the at least one comb electrode.

[0028] According to a preferred embodiment of the present invention, a gap, in particular an air gap, with a width of at most 3 mm, preferably at most 2.75 mm, more preferably at most 2.5 mm, more preferably at most 2.25 mm, more preferably at most 2 mm, more preferably at most 1.75 mm, more preferably at most 1.5 mm, more preferably at most 1.25 mm, more preferably at most 1 mm, is located between a surface of the substrate to be treated and the distal ends of the tines of the comb electrode to the surface of the substrate to be treated, in particular the width of the gap, in particular the air gap, between the distal ends of the tines and the surface of the substrate to be treated. In a particular embodiment of the present invention, it can be provided that the distance of the distal ends of the tines of the comb electrode from the surface of the substrate to be treated, in particular the width of the gap, in particular the air gap, between the distal ends of the tines and the surface of the substrate to be treated, is adjustable.

[0029] Preferably, the distance of the distal ends of the tines of the comb electrode from the surface of a substrate to be treated, in particular the width of the gap, especially the air gap, between the distal ends of the tines and the surface of the substrate to be treated, is adjustable in a range of 0.25 to 3 mm, preferably 0.3 to 2.75 mm, preferably 0.35 to 2.25 mm, preferably 0.4 to 2 mm, preferably 0.45 to 1.5 mm, preferably 0.5 to 1 mm.

[0030] According to the invention, the at least one comb electrode of the device for HF corona treatment of substrate surfaces can be a rigid, in particular stationary, electrode or a movable, in particular movable, preferably rollable, electrode.

[0031] According to a particularly preferred embodiment of the invention, the comb electrode is arranged in a handheld device. Preferably, in addition to the comb electrode, the handheld device comprises a housing, at least one handle, a cable entry, and at least one, preferably two, guide rollers. Particularly preferably, the comb electrode is arranged in the housing of the handheld device between two guide rollers, so that the handheld device can be grasped by the handle and guided, in particular rolled, over the surface to be treated of a substrate arranged on the at least one grounded counter electrode. The handheld device is connected to the at least one high-voltage generator via a cable.

[0032] According to this preferred embodiment of the present invention, the device for RF corona treatment of substrate surfaces is preferably a laboratory corona device for RF corona treatment of substrate surfaces. With such a laboratory corona device, adhesive, paint, or printing ink manufacturers, for example, can test their products with regard to the properties after corona pretreatment of substrates and provide corresponding recommendations for the pretreatment of different substrates in order to achieve the best possible and longest-lasting adhesion of the products to the substrates.Preferably, the handheld device with at least one comb electrode arranged therein, in particular the laboratory corona device, allows the corona pretreatment of substrates over a width of at least 100 mm, preferably at least 150 mm, preferably at least 200 mm, preferably at least 250 mm, preferably at least 300 mm, preferably at least 350 mm, preferably at least 400 mm.

[0033] According to the invention, the handheld device and / or the at least one comb electrode can be interchangeable. In this way, different handheld devices or comb electrodes can preferably be used depending on the substrate to be treated or the desired type of pretreatment, which may differ, for example, in the path width, the number, the spacing and / or the design of the individual tines and / or the distance of the distal ends of the tines from the surface of the substrate to be treated.

[0034] According to the invention, it can also be provided that the at least one comb electrode is fixedly installed in the device for HF corona treatment of substrate surfaces and that the substrate with the surface to be treated is brought between the at least one comb electrode and the at least one counter electrode, particularly preferably through the area between the at least one comb electrode and the at least one counter electrode.

[0035] In a preferred embodiment of the present invention, the device for RF corona treatment of substrate surfaces additionally comprises at least one extraction device, in particular at least one ozone extraction device. Even though the ozone formed during corona pretreatment plays a significant role in the oxidative processes on the surface of the treated substrate, for reasons of occupational safety it is important to ensure that the spread of the strong oxidizing agent in the environment is contained as effectively as possible. For this purpose, the invention provides for the removal of ozone from the work area by means of at least one extraction device.

[0036] According to a further preferred embodiment, the device for HF corona treatment of substrate surfaces may have at least one gas supply, in particular a process gas supply. Through this at least one additional gas supply, in particular a process gas supply, specific gases, in particular process gases, can be introduced into the treatment area, in particular into the gap between the distal ends of the prongs and the substrate surface to be treated, in order to improve the efficiency of the corona pretreatment.

[0037] The present invention further relates to a method for RF corona treatment of substrate surfaces, comprising the steps: a) providing a substrate with at least one surface to be treated and a device according to the invention, b) arranging the substrate in the treatment area of ​​the device, c) generating a high-frequency voltage with a voltage of at least 3 kV and a frequency of 30 to 90 kHz, preferably 60 to 70 kHz, and corona discharge of the high-frequency voltage in the gap (30), in particular air gap, between the at least one surface of the substrate to be treated and the comb electrode (2), d) obtaining a substrate with at least one treated surface.

[0038] According to a preferred embodiment of the present invention, the substrate with at least one surface to be treated, preferably the substrate with at least one non-conductive surface to be treated, has a thickness of at least 2.5 mm, preferably at least 3 mm, preferably at least 3.5 mm, preferably at least 4 mm, preferably at least 4.5 mm, preferably at least 5 mm, preferably at least 5.5 mm, preferably at least 6 mm, preferably at least 6.5 mm, preferably at least 7 mm, preferably at least 7.5 mm, preferably at least 8 mm, preferably at least 9 mm, preferably at least 9.5 mm, preferably at least 10 mm.

[0039] According to the invention, the surface of the substrate to be treated can be a conductive or a non-conductive surface.

[0040] In a preferred embodiment of the present invention, the surface of the substrate to be treated is a non-conductive surface, preferably a plastic or paper surface.

[0041] The surface of the substrate to be treated is particularly preferably a plastic surface made of at least one material selected from the group consisting of polypropylene (PP), polyethylene (PE), polystyrene (PS), polycarbonate (PC), acrylonitrile butadiene styrene copolymer (ABS), cross-linked PE (XLPE / VPE), polytetrafluoroethylene (PTFE), polymethyl methacrylate (PMME), ethylene propylene diene monomer rubber (EPDM), polyurethane (PU / PUR) and silicones.

[0042] In a preferred embodiment, the surface of the substrate to be treated is a non-conductive foam surface.

[0043] According to a further preferred embodiment of the present invention, the surface of the substrate to be treated is a conductive surface, preferably a metal surface.

[0044] According to a preferred embodiment of the present invention, the surface to be treated of the substrate provided in step a) has a surface energy of at most 38 mN / m, preferably at most 37 mN / m, preferably at most 36 mN / m, preferably at most 35 mN / m, preferably at most 34 mN / m, preferably at most 33 mN / m, preferably at most 32 mN / m, preferably at most 31 mN / m, preferably at most 30 mN / m.

[0045] In a preferred embodiment of the present invention, the treated surface of the substrate obtained in step d) has a surface energy of at least 40 mN / m, preferably at least 41 mN / m, preferably at least 42 mN / m, preferably at least 43 mN / m, preferably at least 44 mN / m, preferably at least 45 mN / m, preferably at least 46 mN / m, preferably at least 47 mN / m, preferably at least 48 mN / m, preferably at least 49 mN / m, preferably at least 50 mN / m, preferably at least 51 mN / m, preferably at least 52 mN / m, preferably at least 53 mN / m, preferably at least 54 mN / m, preferably at least 55 mN / m.

[0046] Particularly preferably, the treated surface of the substrate obtained in step d) has a surface energy of 40 to 60 mN / m, preferably 40 to 55 mN / m, preferably 40 to 50 mN / m, preferably 42 to 48 mN / m.

[0047] According to a further preferred embodiment of the present invention, the treated surface of the substrate obtained in step d) has a surface energy that is at least 2 mN / m, preferably at least 3 mN / m, preferably at least 4 mN / m, preferably at least 5 mN / m, preferably at least 6 mN / m, preferably at least 7 mN / m, preferably at least 8 mN / m, preferably at least 9 mN / m, preferably at least 10 mN / m, preferably at least 11 mN / m, preferably at least 12 mN / m, preferably at least 13 mN / m, preferably at least 14 mN / m, preferably at least 15 mN / m, preferably at least 16 mN / m, preferably at least 17 mN / m, preferably at least 18 mN / m, preferably at least 19 mN / m, preferably at least 20 mN / m higher than the surface energy of the at least one surface to be treated of the substrate provided in step a).

[0048] The present invention further relates to the use of a comb electrode for RF corona pretreatment of substrate surfaces of substrates with a thickness of at least 2.5 mm.

[0049] The embodiments and statements described in connection with the device according to the invention for high-frequency (HF) corona treatment of substrate surfaces also apply mutatis mutandis to the method according to the invention for HF corona treatment of substrate surfaces and the use according to the invention of a comb electrode for HF corona pretreatment of substrate surfaces and vice versa.

[0050] According to the invention, a "handheld device" is understood to be a device that can be held and, in particular, guided by the human hand.

[0051] In the context of the present invention, the terms "comprising" and "comprising" are understood to mean that, in addition to the elements explicitly covered by these terms, further, unmentioned elements may be present. In the context of the present invention, these terms are also understood to mean that only the explicitly mentioned elements are covered and no further elements are present. In this particular embodiment, the meaning of the terms "comprising" and "comprising" is synonymous with the term "consisting of." Furthermore, the terms "comprising" and "comprising" also encompass compositions that, in addition to the explicitly mentioned elements, contain further unmentioned elements that are, however, of a functionally and qualitatively subordinate nature. In this embodiment, the terms "comprising" and "comprising" are synonymous with the term "essentially consisting of."

[0052] In the context of the present invention, the term "and / or" means that all members of a group connected by the term "and / or" are disclosed both alternatively to one another and cumulatively to one another in any combination. For the expression "A, B and / or C", this means that the following disclosure content is to be understood: a) A or B or C or b) (A and B) or c) (A and C) or d) (B and C) or e) (A and B and C).

[0053] The present invention is illustrated below with reference to exemplary figures. The inventive concept is not limited to these embodiments.

[0054] This shows

[0055] Figure 1 shows a schematic representation of a device (100) according to the invention for RF corona treatment of substrate surfaces with a high voltage generator (1) for generating a high frequency voltage, a handheld device (40) and a grounded counter electrode (3).

[0056] Figure 2 shows a perspective view of the top of a handheld device (40) for a device according to the invention for RF corona treatment of substrate surfaces with a housing (50), a handle (60) and a cable feed (70).

[0057] Figure 3 shows a perspective view of the underside of the handheld device (40) shown in Figure 2 for a device according to the invention for HF corona treatment.

[0058] Figure 4 schematically shows a comb electrode (2) guided over a substrate (20) by means of rollers (80) with a plurality of prongs (11) from which a corona discharge occurs in the gap (30) of the treatment area (10) onto a grounded counter electrode (3).

[0059] The device (100) according to the invention, shown in Figure 1, for RF corona treatment of substrate surfaces comprises at least one high-voltage generator (1) suitable for generating a high-frequency voltage with a voltage of at least 3 kV and a frequency of 30 to 90 kHz, at least one comb electrode (2) arranged in a handheld device (40), and a grounded counter electrode (3), which is preferably designed as a counter electrode plate. The handheld device (40) is preferably connected to the high-voltage generator (1) via a cable through a cable feed (70). The comb electrode is located within an insulating housing (50) of the handheld device (40), from which a handle (60) preferably extends, with the aid of which the handheld device (40) can be guided.The rollers inside the housing (50), not shown in Figure 1, define the distance between the distal ends of the comb electrode's prongs and the surface of a flat substrate to be treated, which rests positively on the counter electrode (3), in particular on the counter electrode plate. This ensures that the distal ends of the comb electrode's prongs maintain a constant distance from the substrate during corona pretreatment when the handheld device (40) is guided, in particular rolled, across the substrate's surface.The hand device (40) or the comb electrode of the hand device (40) may be interchangeable in order to be able to use different hand devices (40) or comb electrodes depending on the substrate to be treated, which may differ, for example, in the web width, in the number, the spacing and / or the design of the individual tines or in the distance of the distal ends of the tines from the surface of the substrate to be treated.

[0060] Perspective views of the top and bottom of a handheld device (40) are shown in Figures 2 and 3. Figure 3 shows that the housing (50) of the handheld device (40) has an open area on its underside in the illustrated embodiment. In this open area, a plurality of tines (11) of the comb electrode are arranged in a row between two rollers (80).

[0061] Figure 4 shows a schematic front view of a chamber electrode (2) arranged between two rollers (80) with a plurality of prongs (11), the distal ends of which are spaced at a defined distance from the surface of a substrate (20) to be treated, which rests in a form-fitting manner on the counter electrode (3). In the gap (30) thus formed, in particular an air gap, corona discharges occur during pretreatment, and the substrate surface is modified by reactive species formed in the gap (30). For clarity, the housing, handle, and cable entry of the handheld device have been omitted from the illustration in Figure 4.

[0062] REFERENCE MARK LIST

[0063] 1 High-voltage generator

[0064] 2 Comb electrode

[0065] 3 Counter electrode 10 Treatment area

[0066] 11 prongs

[0067] 20 substrate

[0068] 30 gap

[0069] 40 handheld device 50 housings

[0070] 60 handle

[0071] 70 Cable entry

[0072] 80 roller

[0073] 100 Device for RF corona treatment of substrate surfaces

Claims

REQUIREMENTS 1. Device (100) for high-frequency (HF) corona treatment of substrate surfaces, comprising: i) at least one high-voltage generator (1) for generating a high-frequency voltage with a voltage of at least 3 kV and a frequency of 30 to 90 kHz, preferably 60 to 70 kHz, ii) at least one comb electrode (2) with at least 6 prongs (11), iii) at least one grounded counter electrode (3), wherein a treatment area (10) for receiving a substrate is formed between the at least one comb electrode (2) and the at least one counter electrode (3), wherein a substrate (20) arranged in the treatment area (10) contacts the counter electrode (3) and a gap (30) with a width of 0.25 to 3 mm, preferably 0.5 to 1 mm, is located between a surface of the substrate to be treated and the distal ends of the prongs of the at least one comb electrode (2).

2. Device according to claim 1, wherein the at least one comb electrode (2) comprises at least 10, preferably at least 20, preferably at least 30, tines.

3. Device according to claim 1 or 2, wherein the individual tines (11) of the comb electrode (2) have a length of 1 to 3 cm, preferably 1.5 cm, and a diameter of 1 to 2 mm, preferably 1.5 mm.

4. Device according to one of claims 1 to 3, wherein the tines of the at least one comb electrode (2) are made of an aluminum alloy or stainless steel, preferably of AlMg3 or V2A stainless steel.

5. Device according to one of claims 1 to 4, wherein the comb electrode (2) is arranged in a handheld device (40), the handheld device additionally comprising a housing (50), at least one handle (60), a cable feed (70) and at least one roller (80).

6. Method for RF corona treatment of substrate surfaces, comprising the steps: a) providing a substrate with at least one surface to be treated and a device (100) according to any one of claims 1 to 5, b) arranging the substrate in the treatment area (10) of the device (100), c) generating a high-frequency voltage with a voltage of at least 3 kV and a frequency of 10 to 100 kHz, preferably 25 to 50 kHz, and corona discharge of the high-frequency voltage in the gap (30) between the at least one surface to be treated of the substrate and the comb electrode (2), d) obtaining a substrate with at least one treated surface.

7. Method according to claim 6, wherein the substrate with at least one surface to be treated has a thickness of at least 2.5 mm, preferably at least 5 mm, preferably at least 7.5 mm, preferably at least 10 mm.

8. Method according to claim 6 or 7, wherein the surface of the substrate to be treated is a non-conductive surface, preferably a plastic or paper surface.

9. Method according to claim 8, wherein the surface of the substrate to be treated is a non-conductive foam fabric surface.

10. Method according to claim 6 or 7, wherein the surface of the substrate to be treated is a conductive surface, preferably a metal surface.

11. Method according to any one of claims 6 to 10, wherein the treated surface of the substrate obtained in step d) has a surface energy of at least 40 mN / m, preferably at least 45 mN / m, preferably at least 50 mN / m, preferably at least 55 mN / m.

12. Use of a comb electrode for RF corona pretreatment of substrate surfaces of substrates with a thickness of at least 2.5 mm.

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