METHOD FOR MARKING GLASS SHEETS, PREFERABLY SINGLE-PANEL SAFETY GLASS SHEETS

Description

[0001] The present invention relates to a method for marking glass panels, preferably toughened safety glass panels.

[0002] Flat glass refers to any glass in the form of panes or sheets, regardless of the manufacturing process used. To provide flat glass sheets with filtering, mirroring, heating, or other functions, a wide variety of single- or multi-layer functional coatings are applied to the flat glass sheets. These functions can include thermal insulation, solar protection, or heating. In low-E glass (low-E = low emissivity = low heat radiation), one or more metal layers reduce the emissivity of the glass sheets and serve as a thermal and / or solar protection layer.

[0003] Typically, the functional coating is a single functional layer or a layer structure comprising multiple functional layers with a total thickness of < 2 µm. The layer structure is usually obtained by deposition processes, preferably sputtering.

[0004] The individual functional layers are therefore usually metallic and / or ceramic layers. These include, for example, metallic low-emission layers or electrical heating layers. Between the individual metallic functional layers of a functional coating, one or more dielectric (functional) layers, e.g., made of an oxide such as aluminum oxide, can be arranged. In addition, an adhesion-promoting layer of tin oxide is usually present between the functional coating and the glass surface.

[0005] Furthermore, for some time now, there have been types of glass in which the functional coating or even just the uncoated glass surface (in the case of glass panels without a functional coating) is protected by a removable protective film (TPF = temporary protective film) or a polymer protective layer (e.g., EasyPro®< from St. Gobain) to protect it from potential mechanical damage. The polymer protective layer is applied, for example, by spraying and is not removable, but firmly bonded to the respective surface. However, it burns off easily and residue-free during tempering in the furnace. Thus, unlike the functional coating, the protective coating is removed before the glass panel is used for its intended purpose.

[0006] Toughened safety glass (ESG) consists of a single, specially heat-treated pane of glass. The glass pane is heated to temperatures above its transformation temperature and then cooled rapidly, creating a toughened glass pane. Heat treatment is preferably carried out in accordance with DIN EN 12150-1:2015-12. Toughened safety glass has increased impact and shock resistance compared to standard flat glass panels due to the toughened glass.

[0007] Single-pane safety glass is subject to mandatory labeling, at least in Germany. Today, the labeling is done either with ceramic ink using a hand-screen printing process or with a decal. The labeling is applied before heat treatment in the kiln and burned into the glass during tempering. The ceramic ink requires the kiln temperature to permanently bond to the surface.

[0008] If an additional polymer protective layer is present, the marking is applied to the polymer protective layer using conventional processes. This results in the marking being removed along with the polymer protective layer. The marking thus disappears during heat treatment in the furnace.

[0009] For this reason, toughened safety glass panels with a polymer protective layer do not currently meet the legal marking requirements if they have been marked by hand screen printing or decals.

[0010] In the case of the protective film, this is removed before the oven process and then the marking is applied to the functional layer using screen printing or decal.

[0011] Furthermore, laser marking processes for marking glass panels without protective layers are known from the two publications DE 10 2005 026 038 A1 and DE 10 2005 025 982 A1.

[0012] According to DE 10 2005 026 038 A1, a glass-like layer with metal nanoparticles is applied to the surface of the glass panel using a laser. For this purpose, a donor or carrier medium is brought into contact with the glass panel surface to be marked, and a mark is created on the glass panel surface using laser beam-induced processes. The carrier medium comprises, for example, a PET film which, for example, has a low-E functional coating, which has at least one metallic functional layer. For marking, a laser beam is directed onto the functional coating, and due to the laser beam irradiation, material from the functional coating is transferred from the PET carrier film to the glass panel surface to be marked. The material adheres to the glass panel surface as a glass-like matrix with metallic nanoparticles, wherein the matrix is ​​formed from the substances originally present in the functional layers of the functional coating.The PET carrier film remains intact.

[0013] According to DE 10 2005 025 982 A1, the low-E functional coating of a glass panel is similarly changed in color by laser radiation so that a marking is created.

[0014] US 2003 / 0039765 A1 also discloses a method for marking glass panels without a protective coating using a laser. In the method, in a first step, a laser beam is directed at a marking material to vaporize the marking material and deposit it on a specific area of ​​the substrate to be marked. In a second step, the material deposited on the substrate to be marked is removed or converted using a laser beam, depending on the marking to be produced.

[0015] EP 3 031 785 A1 discloses a method for producing a glass ceramic element with a structured coating, wherein a glass ceramic element is provided with a coating that at least partially blocks light in the visible spectral range, the glass ceramic element is irradiated with a pulsed laser beam so that the coating is removed by ablation, and after removal of the coating, the glass ceramic is irradiated with the same laser in the region of the removed coating so that the glass ceramic is optically modified in the irradiated region.

[0016] DE 102 58 522 A1 discloses a method for marking a heat-insulating laminated glass pane consisting of two glass panes, at least one PVB film between the two glass panes, and a thin metal layer transparent in the visible wavelength range. In this method, the metal layer is exposed to a laser beam and discolored due to the effect of the laser beam.

[0017] DE 103 51 226 A1 discloses a method for laser marking glass, in which a protective lacquer is applied to the area of ​​the glass to be marked, dried, and exposed to the laser beam according to the specified marking. This removes the protective lacquer at the marking location(s), and during removal, the protective lacquer serves as an initial absorber for the melting effect of the laser beam on the glass surface alone. Due to the melting, the glass surface is scratched, creating grooves or scores. Immediately after the laser marking process, the remaining protective lacquer layer is removed with a solvent. Furthermore, according to DE 103 51 226 A1, an additional lacquer can be applied in a subsequent step by spin coating. The additional lacquer flows into the grooves and settles in them.

[0018] The object of the present invention is therefore to provide a simple and cost-effective marking method for permanently marking glass panels coated with a protective coating, preferably a protective film or a polymer protective layer, in particular toughened safety glass panels.

[0019] These objects are achieved by a marking method according to claim 1. Advantageous developments of the invention are characterized in the subsequent subclaims.

[0020] Within the scope of the invention, it was surprisingly discovered that it is possible to apply a marking to the glass panels, preferably provided with functional layers, underneath the protective coating by means of laser radiation and to remove the protective coating in the same operation or at the same time.

[0021] The marking is carried out according to the method according to DE 10 2005 025 982 A1, although the glass panel has a protective coating according to the invention.

[0022] According to a method not according to the invention, the protective coating is removed by laser radiation, preferably burned or burnt away. In the same operation, marking material is printed from a donor or carrier medium by laser radiation onto an exposed surface of the glass panel that was previously located beneath the protective coating of the glass panel. For glass panels with a functional coating, the marking material is applied to the outward-facing functional coating surface and / or to the glass surface. For glass panels without a functional coating, the marking material is applied to the uncoated glass surface.

[0023] According to the method according to the invention, the protective coating is removed by means of laser radiation, preferably burned or burnt away, and in the same operation the functional coating previously located underneath is changed in color, so that a marking is created in the functional coating itself due to the contrast between the color-changed areas and the unchanged areas.

[0024] The invention is explained in more detail below using a drawing as an example. The drawings show: Figure 1: Highly simplified and schematic view of a section through a glass panel with a protective layer and a marking device for the marking method according to the invention. Figure 2: Highly simplified and schematic view of a section through a glass panel with a marking device arranged underneath for the marking method not according to the invention.

[0025] A glass panel 1 to be marked according to the invention (Fig. 1 , 2 ) has a first and second glass surface 1a;b and preferably a circumferential glass panel edge 1c. The glass panel 1 preferably has only a single or single glass pane 2 ( Fig. 1 ). Each glass pane 2 has two glass pane surfaces 2a;b. If the glass panel 1 has only a single glass pane 2, the two glass pane surfaces 2a;b form the glass surfaces 1a;b of the glass panel 1a;b. Particularly preferably, the glass panel 1 is a toughened safety glass panel with a single glass pane 2 that is still to be tempered or has already been tempered.

[0026] However, the glass panel 1 can also be a laminated glass panel made up of several interconnected glass panes 2 (not shown). Laminated glass panels are a laminate of at least two individual glass panes 2, each bonded to one another by means of an adhesive intermediate layer made of plastic, in particular a highly tear-resistant, tough, elastic, thermoplastic film. In this case, the two outer glass pane surfaces 2a;b each form the glass surfaces 1a;b of the glass panel 1a;b. The glass panes 2 of the laminated glass panel are preferably at least partially tempered glass panes 2.

[0027] In addition, the glass panel 1 has a superficial functional coating 3 on at least one of its two glass surfaces 1a;b. The functional coating 3 has an outer functional coating surface 3a facing away from the glass pane(s) 2.

[0028] The functional coating 3 can have one or more individual functional layers. If there are multiple functional layers, this constitutes a functional layer laminate. The functional layers change certain properties of the glass panel 1 or impart specific functions to it. These functions can include, for example, thermal insulation, sun protection, or heating. The functional coating 3 is preferably a wavelength-selective or low-E coating. The functional coating 3 is not removed before the intended use of the glass panel 1, but remains in place even during the intended use of the glass panel 1.

[0029] The functional coating 3 of the glass panel 1 has at least one metal-containing functional layer. This is preferably a metal or a metal oxide layer, preferably a ceramic layer. The metallic functional layers are preferably embedded in oxide functional layers, e.g., made of a metal oxide, preferably tin oxide, thereby increasing transmission and durability.

[0030] In addition, the functional coating 3 can have a functional layer made of, preferably ceramic, metal oxide, preferably tin oxide, which is directly bonded to the glass surface 1a;b and connects the remaining layers of the functional coating 3 to the glass surface 1a;b. The functional layer made of metal oxide, preferably tin oxide, thus also serves as an adhesive layer.

[0031] A metal-containing, preferably metallic, functional layer preferably comprises silver, copper, or gold. A functional layer made of metal oxide preferably consists of tin oxide.

[0032] Of course, the ceramic functional layer does not have to be made of oxide ceramic. It can also be a non-oxide ceramic functional layer, for example.

[0033] The functional coating 3 of the glass panel 1 thus has at least one metallic and / or at least one, preferably metal-containing, ceramic functional layer.

[0034] The application of the functional layers to the glass pane 2 is preferably carried out by sputtering or wet-chemical means.

[0035] Furthermore, the functional coating 3 preferably has a thickness of < 2 µm, preferably < 1 µm.

[0036] In addition, the glass panel 1 has a protective coating 4 in the form of a polymer protective layer or a removable protective film on at least one of its two glass surfaces 1a;b. The protective coating 4 covers the respective glass surface 1a;b and the functional coating 3 on the outside and, in particular, protects the functional coating 3 arranged beneath the protective coating 4 or, if no functional coating 3 is present, the bare glass surface 1a;b, from mechanical damage. The protective coating 4 thus forms the outer or exterior layer of the glass panel 1.

[0037] In contrast to the functional coating 3, the protective coating 4 is completely removed before the final use of the glass panel 1. It is therefore not permanently present. The protective film is removed, and the polymer protective layer is burned. The functional coating 3, on the other hand, is permanently present, at least in some areas.

[0038] The polymer protective layer consists of a polymer and cannot be removed from the glass panel 1. The polymer protective layer is firmly, permanently, or non-destructively bonded to the respective surface (functional coating surface 3a or glass surface 1a;b).

[0039] In addition, the polymer protective layer preferably has a thickness of 1 µm to 1 mm, preferably 1 µm to 100 µm.

[0040] The protective film is made of plastic, preferably polyvinyl chloride (PVC), and can be removed from the glass panel 1.

[0041] In addition, the protective film preferably has a thickness of 20 to 100 µm.

[0042] As already explained, a marking is not produced on the glass panel 1 according to the invention by printing marking material by means of laser radiation or by changing the colour of the functional coating 3, wherein at the same time the protective coating 4 in the area of ​​the marking is removed, preferably burned, by means of the laser radiation.

[0043] Fig. 2 shows an example of a marking device 5 for carrying out the marking method not according to the invention.

[0044] Fig. 1 shows an example of a marking device 5 for carrying out the marking method according to the invention.

[0045] The marking device 5 has a laser beam generating device 6 for generating a laser beam 7. To carry out the method not according to the invention, the marking device 5 also has a dispenser or carrier medium 8, several guide rollers 9, and a pressure frame 10.

[0046] The laser beam generating device 6 is used to remove the polymer protective layer or film in the area of ​​the marking to be created and to create the marking in the same operation. For this purpose, the laser beam generating device 6 generates the laser beam 7. The laser beam generating device 6 has a laser radiation source and associated optics. The optics focus the laser beam 7. The laser beam 7 can be pivoted or deflected from an initial position in which it is aligned vertically or perpendicularly to the glass surface 1a;b.

[0047] The laser radiation source preferably generates a laser beam 7 whose wavelength is 190 nm to 12 µm, preferably 500 nm to 2 µm.

[0048] In addition, the laser radiation source preferably generates a laser beam 7 whose laser power is < 20 W, preferably < 10 W, and / or ≥ 0.5 W, preferably ≥ 5 W.

[0049] In addition, the laser radiation source preferably generates a pulsed laser beam 7. However, it can also generate a continuous laser beam 7.

[0050] The dispenser or carrier medium 8 is preferably a coated plastic film, preferably made of PET. The carrier medium 8 is preferably strip-shaped.

[0051] Furthermore, the carrier medium 8 has a surface marking coating made of marking material, which has at least one metal-containing, preferably metallic, marking layer and / or at least one ceramic marking layer.

[0052] The metal-containing marking layer is preferably a metal or, preferably, a ceramic, metal oxide layer. The metallic marking layers are preferably embedded in oxidic functional layers, e.g., made of a metal oxide, preferably tin oxide.

[0053] In addition, the marking coating can comprise a marking layer made of, preferably ceramic, metal oxide, preferably tin oxide, which is directly bonded to the surface of the carrier medium 8 and connects the remaining layers of the marking coating to the surface. The marking layer made of metal oxide, preferably tin oxide, thus also serves as an adhesive layer.

[0054] Preferably, a metal-containing, preferably a metallic marking layer comprises silver, copper or gold.

[0055] Of course, the ceramic marking layer does not have to be made of oxide ceramic. It can also be a non-oxide ceramic marking layer, for example.

[0056] The marking coating of the glass panel 1 thus has at least one metallic and / or at least one, preferably metal-containing, ceramic marking layer.

[0057] The marking layers are preferably applied to the carrier medium 8 by sputtering or wet-chemical means.

[0058] The marking coating is preferably a low-E coating.

[0059] Furthermore, the marking coating preferably has a thickness of < 5 µm.

[0060] The pressure frame 10 serves to press the band-shaped carrier medium 8 against the glass sheet 1 to be marked. The pressure frame 10 is preferably permeable to the laser radiation. Alternatively, the pressure frame 10 has an opening that exposes the marking area.

[0061] The band-shaped carrier medium 8 is also guided around the guide rollers 9.

[0062] For marking, the carrier medium 8 is pressed against the glass panel 1 with its side coated with the marking coating by means of the pressure frame 10. Then, using the laser beam 7 focused on the marking coating, the marking material is transferred from the marking coating to the glass panel 1, in particular the functional coating surface 3a and / or the glass surface 1a;b, and fixed thereto. Because the laser radiation is absorbed by the marking material, it is released from the carrier medium 8 and conveyed to the surface 1a;b;3a to be marked.

[0063] At the same time or in the same operation, the protective coating 4 is removed, in particular burned, by means of the laser beam 7 in order to expose the surface 1a;b;3a to be marked.

[0064] Both the material of the pressure frame 10 and the carrier medium 8 are at most weakly absorbent at the laser wavelength of the laser beam 7, so that the laser beam 7 passes through the carrier medium 8 and the pressure frame 10.

[0065] For marking, the glass sheet 1 and the laser beam 7, and optionally the carrier medium 8, must be moved relative to one another parallel to the glass surfaces 1a;b. Preferably, only the laser beam 7 is moved. The movement of the laser beam 7 is preferably achieved by means of the optics of the laser beam generating device 6. The optics of the laser generating device 6 are preferably capable of moving the laser beam 7 within an area of, for example, 100 mm x 100 mm (scan field) with the aid of two adjustable mirrors (scanning optics). After marking, the strip-shaped carrier medium 8 is then advanced forward.

[0066] Marking is thus carried out by introducing burn marks or laser marks into the protective coating 4 and transferring marking material from the marking coating from the carrier medium 8 to the glass panel 1, in particular to the functional coating surface 3a and / or the glass surface 1a;b. The laser marks can be point-shaped, linear, or planar. In the area of ​​the laser marks, the protective coating 4 is completely removed, in particular evaporated or burned, and the marking material is applied to the surface 1a;b, 3a thus exposed or exposed.

[0067] As already explained, the marking in the method according to the invention is carried out by introducing burn marks or laser marks into the protective coating 4 and the functional coating 3. In the area of ​​the laser marks, the protective coating 4 is completely removed, in particular evaporated or burned, and the functional coating 3 is discolored.

[0068] One of the causes of the discoloration is the absorption of laser radiation in the metallic or ceramic functional layer. This absorption heats the layer to such an extent that the material of the functional coating changes in the irradiated area. As a result of this change, the metal, for example, is present in the form of nanoparticles, embedded in a matrix formed at least partially from material from the other functional layers originally present in the functional coating. Or the chemical structure of the material is altered in such a way that it changes color.

[0069] These mechanisms and the resulting discolorations also usually occur in the marking material of the marking coating of the carrier medium.

[0070] The advantage of the method according to the invention is that even toughened glass panels with a protective coating 4 can be permanently marked. The not yet tempered glass panels 1 can be marked, and the marking remains intact despite the polymer coating burning away during heat treatment. This also allows for the application of test markings, which indicate, through a color change, that the required time for heat treatment has been reached.

[0071] In addition, already toughened ESG glass panels can also be marked with protective film.

[0072] The markings produced according to the invention are highly resistant to abrasion and weather influences, as well as temperatures, solvents, and other chemicals. This ensures optimal marking throughout the entire service life of the glass panel 1.

[0073] The marking device 5 for carrying out the method according to the invention can be easily integrated into cutting and breaking lines or designed as a stand-alone system. For example, the marking device can be integrated into the cutting bridge.

[0074] In addition, the method according to the invention can be used to carry out fully automatic marking with machine-readable codes (e.g. data matrix codes), logos and product IDs, serial numbers, and order-specific data individually for each glass panel.

[0075] It was not immediately foreseeable that the application of a marking to a surface 1a; b; 3a lying beneath the protective coating 4 would be possible. The laser radiation is absorbed by the marking coating, in particular by the marking layer(s). As a result, the marking coating, in particular the marking layer(s), is / are at least partially or partially blasted off the carrier medium 8. It is now assumed that the energy released in this process surprisingly leads to the protective coating 4 being removed, thus exposing the surface to be marked. Temperatures are evidently reached which, similar to the furnace process, lead to the combustion of the protective coating. The marking material or the material of the functional layers, however, cannot burn because it is a metal or a ceramic.

[0076] Furthermore, the laser beam 7 can also be directed through the glass panel 1 onto the marking coating or the functional coating 3. This facilitates the integration of laser marking into the furnace loading workflow. Example:

[0077] A 1 µm laser was directed at the coated glass surface of a toughened safety glass panel with a polymer protective layer. The toughened safety glass panel also had a low-E coating with a silver layer. The laser power was 5 W. The frequency of the pulsed laser beam was 10 kHz. The beam diameter at the focus was 100 µm.

[0078] A permanent mark was created in the low-E coating and the polymer protective layer in the area of ​​the mark was removed.

Claims

1. A marking method for marking glass sheets (1) that comprise at least on one of their two glass surfaces (1a;b) a protective coating (4), in particular in the form of a polymer coating or in the form of a peel-off protective film, and comprise a functional coating (3), situated under the protective coating (4), having at least one metal-containing and / or at least one ceramic functional layer, characterized in that the protective coating (4) is removed, in particular burned, by laser radiation in the region of a marking that is to be applied, and, in the same working step, the functional coating (3) is modified in its color by the laser radiation in the region exposed by the removal of the protective coating (4) in order to produce the marking.

2. The marking method according to Claim 1, characterized in that the laser radiation is absorbed by the functional coating (3) in such a way that the color of the material of the functional coating (3) changes.

3. The marking method according to Claim 2, characterized in that the protective coating (4) is removed by the energy released during the absorption.

4. The marking method according to one of the preceding claims, characterized in that a laser beam (7) a) having a wavelength of from 190 nm to 12 µm, preferably 500 nm to 2 µm, and / or b) having a laser power < 20 W, preferably having a laser power < 10 W, and / or c) having a laser power ≥ 0.5 W, preferably having a laser power ≥ 5 W, is used.

5. The marking method according to one of the preceding claims, characterized in that a pulsed laser beam (7) or a continuous laser beam (7) is used.

6. The marking method according to one of the preceding claims, characterized in that not yet pre-stressed single-pane safety glass sheets are marked.

7. The marking method according to one of the preceding claims, characterized in that a) the functional layer is a metallic layer or a, preferably ceramic, metal oxide layer, and / or b) the functional coating (3) is a low-E coating.

8. The marking method according to one of the preceding claims, characterized in that the polymer protective layer is made of a polymer and cannot be peeled off from the glass sheet (1), and / or in that the polymer protective layer has a thickness of 1 µm to 1 mm, preferably 1 µm to 100 µm.

9. The marking method according to one of the preceding claims, characterized in that the protective film is made of plastic, preferably of polyvinyl chloride (PVC), and can be peeled off from the glass sheet (1), and / or the protective film has a thickness from 20 to 100 µm.

10. The marking method according to one of the preceding claims, characterized in that the laser radiation is radiated through the glass sheet (1) or is not radiated through the glass sheet (1).

11. The marking method according to one of the preceding claims, characterized in that a focused laser beam (7) is used, wherein the laser beam (7) is preferably focused onto the coated glass surface (1a).