EP3272184B1 - Method for depositing a bus bar on plastic vehicle panels with heating function - Google Patents

Description

The present invention relates to a method for depositing an electric busbar on vehicle plastic panes with a heating function by means of the fine powder coating (FPC) plasma process.

In the course of ever more stringent requirements for carbon dioxide emissions from motor vehicles, there are strong efforts to reduce the weight of a vehicle and thus its fuel consumption. Constant further developments in the field of plastics enable the replacement of large parts of the metal body with correspondingly lighter elements made of polymer materials. In particular, parts or the entire window area can be replaced by elements made of polymer materials. In many cases, with a significantly lower weight, these show a comparable hardness, stability and resilience as a body window made of glass. In addition, due to the weight reduction, the center of gravity of the vehicle is shifted further down, which has a positive influence on the driving behavior. In addition, polymer materials can be manufactured, processed and shaped at significantly lower temperatures than glass. This lowers the energy requirement and the costs of manufacturing the materials. Molded parts made of polymeric materials can be produced in practically any desired shape and geometry. Special high-performance plastics such as aramids, for example Kevlar, have very high strength and stability.

The effectiveness of vehicle lighting can also be impaired at low ambient temperatures, especially in winter. Snow, ice or condensed humidity can accumulate on the outside of the cover of the vehicle light. Humidity can also condense and freeze on the inside of the luminaire cover. This reduces the transparency of the luminaire cover and reduces the functionality of the lighting. Road safety is adversely affected. In the past, vehicle headlights were primarily equipped with halogen lamps or xenon lamps. These lamps generate considerable heat during operation. The heat is transferred to the lamp cover and leads to the defrosting and / or drying of the lamp cover. Recently, vehicle headlights have been reinforced with light-emitting diodes (LED), which generate significantly less heat during operation. Active heating of the luminaire cover is therefore required to remove moisture and ice.

Many material parts made of plastics have to meet various requirements and functions. Important parameters here are stability, fracture behavior, scratch resistance, impact strength or notched impact strength. In addition to technical aspects such as weight and strength of the individual material phases, shape, geometry and appearance also play an increasingly important role. In the automotive industry in particular, mechanical properties as well as design and aesthetic features are of great importance. In order to combine different characteristics in polymeric materials, these are composed of differently shaped and differently made basic materials. Established processes for the production of these materials include two- or multi-component injection molding processes. In this way it is possible to combine features such as weather resistance, surface gloss and break resistance or torsional stability. In addition, the proportions of very expensive materials can be reduced.

Vehicle windows, including light covers, which have an active heating function and which essentially consist of plastic, are known.

So is from the international patent application WO 2014/067745 A1 a polymer vehicle glazing made of plastic is known, which has an outer side, ie a side facing the surroundings, and an inner side, ie a side facing the vehicle interior. The vehicle glazing has a partially transparent polymeric material phase on the outside and an opaque polymeric material phase on its inside. The opaque polymeric material phase is injected in at least one section of the partially transparent polymeric material phase by multi-component injection molding.

From the international patent application WO 2014/060338 A1 a polymer vehicle window is known which has an inner, opaque polymeric material phase and an outer, partially transparent, polymeric material phase, which are connected to one another over a large area. The inner, opaque, polymeric material phase has at least one at least partially continuous recess. An LED arrangement, which comprises at least one LED, a circuit board (PCB) and an electrical contact, is arranged in the recess. The LED array is placed so that the LED is placed towards the outer transparent array.

From the international patent application WO 2013/092253 A1 a heatable lamp cover is known which has at least one polymeric disk base body and a first busbar, a second busbar and at least two conductor tracks which are arranged on the inside of the polymeric disk base body. Each conductor track is electrically connected to the first busbar and to the second busbar.

From the international patent application WO 2013/087290 A1 a polymeric workpiece is known which comprises at least an upper major surface and a lower major surface, an injection mold parting surface and a fluting edge surface. The approach edge surface in the area between the injection molding tool separation surface and the lower main surface is formed as a planar surface with an angle alpha to the injection molding tool separation surface of 20 ° to 70 ° and / or deviates by an amount a of 0.0 mm to 0.5 mm from the planar surface. The polymer workpiece is used as a disk, as a component of a disk or as a plastic cover for means of transport for traffic on land, in the air or on water, in particular as a rear, windshield, side and roof window and as a light cover, decorative strip and / or as the roof of cars, trucks, buses, trams, subways, trains and motorcycles.

From the international patent application WO 2008/137946 A1 a polymeric panel system is known which comprises a transparent polymeric panel and an electrically conductive grid. The panel system comprises a substrate, the electrically conductive grid being arranged in such a way that it rests on the substrate. The grid contains at least one electrically conductive holder. Furthermore, an electrical connection, which comprises a plastic part and an electrically conductive part, is attached to the polymeric panel by ultrasonic welding of the plastic part. As a result of the retention of the electrical connection with the panel, the electrically conductive part of the panel is in electrical contact with the electrical connection of the grid. The disadvantage here is that the entire arrangement is comparatively complex and expensive to manufacture.

From the international patent application WO 2007/076502 A1 an arrangement for de-icing for use in a motor vehicle is known. The arrangement comprises a transparent panel and a de-icing grille, which is formed together with the transparent panel with the aid of an automatic spray gun. The defrost grille includes first and second Busbars and a plurality of electrically conductive conductor tracks extending between the first and second busbars.

From the international patent application WO 2006/091955 A1 a method for producing polymeric plastic disks is known. In the process, a transparent polymer panel is first produced, which is then covered with a protective layer. Then electrically conductive ink in the form of a heating grid with several conductor tracks is applied between at least two busbars. The electrically conductive ink is then hardened, thereby establishing the electrical connection to each busbar. Finally, the resistance of the heater grille is reduced by the application of electrical surges.

From the international patent application WO 2006/063064 A1 a plastic pane with a de-icing device is also known, which comprises a grid of electrically conductive conductor tracks which is produced by printing the transparent plastic pane with an electrically conductive ink. The electrically conductive ink has a sheet resistance of less than 8 milliohm □ @ 25.4 µm (note: the name was taken from the patent application).

Some of the known plastic disks have in common that the busbars and in some cases the conductor tracks are produced with electrically conductive inks. Due to the heat sensitivity of the plastic panes, these inks cannot be hardened at temperatures> 300 ° Celsius, as is possible with glass windows, but only at temperatures <300 ° Celsius. As a result, the cured busbars and conductor tracks on the plastic panes do not easily achieve the same electrical conductivity as busbars and conductor tracks on glass, but additional measures must be taken, such as the use of special inks and / or treatment with high-energy current pulses to achieve this.

Furthermore, in the European patent application EP 2 794 366 A1 or the German patent application DE 000010147537 Plastic disks with soldered-on or clamped-on metal strips are described.

From the German patent application DE 10 2009 048 397 A1 an atmospheric pressure plasma process and a corresponding device for producing surface-modified particles and coatings are known. In this procedure, the plasma is generated by a discharge between electrodes in a process gas. At least one of the electrodes is a sputtering electrode, from which particles are sputtered off by the discharge. This process can be used to produce composite materials in which surface-modified particles are incorporated into a matrix. In addition, coatings can be produced with particles dispersed therein, whereby agglomeration problems can largely be avoided even with micro- and nanoparticles.

From the German patent application DE 10 2008 058 783 A1 a method for applying a layer to a nano-surface of a workpiece is known. In this process, an atmospheric plasma jet is generated by electrical discharge in a process gas, and precursor materials are fed directly to the plasma jet, spatially separated from the process gas. The applied layer has a nanosurface corresponding to the nanosurface of the workpiece.

From the German patent application DE 10 2008 029 681 A1 an atmospheric pressure plasma method is also known for applying a self-cleaning layer, in particular a self-cleaning and / or antimicrobial photocatalytic layer, to a surface. In the process, an atmospheric plasma jet is also generated by electrical charge in a process gas, and a precursor material is introduced directly into the plasma jet as an aerosol, separate from the process gas.

WO 2013/091964 A1 discloses a pane in which a heating conductor is not embedded in the area of the busbar and a method according to the preamble of claim 1.

Accordingly, the object of the present invention is to find a method for depositing a busbar on vehicle plastic panes with a heating function, which method no longer has the disadvantages of the prior art. In particular, the process should be simple and completely automated, require no manual labor and only a short cycle time, should not release any solvent vapors or other harmful substances and should be able to be integrated into the manufacturing process without problems.

Whether and, if so, to what extent the known atmospheric pressure plasma processes, the known atmospheric pressure plasma coating (fine powder coating process, FPC) and the devices used for this purpose for the production of busbars for vehicle plastic windows are suitable with a heating function, is not apparent from the above-mentioned patent applications.

The object of the invention is achieved according to the invention by a method according to independent claim 1. Advantageous embodiments are the subject of the dependent claims.

In view of the prior art, it was surprising and not foreseeable for the person skilled in the art that the object of the invention could be achieved with the aid of the method according to the invention. In particular, it was surprising that the method according to the invention for depositing a busbar on vehicle plastic panes with a heating function no longer had the disadvantages of the prior art. The process can be carried out easily and completely automatically and requires no manual work and only a short cycle time. No solvent vapors or other harmful substances are released and the method according to the invention can be integrated into the manufacturing process without any problems.

The vehicle plastic panes produced with the aid of the method according to the invention have excellent application properties and a very long service life.

• einen ein- oder zweikomponentigen, teiltransparenten, polymeren Scheibengrundkörper,
• einen ein- oder zweischichtigen Hardcoat,
• mindestens eine, insbesondere eine, erste und mindestens eine, insbesondere eine, zweite Stromsammelschiene oder Busbar mit entgegengesetzter elektrischer Ladung, die im Wesentlichen oder exakt parallel zueinander in einem (gewissen) Abstand voneinander, insbesondere nahe und längs zweier einander gegenüberliegenden Kanten des Scheibengrundkörpers, angeordnet sind, wobei die Stromsammelschienen,
• über mindestens zwei, vorzugsweise mindestens drei, bevorzugt mindestens vier und insbesondere mindestens fünf Leiterbahnen als Heizdrähte elektrisch miteinander verbunden sind, so dass bei Anlegen einer Spannung ein Heizstrom von der mindestens einen ersten zu der mindestens einen zweiten Stromsammelschiene fließt, sowie
• auf und/oder in jeder Stromsammelschiene mindestens ein, insbesondere ein, Anschlusselement zum elektrischen Verbinden der mindestens einen ersten und der mindestens einen zweiten Stromsammelschiene mit jeweils einem Pol einer Spannungsquelle.

The vehicle plastic pane produced using the method according to the invention comprises, preferably lying one above the other in this order,

• a one- or two-component, partially transparent, polymeric base body,
• a one or two-layer hard coat,
• at least one, in particular one, first and at least one, in particular one, second busbar or busbar with opposite electrical charge, which are arranged essentially or exactly parallel to one another at a (certain) distance from one another, in particular near and along two opposing edges of the disk base body are, where the busbars,
• are electrically connected to one another via at least two, preferably at least three, preferably at least four and in particular at least five conductor tracks as heating wires, so that when a voltage is applied, a heating current flows from the at least one first to the at least one second busbar, and
• on and / or in each busbar at least one, in particular one, connection element for electrically connecting the at least one first and the at least one second busbar, each with one pole of a voltage source.

The at least one first busbar and the at least one second busbar should have an opposite electrical charge, i.e. are intended to be connected to electrical connections of opposite polarity.

In a preferred embodiment of the vehicle plastic window to be produced according to the invention, the arrangement comprising at least one hardcoat, at least two heating wires and at least one first and at least one second busbar is produced on the inside of the window body when installed. In a particularly preferred embodiment, each heating wire is electrically connected to the first and second busbars and is supplied with voltage independently of the other conductor tracks, so that damage to a heating wire does not lead to a complete failure of the heating of the vehicle plastic window.

In the context of the present invention, “inside” means that side of the vehicle plastic pane which faces an interior, in particular of a vehicle, and / or a light source, in particular of a vehicle. In contrast to this, in the context of the present invention, “outside” means that side of the vehicle plastic window that faces the surroundings.

In a further preferred embodiment of the vehicle plastic pane to be produced according to the invention, the partially transparent, polymeric pane base body is equipped with an opaque coating in such a way that the busbars are covered at least towards the outside of the vehicle plastic pane.

In yet another preferred embodiment, the heating wires are applied partly to the opaque coating and partly to the transparent, polymeric disk base body in such a way that they are embedded in the relevant surfaces.

• die Außenseite der Fahrzeug-Kunststoffscheiben und/oder auf ihre Innenseite unmittelbar auf die Oberfläche der opaken Beschichtung und des transparenten, polymeren Scheibengrundkörpers und unterhalb der Stromsammelschienen und/oder
• ihre Innenseite auf die Oberfläche des transparenten, polymeren Scheibengrundkörpers und die Oberfläche der Stromsammelschienen

aufgetragen.In yet another preferred embodiment, a one- and / or two-layer hard coat is applied

• the outside of the vehicle plastic panes and / or on their inside directly on the surface of the opaque coating and the transparent, polymeric pane base body and below the busbars and / or
• their inside on the surface of the transparent, polymeric disk base body and the surface of the busbars

applied.

The two-layer hardcoat also has a basecoat that is covered by the hardcoat.

The vehicle plastic panes described above are produced with the aid of the method according to the invention.

In the first process step of the process according to the invention, the transparent, polymeric base body is provided. It has the typically curved shape that is suitable for the particular application of the motor vehicle plastic window. It therefore does not have to be further reshaped before it is connected to the other components of the vehicle plastic pane. However, processing steps that are not accompanied by a change in the bending of the disk base body, e.g. the production of bores, millings or trims, are possible in the edge area within the scope of the method according to the invention.

According to the invention, the transparent, polymeric disk base body is provided before the heating wires are applied. The heating wires are therefore not loaded during the deformation of the disk base body. The particular advantage lies in the avoidance of damage to the heating wires and / or their electrical contact. The first and second busbars also provide stable electrical contact with each individual heating wire.

The transparent, polymeric disk base body can be produced by all suitable plastics processing methods known to those skilled in the art, for example by thermoforming. In a preferred embodiment of the method according to the invention, the transparent, polymeric disk base body is produced by injection molding or by the two-component injection-compression molding process using reversible plate technology. These methods allow a greater number of suitable shapes to be made. In addition, the transparent, polymeric base body can be produced with virtually no waste because subsequent trimming of the workpiece is not necessary. Complex surface structures can also be produced directly.

The transparent, polymeric pane base preferably contains at least polyethylene (PE), polycarbonates (PC), polypropylene (PP), polystyrene, polybutadiene, polynitriles, polyesters, in particular polyethylene terephthalate (PET), polyurethanes (PU), polymethyl methacrylates (PMMA), polyacrylates, polyamides (PA), acrylonitrile-butadiene-styrene copolymers (ABS), styrene-acrylonitrile copolymers (SAN), acrylic ester-styrene-acrylonitrile copolymers (ASA), acrylonitrile-butadiene-styrene-polycarbonate blends (ABS / PC) and / or their copolymers, cocondensates and / or their blends.

The transparent, polymeric pane base body particularly preferably contains polycarbonate (PC) and / or polymethyl methacrylate (PMMA) or consists of these polymers. These prove to be particularly advantageous in terms of transparency, processing, strength, weather resistance and chemical resistance.

The partially transparent, polymeric disk base body preferably has a thickness of 2 mm to 6 mm. This is particularly advantageous with regard to the strength and processing of the polymeric disk base body. The size of the partially transparent, polymeric disk base body can vary widely and depends on the use according to the invention.

According to the invention, the partially transparent, polymeric disk base body is at least partially transparent. The polymeric disk base body can be colorless, colored or tinted. The polymeric disk base body can be clear or cloudy, but in particular clear.

The heating wires preferably run in a straight line between the first and second busbars. The heating wires can, however, also run, for example, in a wave-like, meander-like manner or in the form of a zig-zag pattern between the first and second busbars. The distance between two adjacent heating wires is preferably constant over the entire length of the conductor tracks. The distance between two adjacent heating wires can, however, also change in the course between the first and the second busbar.

The heating wires can run in any direction, but preferably horizontally or vertically.

The heating wires are preferably applied by means of ultrasound embedding to the partially transparent, polymeric base body and, if present, to the opaque coating. In this case, a sonotrode is guided over the inside of the partially transparent, polymeric disk base body, preferably with a multi-axis robot via a robot program adapted to the three-dimensional geometry of the partially transparent polymeric disk base body. The sonotrode transmits high-frequency mechanical vibrations (ultrasound) generated by an ultrasound generator to the partially transparent, polymeric disk base body and, if present, to the opaque coating. In the process, heat is generated and a surface layer on the inside of the partially transparent, polymeric base body is melted. The heating wires are inserted into the melted surface layer. For this purpose, the sonotrode has a heating wire at its tip, with the heating wire being continuously fed in via a wire roll near the sonotrode. A tool suitable as a sonotrode is, for example, off U.S. 6,023,837 A known.

The depth of penetration of the heating wires into the partially transparent polymeric base body and optionally into the opaque coating is preferably from 50% to 90%, particularly preferably from 60% to 75% of the thickness of the heating wires. The uncomplicated application of the heating wires by means of ultrasonic embedding is particularly advantageous with regard to a stable connection between the heating wires and the partially transparent, polymeric base body and, if applicable, the opaque coating.

The distance between two adjacent heating wires is preferably from 1 mm to 25 mm, particularly preferably 3 mm to 15 mm. This is particularly advantageous with regard to the transparency of the vehicle plastic pane and the distribution of the heating power introduced via the heating wires. The length of the heating wires can vary widely and can thus easily be adapted to the requirements of the individual case. The heating wires have lengths of 5 cm to 50 cm, for example.

The heating wires contain at least one metal, preferably tungsten, copper, nickel, manganese, aluminum, silver, chromium and / or iron, as well as mixtures and / or alloys thereof. The heating wires particularly preferably contain tungsten and / or copper. A particularly good heating effect is achieved in this way. The thickness of the heating wires is preferably 15 μm up to 200 µm, particularly preferably from 25 µm to 90 µm. This is particularly advantageous with regard to the transparency of the vehicle plastic pane, the heating power introduced and the avoidance of short circuits.

It has been shown that particularly good results are achieved with heating wires which contain tungsten and have a thickness of preferably 15 μm to 100 μm, particularly preferably 25 μm to 50 μm. Particularly good results are also achieved with heating wires which contain copper and have a thickness of preferably 25 μm to 200 μm, particularly preferably 60 μm to 90 μm.

Adjacent heating wires can be connected to one another on the side of the first busbar facing away from the second busbar or on the side of the second busbar facing away from the first busbar. The heating wires can thus be applied in the form of a single heating wire to the partially transparent, polymeric disk base body and optionally to the opaque coating, the heating wire comprising two or more sections after application, which are provided as conductor tracks and which are connected to one another in a loop-like manner. Each section of the heating wire provided as a conductor track is connected to the first busbar in the area of one end and to the second busbar in the area of the other end. Each section of the heating wire in the area of the busbars and between the busbars forms a conductor path.

Alternatively, adjacent heating wires on the side of the first busbar facing away from the second busbar and on the side of the second busbar facing away from the first busbar can not be connected to one another. The conductor tracks are applied in the form of several heating wires to the partially transparent, polymeric disk base body and, if necessary, to the opaque coating, each heating wire being connected to the first busbar in the area of one end and to the second busbar in the area of the other end. Each heating wire comprises a conductor track in the area of the busbars and between the busbars.

At least one section of each heating wire is embedded in the partially transparent, polymeric disk base body and, if appropriate, in the opaque coating. The heating wires are embedded in the partially transparent polymeric base body along their entire length. This is particularly advantageous in terms of a stable

Connection between the partially transparent, polymeric base body and the heating wires. The electrical contact with the first and second busbars then takes place on the side of the heating wires facing away from the partially transparent, polymeric disk base body and optionally from the opaque coating.

In one embodiment, which is not part of the invention, the areas provided for electrical contact with the busbars at the ends of the heating wires are not embedded in the partially transparent, polymeric disk base body and optionally the opaque coating and can be lifted off from them. The particular advantage lies in the possibility of a simple and stable electrical contact with the busbars. The particular advantage lies in the effective and very stable electrical contacting of the heating wires. To heat the vehicle plastic window, an electrical potential is applied to the first, in the installed state, lower or left busbar and the second, in the installed state, upper or right busbar.

According to the invention, the first and the second busbar are applied by means of the FPC method. For this purpose, a metal powder is introduced into an atmospheric pressure plasma, melted in the plasma jet and passed onto the substrate to be coated, comprising the heating wires and the disk base body and / or optionally the opaque coating and / or optionally the hardcoat, on which a metal layer is subsequently deposited .

The metal powder is preferably selected from the group consisting of powders of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, Platinum, copper, silver, gold, zinc and aluminum and their mixtures and alloys from at least two of these metals. Tungsten, copper, nickel, manganese, aluminum, silver, chromium and / or iron and their mixtures and / or alloys are preferably used. Copper or aluminum is particularly preferably used.

• DE 10 2009 048297 A1 , Absätze [0017] bis [0070] in Verbindung mit den Figuren 1 bis 3,
• DE 10 2008 058783 A1 , Absätze [0001] bis [0044] in Verbindung mit den Figuren 1 bis 2c, und
• DE 10 2008 029 681 A1 , Absätze [0010] bis [0045] in Verbindung mit den Figuren 1 bis 4,

hervor.The fine powder coating (FPC) method or the atmospheric pressure plasma coating is a common and known method for which common and known devices are used. Examples of suitable methods and devices can be found in the German patent applications

• DE 10 2009 048297 A1 , Paragraphs [0017] to [0070] in connection with the Figures 1 to 3 ,
• DE 10 2008 058783 A1 , Paragraphs [0001] to [0044] in connection with the Figures 1 to 2c , and
• DE 10 2008 029 681 A1 , Paragraphs [0010] to [0045] in connection with the Figures 1 to 4 ,

emerged.

The busbars preferably have a thickness of 10 μm to 200 μm, particularly preferably 50 μm to 100 μm. The width of a busbar, along which the busbar is connected to the heating wires, is preferably from 2 mm to 100 mm, particularly preferably from 5 mm to 20 mm. The length of the busbars can vary widely and thus be perfectly adapted to the requirements of the individual case. The minimum length of the busbars results from the number of heating wires and the distance from neighboring heating wires. The length of the busbars is, for example, from 5 cm to 20 cm. The busbars are connected to an external voltage supply so that an electrical potential difference can be applied between the first and the second busbar.

For aesthetic reasons, it may be desirable that the electrical contacting of the heating wires by means of the busbars is not visible from the outside. For this purpose, for example, the partially transparent, polymeric disk base body in the area of the busbars can be colored or blackened. The partially transparent, polymeric disk base body can be produced, for example, by multi-component injection molding, the partially transparent polymeric disk base body comprising an opaque coating in the areas on which the busbars are to be arranged, which provides a view of the electrical contact through the partially transparent, polymeric disk base body covered.

The opaque coating of the partially transparent, polymeric base body preferably contains at least polyethylene (PE), polycarbonate (PC), polypropylene (PP), polystyrene, polybutadiene, polynitrile, polyester, polyurethane, polymethyl methacrylate, polyacrylate, polyester, polyamide, polyethylene terephthalate, acrylonitrile butadiene Styrene (ABS), styrene-acrylonitrile (SAN), acrylic ester-styrene-acrylonitrile (ASA), acrylonitrile-butadiene-styrene - polycarbonate (ABS / PC) and / or copolymers and cocondensates or mixtures thereof, especially preferably polycarbonate (PC), polyethylene terephthalate (PET) and / or polymethyl methacrylate (PMMA).

The opaque coating of the partially transparent, polymeric base body preferably contains at least one colorant. The opacity of the coating is achieved by the colorant. The colorant can contain inorganic and / or organic dyes and / or pigments. The colorant can be colored or achromatic. Suitable colorants are known to the person skilled in the art and can be looked up , for example, in the Color Index of the British Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. A black pigment is preferably used as the colorant, for example carbon black, aniline black, bone black, iron oxide black, spinel black and / or graphite. This creates a black, opaque coating.

The opaque coating can further contain inorganic or organic fillers, particularly preferably SiO ₂ , Al ₂ O ₃ , TiO ₂ , clay minerals, silicates, zeolites, glass fibers, carbon fibers, glass spheres, organic fibers and / or mixtures thereof. The fillers can further increase the stability of the opaque coating. In addition, the fillers can reduce the proportion of polymeric materials and thus reduce the production costs of the vehicle plastic window.

Alternatively, a colored or blackened element can be arranged between the busbar and the partially transparent, polymeric disk base body. Alternatively, cover screen prints can be applied to a surface of the partially transparent, polymeric disk base body.

In the method according to the invention, a one- or two-layer hardcoat is also applied to the outside of the partially transparent, polymeric window body as a protective coating in order to protect the vehicle plastic window to be produced according to the invention from environmental influences. Thermally curing or UV-curing lacquer systems based on polysiloxanes, polyacrylates, polymethacrylates and / or polyurethanes are preferably used. The hard coat preferably has a layer thickness of 1 μm to 50 μm, particularly preferably 2 μm to 25 μm. The particular advantage lies in the increased scratch resistance and weather resistance of the partially transparent, polymeric base body due to the protective coating.

In the context of the present invention, “two-layer hardcoat” means a combination of at least one, in particular one, hardcoat with at least one, in particular one, basecoat covered by the hardcoat, described in more detail below.

In addition, the one- or two-layer hardcoat can also be applied to the inside of the vehicle plastic pane to be produced according to the invention. It can be applied directly to the surface of the partially transparent, polymeric disk base body and the opaque coating, so that the heating wires are also embedded in the hard coat and the busbars cover the hard coat.

The additional one- or two-layer hardcoat can also be applied in such a way that it covers the busbars.

In addition to coloring compounds and pigments, the hardcoat can also contain UV blockers, preservatives and components to increase scratch resistance, for example nanoparticles.

The hardcoat can be applied to the outside and / or the inside of the partially transparent, polymeric disk base body, for example by a dipping, flooding or spraying process. After application, the hardcoat is preferably cured by applying temperature and / or UV light. When the polymeric disk base body is produced by injection molding, the hardcoat can also be applied to the outside of the polymeric disk base body by an in-mold coating process.

Products suitable as a protective coating or hard coat are, for example, AS4000, AS4700, PHC587 or UVHC3000, which are provided by Momentive Performance Materials.

The hard coat can also comprise several layers, preferably a base coat, which also functions as an adhesion-promoting layer or primer on the partially transparent, polymeric base body of the pane. The basecoat can contain acrylates, for example, and have a layer thickness of 0.4 µm to 5 µm. The hardcoat can contain polysiloxanes, for example, and typically has a layer thickness of 3 μm to 15 μm. The hardcoat can also be covered with a plasma CVD layer, such as Exatec® 900.

The protective coating, i.e. the hardcoat and, if necessary, the basecoat, can or can be applied before or after the heating wires and busbars are attached. The protective coating can be applied before or after connecting the heating wires to the busbars.

In a preferred embodiment, the surfaces to which the busbars are applied by the FPC method can still be activated before application in order to ensure better adhesion of the metal layer. For this purpose, chemical activators or adhesion promoters based on silane can be used, or the surfaces can be activated by means of plasma activation. This plasma activation can be directly upstream of the deposition process and can be implemented by an additional plasma nozzle on the robot arm of the device for atmospheric pressure plasma coating.

The heatable vehicle plastic panes are preferred as panes for means of transport on land, in the air and / or on water, in particular for passenger cars, trucks, buses, trams, subways, trains, motorcycles, ships and planes and as decorative elements and / or used as architectural elements.

In addition, the heatable vehicle plastic panes can be used with advantage as a cover for lights of means of transport for traffic in the country, in the air or on water, in particular for headlights, rear, side marker and / or clearance lights of cars, trucks, buses , Trams, subways, trains, motorcycles, ships and planes.

Figur 1

einen Querschnitt durch einen Ausschnitt aus einer ersten Ausführungsform einer erfindungsgemäß hergestellten Fahrzeug-Kunststoffscheibe FKS,

Figur 2

einen Querschnitt durch einen Ausschnitt aus einer zweiten Ausführungsform einer erfindungsgemäß hergestellten Fahrzeug-Kunststoffscheibe FKS,

Figur 3

einen Querschnitt durch einen Ausschnitt aus einer dritten Ausführungsform einer erfindungsgemäß hergestellten Fahrzeug-Kunststoffscheibe FKS,

Figur 4

einen Querschnitt durch einen Ausschnitt aus einer vierten Ausführungsform einer erfindungsgemäß hergestellten Fahrzeug-Kunststoffscheibe FKS,

Figur 5

einen Querschnitt durch einen Ausschnitt aus einer fünften Ausführungsform einer erfindungsgemäß hergestellten Fahrzeug-Kunststoffscheibe FKS,

Figur 6

eine Draufsicht auf einen Ausschnitt aus einer ersten Ausführungsform einer erfindungsgemäß hergestellten Fahrzeug-Kunststoffscheibe FKS,

Figur 7

ein Fließschema einer Ausführungsform des erfindungsgemäßen Verfahrens und

Figur 8

ein Fließschema einer weiteren Ausführungsform des erfindungsgemäßen Verfahrens.

The invention is explained in more detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and are not true to scale. The drawings do not limit the invention in any way. Show it:

Figure 1

a cross section through a section from a first embodiment of a vehicle plastic window FKS produced according to the invention,

Figure 2

a cross section through a section from a second embodiment of a vehicle plastic window FKS produced according to the invention,

Figure 3

a cross section through a section from a third embodiment of a vehicle plastic window FKS produced according to the invention,

Figure 4

a cross section through a section from a fourth embodiment of a vehicle plastic window FKS produced according to the invention,

Figure 5

a cross section through a section from a fifth embodiment of a vehicle plastic window FKS produced according to the invention,

Figure 6

a top view of a section from a first embodiment of a vehicle plastic window FKS produced according to the invention,

Figure 7

a flow sheet of an embodiment of the method according to the invention and

Figure 8

a flow sheet of a further embodiment of the method according to the invention.

Detailed description of the figures

Figure 7 shows the flow diagram of a preferred embodiment of the method according to the invention. Method step A comprises the provision of two partially transparent, polymeric window body 1 made of polycarbonate PC for the production of vehicle plastic windows FKS, such as those used for rear windows of cars. The disk base body 1 has the dimensions 1 m × 0.5 m × 0.004 m.

In the following process step F, each pane base body 1 is provided in the edge area with the aid of screen printing with a 0.05 m wide, 10 μm thick, circumferential, opaque, carbon black pigment-containing coating 2 based on polyurethane PU.

Subsequently, the outside II of the one disk base body 1 is coated in process step B by flow coating with a commercially available single-layer hardcoat 6 (PHC587C from Momentive Performance Materials).

In a variant of process step B, a customary and known basecoat 5 (SHP470 from Momentive Performance Materials) with an average thickness of 3 μm is applied to the outside II of the other pane base body 1 by flow coating. After the base coat 5 has cured, the hard coat 6 (AS4700 from Momentive Performance Materials) is applied and also dried.

Thereafter, in process step C, a tungsten wire with a length of 1710 mm and a thickness of 60 µm in the form of 38 loops, the distance from one another in the area of the straight wire sections extending parallel to one another, is about 25 mm (cf. the configuration of the Figure 6 ), applied with the help of ultrasonic embedding. The penetration depth of the heating wire is 65% of its thickness.

Then in process step D, at a distance of 50 mm from the two parallel longitudinal edges, a busbar 4 with a length of 980 mm, along which the busbars 4 are connected to the heating wires 3, with the help of the FPC process with a width of 15 mm and a thickness of 75 µm. It turns out that the electrical contact between the busbars 4 and the heating wire 3 is excellent and practically lossless.

Finally, in method step E, a connection element 7 is applied to each of the busbars 4 for contacting one pole of a current source.

The Figure 8 shows the flow diagram of a further preferred embodiment of the method according to the invention, which differs from the first embodiment in that the coating B with a single-layer hardcoat 6 or a two-layer hardcoat 6 with basecoat 5 on both the inside I and the outside II by flow coating according to the Method steps A, F, C, D, E is applied, care having to be taken that the connection elements 7 remain free so that they can be electrically connected to the poles of a voltage source.

The Figures 1 to 5 show cross-sections from details of the vehicle plastic panes FKS which can be produced according to the invention. The respective embodiment of the method according to the invention results in a simple manner from the respective desired structure of the vehicle plastic panes FKS. In the top view, the details of the Figures 1 to 5 the configuration of the Figure 6 .

So shows Figure 1 , seen from the inside I to the outside II, a busbar 4 which covers the contact points with the loop-shaped heating wire 3. The heating wire 3 is embedded in the opaque coating 2. The opaque coating 2 rests on the partially transparent, polymeric disk base body 1. The outside II is covered with a hard coat 6.

The Figure 2 shows, viewed from the inside I to the outside II, a bus bar 4 which covers the contact points with the loop-shaped heating wire 3. The heating wire 3 itself is embedded in the hard coat 6 and the opaque coating 2 underneath. The opaque coating 2 in turn rests on the partially transparent, polymeric disk base body 1. The outside II is also covered with a hard coat 6.

The Figure 3 shows, viewed from the inside I to the outside II, a bus bar 4 which covers the contact points with the loop-shaped heating wire 3. The heating wire 3 itself is embedded in the hard coat 6 and in a basecoat 5 underneath, which rests on the opaque coating 2. The opaque coating 2 in turn rests on the partially transparent, polymeric disk base body 1. The outside II is also covered with a basecoat 5 and a hardcoat 6.

The Figure 4 shows, viewed from the inside I to the outside II, a hard coat 6 on a busbar 4, which covers the contact points with the loop-shaped heating wire 3. The heating wire 3 itself is embedded in the opaque coating 2. The opaque coating 2 in turn rests on the partially transparent, polymeric disk base body 1. The outside II is also covered with a hard coat 6.

The Figure 5 shows, viewed from the inside I to the outside II, a hard coat 6 on a base coat 5 which covers the busbar 4. The busbar 4 in turn covers the contact points with the loop-shaped heating wire 3. The heating wire 3 itself is embedded in the opaque coating 2. The opaque coating 2 in turn, the partially transparent, polymeric disk base body 1 rests on it. The outside II is also covered with a basecoat 5 and a hardcoat 6.

List of reference symbols:

1

Partly transparent, polymeric base body

2

opaque coating

3

Heating wires

4th

Busbar

5

Basecoat

6th

Hard coat

7th

Connection element

I.

inside

II

Outside

FKS

Vehicle plastic window

Claims (11)

1. Method for producing a vehicle plastic pane (FKS) with a heating function, which comprises at least

   - a one- or two-component, semi-transparent polymeric pane base body (1),

   - at least a single-layer hardcoat (6) or double-layer hardcoat (6) with a basecoat (5),

   - at least a first and at least a second busbar (4) having opposing electrical charge, which are arranged substantially or exactly parallel to one another at a certain distance from one another, and

   - are electrically connected to one another using at least two conducting paths as heating wires (3), such that upon application of a voltage, a heating current flows from the at least one first busbar (4) to the at least one second busbar (4), as well as

   - on and/or in each busbar (4), at least one connection element (7) for the electrical connection of the at least one first and the at least one second busbar (4) to, in each case, a pole of a voltage source,

   using the following process steps in the order:

   (A) Providing a one- or two-component, semi-transparent, polymeric pane base body (1),

   (B) Coating the pane base body (1) with at least one single-layer hardcoat (6) or at least one double-layer hardcoat (6) with a basecoat (5),

   (C) Embedding the heating wires (3) in such a way that they can be in direct electrical contact with the busbars (4),

   (D) Depositing the busbars (4) in direct electrical contact with the heating wires (3), as well as

   (E) Mounting at least one connection element (7) on and/or in the at least one first and the at least one second busbar (4)

   or, alternatively, in the order (A), (C), (D), (E) and (B), wherein the connection elements (7) remain exposed,
   characterized in that the heating wires are embedded along their entire length, that the heating wires (3) are partially exposed, at least in the region of the at least one first and the at least one second busbar (4), such that they are in direct electrical contact with the busbars (4), and that
   the process step (D) is performed using the fine powder coating (FPC) plasma process at atmospheric pressure.
2. Method according to claim 1, characterized in that
   (F) the semi-transparent, polymeric pane base body (1) is equipped, at least in the region of the busbars (4), with an opaque coating (2) in such a way that the busbars (4) are optically covered at least in the direction of the outer surface of the vehicle plastic pane (FKS).
3. Method according to claim 2, characterized in that the process step (F) is performed after the process step (A) and before the process step (B) or, alternatively, before the process step (C).
4. Method according to one of claims 1 through 3, characterized in that the embedding (C) of the heating wires (3) is performed before the process step (D).
5. Method according to one of claims 1 through 4, characterized in that the embedding of the heating wires (3) is done using ultrasonic embedding.
6. Method according to one of claims 1 through 5, characterized in that the coating (B) is performed using flow coating.
7. Method according to one of claims 1 through 6, characterized in that the polymeric surface and/or the coating surface, on which the busbar(s) (4) is or are applied, are activated before the deposition (D) in a process step (G).
8. Method according to claim 7, characterized in that the activation (G) is done with chemical activators and/or silane-based adhesion promoters.
9. Method according to claim 8, characterized in that the activation (G) is done by means of plasma activation.
10. Method according to one of claims 1 through 9, characterized in that during the deposition (D) by means of the FPC method, a metal powder is introduced into an atmospheric pressure plasma, melted in the plasma jet, and guided onto the substrate to be coated, comprising the heating wires (3) and the opaque coating (2) as well as the pane base body (1) and/or the hardcoat (6), onto which a metal layer is deposited as a result.
11. Method according to claim 10, characterized in that the metal powder is selected from the group consisting of powders of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, rhenium, iron, ruthenium, osmium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, and aluminum and their mixtures and alloys of at least two of these metals.

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