CH717370B1 - Coating system for a surface, coating, vehicle part, vehicle and method for coating. - Google Patents

Abstract

The present invention relates to a coating system for a surface, comprising a film and a protective varnish, wherein the protective varnish contains at least a two-component varnish and a plasticizer component, and can be applied to the film by means of a painting process. The present invention also includes a coating made from a coating system, a vehicle part and a vehicle with a coating, and a method for coating a surface.

Description

Technical field of the invention

The invention relates to a coating system for a surface. The coating system according to the invention basically comprises a printed and/or labeled film-like substrate onto which a protective varnish can be applied and therefore provides anti-graffiti protection for the surface covered with it. The invention further relates to a coating made from a coating system, a vehicle part and a vehicle with a coating and to a method for coating a surface.

State of the art

Vehicles, for example transport vehicles such as buses, trucks or even boats, airplanes etc., as well as rail vehicles but also vehicle parts, are increasingly being designed visually in order to be used, for example, as advertising media or for identification purposes, such as in police vehicles or ambulances. For this purpose, foiling, which is advantageous in many respects, can be used instead of complex painting of the surface. Accordingly, a coating is known in which films, possibly coated, can be applied or laminated to a surface to be designed. Corresponding films can have a multi-layer structure, in particular an adhesive layer for fixing the film to the surface and one or more coating layers being provided. A film coating represents an ecologically and economically advantageous alternative to the known paint finish and also offers protection of an existing paint finish on the surface against environmental influences and damage.

A film produced using modern printing techniques with a variety of design options is suitable for a film coating, with 3D reliefs and/or lettering, logos, stripes, photographs, etc. being printed onto a film-like carrier material. The film coating can be applied in the form of a full film to a surface covered with a varnish. In a so-called full vehicle wrapping, or car wrapping, for example, a self-adhesive PVC film or a polyester-containing laminate, which is highly elastic, stretchable and mechanically stable, is applied over a large area to the outer skin of a vehicle. Such a film is used for design purposes, but also for labeling purposes or as a paint protection film, with production times and effort being significantly reduced compared to painting. In addition to the visual effect to be achieved, the requirement is also met that the underlying paintwork on the laminated surface is not damaged when the applied film is removed.

In an alternative film coating, a sprayable paint system containing linear polymers is used, which dries as a film-forming liquid film to form a peelable film and thus provides a weatherproof coating. Such a film coating is known in particular for temporary protection of vehicles during transport, whereby it is relevant that the liquid film acting as a protective lacquer prevents the underlying paint layer from swelling.

It is also known to apply a film to the surface of the object to be protected for permanent protection of objects against manipulation, for example through soiling, paint smearing or graffiti. Depending on the object, the surface to be protected can be designed using a film coating or painting. The film, known as a protective film, should in particular be easy to clean and/or have a top layer that makes it difficult for graffiti to adhere. The protective film should also be easy to remove from the object surface in order to replace it with a new one in case of doubt, while the underlying surface should remain as new without any damage. Corresponding film-like protective compositions can have a multi-layer structure, i.e. a protective coating is applied to a possibly self-adhesive polyester film in order to provide a hydrophobic surface which can be easily cleaned, even several times, i.e. residues can be easily removed and also shows high scratch resistance.

Anti-graffiti protection systems are known which contain an adhesion-preventing protective varnish as the first system component and a removable varnish designed as a removable film as the second system component. However, with such known anti-graffiti protection systems, the film cannot be removed without damage.

Defined fire protection regulations apply to the materials used in public transport, such as buses and trains, both in the interior and exterior areas. Accordingly, the paintwork and/or foiling used for the exterior design, for example of rail vehicles, must also be tested and approved accordingly.

Summary of the invention

The object of the present invention is to provide a coating system for a surface which simultaneously ensures protection against vandalism by spraying or smearing with paint and also a high level of fire protection without negatively influencing the visual appearance of the surface designed using the coating system. The application of a suitable protective lacquer to a film, which together form the coating system, and to a film coated in this way on the surface should be unproblematic and should preferably be possible under ambient conditions within a reasonable period of time. Accordingly, the coating system is provided, comprising an optically designed film with a protective varnish which shows excellent anti-graffiti properties.

Surfaces to be laminated, to which the coating system according to the invention can be applied, can in particular be made of metal such as steel, stainless steel, zinc, aluminum or alloys thereof, as well as plastic such as polyurethanes, polycarbonates, polyolefins or other materials suitable for example in automobile construction. The surfaces to be laminated are preferably those of a vehicle, in particular a transport vehicle. The coating system is preferably self-adhesive and adheres to the surface to be laminated without any aids.

The basis of the coating system is a film, also referred to as a film-like substrate. The film can be designed optically using a printing process and in one embodiment is designed as a PVC film (polyvinyl chloride film). A multilayer film, for example a composite film, is also conceivable, with a cover layer being able to be applied to a substrate layer. The substrate layer, i.e. the film-like substrate, can in turn comprise one or more intermediate layers, for example thermoplastic and/or coloring intermediate layers. The cover layer can be designed as a radiation-curable mass, which can be transparent or colored, preferably designed as a clear lacquer layer.

In one embodiment, the protective lacquer to be applied to the previously optically designed film is a composition containing a lacquer system and a plasticizer component. The lacquer system can contain a clear lacquer or a colored and/or pigmented lacquer. The protective lacquer is preferably suitable for being applied in liquid form as a clear lacquer coating to the film-like substrate.

[0012] Basically, compositions which contain at least one binder and water or a solvent are referred to as paint systems. For example, a paint system known as a clear coat generally only has a binder and a solvent, i.e. it does not include any fillers or opaque pigments. In general, paint systems can be differentiated according to the type of binder, the type of solvent and the type of drying. Binders can be present as a dispersion in an aqueous solution or dissolved in the solvent as a one-component system. In a two-component system, the binder is formed from a resin component and a hardener component, which are only mixed together shortly before processing. These react chemically and harden.

According to one embodiment of the protective varnish according to the invention, this comprises a two-component polyurethane varnish as the varnish system. So-called 2-component polyurethane paints can be pigmented or colorless, acrylic-modified or purely polyurethane-based, highly cross-linking or low-cross-linking, with aliphatic or aromatic isocyanate hardeners and can be diluted with solvents or water. 2K polyurethane paints are characterized by high light and weather resistance and can be produced with different properties, for example as a highly elastic paint system. Furthermore, the paint system can also contain a thinner component, which ensures a sufficiently low viscosity for good processability of the paint system.

Pure polyurethane paints prove to be advantageous in terms of surface hardness and long-term chemical resistance compared to acrylic-modified polyurethanes, although the elasticity, flexibility and adhesion of pure polyurethane paints are often not suitable for easy processing.

In order to produce suitable properties for use as a protective varnish in the sense of the invention, the varnish system comprises a predetermined ratio of clear varnish to hardener component. Furthermore, a predetermined proportion of the thinner component is added. The ratio of clear coat to hardener component is a measure of the so-called degree of crosslinking of the binder molecules. In general, a highly cross-linked paint system is desired because the higher the degree of cross-linking, the higher the hardness, solvent and chemical resistance of the cured protective paint. A ratio of clear varnish to hardener component in the range of 3:1 to 1:1 results in a highly cross-linking varnish system, suitable for use as a protective varnish.

To set a suitable processing viscosity of the paint system, the amount of thinner added is important, taking into account the type of processing, i.e. brushing, spraying, rolling, pouring or dipping. According to one embodiment of the invention, an addition of the thinner component of 8% to 12%, preferably up to 10%, based on the total amount of clear coat and hardener component, has proven to be suitable for spray processing. The type of thinner component depends on the type of clear coat used.

When applying the protective lacquer to the film, the difficulty is to apply a homogeneous layer of lacquer to the entire film surface in a constant and defined layer thickness, if possible in a single painting process. According to one embodiment, the protective lacquer comprises at least one plasticizer component in addition to the lacquer system. The ratio of clear varnish to plasticizer component in the protective varnish is between approx. 3:1 and 1:1. Plasticizers are generally liquid or solid, inert organic substances with low vapor pressure that do not undergo a chemical reaction, but do interact with high molecular weight substances and form a homogeneous system with them. Plasticizers influence the processability, including the time available for processing, of polymeric compositions and/or give corresponding coatings certain properties to be achieved, e.g. increased shape changeability, increased elastic properties and/or increased adhesion. A suitable plasticizer should show good compatibility with the components to be mixed and should not have an unfavorable effect on their properties. The addition of the plasticizer component surprisingly improves the effects in terms of processability, flexibility and elastic properties of the protective varnish in combination with the coating of a film laminated to a surface, without reducing fire protection.

A composition based on pentamethyl, for example, is suitable as a plasticizer component.

The proportion of the individual components of the protective lacquer of the coating system, i.e. the lacquer system containing clear lacquer, hardener, thinner and plasticizer component, can vary widely and depend on the requirements of the individual case.

A preferred embodiment of a coating system comprises a protective lacquer, containing a lacquer system with a 2K polyurethane lacquer, which produces a smooth, thick-layered appearance and good gloss properties. In a preferred embodiment, the proportion of clear lacquer in the lacquer system is approximately between 25 and 65% by weight, preferably between 30 and 40% by weight, particularly preferably between 36 and 38% by weight, based on the total weight in the composition of the lacquer system . For the purposes of the invention, commercially available clear varnishes are suitable as a mixture of synthetic resins with solvents. The paint system further comprises a hardener with a proportion between 20 and 40% by weight, preferably between 36 and 38% by weight, and a thinner with a proportion in the range between 4 and 12% by weight, preferably between approximately 5 and 7 % by weight. The protective varnish also contains a plasticizer component with a proportion of between approximately 15 and 20% by weight, with the mixing ratios of hardener and thinner remaining unchanged.

According to one embodiment of the invention, the protective lacquer is applied to the film and then this coated film is applied to the surface to be laminated. In order to apply the protective lacquer, it can be provided that the film is suspended and tensioned in a tensioning device. The surface of the film is particularly cleaned of dust and blown off with ionized air. In a first painting step, an adhesion promoter, a so-called adhesion primer, is sprayed onto the film with a layer thickness in the range of 5 to 7 µm. The adhesive primer you choose should be particularly suitable for use in vehicles. It saves time when completing the coating thanks to quick drying and the possibility of overpainting. After a certain rest phase, which can be one or more hours, for example, the protective lacquer is applied in a single, uniform painting process, in particular with a layer thickness in the range of 40 to 50 µm. The above-mentioned layers are preferably applied at room temperature, with the protective lacquer to be applied also being at room temperature.

The protective varnish is particularly suitable for protecting a surface laminated with a printed film in the area of transport vehicles against manipulation or vandalism and therefore reduces their maintenance costs. A protective varnish suitable for the purposes of the invention, which can be applied to the film, ensures protection against the penetration of solvents and/or color pigments into underlying layers. Components of paint sprays, which are often used for graffiti, are prevented from penetrating the layers underneath the protective paint. The protective varnish can be applied permanently, i.e. not designed as a removable coating, which has to be reapplied again and again with considerable effort.

According to one embodiment of the invention, the protective varnish is applied to a printed PVC film produced by means of a suitable printing process, for example in a digital printing process, by means of a spraying process or using another suitable process. This creates a thick-layered appearance with brilliant gloss retention and high chemical and weather resistance, including high light fastness. A high temperature resistance allows use in a large temperature window, i.e. in a range from approx. -60°C to approx. 110°C, but only for short-term extreme values. The protective varnish is also characterized by high scratch resistance, which is important for cleaning with brushes, for example. The chemical resistance offers the advantage of cleaning even with aggressive solvents to remove graffiti.

Before further processing of the film coated with a protective varnish, it is dried at a temperature higher than room temperature for a defined period of time, for example from 1 to 2 hours, and further at room temperature for a further 11 to 13 hours for post-drying. The films covered with the protective varnish must then relax for a rest period of at least 2 to 3 days, whereby the films are rolled up into rolls and stored standing up to avoid kinks. The rest phase, or until the next step in processing the prepared film takes place, can also extend over several days up to a maximum of 14 days. The films are then cut to size, with a flatbed plotter proving to be particularly suitable, which adapts the prepared films to the surface to be laminated in the mold with a medium cutting speed and a low punching speed.

The cut films are then applied to the surface to be laminated, with optimal results being achieved with films that have rested for at least 7 days since painting, particularly preferably at least 14 days. Further processing is possible for a maximum of 30 days. Particularly good adhesion of the coating system to the surface is achieved using a heat-resistant adhesive tape with high adhesive strength.

The use of aids, for example knifeless self-adhesive tapes, has been proven when applying and precisely adapting the film to the surfaces to be laminated.

When using the protective varnish according to one embodiment in connection with rail vehicles, fire protection regulations in accordance with the European standard, i.e. EN 45545, must be adhered to. This standard is a material testing standard and refers to all materials used for rail vehicles. According to the requirements of standard EN 45545-2, Table 5 R7/R17, the coating system according to one embodiment of the invention meets the requirements in the area of rail vehicles for HL1-3 with regard to a surface made of steel or aluminum, which may include further layers.

The respective maximum value of the heat release rate (MARHE “Maximum Average Rate of Heat Emission”) is determined as a characteristic value using a fire test method. Here, a test specimen is thermally stressed by a heat radiator arranged above and constant irradiation intensity. Based on the detectable oxygen consumption during this fire test, the heat release rate can be calculated, with the average value of several individual tests being used for a product assessment. Depending on the risk level, the MARHE values determined for a tested material structure must be below a specified limit in order to be used in a rail vehicle. Surprisingly, it has been found that a test specimen made of steel as the base material and a coating with a protective varnish, which is also used according to the invention, results in an improved MARHE value compared to a test specimen with a surface made of steel without a protective varnish and thus offers higher fire protection .

Claims (13)

1. Coating system for a surface, comprising a film and a protective varnish, wherein the protective varnish contains at least a two-component varnish and a plasticizer component, and can be applied to the film by means of a painting process, characterized in that the two-component varnish contains a clear varnish and contains a hardener component, in a ratio of 3:1, preferably 1:1, and a thinner component with a proportion in the range between 8 and 12%, preferably 10%, of the total amount of clear coat and hardener component. 2. Coating system according to claim 1, characterized in that the two-component paint is a two-component polyurethane paint. 3. Coating system according to one of the preceding claims, characterized in that the plasticizer component is based on a pentamethyl substance and the plasticizer component is contained in the protective lacquer in a proportion of between 15 and 20% by weight based on the total weight. 4. Coating system according to one of the preceding claims, characterized in that the film is a polyvinyl chloride film printed using a digital printing process. 5. Coating produced from a coating system according to one of the preceding claims, characterized in that the protective lacquer is applied by spraying to a film coated with an adhesion promoter with a layer thickness of approximately 5 to 7 µm. 6. Coating according to claim 5, characterized in that the protective lacquer is applied in a layer thickness of approximately 40 to 50 µm. 7. Vehicle part whose surface has a coating according to one of claims 5 or 6, characterized in that the surface is made of steel, aluminum or plastic. 8. Vehicle part according to claim 7, characterized in that the coating is applied in such a way that it can be removed from the surface without leaving any residue. 9. Vehicle with a vehicle part according to claim 7 or 8, characterized in that the vehicle is a transport vehicle and that the surface is an outside of the transport vehicle. 10. A method for coating a surface with a coating system according to one of claims 1 to 4, with the following steps: – stretching a film in a tensioning device; – Cleaning a film surface from contaminants and neutralizing the film surface; - Applying an adhesion promoter layer with a layer thickness in the range of 5 to 7 µm to the cleaned and neutralized film surface; - after a certain rest period, applying the protective varnish in a painting process over the entire film surface in a layer thickness of 40 to 50 µm; – Drying and maintaining rest periods for the film with protective varnish; – Applying the film with protective varnish to a surface. 11. The method according to claim 10, characterized in that the painting process takes place at room temperature. 12. The method according to claim 10 or 11, characterized in that the application of the film provided with protective lacquer is preceded by an adaptation of the film to the surface by means of cutting and / or punching. 13. The method according to any one of claims 10 to 12, characterized in that the coated film is applied to the surface at least 7 days, preferably 14 days after the painting process.