Method for removing coating from surface

Abstract

The invention relates to a method for removing a covering layer (2) from a surface (1), comprising the following steps: - applying a suitably selected release agent (6) over a large area on the covering layer (2) to be separated to form a material-fitting connection, so that the connection between the release agent (5) and the covering layer (2) to be separated is stronger than the connection between the covering layer (2) to be separated and the surface (1); and - peeling off the release agent (6) together with the covering layer (2) to be separated adhering thereto.

Description

Technical Field

[0001] The invention relates to a method for removing a covering layer from a surface, in particular for removing a covering layer which has become brittle due to environmental influences. Background Art

[0002] It is known in the prior art to apply covering layers (for example in the form of self-adhesive films) to surfaces such as aircraft skins for various purposes. In addition to using appropriately designed films to apply logos, lettering or other graphic elements, aerodynamic functional films are also increasingly being used.

[0003] Aerodynamic functional films are known in the prior art in various forms and fields of application and are often used to reduce wall shear stresses on the surface of objects around which a flow flows. For this purpose, aerodynamic functional films usually have a microstructured surface. A common microstructure is a so-called rib structure, which has very small ribs extending essentially in the main flow direction. If a corresponding rib structure is applied to the outer skin of an aircraft, the flow resistance of the aircraft can be reduced thereby reducing fuel consumption.

[0004] Membranes for attachment to aircraft skins are usually very thin for weight reasons. At the same time, they are also subject to significant environmental influences. In addition to the flow of air, the entrainment of particles such as sand or ice in the air and possible mechanical damage to the membrane or its aerodynamically functional surface, membranes are often exposed to strong solar radiation, especially in commercial aircraft at cruising altitudes.

[0005] Due to the damage that actually occurs, in particular, aerodynamic functional films have to be replaced regularly. However, it has been shown that films applied to the outer skin of an aircraft become fragile and are generally difficult to remove due to their small thickness and due to the strong radiation from the sun during the operation of the aircraft. In this regard, complete and residue-free removal without damaging the outer skin is currently only possible by very time-consuming, manually implemented chemical or mechanical methods. Dust and / or chemical residues that are harmful to health or the environment may also be generated in the corresponding methods.

[0006] The same applies analogously to coatings on surfaces to which paint is applied and in which, for example, the desired microstructures are formed. These coatings can also become brittle and must first be removed with great effort before they can be renewed.

[0007] However, in addition to the described applications on aircraft outer skins, corresponding coverings are also used for other surfaces, such as rotor blades of wind energy plants or high-speed trains, which are exposed to similar environmental influences and which likewise have to be freed of damage before they can be renewed. Summary of the invention

[0008] It is therefore an object of the present invention to provide a method which is improved compared to the prior art for removing covering layers from surfaces, in particular covering layers which have become brittle due to environmental influences.

[0009] Therefore, the present invention relates to a method for removing a covering layer from a surface, comprising the following steps:

[0010] - applying a suitably selected release agent over a large area to the cover layer to be separated in order to form a material-bonded connection such that the connection between the release agent and the cover layer to be separated is stronger than the connection between the cover layer to be separated and the surface; and

[0011] - The release agent is peeled off together with the cover layer to be separated which is attached thereto.

[0012] First, some terms used within the scope of the present invention are explained.

[0013] A first connection is "stronger" than a second connection if the first connection is subjected to a load at which the second connection fails. For example, in the case of an adhesive connection, the adhesive force F of the first connection that must be overcome in order to release the first connection is H1 Greater than the adhesion force F of the second connection H2 (F H1 >F H2 ).

[0014] Conversely, if the first connection bends under the same load while the second connection still holds, the first connection is considered to be "weaker" than the second connection. In the case of an adhesive connection, the adhesive force F of the first connection is H1 Less than the adhesion force F of the second connection H2 (F H1 <F H2 ).

[0015] The invention has recognized that when the release agent is first applied, the release agent is firmly connected to the cover layer to be removed, so that when the release agent is subsequently removed, the cover layer adheres to the release agent and is thus removed together with the release agent, thereby making it possible to remove a cover layer applied to a surface that cannot be removed directly, in particular a cover layer that has become brittle or has "broken" due to environmental influences. In this case, the tensile strength required for the removal can be generated solely by the release agent, so that the tensile strength and / or the degree of brittleness of the cover layer to be removed is no longer important.

[0016] Therefore, when the stripping agent is stripped, the cover layer to be separated actually adheres to the stripping agent and is thus removed from the surface, and it is necessary to make the connection between the stripping agent and the cover layer to be separated stronger than the connection between the cover layer to be separated and the surface. If there is sufficient information about the connection of the cover layer to be separated to the surface (for example the adhesive used), a suitable stripping agent can be selected without any problems, but it can also be determined by simple tests directly on the cover layer to be separated.

[0017] The release agent can be a self-adhesive, flat release body at least on one side and the release body is pressed onto the cover layer to be separated by the self-adhesive side for application. By pressing, a connection of desired, required material combination for further technology is produced between the release body and the cover layer to be separated.

[0018] In principle, the release element can be a self-adhesive release film. However, in order to be able to produce a planar connection between the release element and the cover layer to be separated even if the surface of the cover layer to be separated is damaged and / or microstructured, the release element is preferably deformable in the pressing direction. If the release element is then pressed onto the cover layer to be separated, it can lie against it and connect to it over the entire surface, regardless of whether the surface of the cover layer to be separated is damaged and / or microstructured. In this case, the release element can be plastically and / or elastically deformable.

[0019] In particular, in the case of a deformable release body, the tensile strength of the release body may not be sufficient to allow the release body together with the cover layer adhering thereto to be easily removed from the surface. In this case, it is particularly preferred that the release body has a tensile-resistant release layer, preferably a release film, on the side facing away from the cover layer to be removed. With a corresponding release layer, the tensile strength of the release body can be increased, so that the release agent together with the cover layer to be removed adhering thereto can be removed according to the invention.

[0020] As an alternative to using a stripping body as a stripping agent, a hardenable substance can also be provided as a stripping agent, which is connected to the cover layer to be separated in a material-cooperative manner during hardening. After hardening, the substance forms a stripping agent suitable for stripping together with the cover layer to be separated that adheres thereto.

[0021] Here, the hardenable substance can be liquid or gel-like in the initial state. Therefore, the substance can be easily applied to the cover layer to be separated over a large area. After hardening, the substance is solid.

[0022] The net or fabric can also be introduced over a large area into the material that has not yet hardened, so that it is completely surrounded by the material that has not yet hardened. After the material has hardened, the net or fabric can increase the tensile strength of the release agent.

[0023] Regardless of how the release agent is formed, it is preferably selected in such a way that any connection between the release agent and the surface is weaker than the connection between the release agent and the cover layer to be separated. It is also preferred that any connection between the release agent and the surface is also weaker than the connection between the cover layer to be separated and the surface. This ensures that even in the case of deliberate omissions in the cover layer to be separated or significant damage to the cover layer to be separated, the release agent can be removed without any problems and in particular without damaging the surface in the area where the release agent is in direct contact with the surface during pressing.

[0024] The method according to the invention has proven to be particularly suitable for removing cover layers having a microstructured surface. This applies in particular to the case where the cover layer has a rib structure, i.e. a rib-like surface structure. Since the method according to the invention for removing a cover layer is not dependent on the tensile strength of the cover layer itself, the cover layer to be removed can be designed to be particularly thin and thus very light, and in particular without the tensile-resistant additional layers that are usually provided in the prior art.

[0025] The cover layer to be separated can be a film bonded to the surface or a paint layer applied to the surface, if necessary each with a microstructured surface stamped thereon. The surface can be, in particular, the outer surface of an airplane, a high-speed train or a wind power plant rotor blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will now be described by way of example according to a preferred embodiment with reference to the accompanying drawings.

[0027] Figure 1a-1d : A schematic diagram of a first embodiment of the method according to the present invention;

[0028] Figure 2a-2d : a schematic diagram of a second embodiment of the method according to the present invention; and

[0029] Figure 3a-3c : A schematic diagram of a third embodiment of the method according to the present invention. DETAILED DESCRIPTION

[0030] exist Figure 1a In order to illustrate a first embodiment of the method according to the invention, a part of the outer skin of a commercial aircraft is shown as a surface 1 on which, with the aid of a transfer film (not shown), individual ribs 3 are provided which, although not directly connected to one another, together form a membrane-like covering layer 2 to be separated within the meaning of the invention.

[0031] In order to separate the cover layer 2, firstly a release body 5 is applied as a release agent 6 onto the cover layer 2 ( Figure 1b) and then pressed onto the cover layer 2 or the surface 1. Since the release body 5 is deformable and self-adhesive on the side facing the surface 1, a large-area or full-area material connection is achieved between the release body 5 and the cover layer 2 ( Figure 1c ). The self-adhesive properties of the release element 5 are selected in such a way that the material connection between the release element 5 and the cover layer 2 is stronger than the connection between the cover layer 2 and the surface 1. At the same time, the material connection between the release element 5 and the surface 1 should be small enough in the region of the cover layer 2 between the individual ribs 3 so that the paint which regularly forms the outermost layer of the surface 1 is not subsequently damaged.

[0032] If the release body 5 is fully applied and pressed, the release body 5 can be peeled off from the surface 1 as a release agent 6, wherein, according to the previously described individual connection relationship between the surface 1, the cover layer 2 and the release body 5, the cover layer 2 adheres to the release agent 6 and is thus removed from the surface 1 ( Figure 1d ).

[0033] FIG2 shows a second embodiment of the method according to the invention. On a surface 1 (eg the outer skin of an aircraft), a substantially continuous film with a microstructured surface comprising ribs 3 is arranged as a cover layer 2, which is to be removed ( Figure 2a ).

[0034] In order to separate the cover layer 2 (compared to the embodiment according to FIG. 1 ), firstly a release body 5 as a release agent 6 is applied with its self-adhesive side to the cover layer 2 ( Figure 2b ) and subsequently press it onto the cover layer 2 or the surface 1, thereby generating a material-bonded connection between the release agent 6 and the cover layer 2 ( Figure 2c ). The connection properties with regard to the connection between the cover layer 2 and the surface 1 correspond to the previous exemplary embodiments, so reference is made to the corresponding configurations.

[0035] On the side facing away from the surface 1, the release agent 6 has a release film 7 which is inseparably connected to the release body 5 or is designed integrally therewith, and the release film increases the tensile strength of the release agent 6, thereby simplifying the release process. Figure 2d The release agent 6 depicted in FIG. 1 is peeled off together with the cover layer 2 adhered thereto.

[0036] FIG. 3 shows a third embodiment of the method according to the invention.

[0037] In this example, the cover layer 2 with the ribs 3 is fastened to the surface 1 (the outer skin of the aircraft) by means of a carrier film 4 , wherein the connection between the cover layer 2 and the carrier film 4 is stronger than the connection between the carrier film 4 and the surface 1 .

[0038] In this embodiment, a hardening gel-like substance 8 is applied as a release agent 6 to the cover layer 2 and forms a material connection with the film 2 to be separated during hardening ( Figure 3b The resulting material bond between the release agent 6 and the cover layer 2 is stronger than the bond between the cover layer 2 and the surface 1, so that when the substance 8 is completely hardened, the cover layer 2 adheres to it when the release agent 6 is peeled off and is thus removed from the surface 1 together with the carrier film 4 ( Figure 3c ).

Claims

1. A method for removing a covering layer (2) from a surface (1), the covering layer (2) being a covering layer that has become brittle, the covering layer (2) to be separated being an aerodynamic functional film and having a microstructured surface, the microstructured surface comprising a rib structure, the method comprising the following steps: - in order to form a material-bonded connection, a suitably selected release agent (6) is applied over a large area to the microstructured surface of the cover layer (2) to be separated, so that the connection between the release agent (6) and the microstructured surface of the cover layer (2) to be separated is stronger than the connection between the cover layer (2) to be separated and the surface (1); as well as - peeling off the release agent (6) together with the cover layer (2) to be separated which adheres to the release agent, The release agent (6) is a flat release body (5) which is self-adhesive on at least one side, which is pressed with the self-adhesive side onto the cover layer (2) to be separated for the application, and the release body (5) is deformable in the pressing direction, or The release agent (6) is a hardenable substance which, when hardened, connects with the microstructured surface of the cover layer (2) to be separated, and is in a liquid state in an initial state.

2. The method according to claim 1, characterized in that The release body (5) has a tensile-resistant release layer on a side remote from the cover layer (2) to be separated.

3. The method according to claim 2, characterized in that The release layer is a release film (7).

4. The method according to any one of claims 1 to 3, characterized in that The release agent (6) is selected such that any possible bond between the release agent (6) and the surface (1) is weaker than the bond between the release agent (6) and the cover layer (2) to be separated.

5. The method according to any one of claims 1 to 3, characterized in that The release agent (6) is selected such that any possible connection between the release agent (6) and the surface (1) is weaker than the connection between the cover layer (2) to be separated and the surface (1).

6. The method according to any one of claims 1 to 3, characterized in that The cover layer (2) to be separated is a film bonded to the surface (1) or a paint layer applied to the surface (1).

7. The method according to any one of claims 1 to 3, characterized in that The surface (1) is the outer surface of an airplane, a high-speed train or a rotor blade of a wind power plant.

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