CONSTRUCTION PANEL WITH A HEATING FILM

Description

[0001] The invention relates to a building board with a heating foil, wherein the heating foil comprises a carrier foil with a surface, at least one heating conductor applied to the surface and a cover foil above the at least one heating conductor, the at least one heating conductor covers at least 50% of the surface of the carrier foil and the carrier foil of the heating foil is attached to a surface of the building board and the heating foil has a perforation.

[0002] A heating foil is an electric radiant heater that converts electricity directly into heat. The flexible heating foil has heating elements made of electrically conductive materials, which are applied to a substrate of electrically insulating material, also known as a carrier foil. A cover foil, such as a thin polyester film, encloses the heating elements and protects them from external influences. When the heating elements are connected to a voltage source, such as the power grid, via the attached electrically conductive cables, they absorb electrical energy. The electrically conductive materials of the heating elements have a high resistance, so they heat up evenly when energized. The heating elements release the thermal energy into the environment in the form of infrared radiation.

[0003] A typical application of heating foil is underfloor heating. Due to their particularly thin construction, heating foils can be installed under almost any floor covering. Alternatively, heating foils can also be installed on the walls or ceilings of buildings.

[0004] In addition, heating foils are used, for example, to heat pipes, batteries, medical and optical devices, and equipment for heating food and beverages.

[0005] Heating foils are available by the meter, which can be cut to size as needed and individually adapted to local conditions. Heating foils are also available in prefabricated form, which can be processed to the supplied dimensions.

[0006] To cover as many applications as possible, heating foils are available with different power outputs, for example, between 50 and 1,000 watts. They operate as low-voltage heating foils with 12, 24, 36, or 48 volts, or as high-performance heating foils with 230 volts. To adjust the power of the heating foil to suit your needs, heating foils can also be equipped with a thermostat.

[0007] Heating element alloys are alloys of two or more metals that have a relatively high electrical resistivity and a low tendency to oxidation. Their function is to convert electrical power into heat. Alloying utilizes the positive properties of the individual metals to adapt them to their intended use as heating elements.

[0008] Nickel-copper alloys are currently used for heating conductors, with the added nickel increasing the electrical resistance by a factor of more than 28 compared to pure copper. Nickel exhibits increased absorption in the IR range compared to pure copper.

[0009] Heating foils typically comprise a carrier foil, a heating conductor and a cover foil.

[0010] DE 20 2006 007 729 U1 discloses a building board with a heating foil, a wall heating panel. The wall heating panel consists of a first and a second plasterboard, with a heating foil of the same size as the plasterboards embedded between the two plasterboards. The heating foil consists of a carrier foil on which an electrically operated heating field, consisting of six sub-heating fields arranged one above the other, is attached.

[0011] The partial heating panels consist of a radiant heating coating, which may contain graphite and soot, for example, and preferably emits a high infrared component in the invisible spectrum. A laminated film can be applied to the heating foil as a protective and insulating film. Flat copper conductor strips run along both sides of the partial heating panels for electrical contact. The partial heating panels are designed to operate at a voltage of 24 volts and, for example, with a total power of 150 watts.

[0012] The integration of heating foils into such drywall panels made of plasterboard is intended to ensure effective heating. In addition to the effective conversion of electrical current into heat, the insulating effect of the drywall panel also plays a key role.

[0013] US 2006 / 0289472 A1 discloses a heating foil with a heating conductor that covers more than 50% of the surface of a carrier foil and is made of aluminum. The carrier foil and a cover foil arranged above the heating conductor have large-area cutouts in the longitudinal and transverse directions that promote the adhesion of the heating foil to a cement layer or wall cladding.

[0014] US 2014 / 0178114 A1 discloses a surface heating element comprising a heating element layer and two insulating cover layers covering the outer surfaces of the heating element layer. The heating element layer consists of a metal or alloy layer. The alloy may include aluminum. Two power supply sections are connected to opposite end sections of the heating element layer. The surface heating element is used to heat the interior of a pipe.

[0015] DE 299 22 901 U1 discloses a heating foil for removing and / or preventing moisture from the inside of exterior walls of buildings. The heating foil, equipped with electrical conductors, has perforations between the conductors. The perforations are designed to allow moisture present in the building to diffuse through a wall covered with the heating foil, even in the area of ​​the heating foil. The thin conductors cover only an extremely small portion of the heating foil. The total area of ​​the perforations is approximately 10% to 50%, in particular approximately 20%, of the total area of ​​the heating foil.

[0016] WO 2019 / 068120 A1 discloses a generic building board with a flat heating element for interior construction, comprising a plasterboard panel having a gypsum core arranged between a first and a second cardboard layer, and a flat heating element with an electrically operable heating layer contacted via lateral connecting electrodes. The heating layer can be applied to a carrier film as an intermediate layer. Between the heating layer and the surface of the cardboard layer, a further intermediate layer is arranged, which acts as a barrier layer against mass transport between the heating layer and the cardboard layer. The heating layer and the intermediate layers can extend over the entire length of the plasterboard panel, thus eliminating free areas on the narrow sides. The width of the heating element can also be varied, so that free areas on the long sides are wider or narrower.The intermediate layers and the heating layer have, at least in some areas, evenly distributed openings in the form of perforations so that both layers are permeable to water vapor.

[0017] Furthermore, DE 10 2006 041 775 A1 discloses a heating device which can be inserted into a curable material bed made of tile adhesive, mortar, screed, and the like and which can be produced cost-effectively. The heating device comprises a heating foil with a layer of a resistance material that conducts a heating current, the heating foil having a plurality of perforations. The perforations in the heating foil ensure that the heating device according to the invention can be inserted into the material bed, in that the bed material can flow through the perforations during installation. The heating foil of the heating device can be a carrier foil made of a plastic material that is coated with an electrical resistance material. A composite material, which comprises, for example, carbon, can be used as the resistance material.

[0018] Based on WO 2019 / 068120 A1, the invention is based on the object of creating a building board with an integrated heating foil that not only ensures effective heating but also has an improved insulating effect and at the same time prevents the formation of moisture and mold between the building board and the heating foil.

[0019] This object is achieved by a building board with a heating foil having the features of claim 1. Advantageous embodiments of the invention emerge from the subclaims.

[0020] Building boards, such as plasterboard, can be directly equipped with a heating foil by attaching the heating foil's carrier foil to one surface of the building board. This can be done using an adhesive layer.

[0021] According to the current state of the art, conventional heating foils do not contribute to thermal insulation. The solution is based on the idea of ​​attaching a heating foil to the building board with integrated reflective properties for infrared radiation across the entire energy spectrum, i.e., across the entire wavelength range from approximately 780 nm to 1 mm.

[0022] At least one heating conductor covers at least 50% of the surface of the carrier foil and is made of a metallic material that reflects at least 80% of the infrared radiation incident on the heating conductor. The metallic material of the heating conductor that reflects the infrared radiation is an aluminum alloy with an aluminum mass fraction of at least 98%.

[0023] To allow moisture to pass through the otherwise moisture-impermeable heating foil, the heating foil has a perforation, whereby the perforation is a perforation of the heating foil with micro-holes, the micro-holes have a diameter in a range of 0.1 to 0.3 mm and a maximum of 100 micro-holes are arranged on an area of ​​the heating foil of 1 cm 2<.

[0024] By arranging a maximum of 100 micro-holes in an area of ​​1 cm² of the heating foil, the function of the heating foil is not compromised. However, the micro-perforation of the heating foil attached to a building board prevents the formation of moisture and mold between the building board and the heating foil. Moisture can diffuse through the perforation of the heating foil.

[0025] Microholes with a diameter of 0.1-0.3 mm can be created, for example, by laser drilling. The number typically ranges from 5-100 microholes / cm². All microholes have a consistent shape and size.

[0026] The micro-holes are preferably arranged regularly over the surface of the heating element and / or have a consistent shape and size.

[0027] The micro-holes can penetrate the areas of the heating foil between the heating conductors, but also the areas with the heating conductors.

[0028] Apart from the micro-holes, the carrier film, the cover film, and any heating conductors do not have any other openings, such as perforations, recesses, or the like, penetrating the heating film, so as not to impair the insulating effect of the building board provided with the heating film. The carrier film of the heating film preferably covers the entire surface of the building board.

[0029] A particularly preferred aluminum alloy, EN-AW 8079, as the material for at least one heating conductor, achieves higher tensile strength combined with good formability through the addition of iron and silicon. This alloy is also particularly suitable for forming the heating conductors as foils with a thickness of up to approximately 0.05 mm. The heating conductors are preferably applied to the carrier foil in the form of conductor tracks.

[0030] To improve the adhesion of the electrical contacts to the heating conductor tracks, which are primarily made of aluminum, the surface activation and metallization process for forming the electrical contacts can advantageously be carried out in a single step using plasma metallization. The contacts are made of copper, for example.

[0031] The at least one heating conductor has a low thickness in the range of 1-50 μm, preferably 3-10 μm. This low thickness allows for easy integration of the heating foil. Furthermore, the low thickness of the heating conductor, made of an aluminum alloy, ensures a sufficiently high electrical resistance. The heating conductor is preferably applied as a thin, web-like layer or foil. The width of the heating conductor is at least 20 times the thickness. The thickness of the heating conductor is preferably constant across the entire heating foil. However, the width can vary depending on the available space. Typical widths of the web-like heating conductor are in the range of 100 μm to 5 mm.

[0032] Both the carrier film and the cover film are preferably made of plastics with electrically insulating properties and high heat resistance, such as PET (polyethylene terephthalate) or PI (polyimide).

[0033] To comply with existing fire protection regulations, one embodiment of the invention provides for a flame-retardant surface to be arranged on the heating foil above the cover foil. This surface can be designed, for example, as a flame-retardant paper web or as a flame-retardant decorative surface.

[0034] The heating foil is preferably operated with low voltage in the range between 12 and 50 V. In principle, operation with higher voltages, such as a mains voltage of 230 V, is also possible. However, higher voltages are critical for residential applications on building panels equipped with heating foils, as drilling holes or nails into the building panel, for example, can lead to electric shock.

[0035] The invention is explained in more detail below with reference to the drawings. Figure 1a partial representation of a heating foil of a building board according to the invention with a heating foil in plan view, Figure 2 an overall view of the heating foil according to Figure 1 as well as Figure 3 a diagram showing the reflection properties of different metals.

[0036] Figure 1 shows a section of a heating foil 1 comprising a carrier foil 2 with a surface 3. The surface 3 has a width 3.1 and a length 3.2, as shown in Figure 2 is shown.

[0037] Applied to surface 3 are several heating conductors 4 connected electrically in parallel. Each heating conductor 4 can be deposited as a coating on surface 3 or applied in the form of a film. The film is firmly adhered to surface 3 of carrier film 2, for example, by means of an adhesive layer. Each heating conductor 4 is in the form of a conductor track arranged helically on surface 3.

[0038] The helical heating conductors 4 cover more than 50% of the surface 3 of the carrier film 2 and consist of a metallic material that reflects at least 80% of the infrared radiation incident on the heating conductors 4.

[0039] Figure 3 shows the reflection values ​​for electromagnetic radiation incident on the metals silver (Ag), gold (Au) and aluminum (Al) depending on the wavelength of the radiation. Figure 3 It can be seen that over the entire infrared range from 780 nm to 1 mm the reflection values ​​of the aforementioned metals for infrared radiation are significantly above 80%.

[0040] However, the pure metals have too low a specific electrical resistance and are therefore less suitable for forming the heating elements 4. Therefore, according to the invention, heating element alloys using aluminum as the main component are used, which have a relatively high specific electrical resistance and a low tendency to oxidation. The alloy adapts the favorable reflection properties of aluminum for use as a heating element.

[0041] The aluminum alloy has an aluminum mass fraction of at least 98%. This high mass fraction ensures that at least 80% of the infrared radiation incident on the heating conductor 4 is reflected. Since more than 50% of the surface 3 is covered with heating conductors 4, the transmission of heat through the heating foil 1 is effectively reduced.

[0042] At their ends, the heating conductors 4 are connected to flat, electrical contacts 5. The flat contacts 5 are deposited on the heating conductors 4 by plasma metallization. Connecting cables 6 for electrically connecting the heating foil 1 to a voltage source (not shown) are soldered to the flat contacts 5. To ensure a secure soldered connection, the flat contacts 5 are made of copper or a copper alloy, for example.

[0043] Each heating conductor 4 has a thickness in the range of 3-10 µm. To protect the heating conductor 4, a cover foil 7 is arranged above it. The cover foil 7 has the same dimensions as the carrier foil 2, so that the heating conductor 4, together with the carrier and cover foils 2, 7, forms a laminate. The carrier foil 2 and the cover foil 7 are made of electrically insulating material, in particular plastic.

[0044] The building board not shown in the figures, such as a plasterboard, is equipped with the heating foil 1 by attaching the carrier foil 2 of the heating foil 1 to a surface of the building board. The attachment is achieved, for example, by means of an adhesive layer.

[0045] By arranging a maximum of 100 micro-holes on an area of ​​1 cm² of the heating foil 1, the function of the heating foil is not impaired. However, the micro-perforation of the heating foil 1 attached to the building board prevents the formation of moisture and mold between the building board and the heating foil. Moisture can diffuse through the perforation of the heating foil 1. List of reference symbols

[0046] 1Heating foil 2Carrier foil 3Surface 3.1Width 3.2Length 4Heating conductor 5Contacts 6Connecting cable 7Cover foil

Claims

1. Building panel comprising a heating film (1), wherein - the heating film (1) comprises a carrier film (2) with a surface (3), at least one heating conductor (4) applied to the surface (3) and a cover film (7) above the at least one heating conductor (4), - the at least one heating conductor (4) covers at least 50 % of the surface of the carrier film (2), - the carrier film (2) of the heating film (1) is attached to a surface of the building panel, and - the heating film (1) has a perforation, characterized in that - the at least one heating conductor (4) consists of a metallic material which reflects at least 80 % of the infrared radiation incident on the heating conductor (4), wherein the metallic material is an aluminium alloy with a mass fraction of aluminium of at least 98 %, - the perforation is a perforation of the heating film (1) with micro-holes, - the micro-holes have a diameter in a range of 0.1 to 0.3 mm and - a maximum of 100 micro-holes are arranged on an area of the heating film (1) of 1 cm2.

2. Building panel comprising a heating film according to Claim 1, characterized in that the number of micro-holes is in a range between 5 - 100 micro-holes / cm2 of the heating film.

3. Building panel comprising a heating film according to Claim 1 or 2, characterized in that the micro-holes are regularly distributed over the surface of the heating film (1) and / or have a consistent shape and size.

4. Building panel comprising a heating film according to one of Claims 1 to 3, characterized in that the metallic material is the aluminium alloy EN-AW 8079.

5. Building panel comprising a heating film according to one of Claims 1 to 4, characterized in that the at least one heating conductor (4) is applied as a film or coating to the carrier film (2), preferably in the form of a conductor track.

6. Building panel comprising a heating film according to one of Claims 1 to 5, characterized in that the at least one heating conductor (4) has electrical contacts (5) deposited on the heating conductor by means of plasma metallization.

7. Building panel comprising a heating film according to one of Claims 1 to 6, characterized in that the at least one flat heating conductor (4) has a thickness in the range of 1-50 um, preferably 3-10 µm.

8. Building panel comprising a heating film according to one of Claims 1 to 7, characterized in that the carrier film (2) and / or the cover film (7) consist of plastic.

9. Building panel comprising a heating film according to one of Claims 1 to 8, characterized in that a flame-retardant surface is arranged on the heating film (1) above the cover film (7).