WO2004049763A1

WO2004049763A1 - Heavy-duty, resistant, flexible heating foil

Info

Publication number: WO2004049763A1
Application number: PCT/EP2003/012858
Authority: WO
Inventors: Friedrich Kastner; Johann Hilburger; Martin Bergsmann
Original assignee: Hueck Folien Ges.M.B.H.
Priority date: 2002-11-22
Filing date: 2003-11-17
Publication date: 2004-06-10
Also published as: DE10254622A1; AU2003293696A1; EP1597939A1

Abstract

The invention relates to a preferably flexible heavy-duty heating foil which is resistant and which is composed of at least one flexible support layer and a conductive layer applied thereto, said support layer being an activated supporting substrate and the conductive layer being a vapor-deposited metal conductive layer.

Description

Heavy-duty, durable, flexible heating foil

The invention relates to a preferably flexible heating film which is highly resilient and durable.

Heating foils are used in various areas of technology. For example, heating foils are used for heating vehicle windows, for example rear windows. In automotive engineering, heating foils can also be used for seat heaters, steering wheel heaters.

Also known is flat heating foils for flexible heating devices, for example electric blankets, heating pads, heated carpet underlays, floor mats, seating, in particular padded seating, also for use outdoors, car floor mats, incubators, in horticulture for cold frames in greenhouses or outdoors, in the clothing industry for heatable shoe inserts, for heatable items of clothing, for example over jackets, gloves and the like, but also for water-heating devices or for mirror heating, for example for motor vehicle mirrors or traffic mirrors, bathroom mirrors, satellite mirrors, or sanitary facilities.

From DE 32 10 097, for example, surface heating conductors for flexible heating devices are known which consist of a dense, flexible fabric made of plastic threads, preferably polyester, the entire surface of which is connected to a dense, coherent metal layer.

DE 40 12 643 describes a two-dimensional heating element for use in water heating devices, a heating conductor produced by screen printing of metal conductive adhesives being produced by airtight and bubble-free laminating between plastic films.

BESTÄTSGUNGSKOPIE From DE 16 15 142 an electrical surface heating element is known, this element consisting of a metal film-coated plastic film, the metal coating being vapor-deposited in separate webs extending in the longitudinal direction of the film.

From DE 25 55 428 a method for determining the sheet resistance of metal films is known, wherein a metal (Cu, Ag, Au) is evaporated onto a transparent support and the sheet resistance of the layer on the support is determined.

DE 41 39 959 discloses an electrically heatable, flexible and transparent pane, in which an electrically conductive metal oxide layer with a low surface resistance is applied to a flexible polymer film, preferably a polyester film.

A heating element with a heating foil is known from DE 199 39 174, the heating foil having a carrier layer and a conductive layer. The

Heating element is used in particular for vehicle seats.

The conductive layer preferably has at least one recess around which

To direct current flow in a targeted manner, the recesses being perpendicular to the mechanical load directions.

The thickness or the width of a guide strip or a conductor track can vary over its longitudinal course in order to bring about a local adaptation of the area performance. At least part of the conductive layer can be used to supply power to further electrical functional elements, for example sensors.

A heating foil is known from DE 19939 175, a conductive layer made of metal being deposited on a carrier layer, in particular a polyester, polyimide, polyamide, polypropylene or polycarbonate foil. The known flexible heating elements are controlled by external control devices, are very sensitive to strain and are generally not flame-retardant or flammable.

The object of the invention is to provide a flexible heating foil, which may consist of a plurality of coated foils, the conductive layers on the heating foil having improved resistance to strain due to deformation or the intended use. Furthermore, the heating foil should, if necessary, be equipped with a flame-retardant device, and the heating power should be regulated, if necessary, by means of devices applied directly to the heating foil. A method for producing such a heating foil is also to be provided.

The invention therefore relates to a highly resilient and durable heating film consisting of a flexible carrier layer and at least one conductive layer applied thereon, characterized in that the carrier layer is a carrier substrate activated by plasma or corona treatment and the conductive layer is a vapor-deposited metallic conductive layer, a conductive lacquer layer or a is conductive polymer layer.

The carrier substrate is, for example, carrier films, preferably flexible plastic films, for example made of PI, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC in question. Flame retardant plastic films, such as Hostaphan ^® film types, are particularly suitable.

Furthermore, depending on the structure of the heat conductor, conductive pigmented and / or mixed with conductive polymers plastic foils can be used as carrier substrates.

The carrier films preferably have a thickness of 5 to 700 μm, preferably 8 to 200 μm, particularly preferably 20 to 150 μm. Furthermore, metal foils, for example Al, Cu, Sn, Ni, Fe or stainless steel foils with a thickness of 5-200 μm, preferably 10 to 80 μm, particularly preferably 20-50 μm, can also serve as the carrier substrate. The foils can also be surface-treated, coated or laminated, for example lacquered with plastics or lacquered or printed over the entire surface or in a partially conductive manner.

Furthermore, paper or composites with paper, for example composites with plastics with a weight per unit area of 20-500 g / m ² , preferably 40-200 g / m ² , can also be used as carrier substrates, which are optionally made flame-resistant.

Furthermore, woven or non-woven fabrics, such as continuous fiber non-woven fabrics, staple fiber non-woven fabrics and the like, which can optionally be needled or calendered, can be used as carrier substrates. Such fabrics or nonwovens preferably consist of plastics, such as PP, PET, PA, PPS and the like, but woven or nonwovens made of natural, optionally treated fibers, such as viscose nonwovens, can also be used. The fabrics or nonwovens used have a weight per unit area of approximately 20 g / m ² to 500 g / m ² . If necessary, these fabrics or nonwovens can be surface-treated.

The carrier substrate is pretreated by an energy-intensive process. The carrier substrate is treated by means of an inline plasma (low-pressure or atmospheric plasma), corona or flame process. The surface is cleaned and activated by high-energy plasma, for example Ar or Ar / O ₂ plasma. Terminal polar groups are created on the surface. This improves the adhesion of metals and / or further layers of paint or varnish and the like to the surface. If necessary, a thin metal or metal oxide layer can be applied as an adhesion promoter, for example by sputtering or vapor deposition, simultaneously with the application of the plasma or corona or flame treatment. Cr, Al, Ag, Ti, Cu, Ti0 ₂ , Si oxides or chromium oxides are particularly suitable. This adhesion promoter layer generally has a thickness of 0.1 nm - 5 nm, preferably 0.2 nm - 2 nm, particularly preferably 0.2 to 1 nm.

According to the invention, the following basic structures of the heating foil according to the invention are included:

In a first embodiment, the heating foil has a non-conductive carrier substrate, a conductive metal layer thereon, for example a copper layer, then optionally a conductive lacquer layer or a further copper layer and then optionally a non-conductive carrier substrate or a non-conductive lacquer layer, for example a protective lacquer layer.

In a second embodiment, the heating foil according to the invention consists of a non-conductive carrier substrate, a conductive metal layer, thereon a resistance layer (less conductive layer) and a further conductive layer, for example a metal layer or a layer of conductive polymers.

In a third embodiment, the heating foil according to the invention consists of a conductive carrier substrate, for example a metal foil or a plastic foil mixed with conductive polymers or pigments. A resistance layer and then a further conductive layer, preferably a metal layer or a layer of conductive polymers, are applied to this electrically conductive carrier substrate. In a fourth embodiment, a conductive layer is provided on both sides on a non-conductive carrier substrate, which functions as a resistance layer.

According to the invention, it can also be provided that additional functions can be introduced by means of a corresponding construction of the heating foil.

For example, the load on a seat can be recognized by appropriate arrangement of the layers.

Such a “seat occupied” detection function can be implemented in different ways.

In a first embodiment, in addition to one or more guide layers or intermediate layers provided for the heating function, the heating foil may optionally have two guide layers separated by a spacer layer, the guide layers each being able to be the same or different and made of a metal, a metallic printing ink or an electrically conductive layer Polymer can exist.

The spacer layer applied between the guiding layers changes its thickness when the seat is loaded. Flexible plastic films can therefore be used as the spacer layer, which can be compressed sufficiently under load, for example by at least 10%, preferably at least 30%.

Compositions which foam during production under the influence of temperature, but are stable at the temperatures reached during operation of the heating film, can also be used as the spacer layer. In particular, polyurethane-based compositions that can be foamed with aromatic or aliphatic isocyanates are used. Furthermore, foamable hotmelts known from automotive engineering can be used. The two conductive layers then serve as capacitor plates of a measuring capacitor. If the thickness of the spacer layer changes under load, the capacitance of the capacitor also changes, which is then recognized by the electronics.

It is also possible to switch the two guide layers separated by a compressible spacer layer in such a way that one or both guide layers have both the heating function and the seat-occupied detection function. The change in capacity is measured alternately during a certain period of time and then heated.

Furthermore, several conductive layers can be provided one above the other, which are alternately electrically connected to one another. This enables higher capacities to be achieved in the same area.

It is also possible to partially apply the conductive layers and the spacer layer and / or to make the spacer layer different in thickness. As a result, the seat load can be recorded more precisely over several measuring points.

Furthermore, the air conditioning of the seat can be controlled by the seat occupied detection. If the seat is recognized as occupied, the heating is switched on.

A further possibility of realizing a seat occupied detection function by means of the foils according to the invention is to place a capacitor layer in the backrest and in the seat surface of the seat. The occupancy of the seat is then used to detect the change in the dielectric, since a seated person influences the quiet field of the capacitor. The conductive layers are preferably protected by applying a protective lacquer layer or by lamination.

The individual layers can be applied over the entire surface or partially.

The high-energy pretreatment described above improves the adhesion of a structured or functional layer applied partially or over the entire surface. This is a prerequisite for the creation of functional layers with high precision and good adhesion.

The respective functional layer is then applied to the carrier substrate activated in this way.

The application can be carried out by known methods, for example by vapor deposition, sputtering, printing (gravure, flexographic, screen, digital printing and the like), spraying, electroplating and the like.

This layer consists of a metal, a metal compound or an alloy. Layers of Al, Cu, Fe, Ag, Au, Cr, Ni, Zn and the like are suitable as the metal layer. Examples of suitable metal compounds are oxides or sulfides of metals, in particular TiO ₂ , Cr oxides, ZnS, ITO, ATO, FTO, ZnO, Al ₂ O ₃ or silicon oxides. Suitable alloys are, for example, Cu-Al alloys, Cu-Zn alloys and the like. Examples of insulators are organic substances and their derivatives and compounds, for example dyeing and lacquer systems, for example epoxy, polyester, rosin, acrylate, alkyd, melamine, PVA, PVC, isocyanate, urethane systems, which are radiation-curing can be suitable, for example by heat or UV radiation.

The thickness of the respective layer is 0.001 to 50 μm, preferably 0.1 to 5 μm. The layer can be structured by means of an etching process (application of a full-surface metal layer and subsequent partial removal by etching) or by means of a demetallization process.

When using a demetallization process, a solvent-soluble paint (optionally in the form of an inverse coding) is applied in a first step.

The color application can be carried out by any method, for example gravure printing, flexographic printing, screen printing, digital printing and the like. The color or the color lacquer used is soluble in a solvent, preferably in water, but a color soluble in any solvent, for example in alcohol, esters and the like, can also be used. The color or the colored lacquer can be conventional compositions based on natural or artificial macromolecules. The soluble color can be pigmented or unpigmented. All known pigments can be used as pigments. TiO ₂ , ZnS, kaolin and the like are particularly suitable.

The printed carrier substrate can then optionally be treated again using an inline plasma (low-pressure or atmospheric plasma), corona or flame process in order to clean the surface of toning residues.

To avoid toning residues, for example, a blow bar can also be located between the doctor blade and the pressure roller, with a plurality of nozzles arranged over the entire width. Through these nozzles, filtered air with defined air humidity, possibly heated or cooled, is directed onto the printing cylinder at the same speed, as a result of which the thin layers on the cylinder dry and can no longer be applied to the carrier substrate. Instead of such a blow molding, an IR drying device situated over the entire width can also be used.

If necessary, a thin metal or metal oxide layer can be applied as an adhesion promoter, for example by sputtering or vapor deposition, simultaneously with the application of the plasma or corona or flame treatment. Cr, Al, Ag, Ti, Cu, TiO ₂ , Si oxides or chromium oxides are particularly suitable. This adhesion promoter layer generally has a thickness of 0.1 nm - 5 nm, preferably 0.2 nm - 2 nm, particularly preferably 0.2 to 1 nm.

As a result, the adhesion of the structured functional layer applied partially or over the entire surface is further improved.

The actual functional, electrically conductive layer is then applied.

This layer can consist of a metal, a metal compound, or an alloy. Layers of Al, Cu, Fe, Ag, Au, Cr, Ni, Zn and the like are suitable as the metal layer. Examples of suitable metal compounds are oxides or sulfides of metals, in particular TiO ₂ , Cr oxides, ZnS, ITO, ATO, FTO, ZnO, Al ₂ O ₃ or silicon oxides. Suitable alloys are, for example, Cu-Al alloys, Cu-Zn alloys and the like.

The electrically conductive metallic layer preferably consists of Al, Cu, Ag or Ni.

The electrically conductive layer can also be done in terms of printing technology by applying an appropriate dye or lacquer composition. For setting electrical properties, for example conductivity, graphite, carbon black, conductive organic or inorganic polymers can be used. Metal pigments (for example copper, aluminum, silver, gold, iron, chromium and the like), metal alloys such as copper-zinc or copper-aluminum or also amorphous or crystalline ceramic pigments such as ITO or molecular crystals and the like can be added. Furthermore, doped or undoped semiconductors such as silicon, germanium or ion conductors such as amorphous or crystalline metal oxides or metal sulfides can also be used as additives. Furthermore, polar or partially polar compounds such as surfactants or non-polar compounds such as silicone additives or hygroscopic or non-hygroscopic salts can be used or added to adjust the electrical properties of the layer.

Various natural or synthetic binders come into question as binders, such as e.g. use natural oils and resins such as phenol formaldehyde, urea, melamine, ketone, aldehyde, epoxy, polyterpene resins. For example, polyesters, polyvinyl alcohols, polyvinyl acetates, ethers, propionates and chlorides, poly (methyl) acrylates, polystyrenes, olefins, nitrocellulose, polyisocyanate, urethane systems and others can be used as additional binders.

A further stretchable electrically conductive layer made of electrically conductive polymers is then optionally applied to the metallic electrically conductive layer or the electrically conductive coloring or lacquer layer.

The electrically conductive polymers can be, for example, polyaniline or polyethylene dioxythiophene.

The polymers can be applied to the carrier material in the form of a dispersion in a dispersant. Inert solvents, for example, are preferably aqueous solvents or Alcohols, such as i-propanol in question. Optionally, matrix polymers, for example water-soluble polyesters, polyurethanes, polystyrene sulfonates, polyacrylates or ethylene acrylate copolymers, can also be added to the polymer dispersions as matrix polymers. For example, polyethylene dioxythiophene with polystyrene sulfonate can be used particularly advantageously as a matrix polymer. The particle size of the polymers in the dispersion is 20 nm - 10 μm, preferably 20 - 500 nm.

However, it is also preferred to apply the soluble monomers or prepolymers to form the electrically conductive polymers and to polymerize them in situ. Both radical and redox or photoinitiators, for example UV initiators, can be used as catalysts.

The corresponding monomer or prepolymer is mixed with the catalyst and applied immediately to the carrier substrate. Catalyst residues and other contaminating reaction products can also be removed in situ or, if appropriate, subsequently removed from the layer by treatment with a solvent, generally water. Volatile constituents can optionally also be removed by drying with an IR dryer, a convection dryer and the like.

The electrically conductive polymer layer has a high elasticity. If the heating foil is subjected to excessive strain, the metallic conductive layer may break or be interrupted. The stretchable polymeric conductive layer remains undamaged, a bridging layer is then created which ensures the desired function of the conductive layer.

Several metallic and / or polymeric electrically conductive layers can be present on the heating foil according to the invention. The various conductive layers can either be completely opaque and / or have different dimensions. It is therefore also possible, for example, to initially apply a metal electrically conductive layer over the entire surface, the electrically conductive layer applied thereon can be partially implemented, a further electrically conductive layer on the underlying electrically conductive layer may be applied in an opaque manner but to a small extent in register, whereby contact the different layers with each other.

By arranging the conductive layers appropriately, different heating zones can also be realized on a heating foil with different heating powers.

Furthermore, by printing a PTC or NTC layer between the partial metallic layers or the conductive layers from the functional coloring or lacquer compositions described, it is possible to install corresponding control devices, for example for temperature control, and the like, or Peltier elements. When a certain temperature is reached, the specific resistance changes and with it the current flow.

Such a construction then represents an overtemperature protection at the same time.

The heating film according to the invention can optionally also consist of a plurality of appropriately activated and coated carrier substrates which are connected to one another, for example by lamination, it being possible to use known lamination adhesives and known lamination processes

If necessary, the heating film according to the invention can also have further elements, for example sensors for temperature control and the like, these elements can be represented either by printing using functional printing inks, by metallization or by polymeric conductive elements.

For the use of the single-layer or multilayer heating foils according to the invention, for example in applications in which the flexible heating foil is deformed, for example as a heating foil in vehicle seats, shoe soles, gloves and the like, it is advantageous for the conductive layer or the conductive layers of the heating foil according to the invention have one or more recesses in order to specifically direct the flow of the current through the conductive layer or layers or that the heating film has slots or air distribution channels in order to increase its stability and its flexibility and adaptability under strain.

These recesses or slots can be produced by known mechanical or thermal methods, for example by punching, perforating, cutting, (laser or water jet cutting) deep drawing, molding and the like.

Air distribution ducts can also be created using printing technology or by deep drawing or by partial lamination. Such air distribution channels can be used to blow heated or cooled air, if necessary.

In particular, when using an electrically conductive carrier substrate, for example a metal foil, a pigmented or electrically conductive plastic film or mixed with electrically conductive polymers, the punched-out areas or the slots can be arranged as desired.

At the same time, the redundancy of the interconnects can be increased. If the heating foil is used, for example, in the seat of a vehicle seat, the foil does not wrinkle, but rather unfolds in a controlled manner along the slots. Furthermore, the film can move through the clearance given by the slots also adapt to larger loads without the film tearing and the conductive layers on it being damaged.

The single-layer or multi-layer heating film according to the invention can optionally be coated with a protective lacquer, or be scratch-resistant and / or antistatic. Furthermore, the heating foil according to the invention can be provided with a sealing layer, for example with a hot or cold sealing lacquer or a self-adhesive coating.

The protective lacquer can be pigmented, the pigment content being up to 30%, preferably up to 15%, all known and customary pigments, for example inorganic and / or organic pigments such as titanium dioxide, zinc sulfide, kaolin, barium sulfate, aluminum and chromium - And silicon oxides, metal pigments (for example copper, aluminum, silver, gold, iron, chromium and the like), metal alloys, such as copper-zinc or copper-aluminum, as well as colored, optionally organic pigments, such as phthalocyanine blue, indolide yellow, dioxazine violet, or amorphous or crystalline ceramic pigments such as ITO, ATO, FTO and the like or liquid crystal pigments are also suitable.

Furthermore, colored and / or encapsulated pigments can also be used in chemically, physically or reactively drying binder systems. Suitable dyes are, for example, 1,1- or 1,2-chromium-cobalt complexes.

Furthermore, the protective lacquer according to the invention, optionally matched to the planned area of use, can contain further additives.

In this way, specific properties of the protective lacquer can be set, for example not only to achieve sufficient resistance to external influences, but also to protect the layers under the protective lacquer from the inside and outside, for example against the action of residues from other layers and the like. For example, inorganic corrosion protection additives such as Zn phosphate or organic corrosion protection additives such as toluene triazole derivatives can be added to protect metallic layers.

In order to achieve increased protection against radiation of different wavelengths, for example UV absorbers, radical scavengers (HALS), for example sterically hindered amines and the like can be added. These additives increase the stability of heating foils that are used, for example, as window heaters.

Known antioxidants, for example phenolic antioxidants, flame retardant additives, for example known halogenated or halogen-free flame retardant additives, high-temperature stabilizers based on disulfides or thioethers can also be added.

In order to increase the mechanical resistance, for example the shear and elongation security, the rolling strength and the like, elastomeric modifiers, for example elastomeric polymers and copolymers, such as EPR and the like, are preferably added.

Furthermore, blowing agents, such as Na ₂ CO ₃ , CaCO ₃ or other known blowing agents, or so-called structural colors which foam under the influence of temperature, can also be added. This increases the stability and elasticity of the protective lacquer at the same time. This is particularly important if the data carrier or the carrier substrate has, for example, an electronic component, for example a microchip, and is then to be further processed under mechanical stress. The protective lacquer foams due to the blowing agent, and the protective lacquer layer cushions loads when subjected to mechanical stress. The layers underneath are therefore protected against mechanical stress. To increase the resistance to water vapor, suitable absorbers or barrier layers such as mica, active metals and the like are preferably installed.

Furthermore, silicones, acrylates, silicone oils, waxes and the like can be added to increase the scratch resistance.

If desired, the protective lacquer can also be given an antistatic treatment using known additives.

In general, such additives and modifiers are added in amounts of about 0.1-10%, but higher amounts up to 50% are also conceivable.

1 to 5 show structures for heating foils according to the invention. Therein 1 means a flexible carrier substrate, 2 an electrically conductive metallic layer, 2a an electrically conductive lacquer layer or polymer layer, and 3 a resistance layer.

In FIG. 1, 1 means the non-conductive carrier substrate, for example a polyester film, 2 the conductive metal layer, for example a copper layer, 2a a conductive lacquer layer or 2 another copper layer, and 3 a non-conductive carrier substrate, for example a polyester film.

In FIG. 2, 1 means the non-conductive carrier substrate, 2 a conductive metal layer, 3 a resistance layer and 2a a layer made of conductive polymers.

In FIG. 3, 1 means a conductive carrier substrate, for example a metal foil or a plastic foil mixed with conductive polymers or pigments, 3 a resistance layer and 2 an electrically conductive metal layer. In FIG. 4, 1 denotes a non-conductive carrier substrate, for example a polyester film, which functions as a resistance layer, and 2 denotes the conductive layers located on both sides.

In FIG. 5, 1 denotes a non-conductive carrier substrate, for example a polyester film, and 2 denotes the electrically conductive layers each having different dimensions in terms of their surface extension.

Claims

claims:

1) Heavy-duty and durable heating film consisting of at least one flexible carrier layer and at least one conductive layer applied thereon, characterized in that the carrier layer is an activated carrier substrate and the conductive layer is a vapor-deposited metallic conductive layer.

2) Heating film according to claim 1, characterized in that the heating film has a non-conductive carrier substrate, thereon a conductive metal layer, then optionally a conductive lacquer layer or another copper layer and then optionally a non-conductive carrier substrate.

3) Heating film according to claim 1, characterized in that the heating film consists of a non-conductive carrier substrate, a conductive metal layer, thereon a resistance layer and a further conductive layer, for example a metal layer or a layer of conductive polymers.

4) Heating foil according to claim 1, characterized in that the heating foil consists of a conductive carrier substrate, for example a metal foil or a plastic foil mixed with conductive polymers or pigments, a resistance layer and then a further conductive layer, preferably a metal layer.

5) Heating film according to claim 1, characterized in that the heating film consists of a low-conductive carrier substrate, which acts as a resistance layer, on which a conductive layer is applied on both sides. 6) Heating film according to one of claims 1 to 5, characterized in that the heating film has a plurality of conductive layers, which are optionally partially separated from one another.

7) Heating film according to one of claims 1 to 6, characterized in that the heating film additionally has one or more partial or full-area layers of conductive polymers.

8) Heating film according to one of claims 1 to 7, characterized in that the electrically conductive layer (s) has (have) a thickness of 0.1 nm to 50 microns.

9) Heating film according to one of claims 1 to 8, characterized in that the heating film has recesses for targeted control of the current flow through the conductive layer (s).

10) Heating film according to one of claims 1 to 9, characterized in that the heating film is provided with a protective lacquer layer or is laminated.

11) Heating film according to one of claims 1 to 10, characterized in that the heating film has at least 2 conductive layers separated by a compressible spacer layer, and a seat-occupied detection is carried out by the change in capacity when the thickness of the spacer layer changes.

12) Heating film according to claim 11, characterized in that the guide layers are partially applied. 13) Heating film according to one of claims 11 or 12, characterized in that the spacer layer is a layer of different thickness.

14) Heating film according to one of claims 11 to 13, characterized in that the guide layers serve both for heating and for seat occupied detection.

15) Heating film according to one of claims 1 to 10, characterized in that in each case a heating film with a capacitor layer is located in the backrest and in the seat, the seat occupied detection being carried out by changing the dielectric under load.

16) Method for producing a heating film according to one of claims 1 to 15, characterized in that the carrier substrate is activated by plasma or corona pretreatment, then optionally an adhesion promoter layer is deposited and then the electrically conductive layer is evaporated or printed on.

17) Method according to claim 16, characterized in that multilayer structures are produced by repeating the method.

18) Method for producing a heating film according to claim 9, characterized in that after performing the method according to claim 10, the recesses are made by mechanical or thermal methods.

19) Use of the heating foils according to one of claims 1 to 15 for heating elements in flexible heating devices, for example electric blankets, heating pads, heatable carpet underlays, floor mats, seating, in particular padded seating, also for use outdoors, for car floor mats, incubators, in horticulture for cold frames in greenhouses or outdoors, in the clothing industry for heated shoe inserts, for heated items of clothing, for example over jackets, gloves for water-heating devices or for mirror heating, for example for vehicle mirrors or traffic mirrors, bathroom mirrors, Satellite dish, or sanitary facilities.