EP2000005B1 - Contacting system, heating element and production of a contacting system and heating element - Google Patents

Abstract

The contacting system has heating elements with a strip like surface shape and a structured layered combination with a carrier material (2), a metallic conductor (3) and an electrically conductive layer (1). The carrier material has a plastic manufactured foil. The metallic conductor has a wire mesh and/or a wire cord. The electrically conductive layer (1) has one or more flexible electrically conductive foils, which is based on a polymer. Independent claims are also included for the following: (1) a heating element, has a heating layer with multiple electrically conductive foils (2) a method for producing a contacting system, involves making of a carrier material, a metallic conductor and an electrically conductive layer.

Description

The present invention relates in each case to a method for producing a contacting system and for producing a heating element.

Already known are heating elements based on plastics and suitable electrically conductive particles (carbon blacks, graphites, carbon fibers, metals, metal oxides or mixtures of these components).

Also known are plastics which themselves have electrical conductivity (intrinsically conductive polymers).

In order to use these materials for the production of flexible heating elements, a contact with at least two current-carrying wires is necessary. The basically known possibilities for the application of these wires are:

a) Sew on:

This method represents a quick and uncomplicated way of contacting. However, the problem is that the wire does not have an optimal contact with an electrically conductive foil to be provided at all points, so that a significant contact resistance occurs. This contact resistance leads to a decrease in power of the heating element.

Furthermore, at high current densities, dots with higher power consumption can form at the points with good contact with the film ("hot spots"). These "hot spots" can possibly lead to the destruction of the heating element.

As an additional problem, the contact with the film depending on the mechanical load of the heating element (bending, bending o. Ä.) Vary, a non-reproducible or unpredictable change in the total heating power is the result.

Due to different coefficients of thermal expansion of the film material and the wires used in continuous operation also changes in the contact can occur, which may also be irreversible.

b) sticking on:

By gluing the contact wires with suitable electrically conductive adhesives (conductive paints), a cohesive and permanent contact with the conductive surface of a heating element can be produced. The adhesives used here are polymers filled with conductive solids. These may include carbon blacks or metal particles (preferably silver).

The problems of this technical solution are initially due to the fact that the contact wire is completely surrounded by the adhesive, whereby a large part of the flexibility is lost.

Another problem is the use of metal particles themselves, which require a high degree of filling of the conductive ink due to their high density. As a result, the flexibility of the eligible conductive coatings and thus the flexibility of the contacted wire is greatly reduced.

A further disadvantage is oxidation processes on the metal particles, as a result of which the conductivity of the conductive ink decreases over a longer period of time.

If solvent-based conductive paints are used, these solvents may under certain circumstances dissolve the conductive foil of the heating element and possibly destroy it. The result here too is an increase in the contact resistance or an uneven contacting of the heating element.

The biggest problem, however, is the even application of the conductive ink. If this is not successful, uneven contact can be expected. The result is different contact resistances, which can lead to lower power consumption and to "hot spots".

c) incorporation of the wires during the production process of the film:

By embedding the wires during the production process a reliable all-round contact is guaranteed. Since the wires are completely surrounded by polymer, however, their flexibility is greatly reduced.

Even more problematic, however, is the difficult technical implementation of the process. For subsequent contacting of heating elements, this solution is of course not suitable.

d) Melting of the wires in the electrically conductive foil:

This is only possible when using thermoplastics. However, because of their lack of internal crosslinking, thermoplastics are unsuitable for the production of flexible heating elements, since irreversible changes in shape and thus irreversible changes in the electrical power consumption occur as a result of mechanical or thermal continuous loading.

DE 71 04 860 U shows an electrically heatable textile structure. The structure consists of a textile carrier material and an associated heating conductor. The heat conductor is made of a film-forming, carbon-pigmented plastic dispersion and covers the textile support as a coherent film.

US 4,737,618 discloses a heating element for a de-icing system of a wing structure. In this case, conductive fibers are embedded in a composite fiber structure. Electrical supply lines are connected to the conductive fibers. The conductive fibers are impregnated with resin and have the shape of a band.

US 3 424 362 shows a device for producing electrical resistance heating elements. The heating elements comprise a fabric with electrically conductive fibers. Furthermore, the application of an electrically conductive coating is provided on the fabric.

DE 36 37 978 A1 discloses a heatable bandage. In the bandage parallel conductor tracks are provided, which are interconnected by Flächenheizleiterabschnitte. The Flächenheizleiterabschnitte consist of a polycarbonate foil.

In DE 41 01 290 A1 An electric surface heating element is proposed. This consists of wave-like laid contact conductors, between which wavy, mutually parallel and switched heating conductors are arranged.

In the US 6,974,935 B2 a contact system for electrically conductive films is described.

The power supply is realized there via copper strips, the application of the wires is carried out with the aid of a silver particle-containing conductive ink.

The relative stiffness of the copper strips has the disadvantage that the bendability / Fiexibilität of the resulting heating element is given only transverse to the contacting direction. This excludes applications in which the heating element must have sufficient flexibility in all spatial directions (eg in the case of heating textiles).

The present invention is therefore based on the object of specifying a contacting system and a heating element, in which a simple, uniform, stable, secure and flexible contacting is possible.

• Verfahren zur Herstellung eines Kontaktierungssystems, insbesondere zur elektrischen Kontaktierung von im Wesentlichen flächigen Heizelementen, mit einer im Wesentlichen band- oder flächenartigen Gestalt, wobei das Kontaktierungssystem einen schichtartigen Verbund zumindest der folgenden Komponenten aufweist: ein Trägermaterial, ein metallischer Leiter, eine elektrisch leitfähige Schicht, und wobei das Verfahren die folgenden Schritte aufweist:
  • Bereitstellen eines Trägermaterials,
  • Bereitstellen eines metallischen Leiters,
  • Bereitstellen einer elektrisch leitfähigen Schicht,
  • Herstellen eines Verbundes zwischen dem Trägermaterial und dem metallischen Leiter,
  • Zusammenfügen des Verbundes und der elektrisch leitfähigen Schicht.

The object indicated above is achieved with regard to a method for producing a contacting system having the features of patent claim 1.

• A method for producing a contacting system, in particular for electrical contacting of substantially flat heating elements, with a substantially band-shaped or planar shape, wherein the contacting system comprises a layer-like composite of at least the following components: a carrier material, a metallic conductor, an electrically conductive layer, and wherein the method comprises the following steps:
  • Providing a carrier material,
  • Providing a metallic conductor,
  • Providing an electrically conductive layer,
  • Producing a bond between the carrier material and the metallic conductor,
  • Assembly of the composite and the electrically conductive layer.

In accordance with the invention, a bond between the carrier material and the metallic conductor is first produced to produce the contacting system.

Only then is the composite of the carrier material and the metallic conductor merged with the electrically conductive layer. By this procedure, a particularly high stability of the contacting system and a particularly secure contacting of the metallic conductor is achieved by the electrically conductive layer.

The contacting system obtained by the proposed method is particularly suitable for contacting flat, flexible heating elements. The production of a layer-like composite of carrier material, metallic conductor and an electrically conductive layer does not significantly impair the flexibility of a (surface) heating element.

Furthermore, it has been recognized that the production of such a composite uniform contact of the metallic lead is achieved without significant transition projections occur. In the proposed solution, the metallic conductor is not surrounded by a conductive paint or the like.

Furthermore, it has been recognized that the contacting system can be used particularly easily, since no gluing or sewing of the metallic conductor on the electrically conductive layer is necessary.

By dispensing with the complete enclosure of the metallic conductor within the contacting system, a higher flexibility and stability is achieved according to the invention.

The contacting system obtained according to the invention can be produced, for example, essentially in strip form and distributed in the form of metered goods. The contacting system makes it possible to contact any heating elements electrically. In this case, a special flexibility is achieved in that the necessary metallic conductor is not rigidly connected to the heating element. Rather, the metallic conductor is supported and reduced by the carrier material of the contacting system not the flexibility of the contacting system or the contacted heating element.

The production of a bond between the carrier material and the metallic conductor can be accomplished by sewing the metallic conductor onto the carrier material.

Furthermore, the joining of the composite of the carrier material and the metallic conductor to the electrically conductive layer can be achieved by dissolving or swelling the electrically conductive layer by means of an organic solvent. Thereafter, the dissolved electrically conductive layer can be pressed onto the composite between the metallic conductor and the carrier material and glued. This results in a secure cohesive connection.

1. a) Aufnähen des metallischen Leiters auf das Trägermaterial,
2. b) Anfeuchten dieses Verbundes mit einem organischen Lösungsmittel,
3. c) Auflaminieren der elektrisch leitfähigen Schicht auf diesen Verbund,
4. d) Trocknen/Verdampfen des Lösungsmittels.

A particularly preferred embodiment of the method according to the invention for producing a contacting system has the following steps:

1. a) sewing the metallic conductor onto the carrier material,
2. b) moistening this composite with an organic solvent,
3. c) laminating the electrically conductive layer on this composite,
4. d) drying / evaporation of the solvent.

After complete evaporation of the solvent, a cohesive bond is formed according to the invention. At the same time, a high degree of flexibility of the overall system is maintained.

The carrier material of the contacting system may have a film, if appropriate made of a plastic, and / or a leather, textile or needle felt layer and / or a needle or spunbonded nonwoven and / or a filament composite.

The metallic conductor of the contacting system may comprise a wire mesh and / or a wire mesh and / or a Drahtgewirk and / or one or more wires, Lahnelitzleiter, Metailflachlitzen, metal crocheted mesh bands or Metallgespinstgimpen.

In an advantageous embodiment, the electrically conductive layer of the contacting system has one or more flexible electrically conductive films based on polymer. By using a flexible film, the flexibility of the contacting system can be increased even more.

The electrically conductive layer may comprise metallic and / or non-metallic conductive pigments. If metallic conductive pigments are used, it has to be considered that due to the high density of the metal to achieve a certain degree of filling, a comparatively high metal content must be set. As a result, however, the flexibility of the electrically conductive layer may decrease.

Therefore, it is preferred that the electrically conductive layer has predominantly non-metallic conductive pigments. This embodiment makes it possible to achieve a particularly flexible contacting system.

The electrically conductive layer may have a resistivity of about 0.1 to about 10 Ω · cm. Preference is given to a specific resistance of about 0.1 to about 1 Ω x cm.

In a preferred embodiment, the provided electrically conductive layer can be dissolved or swelled by organic solvents. As a result, it is particularly easy to produce a bond with the carrier material and the metallic conductor with the electrically conductive layer. Furthermore, the production of a heating element is simplified. In this case, the loosened or swollen portion of the electrically conductive layer can serve as an adhesive for producing a cohesive composite.

Alternatively, can be dispensed with the swellability by a solvent, if the electrically conductive layer contains at least portions of thermoplastic material. The thermoplastic can be melted by applying high heat (eg ironing) and then pressed on the layer to be contacted. As a result, a cohesive bond between the contacting system and a surface to be contacted can be produced without the use of solvents. The achievable contact resistance is special low. By forming the electrically conductive layer as a thin layer and / or the only partial use of thermoplastic material in the electrically conductive layer, the disadvantages of thermoplastic materials mentioned above are also avoided.

In an advantageous manner, the contacting system produced according to the invention can additionally have a temperature sensor. The temperature sensor can be connected to a further provided control electronics. As a result, the heating power of the contacted heating element can be controlled precisely with the aid of the contacting system according to the invention. Furthermore, it can be prevented that there is an overheating when contacting a heating element.

The temperature sensor may comprise a thermocouple, a resistance thermometer or the like. For example. The temperature sensor can consist of a Ni-Cr-Ni thermocouple. Alternatively, the temperature sensor may comprise a resistance thermometer, in particular a PTC resistance thermometer. Pt-100 temperature probes are the most widely used in this field. The temperature sensor can be arranged in the immediate vicinity of the metallic conductor in order to detect possibly occurring overheating. In a particularly preferred manner, the temperature sensor is designed as a PTC thermometer and has a wire-like shape. This wire can be arranged parallel to the metallic conductor within the contacting system. For this purpose, the wire-shaped temperature sensor preferably extends between the electrically conductive layer and the carrier material in the immediate vicinity of the metallic conductor. However, such a wire-shaped temperature sensor can also be arranged below the electrically conductive layer or on the carrier material. Furthermore, it is possible that a wire-shaped temperature sensor in the form of a sewing thread is routed at regular intervals from the top of the contacting system on the underside and back. This results in a side effect of a mechanical stabilization of the contacting system by the temperature sensor.

• Verfahren zur Herstellung eines Heizelements mit einer im Wesentlichen flächenartigen Gestalt, wobei das Heizelement einen schichtartigen Verbund eines erfindungsgemäß hergestellten Kontaktierungssystems und einer Heizschicht aufweist, und wobei das Verfahren die folgenden Schritte aufweist:
  • Bereitstellen eines erfindungsgemäß hergestellten Kontaktierungssystems,
  • Bereitstellen einer Heizschicht,
  • Herstellen eines Verbundes zwischen dem Kontaktierungssystem und der Heizschicht.

Finally, the stated object is achieved with respect to a method for producing a heating element having the features of patent claim 10. It is proposed:

• A method of making a heating element having a substantially planar shape, the heating element comprising a layered composite of a contacting system and a heating layer made in accordance with the invention, the method comprising the steps of:
  • Provision of a contacting system according to the invention,
  • Providing a heating layer,
  • Establishing a bond between the contacting system and the heating layer.

The heating element obtained has a substantially planar shape, wherein the heating element has a layer-like composite of a contacting system and a heating layer.

The heating element obtained according to the invention is distinguished by a particularly simple, uniform, stable, safe and flexible contacting of the heating layer by means of the contacting system obtained according to the invention.

To avoid repetition, reference is made to the remarks on the contacting system with regard to further advantages of the produced heating element.

The bond between the contacting system and the heating layer can be produced by dissolving or swelling the electrically conductive layer of the contacting system by means of an organic solvent. Thereafter, a cohesive connection can be established between the contacting system and the heating layer. Furthermore, a secure and flexible contacting of the heating layer is ensured.

In a development of the method according to the invention, in addition to the cohesive connection, a form-fitting connection between the contacting system and the heating layer can be established. For example. The two (flat) elements can be sewn together. As a result, a particularly stable heating layer is realized.

The heating layer of the heating element may comprise one or more electrically conductive films or layers based on polymer and / or one or more layers of conductive textiles, carbon fibers or mixtures of carbon fibers and carrier fabrics.

In a preferred embodiment, the heating layer of the heating element is designed to be flexible. This results in desirable flexibility of the entire heating element in conjunction with a flexible contacting system.

It is preferred that the heating element has flexibility in all surface directions.

In a further embodiment, the heating element has a temperature sensor. In this case, it is particularly preferred that the temperature sensor is arranged next to the contacting system and possibly runs parallel to this on the heating element. This embodiment of the heating element is particularly preferred if the contacting system itself has no temperature sensor. With regard to possible designs and positioning of a temperature sensor, reference is made to the above statements with respect to the contacting system to avoid repetition.

1. a) Anfeuchten der Unterseite des Kontaktierungssystems mit einem geeigneten organischen Lösungsmittel, wodurch die elektrisch leitfähige Schicht des Kontaktierungssystems aufgequollen bzw. leicht angelöst wird,
2. b) Zusammenfügen des vorbehandelten Kontaktierungssystems und der Heizschicht und anschließendes Aufeinanderpressen,
3. c) Trocknen und anschließendes Verdampfen des Lösungsmittels, bspw. durch eine kurze Ausheizphase bei einer Temperatur von ca. 60°C bis ca. 90°C, das Kontaktierungssystem trocknet dadurch vollständig an der Heizschicht an.

A particularly preferred embodiment of the method according to the invention for producing a heating element has the following steps:

1. a) moistening the underside of the contacting system with a suitable organic solvent, whereby the electrically conductive layer of the contacting system is swollen or slightly dissolved,
2. b) assembling the pretreated contacting system and the heating layer and then pressing them together,
3. c) drying and subsequent evaporation of the solvent, for example. By a short bake phase at a temperature of about 60 ° C to about 90 ° C, the contacting system dries completely on the heating layer.

The use of volatile organic solvents ensures that a good contact of the contacting system with the heating layer is reached after only a short time.

An alternative embodiment of the two proposed methods can be realized if the electrically conductive layer of the contacting system and / or the heating layer of the heating element contain at least a portion of one or more thermoplastics. Accordingly, for the production of the contacting system, the electrically conductive layer can be melted and connected by pressurization with the metallic conductor and the carrier material. Furthermore, a bond between the contacting system and the heating layer of the heating element can be produced by the aforementioned method step. In this case, the electrically conductive layer of the contacting system and / or the heating layer of the heating element is melted and joined the two sheet-like elements under pressure to a cohesive composite. This can be realized, for example, by ironing.

If desired, the mechanical strength of the heating element can be additionally increased by sewing the contacting system with the heating layer.

To avoid repetition, reference should be made to the statements relating to the respective device with regard to advantageous embodiments of the proposed method.

Fig. 1

eine perspektivische Darstellung eines Ausführungsbeispiels des erfin- dungsgemäß erhaltenen Kontaktierungssystems,

Fig. 2

einen Querschnitt durch das Kontaktierungssystem aus Fig. 1,

Fig. 3

eine von schräg oben gesehene perspektivische Darstellung eines Ausführungsbeispiels des erfindungsgemäß erhaltenen Heizelements, und

Fig. 4

einen Querschnitt durch das Heizelement aus Fig. 3.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand to the subordinate claims, on the other hand, reference is made to the following explanation of a preferred embodiment of the contact system according to the invention and the heating element obtained according to the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments with reference to the drawings, generally preferred embodiments and developments of the teaching are explained. In the drawing shows

Fig. 1

a perspective view of an embodiment of the present invention obtained contacting system,

Fig. 2

a cross section through the contacting system Fig. 1 .

Fig. 3

a perspective view of an embodiment of the heating element according to the invention seen from obliquely above, and

Fig. 4

a cross section through the heating element Fig. 3 ,

Fig. 1 shows a perspective view of an embodiment of the contact system according to the invention produced. On the underside of the contacting system, an electrically conductive layer 1 is arranged. On the upper side of the contacting system is a carrier material 2. Between these two layers, a metallic conductor 3 is arranged.

In the embodiment shown, the electrically conductive layer 1 has a flexible, electrically conductive, polymer-based film. The carrier material 2 may consist of a textile or leather layer, a spunbonded fabric or the like. The metallic conductor 3 is a wire or a stranded wire in the exemplary embodiment shown. However, the metallic conductor 3 may also consist of a wire mesh, a wire mesh, a metal spun or the like.

Fig. 2 shows a cross section through the in Fig. 1 shown contacting system. This illustration further clarifies the basic structure of the contacting system according to the invention.

Fig. 3 shows a perspective view of an embodiment of the heating element according to the invention seen from obliquely above. On the underside of the heating element is a heating layer 4. On the heating layer 4 two contacting systems have been applied. The contacting system consists - from bottom to top - of an electrically conductive layer 1, a metallic conductor 3 and a substrate 2. In the manufacture of the heating element is particularly important to establish a good electrical contact between the contacting system and the heating layer 4. For the contacting system as an electrically conductive layer 1 is a flexible, electrical conductive polymer-based film has been used. The electrically conductive film can be dissolved or swollen by organic solvents. In this state, the contacting system can then be applied to the heating layer 4. By pressing and drying the entire composite, a secure connection between the contacting system and the heating layer 4 is produced. At the same time, a particularly flexible and secure contacting of the heating layer 4 by the electrically conductive layer 1 is realized.

Fig. 4 shows a cross section through the heating element Fig. 3 , As a result, the basic structure of the heating element according to the invention is illustrated once again.

Finally, it should be emphasized that the exemplary embodiments described above discuss the claimed teaching, but do not restrict it to one of these exemplary embodiments.

Claims (13)

1. A method for producing a contacting system, in particular for the electrical contacting of substantially two-dimensional heating elements, having a substantially band-like or flat form, the contacting system comprising a layered composite structure of the following component: a substrate (2), a metallic conductor (3), an electrically conductive layer (1), and the method comprising the following steps:

   - preparation of a substrate (2),

   - preparation of a metallic conductor (3),

   - preparation of an electrically conductive layer (1),

   - making of a composite structure comprising the substrate (2) and the metallic conductor (3),

   - joining together the composite structure and the electrically conductive layer (1).
2. A method according to claim 1, characterised in that the making of a composite structure comprising the substrate (2) and the metallic conductor (3) comprises sewing the metallic conductor (3) onto the substrate (2).
3. A method according to claim 1 or 2, characterised in that the joining together of the composite structure and the electrically conductive layer (1) comprises the partial dissolving or the swelling of the electrically conductive layer (1) by means of an organic solvent and the subsequent creation of a substance-to-substance bond.
4. A method according to any one of claims 1 to 3, characterised in that a substrate (2) is prepared, which comprises a sheet optionally made of plastics material, and/or a leather, textile or needle felt layer and/or a needle-punched non-woven or spunbonded fabric and/or a filament composite structure.
5. A method according to any one of claims 1 to 4, characterised in that a metallic conductor (3) is prepared, which comprises a wire mesh, and/or a knitted wire fabric and/or an interlaced wire fabric and/or one or more wires, tinsel conductors, crocheted metal lattice bands or metallic spun gimp cords.
6. A method according to any one of claims 1 to 5, characterised in that an electrically conductive layer (1) is prepared, which comprises one or more flexible, electrically conductive sheets based on polymers, and/or metallic and/or non-metallic conductive pigments, in particular wherein the electrically conductive layer (1) comprises predominantly non-metallic conductive pigments.
7. A method according to any one of claims 1 to 6, characterised in that an electrically conductive layer (1) having a resistivity of from approximately 0.1 to approximately 10 Ω·cm, in particular from approximately 0.1 to approximately 1 Ω·cm is prepared.
8. A method according to any one of claims 1 to 7, characterised in that an electrically conductive layer (1) is prepared that is partially dissolvable or swellable by organic solvents.
9. A method according to any one of claims 1 to 8, characterised in that a contacting system having a temperature sensor is produced, in particular wherein the temperature sensor is a thermo element, a resistance thermometer or the like, and wherein the temperature sensor is optionally arranged next to the metallic conductor (3) and/or runs substantially parallel to this.
10. A method for producing a heating element having a substantially flat form, wherein the heating element comprises a layered composite structure of a contacting system produced according to any one of claims 1 to 9 and a heating layer (4), and wherein the method comprises the following steps:

    - preparation of a contacting system by a method according to any one of claims 1 to 9,

    - preparation of a heating layer (4),

    - making of a composite structure comprising the contacting system and the heating layer (4).
11. A method according to claim 10, characterised in that the making of a composite structure comprising the contacting system and the heating layer (4) comprises the partial dissolving or the swelling of the electrically conductive layer (1) of the contacting system by means of an organic solvent and the subsequent creation of a substance-to-substance bond.
12. A method according to claim 10 or 11, characterised in that the making of a composite structure comprising the contacting system and the heating layer (4) additionally comprises a positive-locking joining, especially by sewing.
13. A method according to any one of claims 10 to 12, characterised in that a heating layer (4) is prepared, which comprises one or more electrically conductive sheets or layers based on polymers, and/or one or more layers of conductive textiles, carbon fibres or mixtures of carbon fibres and backing fabrics, optionally wherein the heating layer (4) is of flexible construction, and in particular has a flexibility in all surface directions.

Images