EP2592898A2 - Heating tape - Google Patents

Abstract

The heating tape (1) has two mutually parallel flat strip conductors (4) made of electrically conductive material, and support layer (3) made of insulating material. The conductors are spaced apart from each other on surface side of support layer. The ribs (5) made of carbon nanoparticle material are provided for interconnecting the strip conductors in electrically conductive manner. The thickness of ribs is set in the range of 10-1000 Nm, and gate width of ribs is set in the range of 1-20 mm. The distance between the adjacent ribs are set in the range of 1-20 mm. An independent claim is included for method for manufacturing heating tape.

Description

The invention relates to a heating tape and a method for producing the heating tape. The heating tape is particularly suitable as a heater or resistor network.

The heating of substances by means of heaters has been known for a long time and in a variety of applications. Consumers are particularly familiar with the use of domestic and automotive heaters. In many cases, it is necessary to prevent liquids, in particular solutions, from freezing or to effect a rapid thawing of a frozen liquid.

Disadvantage of known heaters is their low flexibility, their high weight, the high required voltage of typically 220 V and their high price. Moreover, in view of these properties, the known heating devices require complex and thus expensive processes for their production.

Furthermore, the adaptation of known heaters is not or only partially possible, both in terms of their total resistance as well as to specific tasks. For example, heated hoses are used to transport urea solutions to be injected into the exhaust stream of diesel engines. The urea solution is heated in these tubes by means of heating wires, which are embedded in an insulating material such as ethylene-propylene-diene rubber (EPDM). However, it has been found that the insulating material begins to swell due to the contact with the urea solution, which reduces the life expectancy of the heated hose.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, a heating band is to be specified which has a high degree of flexibility, easy adjustability of the total resistance, a low weight and a comparatively low price. Furthermore, a method for producing such a heating band is to be specified.

This object is solved by the features of claims 1 and 10. Advantageous embodiments of the invention will become apparent from the features of the dependent claims.

According to the invention, a heating tape is provided which comprises at least two mutually parallel flat conductor tracks made of an electrically conductive material and a carrier layer made of an insulating material, wherein the conductor tracks are spaced from one another on a surface side of the carrier layer and the heating tape further comprises webs, the at least two interconnects electrically conductively interconnect, characterized in that the webs consist of a material containing carbon nanoparticles.

If more than two conductor tracks are provided, then all the conductor tracks can be connected to one another via webs made of the material which contains the carbon nanoparticles. For example, all or part of the webs may extend over all tracks. If only part of the webs extends over all printed conductors, then the other part of the webs can each connect two adjacent printed conductors to one another, wherein this part of the webs can connect different printed conductors, provided that they lie next to one another. Likewise, it can be provided that all webs extend only over two adjacent conductor tracks, wherein each conductor of the heating tape is connected at least to an adjacent conductor track via webs. This means, in the case of a heating strip with three tracks, that a first part of the webs connects the first and second tracks together and a second part connects the second and third tracks together. In a heating strip with four tracks, a third part of the webs connects the third and fourth tracks together.

The term "flat trace" refers to a trace having a substantially rectangular cross-section wherein the height of the trace is less than the width of the trace. The edges of a track can be rounded.

The carbon nanoparticles are preferably selected from the group consisting of graphene, carbon nanotubes, and combinations thereof. The size of the nanoparticles is typically between 0.2 and 100 nm.

Graphene is single layer graphite.

Carbon nanotubes, also referred to as carbon nanotubes (CNTs), are tubular structures whose ends can be open or closed. In the present invention, the carbon nanotubes may be one or two-walled. In the case of two-walled carbon nanotubes, the individual tubes are arranged concentrically.

Preferably, the lands are formed of carbon nanoparticles, i. the webs are made of carbon nanoparticles. In this case, the material from which the lands are formed contains only carbon nanoparticles. In other words, the material of which the webs consist contains 100% by weight or approximately 100% by weight of carbon nanoparticles, each based on the material. The term "approximate" is intended to mean that the material may contain traces of components other than carbon nanoparticles.

The material from which the webs are formed, in addition to the carbon nanoparticles contain other components. For example, these components may be compounds having temperature-dependent physical properties, such as density. Examples of such compounds are plastics such as polyamides.

If the material contains other components in addition to the carbon nanoparticles, the proportion of carbon nanoparticles should be at least 50% by weight, based on the weight of the material from which the webs are formed. Such a proportion is required to ensure that the electrical properties of the lands are maintained.

The webs preferably have a thickness which is 10 to 1000 nm, more preferably 100 to 500 nm and particularly preferably 150 to 250 nm. Through the thickness of the webs, the resistance between the interconnects can be varied fluently until the desired resistance is reached.

Preferably, the webs have a web width which is 1 to 20 mm, more preferably 1 to 10 mm and particularly preferably 1 to 6 mm. The webs are preferably spaced from each other. Particularly preferably, the webs are evenly spaced from each other. Alternatively, they may have different distances. The distance between adjacent lands is preferably 1 to 20 mm, more preferably 2 to 15 mm, and particularly preferably 4 to 12 mm.

Conveniently, the webs are formed transversely to the longitudinal axis of the conductor tracks. Alternatively, one or more webs can also intersect the longitudinal axes of the printed conductors at an angle other than 90 °, as long as they do not run parallel to the printed conductors.

The webs may have any shape. Preferably, the webs are flat, ie they have a substantially rectangular cross-section. The bars can be straight bars. They can also be meandering webs. By means of meaderförmiger webs, the length can be increased compared to straight webs, which must cover the electrons, which also increases the resistance of the web.

The webs may extend over the entire width of the carrier layer. However, it may be sufficient if the webs extend from one track to the adjacent track. If more than two conductor tracks are provided, then the webs can extend over all conductor tracks or only part of the conductor tracks.

The heating tape according to the invention may comprise a cover layer of an insulating material, in which case the conductor tracks and the webs between the support layer and the cover layer are arranged. The cover layer may be, for example, a plastic film or a lacquer. The paint may be, for example, a purethane paint.

The carrier layer is expediently a plastic film.

If the conductor tracks are supplied with power, the carbon nanoparticles convert the electrical energy supplied via the conductor tracks into heat energy. This heat energy can then be used to heat, for example, liquids, such as solutions.

The heating tape according to the invention may be a ribbon cable having a carrier layer made of an insulating material and at least two mutually parallel and spaced-apart interconnects of an electrically conductive material. The conductor tracks are located on one surface side of the carrier layer and are connected to one another by webs which consist of carbon nanoparticles or a material which contains carbon nanoparticles. In contrast to typical flat ribbon cables (FFC), the heating tapes according to the invention do not necessarily have a cover layer in the form of a plastic film, even if this is possible. Instead of a plastic film, a lacquer layer can be provided or dispensed entirely with a cover layer.

The heating tape according to the invention is characterized by high flexibility, low weight and a comparatively low price. A special advantage lies in the fact that the total resistance of the heating tape can be adjusted by cutting. If, for example, the heating tape is produced as a roll product, it is possible over the length of the segment cut off from the roll to set the total resistance of the heating tape. The length of the heating tape is proportional to the total resistance of the heating tape. For this purpose, it is particularly advantageous if the webs are equidistant from each other. It is also possible to determine the number of webs per unit length of the heating tape. If the resistance value of the lands is known, it is easily possible to obtain the desired total resistance by cutting the heating tape to a length having the number of lands whose resistance values in sum give the desired total resistance.

The heating tape according to the invention is in particular as a heater for diesel engines whose nitrogen oxide content in the exhaust gas by means of selective catalytic reduction (SCR) is to be lowered. In particular, the urea solution required for the SCR can be heated by means of a heating tape according to the invention, so as to ensure the required temperature of the solution for injection into the exhaust gas stream. For this purpose, the heating tape can for example be applied to the outer surface of the tube through which the urea solution is transported from a reservoir to the injection point. The heating tape can be wound around the hose or, based on its longitudinal axis, applied parallel to the longitudinal axis of the hose.

Likewise, the heating tape for heating lines, containers, thin-walled elements such as glass panes, such as windows of vehicles, etc. can be used. Such lines or containers, for example, contain liquids that change their state of aggregation from solid to liquid under the action of heat. The heating bands are advantageously glued to the object to be heated. Thin-walled elements, such as glass panes, can be protected from freezing or fogging by means of the heating tapes.

In the present invention, a thin-walled element is understood to be an element whose extent in a surface direction is greater than the extent in the thickness direction. For example, the dimension in the surface direction may be more than three times, more than five times or more than ten times the dimension in the thickness direction.

The heating tape according to the invention can be operated with any DC or AC voltage. The tension is limited only by the dielectric strength of the carrier and, if present, the cover layer. The voltage can be varied to vary the total power of the heating band. Due to the low voltage required to operate the heating tape according to the invention, the heating tape can be operated, for example, with solar energy. For this purpose, the heating cable can be supplied, for example with solar cells with electricity. If, for example, a glass pane is to be protected from frost by the heating tape, solar cells attached to the glass pane can provide the current with which the heating tape heats the glass pane.

wobei

• I_ges = Gesamtstromstärke in A
• R_ges = Gesamtwiderstand in Ω
• U = Spannung in Volt
• N = Anzahl Stege

The electric power P per bar can be calculated by the following equation: $$P=I^2*R_{\mathit{ges}}/N=U*I_{\mathit{ges}}/N={\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="imgf0001.png"\; state="\{\{state\}\}">U</figure-callout>}}^2/\left(R_{\mathit{ges}}*N\right)$$

in which

• I _tot = total current in A
• R _tot = total resistance in Ω
• U = voltage in volts
• N = number of webs

The backing layer is preferably a web or strip-shaped plastic film. It is preferably made of polyimide, polyethylene naphthalate (PEN), polyamide or polyester. The plastic film may be a fiber-reinforced plastic film.

The thickness of the carrier layer is preferably 10 or more micrometers. Its width is preferably 2 or more mm. An example of a commercially available polyimide is Kapton (manufacturer: DuPont).

If a cover layer is provided and if the cover layer is a plastic film, it preferably consists of polyimide, polyethylene naphthalate (PEN), polyamide or polyester, with polyimide being particularly preferred.

The thickness of the cover layer is preferably 10 or more micrometers. If a plastic film is provided as a cover layer, it preferably consists of the same material as the carrier layer. If the cover layer is formed from a lacquer, then any lacquer can be used which can withstand the temperature requirements, for example a lacquer of a silicone-based material. In the case of a lacquer, the cover layer preferably has a layer thickness of 20 to 50 micrometers. It can be applied for example by spraying, spraying or extrusion.

The material and the thickness of the cover layer and the material and the thickness of the support layer are selected so that the surface side of the heating tape according to the invention, which is to be the heat dissipating surface side in its application, has a better heat transfer, as the other surface side. If, for example, the heating tape according to the invention with its carrier layer is applied to the hose for guiding the urea solution of an SCR system, then the carrier layer is the heat-dissipating side. The carrier layer then preferably has a better heat transfer than the cover layer.

The interconnects are preferably made of copper or aluminum, with copper being preferred. The distance between two adjacent conductor tracks is preferably determined as a function of the extent of the resistance in the transverse direction to the longitudinal direction of the conductor tracks. The conductor tracks preferably have an approximately rectangular cross-section. The term "approximately rectangular cross-section" of the interconnects is intended both conductor tracks with rectangular cross-section and interconnects with a cross section that deviates from an ideal rectangular cross section, for example by having rounded corners. The thickness of the conductor tracks is preferably 10 or more micrometers. The conductor tracks are preferably spaced from the longitudinal edges of the plastic film. Preferably, the tracks have the same dimensions and are made of the same material, but this is not required.

In one embodiment of the invention, the conductor tracks are glued to the surface side of the carrier layer. For this purpose, the carrier layer may be coated with an adhesive layer. The adhesive may be an adhesive composition based on a poly (meth) acrylate. The thickness of the adhesive layer is preferably between 10 and 80 micrometers. Preferably, the adhesive layer is applied over the entire surface of a surface side of the plastic film, but this is not required. The attachment of the conductor tracks to the plastic layer can also be effected by means of other methods known to the person skilled in the art, which are known to him, for example, from the production of FFC.

The thickness and width of the plastic film, the conductive layers and, if present, the adhesive layer can be determined by the person skilled in the art on the basis of his knowledge of the production of FFC, for example.

The heating tape according to the invention may comprise further components, for example a housing, but this is not necessary.

According to the invention, a method for producing a heating tape is further provided, in which a material containing carbon nanoparticles for forming the webs by spraying or printing on the surface side of the support layer on which the conductor tracks are arranged, is applied.

The surface side, applied to the at least two mutually parallel and spaced-apart interconnects of an electrically conductive material are hereinafter referred to as "populated surface". In this case, the tracks are considered part of the populated surface. In other words, the equipped surface comprises the broad sides of the conductor tracks which are remote from the carrier layer and the areas of this surface side of the carrier layer which are not covered by the conductor tracks.

• (1a) Bereitstellen einer Trägerschicht mit einer Flächenseite, auf die zumindest zwei parallel zueinander verlaufende und voneinander beabstandet Leiterbahen aus einem elektrisch leitfähigen Material aufgebracht sind (bestückte Oberfläche). Dabei kann es sich um ein Flachbandkabel handeln, das keine Deckschicht aufweist.
• (1b) Aufbringen einer Schicht aus einem Material, das Kohlenstoff-Nanoteilchen enthält, auf die bestückte Oberfläche. Dabei wird zweckmäßigerweise eine Schicht aus Kohlenstoff-Nanoteilchen ausgebildet.
• (1c) Ausbilden der Stege unter Entfernen der Schicht von der bestückten Oberfläche in den Bereichen, in denen keine Stege ausgebildet werden sollen. Das Entfernen der Schicht wird vorzugsweise durch Verdampfen des Kohlenstoffes der Kohlenstoff-Nanoteilchen unter Verwendung eines Lasers vorgenommen.

Preferably, the method comprises the following steps:

• (1a) providing a carrier layer having a surface side, are applied to the at least two mutually parallel and spaced-apart Leiterbahen of an electrically conductive material (populated surface). It may be a ribbon cable that has no cover layer.
• (1b) applying a layer of a material containing carbon nanoparticles to the loaded surface. In this case, a layer of carbon nanoparticles is expediently formed.
• (1c) Forming the webs with removal of the layer from the populated surface in the areas where no webs are to be formed. The removal of the layer is preferably carried out by evaporating the carbon of the carbon nanoparticles using a laser.

• (2a) Bereitstellen einer Trägerschicht mit einer Flächenseite, auf die zumindest zwei parallel zueinander verlaufende und voneinander beabstandet Leiterbahnen aus einem elektrisch leitfähigen Material aufgebracht sind (bestückten Oberfläche). Dabei kann es sich um ein Flachbandkabel handeln, das keine Deckschicht aufweist.
• (2b) Aufbringen einer Maske, die Öffnungen in den Bereichen aufweist, in denen Stege ausgebildet werden sollen, auf die bestückte Oberfläche. Bei der Maske kann es sich beispielsweise um Klebestreifen handeln, die auf die Bereiche der Trägerschicht und der Leiterbahnen aufgeklebt werden, auf denen keine Stege ausgebildet werden sollen.
• (2c) Aufbringen einer Schicht aus dem Material, das die Kohlenstoff-Nanoteilchen enthält, auf die Oberseite der Maske unter Ausbildung der Stege. Anschließend kann die Maske entfernt werden.

Alternatively, the method according to the invention may comprise the following steps:

• (2a) providing a carrier layer having a surface side, are applied to the at least two mutually parallel and spaced conductor tracks made of an electrically conductive material (populated surface). It may be a ribbon cable that has no cover layer.
• (2b) applying a mask, the openings in the areas in which webs are to be formed, on the equipped surface. The mask may be, for example, adhesive strips which are adhesively bonded to the regions of the carrier layer and of the conductor tracks on which no webs are to be formed.
• (2c) applying a layer of the material containing the carbon nano-particles to the top of the mask to form the ridges. Then the mask can be removed.

• (3a) Bereitstellen eines Flachbandkabels, wobei zumindest zwei parallel zueinander verlaufende und voneinander beabstandet Leiterbahnen aus einem elektrisch leitfähigen Material in eine Hülle aus einem isolierendes Material eingebettet sind;
• (3b) Entfernen des isolierenden Materials von einer Flächenseite des Flachbandkabels zumindest in den Bereichen, in denen Stege ausgebildet werden sollen; und
• (3c) Aufbringen einer Schicht aus dem Material, das die Kohlenstoff-Nanoteilchen enthält, in Bereichen, in denen das isolierende Material entfernt worden ist, unter Ausbildung der Stege.

In a third variant, the method according to the invention may comprise the following steps:

• (3a) providing a ribbon cable, wherein at least two mutually parallel and spaced-apart interconnects of an electrically conductive material are embedded in a shell made of an insulating material;
• (3b) removing the insulating material from an area side of the ribbon cable at least in the areas where webs are to be formed; and
• (3c) applying a layer of the material containing the carbon nanoparticles in areas where the insulating material has been removed to form the lands.

In step (3b), the insulating material can be removed only where later webs are to be formed. Alternatively, the insulating material can also be removed over the entire length of the ribbon cable, so that the tracks are completely exposed.

If the insulating material has been removed in step (3c) over the entire length of the ribbon cable, then the formation of the webs can be done by removing the layer of carbon nanotubes in the areas where no webs are to be formed. Alternatively, the coating with the layer of carbon nanotubes can take place by means of a mask.

Conveniently, in the process of the invention, the material containing the carbon nanoparticles is provided as a suspension. In this way it is possible to spray the material onto the carrier layer.

The process according to the invention can be carried out as a continuous process in a plant.

In a preferred embodiment, the carrier layer is provided with the traces as a ribbon on a first roll, one portion of which is unrolled from the roll, tensioned and, after performing steps (a) through (c) of the three alternative processes, the loaded one thus obtained Section is wound on a second roll. In this way, the heating tape according to the invention is obtained in roll form. From this role, each one segment can be unwound with the desired number of webs by the user and separated by a section transverse to the longitudinal axis of the conductor tracks. The provision of the heating tapes according to the invention as a roll product facilitates their adaptation to the actual use, since by selecting the length of the segment and thus the number of webs, which are located on the segment, the heating power can be easily adjusted. Each of these segments is itself a heating band in the context of the invention.

It can be provided that, following step (c) and, if provided, before winding onto the second roll, the cover layer is applied to the carrier layer so that the conductor tracks and the webs are arranged between the carrier layer and the cover layer ,

• (α) Beschichten einer Flächenseite der Trägerschicht mit einer Klebstoffschicht; und
• (β) Laminieren der Leiterbahnen auf die Klebstoffschicht. Nach dem Aushärten der Klebstoffschicht können die Schritte (a) bis (c) der beiden alternativen Verfahren zur Herstellung der erfindungsgemäßen Heizbänder ausgeführt werden werden.

The following procedure can be used to produce the carrier layer provided in step (a), one side of which carries conductor tracks:

• (α) coating an area side of the carrier layer with an adhesive layer; and
• (β) laminating the conductor tracks on the adhesive layer. After the adhesive layer has cured, the steps (a) to (c) of the two alternative methods for producing the heating strips according to the invention can be carried out.

Fig. 1

eine schematische Draufsicht einer ersten Ausführungsform eines erfindungsgemäßen Heizbandes;

Fig. 2

eine vergrößerte Wiedergabe des Ausschnittes B der in Fig. 1 gezeigten Draufsicht;

Fig. 3

eine schematische Querschnittsdarstellung entlang der Schnittlinie A-A in Fig.1;

Fig. 4

eine schematische Querschnittsdarstellung einer zweiten Ausführungsform eines erfindungsgemäßen Heizbandes; und

Fig. 5

eine schematische Querschnittsdarstellung einer dritten Ausführungsform eines erfindungsgemäßen Heizbandes;

The invention will be explained in more detail below with reference to embodiments, which are not intended to limit the invention, with reference to the drawings. Show

Fig. 1

a schematic plan view of a first embodiment of a heating tape according to the invention;

Fig. 2

an enlarged reproduction of the section B of the Fig. 1 shown top view;

Fig. 3

a schematic cross-sectional view along the section line AA in Fig.1 ;

Fig. 4

a schematic cross-sectional view of a second embodiment of a heating tape according to the invention; and

Fig. 5

a schematic cross-sectional view of a third embodiment of a heating tape according to the invention;

In the drawings, like reference characters designate like elements throughout. If a distinction between elements is required, this is done by adding a digit after a point.

In the following examples carbon nanotubes are used to form the ridges. However, it is also possible to use graphenes or mixtures of graphenes and carbon nanotubes.

The in the FIGS. 1 to 3 Section 2 of an embodiment of a heating strip 1 according to the invention shown comprises a band-shaped plastic film as a carrier layer 3. On the carrier layer 3, an adhesive layer 7 is applied to the two printed conductors 4.1, 4.2 are laminated with their first broad sides. The two conductor tracks 4.1, 4.2, which have a rectangular cross-section and are spaced from the longitudinal edge of the plastic film 3, extend parallel to each other and are spaced apart, so that between the facing narrow sides of the two conductor tracks 4.1, 4.2, a distance C is formed. Webs 5 made of carbon nanotubes or a material containing carbon nanotubes are formed transversely to the longitudinal directions of the interconnects 4.1, 4.2. The webs 5 extend over the entire width of the carrier layer 3 and over the second broad side of the two conductor tracks 4.1 and 4.2. The webs 5 are equally spaced from each other.

In the Fig. 4 shown second embodiment corresponds to the first embodiment, except that in addition a cover layer 6 is provided, so that the conductor tracks 4.1 and 4.2 and the webs 5 between the support layer 3 and the cover layer 6 are.

In Fig. 5c a third embodiment is shown, which corresponds to the first embodiment, except that it consists of a ribbon cable with extruded flat conductors 4.1 and 4.2 is obtained and the support layer 3 extends to the longitudinal edges of the flat conductor ribbon cable to the level of the webs 5.

As in Fig. 5a 1, the flat conductors are initially completely enclosed by a sheath made of the insulating material of which the carrier layer 3 is made. On a flat side of the insulating material then the insulating material, for example using a laser removed. In this case, the insulating material can be removed only where later webs 5 are to be formed or over the entire length of the ribbon cable, so that the conductor tracks 4.1 and 4.2 are completely exposed. As in Fig. 5b As shown, the insulating material can remain at the edges of the ribbon cable, so that also the webs 5 are protected at the edges by the insulating material. After removal of the insulating material, the now exposed regions of the conductor tracks are then coated to form the webs 5 with a layer of carbon nanotubes.

If the insulating material has been removed over the entire length of the ribbon cable, then the formation of the webs can be done by removing the layer of carbon nanotubes in the areas where no webs are to be formed. Alternatively, the coating with the layer of carbon nanotubes can take place by means of a mask.

In the Fig. 5d embodiment shown corresponds to in Fig. 5c embodiment shown, except that in addition a cover layer 6 is provided, so that the conductor tracks 4.1 and 4.2 and the webs 5 between the support layer 3 and the cover layer 6 are.

Example 1 Production of Heating Tapes According to the Invention Step 1: Apply the carbon nanotubes

A ribbon cable approximately 20 cm in length was provided, which had a carrier layer with a surface side on which two copper interconnects are separated from each other spaced and parallel to each other were applied. On this surface side of the ribbon cable, a layer of carbon nanotubes was applied by means of manual spray coating. The length of the layer was about 17 cm, based on the longitudinal direction of the ribbon cable. The ready of the layer corresponded to the ready of the ribbon cable. The layer thickness of the layer of carbon nanotubes (CNT layer) was set to about 200 nm, resulting in a resistance of 20 Ω. To produce a layer of this layer thickness, about 40 sprays were required with a spray liquid containing 10 wt% carbon nanotubes. In total, 40 ml of spray liquid were used per heating band.

Purified single-wall carbon nanotubes were used to make the CNT layer.

Step 2 : Structure the CNT layer

To form the webs, the CNT layer was removed wherever no webs are provided on the ribbon cable. In these areas, the CNT layer was removed by laser treatment, whereby the webs of about 5 mm width between the tracks were obtained. The webs were each about 5 mm apart.

The laser treatment used to pattern the CNT layer was performed using a Q-switched Nd: YAG laser (1064 nm) with pulses in the ns range and a pulse frequency of 20 kHz. The laser worked with highly dynamic beam deflection by means of galvanometer scanner. The CNT layer was removed by pulsewise evaporation. This is due to the fact that the carbon nanotube suction evaporates the good absorptivity of the carbon, while the copper of the flat conductors and the plastic of the support layer have only a low absorption or a high reflection and therefore have not been changed. For the laser treatment about 30 s were needed.

Example 2: Properties of the manufactured heating tapes

The properties of the heating tapes produced according to Example 1 were determined as follows.

(a) Visual inspection

Subsequent visual inspection of the heating bands showed that the copper of the flat conductors remained unchanged. Melting of the carrier layer was not observed.

(b) characterization of the resistive elements

To determine the resistance and the disturbance, a voltage of 14 V was applied across the copper flat conductors. The measurements showed that the power / ridge lies between 0.09 and 0.25 W. The power was calculated according to the equation given above.

The measurements were repeated after 24 h for control purposes. It was found that the resistance and the current remained stable.

(c) Evaluation of the heating effect

To evaluate the heating effect, images of the heating strips produced in Example 2 were recorded at an operating voltage of 14 V using an infrared camera. The temperature measurement was carried out 5 to 10 seconds after switching on the voltage (U = 14 V). It showed that the temperature at the webs about 140 ° C, the temperature between the webs was about 40 ° C.

(d) Results

The results show that the heating tapes according to the invention are very good electrical resistance heaters. Bridge width and distance between the bars can be matched exactly to the desired heating capacity.

LIST OF REFERENCE NUMBERS

1

heating tape

2

Section of the heating tape

3

backing

4

conductor path

5

Stege

6

topcoat

7

adhesive layer

Claims (15)

Heating strip, comprising at least two mutually parallel flat conductor tracks (4) made of an electrically conductive material and a carrier layer (3) of an insulating material, wherein the conductor tracks (4) spaced from each other on a surface side of the carrier layer (3) are arranged and the heating tape (1) further comprises webs (5), the at least two interconnects (4) electrically conductively interconnect, characterized in that the webs (5) consist of a material containing carbon nanoparticles. Heating tape according to claim 1, characterized in that the webs (5) have a thickness which is between 10 and 1000 nm. Heating tape according to claim 1 or claim 2, characterized in that the webs (5) have a web width of 1 to 20 mm. Heating strip according to one of the preceding claims, characterized in that the webs (5) are spaced apart from each other. Heating tape according to one of the preceding claims, characterized in that the webs (5) are spaced apart uniformly or at predetermined intervals. Heating tape according to one of the preceding claims, characterized in that the distance between adjacent webs (5) is 1 to 20 mm. Heating tape according to one of the preceding claims, characterized in that the webs (5) are arranged transversely to the longitudinal axis of the conductor tracks (4) or at an acute or obtuse angle to the longitudinal axis of the conductor tracks (4). Heating tape according to one of the preceding claims, characterized in that it comprises a cover layer (6) made of an insulating material, wherein the conductor tracks (4) and the webs (5) between the support layer (3) and the cover layer (6) are arranged. Heating tape according to claim 8, characterized in that the carrier layer (3) is a plastic film and that the cover layer (6) is a plastic film or a lacquer. A method for producing a heating tape according to any one of claims 1 to 9, characterized in that the material containing carbon nanoparticles for forming the webs (5) by spraying or printing on the surface side of the carrier layer (3) on which the conductor tracks (4) are arranged (equipped surface) is applied. Method according to claim 10, characterized in that it comprises the steps (A) providing a carrier layer (3) with a surface side, are applied to the at least two mutually parallel and spaced-apart interconnects (4) made of an electrically conductive material (populated surface); (b) applying a layer of a material containing carbon nanoparticles to the assembled surface; and (c) forming the webs (5) with removal of the layer from the populated surface in the areas in which no webs (5) are to be formed. A method according to claim 11, characterized in that the removal of the layer by evaporation is carried out using a laser. Method according to claim 10, characterized in that it comprises the steps (A) providing a carrier layer (3) with a surface side, are applied to the at least two mutually parallel and spaced-apart interconnects (4) made of an electrically conductive material (populated surface); (b) applying a mask, which has openings in the areas in which webs are to be formed, on the equipped surface; and (c) applying a layer of the material containing the carbon nano-particles to the top of the mask to form the ridges (5). Method according to one of claims 10 to 13, characterized in that the material containing the carbon nanoparticles is provided as a suspension. Use of a heating tape according to any one of claims 1 to 9 for heating a urea solution in a diesel vehicle.

Images