KR20010040504A - Flat heating element and use of flat heating elements - Google Patents

Abstract

The present invention relates to the use of planar heating elements in heatable pipes, heatable transport devices and heating rollers, comprising at least one side of a resistive layer comprising a thin resistive layer comprising an electrically conductive polymer and separated from each other. It relates to a planar heating element consisting of two planar electrodes.

Description

FLAT HEATING ELEMENT AND USE OF FLAT HEATING ELEMENTS

Resistance-heating elements are used to generate heat in other areas. In general, such heating elements require a high voltage at the heating element to generate a sufficiently high temperature. However, such high voltages can pose a safety hazard, especially when used to heat the medium or in contact with the human body. In addition, because of the materials used here, the most traditional resistance-heating elements are only suitable for low temperatures, especially in long-term operation. Other proposals of the prior art require a complex structure of resistance-heating elements, thus limiting the applicability of the resistance-heating elements.

The present invention relates to planar heating elements, in particular resistance-heating elements and the use of said planar heating elements.

The objects of the present invention are explained below with reference to the accompanying drawings.

1 is a partial cross-sectional view of a heating element according to an embodiment of the invention;

2 is a schematic side view of an embodiment having a plurality of float electrodes;

3 shows a schematic view of the area developed in the embodiment according to FIG. 2;

4 is a cross-sectional view of a pipe embodiment according to the present invention without an insulating layer;

5 is a cross-sectional view of a pipe embodiment according to the present invention including a thermal insulation layer;

6 shows a cross-sectional view of an embodiment of a device according to the invention without a thermal insulation layer;

7 shows a cross-sectional view of an embodiment of the device according to the invention when the resistance-heating element is integrated into a thermal insulation layer;

8 is a perspective view of an embodiment of the device according to the invention shown in FIG. 7;

9 shows an embodiment of a heating roller according to the invention with a resistive layer sandwiched between electrodes;

10 is a longitudinal sectional view of a heating roller according to the invention with two electrodes arranged side by side on one side of the resistive layer.

It is an object of the present invention to provide a heating element capable of generating a high output and a high temperature per unit area even during long term operation with a low voltage prevailing in the heating element. This heating element must also be simple to have contact terminals and have various uses.

The invention also relates to a heatable pipe to which a resistance-heating element is applied.

Pipes are widely applied, for example, for transporting fluid media. For example, when the pipe is placed in the cold zone as an outdoor pipe or underground, there is a risk that the medium in the pipe may solidify due to low temperatures and block the pipe.

It is therefore another object of the present invention to provide a pipe which can be heated by a simple device and which can be used for various purposes.

The invention also relates to a transport device capable of heating to a medium.

Media such as gases and liquids are transported in tanks installed on railroad cars or trucks. When the ambient temperature is low, the medium in the tank may freeze and may destroy the tank. Installing a heating element in the vehicle described above is a great requirement for the heating element as well as the heat transfer that can occur between the heating element and the vehicle. Hazardous materials are then transported from this tank. It is important that the heating element does not cause any local temperature rise. In addition, in order to prevent condensation of the medium, it is necessary to prevent abnormality in the heating element, for example, by separating it from the tank.

It is therefore an object of the present invention to provide a transport apparatus for a medium which can be maintained at a predetermined temperature while transporting the medium without causing dangerous situations such as condensation, explosion or fire.

The invention also relates in particular to a heating roller for use as a radiation or membrane-coated roller.

In various areas of heating technology, there is a need to provide a roller that can be heated to a constant temperature. To date, such heating rollers have been produced with heating elements having resistance wires embedded in insulation. Another mode of operation of a heating roller, for example in a copier, is to install a halogen emitter in the roller. The two examples above have the disadvantage of being very expensive to manufacture and having low heat transfer efficiency.

It is an object of the present invention to provide a heat roller with a simple structure which can be operated at a low voltage while at the same time having a high heat transfer efficiency. In addition, this heating roller should have various uses.

The present invention can be realized as the above-mentioned object can be achieved by a resistance-heating element in which a heating current flows optimally through a suitable resistance material.

Another object of the present invention can be achieved by a heating roller with a pipe, a transport device and a resistance-heating element, wherein the resistance-heating element is made of a suitable resistive material and the heating current is in an optimal manner through this material. And the heating element is formed in a flat shape and ensures uniform heat transfer across the area.

According to the present invention, the above object is achieved by a planar heating element consisting of at least two planar electrodes spaced apart from each other on one side of the resistive layer and a thin resistive layer comprising a unique electrically conductive polymer.

In the heating element according to the invention, the resistive layer comprises an intrinsically conductive polymer.

According to the present invention, the polymer used in the resistance layer has a configuration in which a current flows along the polymer. Because of the structure of the polymer, the heating current passes through the resistive layer along the polymer. Due to the electrical resistance of the polymer, heat is generated which can be transferred to the object to be heated. The heating current cannot follow the shortest path between the two electrodes and follows the polymer batch structure. Therefore, since the length of the current path is predetermined by the polymer, a relatively high voltage can be applied without causing voltage breakdown even at a thin layer thickness. Even at high currents such as those which generate a current, there should be no risk of disconnection. Further, the distribution of current at the first electrode and the conduction along the polymer structure in the resistive layer make the distribution of temperature uniform in the resistive layer. This distribution occurs immediately after applying a voltage to the electrode.

Because of the polymers applied according to the invention, the resistance-heating element can be operated at high voltages, such as line voltage. The heating power achievable increases in proportion to the square of the operating voltage, so that the resistance-heating element according to the invention can generate high heating power and high temperature. According to the present invention, the current density is minimized since a relatively long current path is provided along the electroconductive polymer or at least two contiguous regions including the inherent electroconductive polymer used according to the invention are formed.

In addition, the electroconductive polymer used according to the present invention has long-term stability. This stability is explained by the fact that the polymer is ductile so that when the temperature rises, the polymer chain is not broken and the current path is not interrupted. These polymer chains are not damaged by repeated temperature changes. In conventional resistance-heating elements in which conductivity is generated by the carbon black skeleton, this thermal expansion causes interruption of the current path and overheating. This causes disconnection and strong oxidation of the resistive layer. The intrinsically conductive polymers used in accordance with the present invention do not suffer from aging.

The inherently conductive polymers used in accordance with the present invention do not age in reaction environments such as air oxygen. In addition, current conduction through the resistive material is of an electron conduction type. No automatic breakdown of the resistive layer by the electrolysis reaction generated by the electric current occurs in the resistive-heating element according to the invention. In the resistance-heating element according to the invention, the time-dependent decrease in heating power per unit area as high as 50 mW / m 2 and at temperatures as high as 500 ° C. is very small and almost zero.

Due to the use of intrinsically conductive polymers, the resistive layer used in accordance with the present invention as a whole provides a uniform structure allowing uniform heating across the entire layer.

According to the invention, the resistance-heating element and the contact are provided by two electrodes arranged on one side of the resistive layer and made of a material having high electrical conductivity. This kind of contact arrangement can advantageously utilize the mode of operation of the inherently conductive polymers used according to the invention. The applied current diffuses in the first electrode and then traverses the thickness of the resistive layer along the polymer structure and is delivered to the second contact electrode. Therefore, the current path extends over what is present in the structure in which the resistive layer is sandwiched between the two electrodes. Because of this current flow, the thickness of the resistive layer can be kept small. An advantage of the heating element according to the invention is that it is versatile. This electrode has a contact portion on one side of the resistive layer. Therefore, the opposite side of the resistive layer is formed in a flat shape because there is no contact terminal. This flat surface can be applied directly to the body to be heated. The contact surface between the resistance-heating element and the body to be heated is not broken by the contact terminal, thus allowing ideal heat transfer.

In a preferred embodiment, the flat flotation electrode is disposed on the side of the resistive layer opposite the two flat electrodes.

In the scope of the present invention, the electrode is called floating when not connected to a power source. It includes insulation to prevent electrical contact with the power source.

The flotation electrode maintains a flow of current through the resistive layer. In this embodiment, the current spreads in the first electrode, traverses the thickness of the resistive layer to reach the flotation electrode on the opposite side, and is transmitted within this electrode and finally penetrates through the thickness of the resistive layer of the same resistive layer as the first electrode. Flow to the other electrode disposed on the side.

In the heating element according to this embodiment, the current flows through the thickness of the resistive layer, in particular at right angles to the surface. In particular, both areas develop inside the resistive layer. Inside the first region, current flows vertically from the first contact electrode to the lift electrode, and inside the second region current flows vertically from the lift electrode to the second contact electrode. Thus, a series of arrangements of various resistors is obtained by the arrangement. This effect means that the dominant partial voltage in each area is smaller than the voltage applied. Therefore, in the embodiment of the present invention, the dominant voltage in each region is 1/2 of the voltage applied. Because of the prevailing low voltage in the resistive layer, the heating element according to the invention can avoid the hazard and can be used for various purposes. The heating element may be used in a device which must be in immediate contact with the medium to be heated or by a person operating or using the device.

In addition, the gap provided between the electrodes to be contacted is used as an additional resistor disposed in parallel. With air as the insulator in this gap, the resistance will be determined by the mutual distance of the electrodes and the surface resistance of the resistive layer.

Electrodes and flotation electrodes have good thermal conductivity. This may exceed 200 W / m · K, preferably 250 W / m · K. Local overheating can be quickly removed by good thermal conductivity at the electrode. The overheating therefore takes place only in the direction of the layer thickness but is not adversely affected by the thin layer thickness which can be realized in the resistance-heating element according to the invention. The advantage of the resistance-heating element is that the local temperature rise resulting from the outside, for example the body to be heated, can be balanced in an ideal way by the resistance-heating element.

Electrodes and flotation electrodes are preferably made of a material having high electrical conductivity. Thus, the specific electrical resistance of this electrode is 10 ⁻⁴ Pa · cm or less, preferably 10 ⁻⁵ Pa · cm or less. Suitable materials are for example aluminum and copper. By choosing such an electrode material it is ensured that the current applied before passing through the resistive layer is conducted in the planar electrode, i.e. diffused therein. This uniformizes the flow of heating current through the resistive layer and uniformly and completely heats the resistive layer. Such resistance-heating elements can generate and transfer heat uniformly. By selecting the above electrode materials it is possible to make large resistance-heating elements without the need for voltage supply to the various parts along the length or width of the electrode. Therefore, the power supply line does not need to be installed along the surface. According to the invention, it will only be selected for embodiments in which the resistance-heating element covers a long area or length, for example at least 60 cm ² , preferably at least 80 cm ² . The limit size of the resistance-heating element meaningful for providing multiple contact points depends on the location of the contact as well as the selected electrode material. Therefore, when the electrode is able to approach the surface center point and has a contact, a number of contact points will not be required even for areas larger than those described above.

The size of the resistance-heating element that can be operated with a single contact depends on the thickness of the selected electrode. According to an embodiment of the invention, the electrode and the lift electrode have a thickness of 50-150 μm, preferably 75-100 μm. This thin layer thickness is advantageous because the heat generated by the resistance-heating element can be easily transferred. In addition, the thin electrode has greater elasticity, which can prevent separation of the electrode from the resistive layer and interruption of the electrical contact during thermal expansion of the resistive layer.

According to the present invention, the resistance layer is thin. This thickness depends on the breakdown voltage and is 0.1-2 mm, preferably 1 mm. The advantage of the resistive layer having a thin layer thickness is that the heating time is short, the heat can be rapidly transferred, and high heating power per unit area can be given. However, this layer thickness is possible with the resistance-heating element according to the invention. On the other hand, the current path in the resistive layer is determined by the polymer used according to the present invention and is long enough to prevent voltage breakdown even when the layer thickness is thin. On the other hand, the one-contact arrangement of the resistive-heating element can subdivide the resistive layer into regions of lower voltage, which reduces the risk of destruction.

The advantage of the resistance-heating element according to the invention is further enhanced when the resistance layer has a positive temperature coefficient (PTC) of electrical resistance. This has a self-regulating effect on the highest temperatures achievable. This effect occurs because the flow of current through each mass is regulated as a function of temperature due to the PTC of the resistive layer. The higher the temperature, the lower the current, especially until it becomes very small at thermal equilibrium. Local overheating and melting of the resistive material can be reliably prevented. This self-regulating effect is important for the heating element according to the invention, since a local temperature rise can occur when the heat transfer is low due to insufficient contact of the heating element according to the invention with the body to be heated.

Selecting a PTC material for the resistive layer means that the entire resistive layer is heated to the same temperature as a result. This allows for uniform heat transfer, which is necessary for the application of certain resistance-heating elements.

According to the invention, the resistive layer can be metallized on the surface facing the electrode, the flotation electrode. By metallization, the metal is attached to the surface of the resistive layer to improve current flow between the electrode or the lift electrode and the resistive layer. In this embodiment, heat transfer from the resistive layer to the floating electrode to the body or the object to be heated is also improved. This surface can be metallized by spraying metal. Such metallization is possible only with the material of the resistive layer used according to the invention. Expensive metallization, for example by metal electroplating, is unnecessary and can significantly reduce manufacturing costs.

Inherently electrically conductive polymers are produced by doping the polymer. Such doping is metal or semimetal doping. In this polymer, the defect carrier is chemically bonded to the polymer chain and causes this defect. Doping atoms and matrix molecules form a charge-transfer matrix. During doping, electrons are transferred to the dopant in the polymer-filled band. Due to the electron holes thus formed, the polymer has the same electrical properties as the semiconductor. In this embodiment, the metal or semimetal atoms are integrated or attached to the polymer structure by chemical reaction to produce free charge that can flow current along the polymer structure. This free charge is present in the form of free electrons or holes. In this way an electrical conductor is created.

Preferably, the dopant and the polymer are mixed in an amount such that the ratio of atom to polymer number of the dopant is at least 1: 1, preferably 2: 1 to 10: 1, for doping. In this ratio all polymers may be doped with at least one atom of the dopant. The conductivity of the polymer and the resistive layer as well as the resistive temperature coefficient of the resistive layer can be adjusted by selecting this ratio.

The inherently electrically conductive polymer used in accordance with the invention can be applied as a material for the resistive layer in the resistive-heating element according to the invention without the addition of graphite, but in another embodiment the resistive layer can contain graphite particles. have. These particles can contribute to the conductivity of the complete resistive layer and do not contact each other and in particular do not form a reticulated or skeletal structure. Graphite particles can move freely without being tightly bound to the polymer structure. When graphite particles come in contact with two polymers, an electric current can jump through graphite from one chain to the next. The conductivity of this resistive layer can be raised in this way. Due to free mobility in the resistive layer, the graphite particles may move to the surface of the layer and may improve contact with the electrode or the lift electrode.

These graphite particles are present in an amount of 20 vol.%, Preferably 5 vol.%, Based on the total volume of the resistive layer and have an average diameter of 0.1 μm. With a short diameter and a small amount of graphite, it prevents the formation of graphite networks that pass through the network and cause current conduction. The current thus contributes to the flow by electrical conduction through the polymer structure, thus ensuring that the above-mentioned advantages can be obtained. In particular, conduction does not have to occur along the graphite network or skeleton, which is easily broken under mechanical and thermal stress and the graphite particles must be in contact with each other, but rather occurs along soft and anti-aging polymers.

Electrically conductive polymers such as polystyrene, polyvinyl resins, polyacrylic acid derivatives, electrically conductive polyamides and derivatives thereof, polyfluorinated hydrocarbons, epoxy resins and polyurethanes can be used as the inherently electrically conductive polymers. Polyamides, polymethyl methacrylates, epoxides, polyurethanes and polystyrenes or mixtures thereof may be used. Polyamides have good adhesion, which is advantageous for the production of resistance-heating elements according to the invention. Polymers such as polyacetylene are removed from the use according to the invention because of the low aging resistance due to reaction with oxygen. The length of the polymer used varies within a wide range depending on the polymer type and structure, but is at least 500, preferably 4000 kPa.

In this embodiment, the resistive layer has a support material. This support material is used on the one hand as a carrier material for the inherently conductive polymer and on the other hand it is used as a spacer between the electrode and the flotation electrode. Since the support material imparts a constant strength at the resistance-heating element, it can withstand mechanical stress. In addition, when the support material is used, the layer thickness of the resistive layer can be precisely adjusted. Glass or glass fibers, rock wool, ceramics or plastics such as barium titanate may be used as the support material. For example, the support material imparted as a tissue or mat made of glass fibers may be inserted into the material constituting the inherently electrically conductive polymer and injected into the inherently electrically conductive polymer. The layer thickness is then determined by the thickness of the grid or mat. For example, methods such as scraping, spreading or known screen-printing methods may be used.

Advantageously, the support material is a flat, porous, electrically insulating material. This material prevents the heating current from passing through the support material rather than the polymer structure.

The possibility of forming a layer that deviates from the desired layer thickness with minimal error (eg 1%) across the surface is particularly important when the layer thickness is thin as used in the present invention. This is because care must be taken not to directly contact between the contact electrode and the float electrode. The change in layer thickness across the layer surface affects the temperature generated and leads to an uneven temperature distribution.

The support material has the effect that current cannot travel along the shortest path between the electrode and the flotation electrode but is deflected or divided in the filler. Therefore, the energy supplied can be optimally utilized.

The heating element 1 has two planar electrodes 3, 4 and a thin resistive layer 2 which cover all resistive layers and are arranged side by side spaced apart from one another. On the opposite side of the resistive layer 2, a floatation electrode 5 is arranged, which covers the resistive layer not only in the gap between the electrodes but in the entire area formed by the electrodes 3,4. When the electrodes 3, 4 are in contact with a power source (not shown), the current initially unfolds inside the electrode 3, then passes through the resistive layer 2, and is perpendicular to the surface facing the flotation electrode 5. It is transmitted in this electrode, flows from the resistive layer 2 to the electrode 4 and is discharged therefrom. Depending on the contact arrangement at the electrodes 3, 4, the current may flow in the opposite direction. In the embodiment shown, the insulation between the electrodes 3, 4 is formed by air gaps.

In FIG. 2, a heating element with a thin resistive layer 2 is shown. On one side of the resistive layer 2, two planar electrodes 3, 4 as well as a plurality of intermediate flotation electrodes 5 are provided. The electrodes 3 and 4 and the floating electrode 5 are separated from each other and separated from each other with respect to the floating electrode 5 disposed on the opposite side of the resistive layer 2. In this arrangement, the current supplied to the electrodes 3, 4 flows through the resistive layer 2 and the supporting electrode 5 in the direction of the arrow in the figure. With this current flow, the resistive layer 2 is used as a series of devices having a plurality of electrical resistances, which can obtain high power while the low voltage prevails in the region of each resistive layer. Here, the surface resistance is used in the gap between the resistance and the electrodes 3 and 4 and the supporting electrode 5 in the thickness of the resistance layer 2. The long distance in the space between the electrodes in contact gives the advantage of preventing direct contact therebetween.

3 is a schematic view that can be used to explain the electro-technical dimensions of a resistance-heating element embodiment according to the present invention. The resistance-heating element is derived from the ratio between the only maximum maximum voltage applied to each partial area initially arranged continuously, and the total voltage to be applied to the contact electrode, starting with the heating power per unit area of the desired total resistance-heating element in a particular case. Determine the number of heating zones required across the width of. The length of the heating zone is represented as S, and the width Z of each zone is calculated by the equation (1).

Z = [B-n · A / 2-2 · K] / n

In Equation 1

B = overall width of the flat heating element in mm

A = distance (mm) between the electrode and the floating electrode on one side of the resistive layer

K = transverse band width (mm)

n = the number of each heating zone arranged in succession

The die width of each electrode or flotation electrode alternately arranged on each side of the resistive layer can be obtained from the sum of the distance A and the width of the two regions between the electrodes arranged on one side of the resistive layer.

The heating power N _Z of each region of the resistance-heating element can be found from Equation 2:

_Z = _Z · I _G U N = _Z U ² = U L · _Z ² · Z · S / ρ · D

In equation (2)

U = the maximum permissible electric field voltage (V) applied to the partial resistance due to the electrical insulation (breakdown resistance) of the resistance-heating layer required for each application

I = Current (A) constant and equal to total current across all partial resistors due to a series of placements

L = electrical conductivity (S) of the intrinsic electrically conductive polymer resistive layer (S)

ρ = specific resistance of the polymer layer (Ω · cm)

S = electrode length of the resistance-heating element (mm)

Z = width of each heating zone in mm

D = thickness of the resistive layer (mm)

In the heating element according to the invention the electrodes and the flotation electrodes may consist of a metal foil or a metal plate. The electrically conductive layer can also be coated with black plastic in terms of facing away from the resistive layer. With this additional layer, the heating element according to the invention can function as an assay body and generate the penetrating effect of the resulting radiation.

In the heating element according to the invention, a plurality of electrodes can be provided on one side of the resistive layer. When providing a plurality of electrodes separated from each other by insulation, which are used as pairs of electrodes to which a voltage can be applied and arranged next to each other, it is possible to heat the heating elements on a per area basis.

Insulation is realized between the electrodes with an insulating material sandwiched between the electrodes within the scope of the present invention. Conventional dielectrics and plastics can be used as insulation.

If no voltage is applied at the surface of the heating element facing the body to be heated, the resistive layer or the lift electrode can be laminated with polyester, PTFE, polyimide and other thin films. Simple forms such as thin films and conventional insulation materials can be used in the heating element according to the invention, since the flotation thin film has no terminals and has a smooth surface.

The resistive layer may have a structure in which different resistive materials having different specific electrical resistances are present in layer form.

According to an advantage of this embodiment, by properly selecting the material in the resistive layer, the side of the resistive layer can have a higher temperature where heat is transferred from the side to the body to be heated, and different heating currents in each layer of the resistive layer There is no need to conduct it separately to the heating wire. This is achieved when a particular electrical resistance of the polymer is selected that is applied to increase from the layer adjacent to the electrode, in the lateral direction towards the body or object to be heated.

Because of the contact arrangement with the resistive layer applied, the resistance-heating element according to the invention can be operated with a low voltage of 24 V and a high voltage of 240, 400 V, 1000 V.

With the resistance-heating element according to the invention, heating power per unit area in excess of 10 mW / m 2, preferably 30 mW / m 2, can be achieved. With this heating element, heating powers up to 60 mW / m 2 can be achieved. Heating power up to 60 mA / m 2 may be achieved with a layer thickness of a resistive layer of 1 mm. When a voltage of 240V is applied continuously, the heating power which decreases with time may be 0.01% or less.

The temperature achievable with the resistance-heating element is limited by the thermal properties of the selected polymer, but is at least 240 ° C and up to 500 ° C. Even at the temperatures achieved, the polymer must be selected to continue conducting into the electronic device.

The heating element can take many forms when using the resistive layer applied according to the invention. The resistance-heating element has the shape of a tape having a length longer than the width where the electrode is a strip extending over the entire length of the tape and arranged side by side in the width direction of the resistance-heating element. It is also possible to make a square shape with the heating element according to the invention.

The resistance-heating element can be mounted inside or outside the pipe. The one-way contact arrangement of the heating element is particularly advantageous because the heat transfer from the resistance-heating element to the body to be heated, such as a pipe, is not interrupted by the contact terminal. Electrical insulation between the resistance-heating element and the body to be heated is made simple by the lack of contact points in the electrically conductive layer.

Intrinsically conductive polymers may be selected to have a negative electrical resistance temperature coefficient for a range of temperatures within the scope of the present invention. Thus, this temperature coefficient can be a positive value of a certain temperature, for example 80 ° C. or higher.

Another object of the present invention is a thin resistive layer containing an intrinsically electrically conductive polymer, wherein at least two planar electrodes partially covering the resistive layer on the outside of the resistive layer are separated from each other when the inner pipe is directly or indirectly partially coated on the outside. When spaced apart relative to, it is achieved by a pipe capable of heating.

In the pipe according to the invention, the resistive layer comprises an intrinsically electrically conductive polymer. The polymer used in the resistive layer according to the present invention has a composition in which a current flows along the polymer. Because of this polymer structure, a heating current is transferred through the resistive layer along the polymer. Because of the electrical resistance of the polymer, heat is generated that can be transferred to the inner pipe to be heated. The heating current here does not follow the shortest path between the two electrodes but follows the polymer structure. Therefore, the length of the current path is predetermined by the polymer, so that even when the layer thickness is thin, a relatively high voltage can be applied without causing voltage breakdown. Even with high currents, such as when generating currents, there is no risk of disconnection. In addition, conduction along the polymer structure in the resistive layer and the distribution of current at the first electrode makes the temperature distribution uniform in the resistive layer. This distribution occurs immediately after applying a voltage to the electrode.

Because of the polymers applied according to the invention, the pipes can be operated at high voltages, such as line voltage. The heating power that can be achieved increases by the square of the operating voltage, so that the resistance-heating element according to the invention can generate high power and high temperature. According to the invention, the current density is minimized. This is because a relatively long current path is provided along the electrically conductive polymer, and two electrically in series regions are formed, including the inherently electrically conductive polymer used in accordance with the present invention.

In addition, the electroconductive polymer used according to the present invention has long-term stability. This stability can be explained by the fact that the polymer is ductile, so that even when the temperature rises, the breakage of the polymer chain and the interruption of the current path do not occur. Repeated temperature changes do not damage the polymer chain. In conventional resistance-heating elements in which conduction by the carbon black backbone occurs, this thermal expansion causes disturbance and overheating of the current path. This causes strong oxidation and disconnection of the resistive layer. The intrinsically conductive polymers used in accordance with the present invention do not suffer from this aging phenomenon.

The intrinsically conductive polymers used in accordance with the invention do not age even in reaction environments such as air oxygen. In addition, the current conduction through the resistive material used in accordance with the invention is of electrically conductive type. Automatic breakdown of the resistive layer by the electrolytic reaction caused by the current does not occur in the resistive-heating element according to the invention. In the resistance-heating element according to the invention, the reduction in heating power with time per unit area is very small or near zero even at temperatures above 500 ° C. and heating power per unit area as high as 50 mW / m 2.

This long term stability or aging resistance is particularly important in the pipes according to the present invention, since frequent heating is not desirable since the heatable pipes are used underground or elsewhere not easily accessible.

Due to the use of inherently electrically conductive polymers, the resistive layer used in accordance with the invention as a whole imparts a homogeneous structure that can be heated uniformly across the entire layer.

According to the invention, the pipe and the contact are provided by two electrodes made of a material having high electrical conductivity and arranged on one side of the resistive layer. This type of contact arrangement makes it particularly advantageous to utilize the mode of operation of the inherently electrically conductive polymers used according to the invention. The applied current spreads inside the first electrode and then traverses the thickness of the resistive layer along the polymer structure and is conducted to the second contact electrode. Thus, the current path extends above what is present in the structure with the resistive layer inserted between the two electrodes. Because of this current flow, the thickness of the resistive layer can be kept thin.

Pipes according to the invention have the advantage that they are versatile in use. This electrode has a contact portion on one side of the resistive layer. It is facing away from the inner pipe and easily accessible for making connections. The opposite side of the resistive layer facing the inner pipe has no contact terminals and is constructed in a flat shape. This flat surface allows for direct application of the resistive layer to the inner pipe. The contact surface between the inner pipe to be heated and the resistance-heating element is not broken by the contact terminal, thus allowing ideal heat transfer to the inner pipe.

With this structure according to the invention, the pipe is easily heated. The inner pipe has a resistive layer and an electrode and, if necessary, is integrated into the pipeline in the finished state and has an interlayer at the place of manufacture.

In an embodiment of the pipe according to the invention, the pipe has an inner layer made of a material having high electrical conductivity between the inner pipe and the resistive layer.

The interlayer here is used as a floatation electrode. In the scope of the present invention, the electrode is said to be floating when not connected to a power source. It has insulation to prevent electrical contact with the power supply.

This flotation electrode supports the flow of current through the resistive layer. In this embodiment, the current diffuses inside the first electrode, traverses the thickness of the resistive layer to reach the flotation electrode on the opposite side, conducts inside the electrode, passes through the thickness of the resistive layer and is spaced apart from the pipe to face the resist It flows to the other electrode which can be found on the side of the layer. The interlayer can be insulated from the inner pipe by a thin film. Insulation of the interlayer without a contact part can be performed with a well-known thin film comprised from polyimide, polyester, and a silicone rubber.

In the heatable pipe according to this embodiment, the current flows through the thickness of the resistive layer, in particular in a direction perpendicular to the surface. In particular, both areas develop inside the resistive layer. Inside the first region current flows vertically from the first contact electrode to the levitation electrode, and inside the second region current flows vertically from the levitation electrode to the second contact electrode. Thus, a series of arrangements having a plurality of resistor portions is achieved by this arrangement. This effect means that the dominant partial voltage in each area is lower than the applied voltage. Therefore, in the embodiment of the present invention, the dominant voltage in each region is 1/2 of the voltage applied. Due to the prevailing low voltage in the resistive layer, the safety of the pipe according to the invention can be reliably maintained and used in various applications. Thus, the pipe according to the invention finds use in wet areas and where people have to come in contact with the pipe.

Moreover, the gap provided between the contacted electrodes is used as an additional resistance part arrange | positioned in parallel. Using air as the insulator in this gap, the resistance will be determined by the mutual distance of the electrodes and the surface resistance of the resistive layer. This distance should be longer than the resistive layer thickness, for example twice the thickness of the resistive layer.

Electrodes and flotation electrodes have good thermal conductivity. This may exceed 200 W / m · K, preferably 250 W / m · K. Local overheating can be quickly removed by good thermal conductivity at the electrode. Superheating is possible only in the direction of the layer thickness and has no negative effect because of the thin layer thickness that can be realized in the pipe according to the invention. The advantage of this pipe is that the local temperature rise resulting from the internal, ie internal pipe to be heated, can be equilibrated in an ideal manner by the heat-resisting element. This temperature rise can occur in partially filled pipes, since in the area filled with air little heat is transferred from the pipes to the air.

The advantage of heatable pipes is that the resistive layer disposed in the inner pipe can withstand high stresses without causing a local temperature rise. In general, the mechanical stresses acting especially on the pipes arranged underground are directed in the radial direction. This is the direction of current flow in the resistive layer of the resistive-heating element. Therefore, such stress does not cause an increase in resistance at the place where pressure is applied, unlike a resistance-heating element in which current flows in a direction perpendicular to the compressive load.

In another embodiment of the heatable pipe according to the invention, the resistive layer is arranged directly on the inner pipe, which consists of an electrically conductive material.

In this embodiment, the current flow from one electrode to the next is directed via the resistive material and the inner pipe. When the low voltage prevails in the resistive layer of the pipe according to the invention, the inner pipe used as the floatation electrode can be presented as a current conductor without causing problems to safety. In this embodiment, the generated heat can be easily transferred to the medium present in the pipe. In this example, the inner pipe can be covered with a resistive layer over the entire circumference, and the electrode can completely cover this layer. However, a gap between the electrodes that must be provided for electrical reasons also exists in this embodiment.

According to another embodiment of the present invention, the resistive layer and the electrodes disposed thereon extend longitudinally in the axial direction, and the electrodes are disposed in the resistive layer spaced apart from each other in the circumferential direction.

In the resistive layer and the longitudinal extension of the electrode, a length of pipe can be heated when a current supply is required only at a single point of each of the two electrodes.

In a preferred embodiment, the resistive layer covers only the outer circumferential portion of the inner pipe and extends longitudinally in the axial direction. Preferably, the length of the resistive layer and the electrode matches the length of the pipe.

In this embodiment, heat can be transferred to the pipe within a confined area where a resistive or interlayer is applied to the inner pipe. In the case of a pipe having an inner pipe with good thermal conductivity, the heat transferred from the resistive layer can be distributed over the outer circumference of the inner pipe to completely heat the medium present in the pipe. This structure can heat the medium with little engineering effort. However, this embodiment is possible only when the heatable pipe has the structure according to the invention. This structure only allows high power per unit area to be achieved while preventing all damage to the resistive layer during extended operation under the influence of reactive materials such as water or air oxygen.

This resistance layer covers a part of the outer circumference which is placed in the lower part of the pipe when the pipe is installed. This ensures that the medium to be heated is heated reliably and quickly in contact with the partial region even in a pipe that is not completely filled.

In the pipe according to the invention, the electrode and the interlayer are composed of a material having a specific electrical resistance of 10 ⁻⁴ Pa · cm or less, preferably 10 ⁻⁵ Pa · cm or less. Examples of suitable materials are aluminum and copper. This is particularly important in the pipe according to the invention. Usually, pipes are used to build pipelines. When the electrical resistance of the electrode is low, the resistance layer and the electrode in the pipeline consisting of the pipe according to the invention are advantageous because they are very long. This electrode material prevents voltage drops that occur across the electrode surface causing a total reduction in power. In addition, conductivity ensures quick distribution of current inside the electrode, which can quickly and uniformly heat the length of the entire resistive layer and pipe without applying a voltage to the electrode at various parts along its length and width. It is not necessary to arrange the power supply line along the pipe. This pipe may have a length of up to 1 m. According to the invention, this arrangement with multiple contact points is chosen in embodiments where the pipe is longer. The limit length for which a number of contact arrangements are meaningful depends on the electrode material and the contact portion selected. Therefore, when the electrode is accessible at the midpoint of its length and a contact is provided at this point, a number of contact points are unnecessary for lengths that are more important than those described above.

The length of the pipe that can be operated with a single contact depends on the thickness of the selected electrode. According to an embodiment of the present application, the electrode and the interlayer have a thickness in the range of 50-150 μm, preferably 75-100 μm. The advantage of this thin layer thickness is that the heat generated by the resistance-heating element can be easily transferred from the interlayer to the pipe. In addition, since the thin electrode has greater elasticity, it is possible to prevent interruption of electrical contact during separation of the electrode from the resistive layer and thermal expansion of the resistive layer.

In long length pipelines, multiple contact arrangements may be required. In a pipe according to the invention this is easily provided. Since the electrode has a contact terminal on the outside, it is easily accessible. Therefore, a power line extending along the pipe and connecting the electrodes to the sparse voltage source can be provided along the pipeline. This makes it possible to operate the long pipes according to the invention.

According to the present invention, the resistance layer is thin. This thickness has a minimum limit depending on the breakdown voltage, and is 0.1-2 mm, preferably 1 mm. The thin layer thickness of the resistive layer gives the advantage of providing fast heating time, rapid heat transfer and high heating power per unit area. However, this layer thickness is only possible with the inherently conductive polymer and contact arrangements used. On the other hand, the current path in the resistive layer can be long enough to prevent voltage breakdown even when the layer thickness is predetermined and predetermined by the polymer used according to the present invention. On the other hand, one-way contact arrangements can subdivide the resistive layer into regions with lower voltages, which reduces the risk of breakdown.

The advantage of the pipe according to the invention is further enhanced when the resistive layer has a positive temperature coefficient (PTC) of electrical resistance. This produces an auto-regulation effect for the highest temperatures achievable. The overheating of the pipe and the reaction in the pipe caused by this overheating can be prevented by the above-described effect. The above-mentioned effect occurs because the flow of current through the resistive material is regulated as a function of temperature because of the PTC in the resistive layer. The higher the temperature, the lower the current, until it becomes very small at a certain thermal equilibrium. Local heating and melting of the resistive material can be reliably prevented. This effect is particularly important in the present invention. For example, if a pipe is only half filled with liquid medium, it is easier to remove heat in the area of the pipe than in the area of the pipe filled with air. Conventional resistance-heating elements are heated and melted due to incomplete heat recovery. In the heatable pipe according to the invention, this melting is prevented by the self-regulating effect.

Selecting PTC for the resistive layer means that as a result the entire resistive layer is heated to the same temperature. This allows for uniform heat transfer, which may be necessary for the particular use of the pipe when the heat-sensitive medium is transported through the pipe.

According to the invention, the resistive layer can be metallized at the surface facing the electrode and the interlayer. By metallization, the metal is attached to the surface of the resistive layer and improves the current flow between the electrode or the lift electrode and the resistive layer. Also in this embodiment the heat transfer from the resistive layer to the flotation electrode and the inner pipe to be heated is improved. This surface can be metallized by spraying metal. Such metallization is possible only with materials consisting of resistive layers used according to the invention. Costly metallization by metal electroplating is unnecessary and manufacturing costs can be reduced.

Inherently electrically conductive polymers are formed by doping of the polymer. Such doping may be metal or semimetal doping. In this polymer, the defect carrier is chemically bonded to the polymer chain and causes this defect. Doping atoms and matrix molecules form a charge-transfer complex. During doping, electrons are transferred to the dopant in the polymer-filled band. Because of the electron holes created, the polymer has the same electrical properties as the semiconductor. In this embodiment, metal or semimetal atoms are integrated and attached to the polymer structure to produce free charge that can carry current along the polymer structure. Free charge is present in the form of free electrons or holes. In this way, an electronic conductor is created.

Preferably, the dopant and the polymer are mixed in an amount of at least 1: 1, preferably 2: 1 to 10: 1, ratio of the number of atoms of the dopant to the polymer for doping. In this ratio all polymers may be doped with at least one atom of the dopant. The conductivity of the polymer and the resistive layer as well as the resistive temperature coefficient of the resistive layer can be adjusted by selecting this ratio.

The intrinsically conductive polymer used in accordance with the invention can be applied as a material for the resistive layer in the resistive-heating element according to the invention without the addition of graphite, but according to another embodiment the resistive layer is characterized by It may contain. These particles can contribute to the conductivity of the complete resistive layer and do not contact each other, in particular, do not form a reticulated or skeletal structure. These graphite particles can move freely without being tightly bound to the polymer structure. When graphite particles come in contact with two polymers, an electric current can jump through graphite from one chain to the next. The conductivity of the resistive layer can be raised in this way. Because of the free movement in the resistive layer, the graphite particles can also move to the surface of this layer and improve contact with the electrode or interlayer or inner pipe.

The graphite particles are imparted in an amount of 20 Vol.%, Preferably 5 Vol.%, Based on the total volume of the resistive layer, and have an average diameter of 0.1 μm. Small amounts of graphite and short diameters prevent the formation of graphite networks that can cause current conduction through the network. Since the current is guaranteed to continue to flow through the conduction through the polymer, the above-mentioned advantages can be achieved. In particular, they occur along polymers that have to be in contact with each other and do not conduct along graphite networks or frameworks that are easily broken under mechanical and thermal stresses, but rather are ductile and resistant to aging phenomena.

Electrically conductive polymers such as polystyrene, polyvinyl resins, polyacrylic acid derivatives and mixed polymers, electrically conductive polyamides and their derivatives, polyfluorinated hydrocarbons, epoxy resins and polyurethanes can be used as inherently electrically conductive polymers. As well as polystyrene or mixtures thereof, polyamides, polymethylmethacrylates, epoxides, polyurethanes can be used. Polyamides have good adhesion, which is advantageous for producing pipes according to the invention. This is because it facilitates application to inner pipes or interlayers. Polymers such as polyacetylene are removed from use according to the invention because they have a low aging resistance by reactivity with oxygen.

The length of the polymer used varies within a wide range depending on the type and structure of the polymer, but is at least 500 kPa, preferably 4000 kPa.

In one embodiment of the invention, the resistive layer has a support material. This support material is used on the one hand as a carrier material for the inherently conductive polymer and on the other hand as a spacer between the electrode and the interlayer or electrically conductive inner pipe. This support material imparts constant strength to the resistance-heating element, so it can withstand mechanical stress. It is also possible to precisely control the layer thickness of the resistive layer when using the support material. Glass or glass fibers, rock wool, ceramics or plastics such as barium titanate can be used as the support material. The support material, made of glass fibers, imparted as a tissue or net, can be immersed in a material consisting of an intrinsically conductive polymer and injected into the intrinsic electrically conductive polymer. This layer thickness is determined by the thickness of the grid or net. Methods such as scraping, spreading or known screen-printing methods may be used.

Advantageously, the support material is a flat porous, electrically insulating material. This material prevents the heating current from flowing through the support material rather than through the polymer structure.

At thin layer thicknesses used according to the invention, the possibility of producing layers which deviate from the desired layer thickness across the surface with a minimum error of 1% is of particular importance. Otherwise there is a risk of direct contact between the contact electrode and the support electrode. Changes in layer thickness across the layer surface affect the temperature generated and result in inconsistent temperature distribution.

The current cannot flow along the shortest path between the electrode and the flotation electrode, but the support material has the effect of deflecting or dividing in the filler. Therefore, the energy supplied can be optimally utilized.

The pipe 10 that can be heated in FIG. 4 consists of an inner pipe 11 and a resistive layer 12 arranged inside covering the inner pipe 11 around its entire circumference. Two electrodes 13 and 14 which are flat and separated from each other by the electrical insulation 16 are arranged in the resistive layer 12. When a current is applied from the power source to the electrodes 13, 14, it flows from one electrode 13 through the resistive layer 12 to the inner pipe 11. In this embodiment, the inner pipe 11 is made of an electrically conductive material. Current is conducted inside the wall of the inner pipe 11 and flows through the resistive layer 12 to the second electrode 14. The entire resistive layer 12 is heated by this heating current and can transfer heat through the inner pipe 11 to the interior of the pipe.

In FIG. 5, the resistance-heating elements 12, 13, 14, 15, 16 are applied to the outer circumferential portion of the inner pipe 11. This element comprises an electrically conductive layer 15 facing the inner pipe 11. This layer 15 is flat and covered by a resistive layer 12 on the side facing away from the inner pipe 11. In the resistive layer 12, the two electrodes 13, 14 are disposed apart from each other. The inner pipe 11 is covered with a heat insulating layer 17 across the area that is not in contact with the resistance-heating element. Around this insulating layer 17, an insulating shell 18 is arranged which surrounds the insulating layer 17 and the resistance-heating elements 12, 13, 14, 15, 16. The pipe comprises a power supply facility 19. The power supply 19 is connected to a supply line 19a which runs through the insulating shell 18 and extends parallel to the axis of the inner pipe 11. This supply line 19a extends along the entire length of the pipe and can be connected to a power source (not shown) at the end of the pipe and coupled with the supply line 19a of the next pipe. A material that enhances heat transfer is provided between the inner pipe 11 and the electrically conductive layer 15 facing the inner pipe 11. This material is a thermally conductive paste, a pad having a thermally conductive material, silicone rubber and the like. In this embodiment, however, the resistance-heating elements 12, 13, 14, 15, 16 can be adjusted to the curvature of the inner pipe 11, which ensures instant heat transfer.

In the embodiment shown, the electrodes 13, 14 extend in the longitudinal direction of the pipe and are arranged side by side. Within the scope of the present invention, the electrodes 13, 14 are arranged in the resistive layer 12 so that they extend around and are arranged side by side in the axial direction.

In a supply line extending parallel to the pipe axis, the pipe of several parts having the structure according to the invention is arranged in series and the power supply of each resistance-heating element of the pipe piece is arranged in parallel. This supply line is protected from being in contact with water or damaged by an insulating shell.

The insulating layer aims to direct heat generated by the resistance-heating element in the direction of the inner pipe and to prevent heat loss by radiation in the direction away from the inner pipe. The heat insulating layer may be composed of an insulating material and a reflective layer.

It is also possible to apply a heat insulating layer around the pipe when the resistive layer as well as the electrode and interlayer are arranged in the longitudinal groove of the heat insulating layer facing the inner pipe. The thermal insulation layer here prevents heat from being transferred across the remainder of the inner circumference of the inner pipe which is not covered by the resistive or interlayer layers. By placing the resistance-heating element in the insulating layer, good contact between the inner pipe and the layer is ensured for the remainder of the outer circumference. 4 and 5 have a clamping device. Alternatively, this clamping device may be mounted outwardly in each heatable pipe represented by an adhesive tape or locking ring and in the embodiment shown in FIG. 5 it may be arranged directly on the outer face of the resistance-heating element. In this case the device consists of foam rubber. In the case of particularly large pipes, the expandable foam chamber can be provided on the side of the resistance-heating element facing away from the inner pipe. The clamping device ensures a constant fixed pressure and good heat transfer from the resistance-heating element to the inner pipe.

Resistance-heating elements such as those shown in FIG. 2 may be used. In the pipe according to the invention, the resistance-heating element is used such that the side of the resistance-heating element on which the contact electrode is disposed faces away from the inner pipe. Advantageously, the electrodes and the lift electrodes are arranged to be axially spaced apart from each other at the outer periphery of the pipe. This forms a number of peripheral regions when a voltage lower than the applied voltage prevails in each region. When the resistance-heating element is used, the electrical magnitude is set according to the equation and schematic 3 involved.

In the heatable pipe according to the invention, the inner pipe is made of metal or plastic, in particular of polycarbonate. When a non-electrically conductive material is selected for the inner pipe, the resistance-heating element comprises an intermediate layer between the inner pipe and the resistive layer. However, within the scope of the present invention there is provided a resistance-heating element for an inner pipe consisting only of an electrode and a resistance layer. In this embodiment, the heating element conducts a heating current from one electrode to the other through the resistive portion of the resistive layer, ie through the electrically conductive polymer. This current path is feasible with the pipe according to the invention because the structure of the polymer ensures a sufficiently large current flow and sufficient heat generation through the resistor.

In the area of the invention it is possible to arrange the supply lines connected to the electrodes of the resistance-heating elements on the outer side of the insulating shell via the power supply.

Conventional dielectrics and plastics can be used as insulation between the electrodes in contact with the current.

Terminals for supplying current to the heating element are provided by permanently coupled contact terminals using known systems for insulation braids or connections having a desired length.

Within the scope of the invention use is made of a material for a resistive layer having a negative temperature coefficient of electrical resistance.

A small amount of generated current is required when the temperature coefficient of the electrical resistance has a negative value. The resistive material used in accordance with the present invention at a specific temperature of about 80 ° C. may be returned so that the material of the resistive layer may be selected such that the temperature coefficient of the electrical resistance above the aforementioned temperature has a positive value.

This resistive layer comprises a structure in which a resistive material having another specific electrical resistance is present in the form of a layer.

In this embodiment, by selecting a suitable material in the resistive layer, the side of the resistive layer has a higher temperature where heat is transferred from the side of the resistive layer to the body to be heated, and in each layer of the resistive layer another heating with a heating wire. The advantage is that the current does not need to be conducted separately. This is achieved when the specific electrical resistance of the polymer is selected to increase in the layer adjacent to the electrode, in the lateral direction towards the pipe to be heated.

Because of the contact arrangement with the resistive layer applied, the pipe according to the invention can be operated with a low voltage of 24V and a high voltage of 240,400 and 1000V.

With the pipes according to the invention, heating power per unit area in excess of 10 mW / m 2 and preferably in excess of 30 mW / m 2 can be achieved. With this heating element, heating powers up to 60 mW / m 2 can be achieved. Heating power up to 60 mA / m 2 can be achieved with a layer thickness of a resistive layer of 1 mm. The reduction of heating power over time can be less than 0.01% per year when a voltage of 240V is applied continuously.

The temperature that can be achieved with this pipe is limited by the thermal properties of the selected polymer but is above 240 ° C and below 500 ° C.

Pipes according to the invention are pipes of any desired length. This pipe can be combined with other pipes according to the invention or with conventional non-heatable pipes to form a pipeline. Therefore, only segments of the pipeline where a certain temperature must be set to prevent freezing can be heated. With this selective heating the cost of the pipeline can be optimized. Pipes according to the invention can be made up to 10 cm in length and up to 2 m in length.

It is also possible to provide only part of the length of the pipe having the structure according to the invention. And one or more resistance-heating elements can be arranged in a heat insulating layer of the pipe according to the invention. It may extend in the radial or axial direction. The resistance-heating element may be distributedly disposed around the plurality of longitudinal grooves of the insulating layer.

When a direct current is applied to the electrodes of the heating element and the inner pipe is made of an electrically conductive material, a cathodic protection voltage can be generated in the inner pipe which prevents corrosion of the pipe.

The pipe may be constructed such that the inner pipe is formed from a conventional pipe and at least one of the half shells is surrounded by two half shells comprising a resistance-heating element. The half shell is made of an insulating material such as glass fiber or plastic foam.

When using the pipe according to the invention, the pipeline can be arranged even in areas where there is no risk of condensation of the pipe.

Another object of the invention is achieved by a transport device heatable to a medium comprising a container containing the medium, on the outer side the container is directly or indirectly partially covered with a thin resistive layer comprising an inherently electrically conductive polymer and At least two of the at least two planar electrodes covering are disposed away from each other on the outer side of the resistive layer.

With the transport device according to the invention, this container can be heated easily and reliably.

In the transport device according to the invention, the resistive layer comprises an intrinsic electrically conductive polymer. The polymer used in the resistive layer according to the present invention has a composition in which a current moves along the polymer. Because of the polymer structure, the heating current is conducted through the resistive layer along the polymer. Due to the electrical resistance of the polymer, heat is generated which can be transferred to the container to be heated. The heating current can follow the shortest path between the two electrodes, but follows the polymer batch structure. Therefore, the length of the current path is set by the polymer so that a relatively high voltage can be applied without causing voltage breakdown even when the layer thickness is thin. Even at high currents such as those which generate a current, there is no risk of disconnection. In addition, the distribution of current in the first electrode and continuous conduction along the polymer structure in the resistive layer cause homogeneous temperature distribution in the resistive layer. This distribution occurs immediately after applying a voltage to the electrode.

Because of the polymers applied according to the invention, the transport device can be operated even at high voltages such as line voltage. The heating power achievable is increased by the square of the operating voltage, so that high heating power and high temperature can be achieved with the transport device according to the invention. According to the present invention, the current density is minimized because a relatively long current path is provided along the electrically conductive polymer and two regions in series are formed containing the intrinsically conductive polymer used in accordance with the present invention.

In addition, the electroconductive polymer used according to the present invention has long-term stability. This stability is explained by the fact that the polymer is ductile so that the breakdown of the polymer and the interruption of the current path do not occur when the temperature rises. The polymer chain is not damaged after repeated temperature changes. In conventional resistance-heating elements used in heatable transport devices in which conductivity is generated by the carbon black skeleton, this thermal expansion causes interruption of the current path and overheating. This causes strong oxidation and disconnection of the resistive layer. The inherently electrically conductive polymers used in accordance with the present invention do not suffer from this aging phenomenon.

The intrinsically conductive polymers used in accordance with the present invention resist aging even in reaction environments such as air oxygen. Thus, automatic breakdown of the resistive layer by the electrolysis reaction caused by the electric current does not occur in the transport apparatus according to the present invention. In the resistance-heating element according to the invention, the reduction in heating power per unit area over time is very small or close to zero even at temperatures of 500 ° C. and heating power per unit area of 50 mW / m 2.

Due to the use of intrinsically conductive polymers, the resistive layer used in accordance with the present invention provides a homogeneous structure that allows uniform heating across the entire layer.

According to the invention, the transport device and the contact are provided by two electrodes made of a material having high electrical conductivity and arranged on one side of the resistive layer. This type of contact arrangement makes it possible to exploit the mode of operation of the inherently conductive polymers used according to the invention in a very advantageous manner. The applied current is injected inside the first electrode and then conducts to the second contact electrode across the thickness of the resistive layer along the polymer structure. Thus, the current path extends over what the resistive layer is in the structure sandwiched between the two electrodes. Because of this current flow, the thickness of the resistive layer can be kept thin.

The transport device according to the invention has the advantage of its versatile use. This electrode has a contact portion on one side of the resistive layer. This is the easily accessible side to make the connection and is facing away from the container. The opposite side of the resistive layer facing the container has a flat form without contact terminals. This flat surface allows the resist layer to be applied directly to the container. The contact between the resistive layer and the container is not broken by the contact terminals, thus allowing ideal heat transfer.

In an embodiment of the container according to the invention, the container comprises an intermediate layer made of a material having high electrical conductivity between the container and the resistive layer.

The intermediate layer is used here as a floatation electrode. In the present invention, when not connected to a power source, the electrode is said to be supported. It includes insulation to prevent electrical contact with the power source.

This flotation electrode supports the flow of current through the resistive layer. In this embodiment the current is distributed inside the first electrode, traverses the thickness of the resistive layer to reach the flotation electrode on the opposite side, conducts inside the electrode, and finally penetrates away from the container through the thickness of the resistive layer. It flows to the other electrode arrange | positioned at the side of a resistance layer. The intermediate layer can be insulated from the container by a thin film. Insulation of the intermediate layer without contacts can occur with known thin films made of polyimide, polyester and silicone rubber.

In an embodiment of the transportable device, the current flows through the thickness of the resistive layer in a direction perpendicular to the surface. Both areas develop inside the resistive layer. Within the first region, current flows in a vertical direction from the first contact electrode to the lift electrode, and within the second region current flows vertically from the lift electrode to the second contact electrode. Thus, a series of arrangements of a plurality of resistor sections is achieved by the arrangement. This effect means that the dominant partial voltage in each area is lower than the voltage applied. Therefore, in the embodiment of the present invention, the dominant voltage in each region is one half of the applied voltage. Because of the prevailing low voltage in the resistive layer, it is possible to reliably avoid the hazards and apply various applications to the other transport devices in the present invention. The transport device according to the invention can also be used in applications where people have to contact. In transport of this medium the device according to the invention is exposed to the atmosphere. Therefore, the device is in contact with water, in particular rain or snow. However, no danger is caused by the contacts due to the prevailing low voltage in the resistive layer of the device according to the invention. It is also possible to operate the device according to the invention from a conventional power source such as a battery. It can also be easily installed on railroad cars or trucks. In this case the device according to the invention can be powered by the truck's battery, which further simplifies the structure.

In addition, the gap provided between the contact electrodes serves as additional resistance portions arranged in parallel. Using air as the insulation in this gap, the resistance will be determined by the mutual distance of the electrodes and the surface resistance of the resistive layer. This distance is longer than the resistive layer thickness, for example twice the thickness of the resistive layer.

Electrodes and flotation electrodes have good thermal conductivity. This exceeds 200 W / m · K, preferably 250 W / m · K. Local overheating can be quickly resolved by good thermal conductivity at the electrode. Overheating is only possible in the layer thickness direction and has no negative effect due to the thin layer thickness that can be realized in the transport apparatus according to the invention. Another advantage of this transport device is that the local temperature rise caused in the environment by the outside, for example solar radiation, can be ideally balanced by the resistance-heating element. This rise in temperature occurs outside when the container is only partially filled because the heat transfer from the container to the air is lower than in the area filled with air.

Another advantage of the heating device capable of heating is that the resistive layer disposed in the container can withstand large stresses without causing a local temperature rise. As a rule, mechanical stresses acting on the container are applied in the radial direction. This is the direction of current flow in the resistive layer of the resistive-heating element. This stress does not cause an increase in resistance at the place where pressure is applied, unlike a resistance-heating element in which current flows in a direction perpendicular to the compressive load.

In another embodiment of the heatable transport apparatus according to the invention, the resistive layer is arranged directly in the container, which consists of an electrically conductive material.

In this embodiment, current flows from one electrode to the next through the resistive material and the container. At low voltage prevailing in the resistive layer of the transport device according to the invention, the container used as the flotation electrode can be presented without danger as a current conductor. In this embodiment, the generated heat can be easily transferred to the medium imparted to the container. In this example, the container is covered with a resistive layer over the entire circumference, and the electrode can completely cover this layer. However, a gap between the electrodes that must be provided for electrical reasons exists in this embodiment.

According to another embodiment of the present invention, the resistive layer and the electrodes disposed thereon extend longitudinally in the axial direction, and the electrodes are disposed in the resistive layer spaced apart from each other in the circumferential direction.

In the longitudinal extension of the resistance-heating element formed by the resistive layer and the electrode and the intermediate layer, when a power supply is required at one point of each of the two electrodes, it is possible to heat a specific area of the container.

In a preferred embodiment, the resistance layer covers only the outer circumferential portion of the container and extends longitudinally in the axial direction. Preferably, the length of the resistive layer and the electrode matches the container.

In this embodiment, heat can be transferred to a container in a defined region where the heating element formed by the resistive layer and the electrode and the intermediate layer has good thermal conductivity. In a transport device in which the container has good thermal conductivity, the heat generated by the resistance-heating element can be distributed over the entire outer circumference of the container and can completely heat the medium in the container. This structure can heat the media well with little engineering effort. However, this embodiment is possible only with the structure of the heatable transport device according to the invention. This structure makes it possible to achieve high power per unit area without damaging the resistive layer during extended operation under the action of reactive materials such as water or air oxygen.

This resistive layer covers a portion of the outer circumference placed on the bottom of the container when mounted. This ensures that even in a container that is not completely filled, the medium to be heated is in contact with this partial region and reliably and quickly heats up.

In the transport device according to the invention, the electrode and the intermediate layer are made of a material having a specific electrical resistance of 10 ⁻⁴ Pa · cm, preferably 10 ⁻⁵ Pa · cm or less. Suitable materials include aluminum and copper. This is particularly important in the transport device according to the invention. In general, containers made for transport devices are very long. Since the resistance-heating element in this transport device is very long, it is advantageous to include an electrode with low electrical resistance. With this electrode material, it is possible to prevent voltage drops that occur across the electrode surface causing a reduction in overall power. The conductivity also ensures a rapid distribution of current within the electrode, which allows for fast and uniform heating of the entire resistive layer and the length of the container and does not require voltage to be applied to the electrode at various points along its length and width. Thereafter, there is no need to place the power supply line along the container. This container has a length of up to 1m. According to the invention, this arrangement with multiple contact points is selected only in embodiments where the container is very long. The limit length for which a number of contact arrangements are meaningful depends on the electrode material selected and the location of the contact. Therefore, a number of contact points are unnecessary even for lengths that are more important than those described above when the electrode can make contact at the midpoint of its length, and contacts can be provided at this point.

The length of the transport device, which can be operated with a single contact, depends on the thickness of the selected electrode. According to one embodiment of the invention, each of the electrode and the intermediate layer has 50 to 150 μm, preferably 75 to 100 μm. This thin layer thickness is advantageous in that the heat generated by the resistive layer can be easily transferred from the intermediate layer to the container. And, since the thin electrode has greater elasticity, the blackout of the electrical contact will be prevented during separation of the electrode from the resistive layer and thermal expansion of the resistive layer.

In long length containers, multiple contact arrangements are also required. In the transport device according to the invention, this is easily provided. Since the electrode has a contact terminal on the outside, it is easily accessible. Thus a power line extending along the container and connecting the electrode to the spacing voltage source can be provided for the container. This makes it possible to operate the transport device according to the invention having all the desired lengths.

According to the present invention, the resistance layer is thin. This thickness has a lower limit value that depends on the breakdown voltage and is 0.1 to 2 mm, preferably 1 mm. The thin layer thickness of the resistive layer gives short heating time, fast heat transfer and high heating power per unit area. However, this layer thickness is possible when using the contact arrangements used and the inherently conductive polymers. On the other hand, the current path in the resistive layer is determined by the polymer used according to the present invention, and may be long enough to prevent voltage breakdown even when the layer thickness is thin. On the other hand, the one-contact arrangement of the resistive-heating element can subdivide the resistive layer into regions with low voltage, which reduces the risk of destruction.

The advantage of the transport device according to the invention is further improved when the resistive layer has a positive temperature coefficient (PTC) of electrical resistance. This has a self-regulating effect on the highest temperatures achievable. This effect prevents overheating of the container and the reaction in the container caused by the overheating. This effect occurs because the current flow through the resistive layer is controlled as a function of temperature because of the PTC of the resistive layer. At a certain thermal equilibrium, the current increases as the temperature increases until it becomes very small. Local overheating and melting of the resistive material can be reliably prevented. This is particularly important in the present invention. For example, if the container is only half filled with liquid medium, heat in the area of the container is more easily dissipated in the area where air is present in the container. Because of the lack of heat dissipation, conventional resistance-heating elements will be heated and melted. In containers that can be heated according to the invention, this melting is prevented by the self-regulating effect.

Selecting PTC for the resistive layer means that the entire resistive layer is heated to the same temperature. This allows for uniform heat transfer, which is essential for the specific use of the container when transporting heat-sensitive media in the container.

According to the present invention, the resistive layer can be metallized on the surface facing the electrode and the intermediate layer. By metallization, the metal is attached to the surface of the resistive layer and improves the current flow between the electrode or the lift electrode and the resistive layer. In this embodiment, heat transfer from the resistive layer to the floating electrode and the container is also improved. The surface can be metallized by spraying metal. Such metallization is possible only with the metal of the resistive layer used according to the invention. By metal electroplating, expensive metallization steps are unnecessary and the manufacturing costs are significantly reduced.

Inherently electrically conductive polymers are produced by doping the polymer. This doping is metal or semimetal doping. In these polymers, defect carriers are chemically bonded to the polymer chain and create defects. Doping atoms and matrix molecules form a charge-transfer complex. During doping, electrons in the filled band of polymer are transferred to the dopant. Because of the electron holes created in this way, the polymer has the same electrical properties as the semiconductor. In this embodiment, metal or semimetal atoms can be incorporated into or attached to the polymer structure by chemical reactions to generate free charge that can flow current along the polymer structure. Free charge is given in the form of free electrons or holes. In this way an electron conductor is created.

Preferably, the dopant and the polymer are mixed in an amount such that the number of atoms of the dopant to polymer molecules for the doping is at least 1: 1, preferably in the range of 2: 1 to 10: 1. In this ratio all polymer molecules are doped with at least one atom of the dopant. The resistivity temperature coefficient of the resistive layer as well as the conductance of the resistive layer and the polymer can be adjusted by selecting the ratio.

The intrinsically conductive polymer used according to the invention can be applied as a material for the resistive layer in the resistive-heating element according to the invention without the addition of graphite, and in another embodiment the resistive layer comprises graphite particles. . These particles can contribute to the conductivity of the complete resistive layer, do not contact each other and do not form a reticulated or skeletal structure. These graphite particles can move freely without being tightly bound to the polymer structure. When graphite particles are in contact with two polymer molecules, current can jump through graphite from one chain to the next. The conductivity of the resistive layer can be further raised in this way. Because of the free mobility in the resistive layer, the graphite particles can move to the surface of the layer and improve contact with the electrode or the interlayer or container.

Graphite particles are present at 20 vol.%, Particularly preferably 5 vol.%, Based on the total volume of the resistive layer and have an average diameter of 0.1 μm. With a small amount of graphite and a short diameter, it is possible to prevent the formation of a graphite network causing current conduction through the network. The electric current is ensured to flow continuously by electron conduction through the polymer molecule, and the aforementioned advantages can be achieved. In particular, the conduction does not need to occur along the graphite network or the framework where the graphite particles must contact each other and are easily broken under mechanical and thermal stresses, but rather occur along the aging resistance polymer with ductility.

Polystyrenes, polyvinyl resins, polyacrylic acid derivatives and mixed polymers thereof, electrically conductive polyamides and derivatives thereof, polyfluorinated hydrocarbons, epoxy resins and polyurethanes can be used as intrinsically conductive polymers. Polyamides, polymethyl methacrylates, epoxides, polyurethanes, polystyrenes or mixtures thereof may be used. Polyamides exhibit good adhesion, which is advantageous for the production of the transport device according to the invention. This is because it can be easily applied to containers or intermediate layers. Some polymers, such as polyacetylene, are removed in use according to the invention because of the low aging resistance due to reaction with oxygen.

The length of the polymer molecule used varies within a wide range depending on the type and structure of the polymer, but is at least 500 kPa, preferably 4000 kPa.

In an embodiment of the invention, the resistive layer comprises a support material. This support material is used on the one hand as a carrier material for the inherently conductive polymer and on the other hand as a spacer between the electrode and the interlayer or container. Since the support material imparts a constant strength to the resistance-heating element, it can withstand mechanical stress. In addition, when the support material is used, the layer thickness of the resistive layer can be precisely adjusted. Glass or glass fibers, rock wool, ceramics or plastics such as barium titanate can be used as the support material. The support material imparted as a tissue or web, such as glass fibers, can be injected into a material composed of an intrinsically electrically conductive polymer and can be submerged into the intrinsic electrically conductive polymer. Layer thickness is determined by the thickness of the grid or net. Methods such as scraping, spreading or known screen-printing methods may also be used.

Advantageously, the support material is a flat porous, electrically insulating material. This material prevents the heating current from flowing through the support material rather than through the polymer structure.

The possibility of making a layer deviating from the desired layer thickness with a minimum error of about 1% across the surface is particularly important when having a thin layer thickness used according to the invention, because between the contacted electrode and the intermediate layer or container There is no risk of direct contact. Changes in layer thickness across the surface of the layer affect the temperature generated, resulting in non-uniform temperature distribution.

The support material has the effect that current cannot flow along the shortest path between the electrode and the interlayer or inner pipe but is deflected or divided in the filler. The optimum utilization of the energy supplied is thus achieved.

In FIG. 6 the device 20 consists of a tubular container 21 and a resistive layer 22 arranged in a container covering the container 21 with respect to the entire circumference. Two electrodes 24, 24 ′ separated and flattened by the electrical insulation 26 are disposed over the resistive layer 22. When current is applied to the electrodes 23, 24 from a power source (not shown) it will flow from one electrode 23 through the resistive layer 22 to the container 21. In this embodiment the container 21 is made of an electrically conductive material. Current is conducted along the wall of the container 21 and flows through the resistive layer 22 to the second electrode 24. The entire resistive layer 22 is heated by this heating current and transfers heat through the container 21 to the interior of the container.

In FIG. 7 the resistance-heating element is applied to a part of the outer circumference of the tubular container 21. This element comprises an electrically conductive layer 25 facing the container 21. This layer 25 is flat and covered with a resistive layer 22 on the opposite side facing away from the container 21. The two electrodes 23, 24 are disposed apart from each other in the resistive layer 22. For areas not in contact with the resistance-heating element, the container 21 is covered by a heat insulating layer 27. An insulating shell 28 surrounding the insulating layer 27 and the resistance-heating elements 22, 23, 24, 25, 26 is disposed around the insulating layer 27. The apparatus includes a power supply facility 29. The power supply arrangement 29 is connected to a supply line 29a which extends parallel to the axis of the tubular container 21 via an insulating shell 28. The supply line 29a extends along the entire length of the insulated shell 28 and supplies an insulated shell 28 having a heat-insulating layer 27 and a resistance-heating element connected to a power source at the end or disposed in the container 21. Is coupled with line 29a. Between the container 21 and the electrically conductive layer 25 facing the container 21, a material which improves heat transfer can be provided. This may be a thermally conductive paste, a pad with a thermally conductive material, silicone rubber, or the like. In this embodiment, the resistance-heating elements 22, 23, 24, 25, 26 can be adjusted to suit the curvature of the container 21, which ensures immediate heat transfer.

In the embodiment shown here, the electrodes 23, 24 extend in the longitudinal direction of the container 21 and are arranged side by side at the outer periphery. According to the present invention, the electrodes 23 and 24 may be arranged to extend in the outer circumferential direction of the container 21 in the resistance layer 22 and to be disposed side by side in the axial direction.

The supply line extending parallel to the container axis makes it possible to arrange a plurality of insulating shells having a resistance-heating element and a thermal insulation layer in series in the container and to arrange the power supply of each resistance-heating element in parallel. The supply line is protected from contact with water or damage by an insulating shell.

The resistance-heating element is disposed inside the insulated shell so as to be adjacent to the container from below. The advantage of this heating element position is that heat can be easily transferred from the heating element to the small filled container.

In FIG. 8, the container 21 is surrounded by an insulating shell 28 for the maximum length portion. The resistance-heating elements 22, 23, 24, 25, 26 as well as the supply line 29a and the power supply facility 29 are arranged inside the insulating shell 28. The resistance-heating element extends over the long length of the insulating shell 28 and ends inside the insulating shell 28. Supply line 29a protrudes from the end of the insulated shell and can be connected to a power source. A fastener device is schematically shown in FIG. 8, in which the transport device according to the invention can be arranged in a railroad car or truck. The fastener device is arranged such that neither the insulating shell nor the resistance-heating element is subjected to compressive stress when the container is placed over the fastener device.

Resistance-heating elements such as those shown in FIG. 2 may be used. In the transport apparatus according to the invention, a resistance-heating element is used such that the side of the resistance-heating element on which the contacted electrode is disposed is directed in a direction away from the container. When using this resistance-heating element, the electrical dimensions are determined according to the schematic 3 and the associated mathematical relationship. In the device according to the invention, a resistance-heating element is used so that the side of the resistance-heating element on which the electrode is disposed faces away from the container. In a cylindrical container, electrodes and flotation electrodes are placed to extend in the direction of the container axis and to be disposed on the outer periphery above the container. Multiple regions are formed on the outer periphery, where voltage is predominantly lower than the applied voltage.

The insulating layer serves to direct heat generated by the resistance-heating element in the direction of the inner pipe and to prevent heat loss by radiation in the direction away from the container. The heat insulation layer consists of an insulation material and a reflection layer.

The entire container is also surrounded by a heat insulating layer and the resistive layer as well as the electrode and the intermediate layer are arranged inside the longitudinal groove of the heat insulating layer facing the container. In this embodiment, heat can be transferred to the container across the specific area where the heating element is in contact with the container. At the same time heat loss across the remaining areas of the container is prevented by the thermal insulation layer. By placing a resistance-heating element inside the insulating layer, good contact between the container and the single layer across the remaining area is ensured. This embodiment may be used in devices where the container has good thermal conductivity. With this container, the heat generated by the resistance-heating element can distribute over the entire surface area of the container wall and heat the medium present in the container. This structure heats the medium on the one hand by means of infrared radiation incident from the resistance-heating element and on the other hand directly by the resistance-heating element and the container wall.

The illustrated embodiment has a clamping device. Optionally, this clamping device can be mounted outwardly in each device according to the invention, represented by an adhesive tape or locking ring, which in the embodiment shown in FIGS. 7 and 8 can be placed directly on the outer face of the resistance-heating element. It may be. In this case the device consists of foam rubber. In particular, the expandable foam chamber is provided on the side of the resistance-heating element facing away from the container. This clamping device ensures a constant clamping pressure and good heat transfer from the resistance-heating element to the container.

Preferably, the container is tubular. However, this may have other forms, such as a rectangle.

In the device according to the invention, the container consists of metal or plastic, preferably polycarbonate. When a non-electrically conductive material is selected for the container, the resistance-heating element comprises an intermediate layer between the container and the resistive layer. However, it is possible to provide a resistance-heating element for a container comprising an electrode and a resistance layer within the scope of the present invention. In this embodiment the heating current is conducted from one electrode to the other through the resistive material of the resistive layer, for example an electrically conductive polymer. This current path is feasible with the device according to the invention because the structure of the polymer ensures a sufficiently large current flow through the resistive material and ensures sufficient heat generation.

According to the invention, a supply line is connected to the electrode of the resistance-heating element via a power supply on the outer side of the insulated shell.

Conventional dielectrics and certain plastics can be used as insulation between electrodes in contact with current.

The terminal for supplying current to the heating element is provided by a permanently adhesive contact terminal using an insulation braid having a desired length and a system known for the connection.

The present invention uses a material for the resistive layer having a negative temperature coefficient of electrical resistance.

Very low current generation is required when the temperature coefficient of the electrical resistance is negative. The material of the resistive layer can be chosen such that at a certain temperature, 80 ° C., the resistive material used in accordance with the invention is returned so that the temperature coefficient of the electrical resistance is positive when it is above this temperature.

This resistance layer may have a structure in which another resistance material having another specific electrical resistance is imparted in the form of a layer.

The advantage of this embodiment is that by properly selecting the material in the resistive layer, the side of the resist can have a higher temperature where heat is transferred from the side to the container, with heating wires in each layer of the resistive layer, There is no need to evangelize separately. This is achieved when a particular electrical resistance of the polymer is chosen which is applied to increase in the layer adjacent to the electrode in the lateral direction towards the container to be heated.

Because of the contact arrangement with the resistive layer applied, the transport device according to the invention can be operated at low voltages of 24V, high voltages of 240, 400 and 1000V.

With the transport device according to the invention, heating power per unit area of more than 10 mW / m 2 and preferably of more than 30 mW / m 2 can be achieved. With this container, heating power of up to 60 mW / m 2 can be achieved. This heating power up to 60 mA / m 2 can be achieved with a layer thickness of a resistive layer of 1 mm. The time-dependent decrease in heating power when the voltage of 240 V is applied continuously is less than 0.01% per year.

The temperature achievable with the transport device is limited by the thermal properties of the selected polymer but can be at least 240 ° C. and up to 500 ° C.

An insulating shell having a resistance-heating element and an insulating layer may be provided for a portion of the container length. And depending on the particular application, the size of the resistance-heating element can be selected such that one or more resistance-heating elements are disposed inside the insulation layer. In the case of a tubular container, it may extend in the radial or axial direction. The resistance-heating element here can be arranged in a plurality of longitudinal grooves of the insulating layer.

The device can be structured such that at least one halfshell is surrounded by two halfshells comprising a resistance-heating element such that the inner pipe is formed by a conventional container. Barn shells are made of insulation, such as glass fiber or plastic foam.

Another object of the present invention is a roller with at least one planar resistance-heating element disposed on the inner side of the roller shell, when the resistance-heating element consists of a thin resistive layer containing an intrinsically conductive polymer and at least two planar electrodes. Achieved by a heating roller consisting of a shell.

In the roller according to the present invention, the resistive layer contains an intrinsic electrically conductive polymer. According to the present invention, the polymer used in the resistive layer has a configuration in which a current flows along the polymer molecule. Because of the polymer structure, the heating current moves through the resistive layer along the polymer. Due to the electrical resistance of the polymer, heat is generated which can be transferred to the roller shell to be heated. The heating current here follows the polymer batch structure rather than the shortest distance between the two electrodes. Therefore, the length of the current path is preset by the polymer so that a relatively high voltage can be applied without causing voltage breakdown even when the layer thickness is thin. Even at high currents such as those which generate current, there is no need to worry about the risk of disconnection.

In addition, conduction along the polymer structure in the resistive layer and distribution of current at the first electrode results in homogeneous temperature distribution inside the resistive layer. This distribution occurs immediately after applying a voltage to the electrode.

Because of the polymers applied according to the invention, the rollers can be operated at high voltages, such as line voltage. As the heating power achievable increases by the square of the operating voltage, the heating roller according to the invention can generate high heating power and high temperature. According to the present invention, a relatively long current path is provided along the electrically conductive polymer, so that the current density is minimized.

In addition, the electrically conductive polymers used according to the present invention have long-term stability. This stability is explained by the fact that the polymer is ductile so that the breakage of the polymer chain and the interruption of the current path do not occur at elevated temperatures. The polymer chains are not damaged even after repeated temperature changes. In conventional resistance-heating elements used in heating rollers in which conduction is carried out by the carbon black skeleton, such thermal expansion causes disturbance and overheating of the current path. This causes disturbance and overheating of the current path. This causes strong oxidation and disconnection of the resistive layer. The intrinsically conductive polymers used in accordance with the present invention do not suffer from the aging phenomenon described above.

The intrinsically conductive polymers used according to the invention are resistant to aging even under reaction conditions such as air oxygen. Therefore, the automatic destruction of the resistive layer by the electrolysis reaction caused by the electric current does not occur in the heating roller according to the present invention. The reduction in heating power per unit area with time achieved in this resistive layer is very small or near zero even at temperatures such as 500 ° C. and heating power per unit area of 50 mW / m 2.

When using inherently electrically conductive polymers, the resistive layer according to the invention has an overall homogeneous structure which allows uniform heating across the entire layer.

By selecting the intrinsically conductive polymer as the material of the resistive layer, it ensures sufficient elasticity of the heating element so that this element is easily applied to the inner side of the roller, while heat is generated uniformly over a large area. In operation, the resistance-heating element is protected against mechanical stress when provided on the inner face of the roller shell.

Resistance-heating elements with electrically conductive polymers are used as "black bodies". This body can emit radiation of all wavelengths. The wavelength of the emitted radiation moves more towards infrared light as the temperature decreases. When the roller is made of a material that transmits radiation, such as glass or plastic, the infrared radiation of the roller can act on the material to be heated. In the resistive layer itself, no high temperature is required because of the penetration effect.

In an embodiment herein, the resistive layer is disposed between the electrodes that partially cover the resistive layer and are connected to a power source. In this embodiment the roller shell itself is used as one of the electrodes. The resistive layer is applied directly to the inner surface of the roller with the set thickness. The counter electrode will be placed on the side of the resistive layer facing away from the roller shell. The roller shell used as the electrode and the heating current applied to the electrode flow through the resistive material, in particular across its thickness. This structure ensures good heat transfer to the material to be heated because the roller shell is in direct contact with the resistive layer.

However, in this embodiment a planar electrode covered with a resistive layer on the side facing away from the roller shell can be arranged on the inner side of the roller shell. The other electrode is then placed on top of the resistive layer. The heating current flows between the two electrodes and the roller surface remains unvoltageed. This embodiment is particularly advantageous when direct contact occurs between the user of the device and the heating roller.

In another embodiment, the at least two planar electrodes are disposed away from each other at the side of the resistive layer facing away from the roller shell.

According to the invention, the rollers are contacted by two electrodes arranged on one side of the resistive layer. The mode of operation of the inherently conductive polymer used according to the invention in this contact arrangement can be used particularly advantageously. The applied current diffuses in the first electrode and then flows through the polymer structure through the thickness of the resistive layer in a direction perpendicular to the surface and moves to the second contact electrode. This current path further extends with respect to the current path in a structure in which a resistive layer is sandwiched between two electrodes. Because of this current path, the thickness of the resistive layer can be kept thin.

An advantage of the roller embodiment according to the invention is that the electrode has a contact on one side of the resistive layer. This side faces away from the roller shell and is easily accessible to provide a contact terminal. The opposite side of the resistive layer facing the roller shell is constructed in a flat form without contact terminals. This flat surface allows the direct application of a resistive layer to the roller shell. Up to 98% of the roller shells provide ideal heat transfer because the contact surface between the body to be heated and the resistance-heating layer is not destroyed by the contact terminals. In addition, uniform heat transfer can occur reliably from the resistance-heating element to the roller shell and the material to be heated.

In terms of the resistive layer facing away from the electrode, an intermediate layer made of a material having high electrical conductivity may be provided between the resistive layer and the roller shell. This intermediate layer is used as a floating electrode. However, this is within the scope of the present invention when the resistive layer is applied directly to the roller shell in this embodiment. Electrical insulation of the intermediate or resistive layers from the roller shell may be realized by simple means such as thin films.

In an embodiment of the heating roller, the current flows through the thickness of the resistive layer in a direction perpendicular to the surface. In particular, both areas develop inside the resistive layer. In the first region the current flows in a vertical direction from the first contact electrode to the lift electrode, and in the second region the current flows in a vertical direction from the lift electrode to the second contact electrode. Therefore, a series arrangement of a plurality of resistor portions can be obtained by the arrangement. This effect means that the dominant partial voltage in each area is lower than the voltage applied. Thus, in the embodiment of the present invention, the dominant voltage in each region is one half of the applied voltage. Because of the prevailing low voltage in the resistive layer, the heating roller according to the invention can reliably avoid the risk.

And, the gap provided between the contact electrodes is used as the additional resistance portion arranged in parallel. With air as the insulation in this gap, the resistance will be determined by the mutual distance of the electrodes and the surface resistance of the resistive layer. This distance is longer than the thickness of the resistive layer, for example twice the thickness of the resistive layer.

Electrodes and flotation electrodes have good thermal conductivity. This will exceed 200 W / mK, preferably 250 W / mK. Local overheating can be quickly resolved by good thermal conductivity at the electrode. Superheating is only possible in the layer thickness direction and has no negative effect due to the thin layer thickness that can be realized in the heating roller according to the invention. According to another advantage of the heating roller, the local temperature increase caused externally, for example in the material to be heated, can also be offset in an ideal way by the resistance-heating element. This temperature rise may occur inward, for example, when heat build up occurs in the roller. For this reason, insulation is provided inside the roller.

Another advantage of heatable heating rollers is that the resistive layer disposed in the roller shell can withstand high stresses without causing local temperature rise. Usually, the mechanical stresses acting on the roller shells are directed in the radial direction. This is the direction of current flow in the resistive layer of the resistive-heating element. This stress does not cause an increase in resistance where pressure is applied, unlike a resistance-heating element in which current flows in a direction perpendicular to the compressive load.

According to the invention, the electrode applied to the side of the resistive layer facing away from the roller shell may extend about the entire circumference and be arranged in the axial direction.

This arrangement is advantageous because a current supply occurs from two roller ends in a heating roller that is rotating in motion.

According to another embodiment of the present invention, the resistive layer has a structure in which a layer made of another resistive material having another specific electrical resistance is provided. In this embodiment the side of the resistive layer facing the interior of the roller is made of a material having a low resistance. At the top of this layer is applied a layer of material with a specific resistance which increases from one layer to the next. In this arrangement, the side facing the roller shell has the highest resistance of the resistive layer so that the surface is heated more strongly. This is because the highest voltage drop occurs here.

In the roller according to the invention, the electrode and the intermediate layer are composed of a material having a specific electrical resistance of 10 ⁻⁴ Ω · cm or less, preferably 10 ⁻⁵ Ω · cm or less. Suitable materials are aluminum or copper. This is particularly important in the rollers according to the invention. Heating rollers used as radiation rollers or thin film coated rollers must heat up quickly and have a uniform temperature over the entire length. With an electrode having a certain resistance, it is possible to prevent voltage drops that occur across the surface of the electrode causing different temperatures across the surface and overall running drop. This conductivity ensures fast diffusion of current in the electrode, which allows fast and constant heating over the entire resistive layer and roller length, with no need for voltage to be applied at multiple points along the length or width of the electrode. .

The heating rate and temperature that occurs across the roller surface depends on the thickness of the selected electrode. According to one embodiment of the present application, the electrode and the intermediate layer have a thickness in the range of 50-150 μm, preferably 75-100 μm. The advantage of this thin layer thickness is that the heat generated by the resistive layer can be easily transferred from the intermediate layer to the roller shell. In addition, the thin electrode has greater elasticity, so that the blackout of the electrical contact will be prevented during separation of the electrode from the resistive layer and thermal expansion of the resistive layer.

According to the present invention, the resistance layer is thin. This thickness is 0.1-2mm, preferably 1mm, with the lowest limit depending on the breakdown voltage. The thin layer thickness of the resistive layer gives the advantage of being able to heat quickly, heat transfer and achieve high heating power per unit area. However, this layer thickness is possible with the inherently conductive polymer used and can be improved by the kind of contact arrangement used. On the one hand, the current path in the resistive layer is determined by the polymer used according to the invention and can be long enough to prevent voltage breakdown even when the layer thickness is thin. On the other hand, the unilateral contact arrangement of the resistance-heating element subdivides the resistance layer into regions of low voltage, which reduces the risk of destruction.

The advantage of the roller according to the invention is further improved when the resistive layer has a positive temperature coefficient (PTC) of electrical resistance. This has a self-regulating effect on the highest temperatures achievable. This effect can be used to prevent local overheating of the roller shell. This effect occurs because the current flow through the resistive material is regulated as a function of temperature due to the PTC of the resistive layer. The higher the temperature, the lower the current, until it becomes very small at a certain thermal equilibrium. Local overheating and melting of the resistive material can be reliably prevented. This effect is particularly important in the present invention.

Selecting PTC for the resistive layer means that as a result the entire resistive layer is heated to the same temperature. This allows for uniform heat transfer, which is essential for the particular use of the roller. Otherwise, the thin film applied by the roller in some areas is not sufficiently heated and does not adhere to the substrate.

According to the invention, the resistive layer can be metallized at the surface facing the electrode and the intermediate layer. By metallization, the metal is attached to the surface of the resistive layer and improves the current flow between the electrode or the lift electrode and the resistive layer. Also in this embodiment the heat transfer from the resistive layer to the lift electrode and the roller shell is improved. The surface can be metallized by spraying metal. Such metallization is possible only with the material of the resistive layer used according to the invention. Expensive metallization steps by metal electroplating are unnecessary and significantly reduce manufacturing costs.

Intrinsic electroconductive polymers are produced by doping the polymer. This doping is metal or semimetal doping. Defect carriers in this polymer are chemically bonded to the polymer chain and create this defect. Doping atoms and matrix molecules form a charge-transfer complex. During doping, electrons are transferred to the dopant in a band of polymer. Because of the electron holes thus formed, the polymer has the same electrical properties as the semiconductor. In the present embodiments, metal or semimetal atoms are integrated into the polymer structure by chemical reactions to create free charge that allows current to flow along the polymer structure. This free charge is provided in the form of free electrons or holes. In this way an electrical conductor is created.

Preferably, the polymer is mixed with an appropriate amount of dopant such that the number ratio of atoms to polymer of the dopant is within the range of 1: 1, 2: 1 to 10: 1 for doping. In this ratio all polymer molecules can be doped with at least one atom of the dopant. The resistivity temperature coefficient of the resistive layer as well as the conductivity of the polymer and resistive layer can be adjusted by selecting the ratio.

The inherently electrically conductive polymer used in accordance with the present invention may be applied as a material for the resistive layer in the rollers according to the present invention without the addition of graphite, but in another embodiment the resistive layer may contain graphite particles. These particles can contribute to the conductivity of the complete resistive layer and do not contact each other and do not form a network or framework structure. Graphite particles are free to move without being bound to the polymer structure. When graphite particles are in contact with two polymer molecules, current can jump through graphite from one chain to the next. The conductivity of the resistive layer can be raised in this way. Because of the free mobility in the resistive layer, the graphite particles can move to the surface of this layer and improve contact with the electrode or intermediate layer or the roller shell.

Graphite particles are present in an amount of 20 Vol.%, Preferably 5 Vol.%, Based on the total volume of the resistive layer, and have an average diameter of 0.1 μm. Small amounts of graphite and short diameters prevent graphite networks from causing current conduction through the network. The current therefore flows continuously by electrical conduction through the polymer molecule and ensures that the above-mentioned advantages are achieved. In particular, they are easily broken under the action of mechanical and thermal stresses and do not have to conduct along the graphite network or backbone where the graphite particles have to contact each other and this occurs along with polymers that are ductile and resistant to aging.

Electrically conductive polymers such as polystyrene, polyvinyl resins, polyacrylic acid derivatives and mixtures thereof, and electrically conductive polyamides and derivatives thereof, polyfluorinated hydrocarbons, epoxy resins and polyurethanes can be used as the intrinsically conductive polymers. Polyamides, polymethyl methacrylates, epoxides and polyurethanes as well as polystyrenes or mixtures thereof may be used. Polyamides have good adhesion, which is advantageous for producing the rollers according to the invention. This is because it is easily applicable to roller shells or intermediate layers. Some polymers, such as polyacetylene, are removed in use according to the invention because of the low aging resistance due to reaction with oxygen.

The length of the polymer molecule used varies within a wide range depending on the type and structure of the polymer, but is at least 500 kPa, preferably 4000 kPa.

In an embodiment herein, the resistive layer comprises a support material. This support material is used on the one hand as a carrier material for the inherently conductive polymer and on the other hand as a spacer between the electrode and the intermediate layer or roller shell. Since the support material imparts a constant strength to the resistance-heating element, it can withstand mechanical stress. This stress can be generated by a clamping device such as a locking ring used to secure the heating element to the roller shell. In addition, when the support material is used, the layer thickness of the resistive layer can be precisely adjusted. Glass or glass fibers, rock wool, ceramics or plastics such as barium titanate can be used as the support material. The support material imparted to the tissue or the network of glass fibers may be injected into a material consisting of an intrinsically conductive polymer and submerged into the intrinsic electrically conductive polymer. The layer thickness is determined by the thickness of the grid or mat. Methods such as scraping, spreading or known screen-printing methods may be used.

Advantageously, the support material is a flat porous, insulating material. This material prevents the heating current from flowing through the support material rather than through the polymer structure.

Especially in the thin layer thicknesses used according to the invention, the possibility of producing layers which deviate from the desired layer thickness with a minimum error of 1% relative to the surface is of particular interest, not afraid of the risk of direct contact between the contact electrode and the flotation electrode. Because you do not have to. Changes in layer thickness across the layer surface affect the temperature generated and cause non-uniform temperature distribution.

The support material has the effect that current cannot flow along the shortest path between the electrode and the flotation electrode but is deflected or divided in the filler. Therefore, optimal utilization of the supplied energy is achieved.

In FIG. 9, a heating roller 30 is shown in which the inner surface of the roller shell 31 is covered with a planar electrode 33. This resistance layer 32 is disposed on the electrode 33 and has another electrode 34 on the side facing away from the electrode 33. Inside the roller, a heat insulator 37 is disposed which completely fills the interior of the heating roller and is adjacent to the inner electrode 34. In the embodiment shown, electrodes 33 and 34 are connected to a power source (not shown). The current flowing through the resistive layer 32 heats this layer and causes the roller shell 31 to heat up.

10 shows an embodiment of a heating roller 30 according to the present invention. In this embodiment, the resistive layer 32 is disposed directly on the roller shell 31 and completely covered by two electrodes 33, 34 on the side facing away from the roller shell 31. The electrodes 33 and 34 are electrically separated from each other by the insulating portion 36.

Conventional dielectrics such as air or plastic may be used as the material for the insulator 36.

The electrode 34 may be connected to the power supply at the left side of the radiation roller, and the electrode 33 may be connected at the right side. In this embodiment, the heating current flows from the first electrode 33 to the roller shell made of a material which is a good electrical conductor and then back to the other electrode 34 through the resistive material 33 at the roller shell.

If at least two electrodes are disposed on one side of the resistive layer and an intermediate layer of high conductivity material is provided on the opposite side, the heating current flows from one electrode through the resistive layer to the intermediate layer, again through this layer and the resistive layer. Will flow to the other electrode. However, because of the resistive material, the roller shell can also operate without an intermediate layer, even where it is made of non-conductor. In this case the heating current flows through the resistive layer, where the entire resistive material is heated because of the polymer structure. Finally, the roller shell is also made of a conductive material and serves to conduct current. The current applied to the electrode flows from one electrode through the resistive material and through the roller shell and the resistive material to the other electrode.

In all embodiments in which current is supplied to the resistive material on one side, the prevailing voltage in this region is reduced to one half of that with a two sided current supply.

The distance provided between the electrodes serves as a parallel additional resistor. Using air as the insulator 36, the resistance is determined by the distance between the electrodes and the surface resistance.

It is also possible to use a resistance-heating element as in FIG. This resistance-heating element is used in a heating roller according to the invention so that the side of the resistance-heating element on which the contact electrode is disposed faces away from the roller shell. When a resistance-heating element is used, the electrical dimensions are determined according to the schematic 3 and the associated mathematical relations.

Known insulation, which is in the form of polyester, polyimide and other thin films, may be provided between the resistance-heating element and the roller shell if it is desired to keep the surface of the heating roller in a voltageless state. The part that supplies the electrode is provided via a slip ring or bearing used as an electrical contact terminal or by known contact-manufacturing techniques in the case of a flat heating element.

Depending on the particular application, the metal thin film or sheet may be used as the electrode. In the present invention, the resistance-heating element can be fixed to the roller shell by means of a clamping device. A locking ring which at the same time serves as an electrode may be used as the clamping device. Thermoplastic materials in the form of a thin film or heat-conductive paste may be provided between the resistance-heating element and the roller shell to enhance heat transfer between the resistance-heating element and the roller shell.

In the roller according to the invention, a plurality of resistance-heating elements distributed and spaced along the length of the roller are provided inside the roller. However, it is possible to provide a continuous resistance layer inside the roller in which a plurality of electrodes are applied in the form of segments. This segment extends over the entire inner circumference of the roller shell, which is covered with a resistive layer and can easily fit into the roller. This allows for quick assembly. In addition, each region of the roller can be heated by providing a plurality of electrodes in the heating roller according to the present invention, which are used as pairs of electrodes alternately supplied with current. The electrodes extend about the entire circumference and are spaced apart in the axial direction. For example, the edge region of the roller may be heated further when the heating roller is used as a thin film coated roller. This additional heating supply can provide a uniform temperature distribution over the area in contact with the object to be heated, since the temperature drop along the edge can be offset by further heating.

Within the scope of the present invention, it is also possible to select a resistive material having a negative temperature coefficient of electrical resistance. In this embodiment, very low formation current is required. In the resistive material according to the invention, the temperature coefficient of the electrical resistance will have a positive value at a certain temperature, for example at least 80 ° C.

In the interior of the roller, an insulating material completely filling the interior of the roller may be provided on the side of the electrode facing away from the resistive layer. This insulation prevents the radiation of heat from the resistance-heating element towards the interior of the roller and the accumulation of heat inside the roller.

Because of the contact arrangement with the resistive layer applied, it can be operated with low voltages of 24V and high voltages of 240,400 and 1000V.

In the rollers according to the invention heating power per unit area in excess of 10 mW / m 2 and preferably in excess of 30 mW / m 2 can be achieved. With this heating roller, heating power of up to 60 mW / m 2 can be achieved. Heating power up to 60 mA / m 2 can be achieved with a layer thickness of a resistive layer of 1 mm. When a voltage of 240 V is applied continuously, the reduction of heating power over time is less than 0.01% per year.

The temperature achievable with the roller is limited by the thermal properties of the selected polymer, but higher than 240 ° C. and up to 500 ° C.

The heating roller according to the invention is suitable for use as a thin film coated roller for sealing a material into a thin film or as a radiation roller in photocopy equipment.

According to the invention, the polymer conducting through the metal or semimetal atoms attached to the polymer can be used as an electrically conductive polymer in the resistive layer of the resistance-heating element, the heatable pipe and the heating roller. This polymer has a specific resistance to current flow in the range of values achieved with a semiconductor. It can have values up to 10 ² and 10 ⁵ Pa · cm. The polymer may be obtained by a process of adding a metal or semimetal compound or a solution thereof to the polymer dispersion, polymer solution or polymer such that one metal or semimetal atom is provided per polymer molecule. A small amount of reducing agent is added to this mixture, and metal or semimetal atoms are formed by known thermal decomposition. Thereafter, when graphite or carbon black is added to the dispersion or particulate matter, the ions already present or formed are washed off.

The electrically conductive polymers used according to the invention do not have metal ions. The maximum content of free ions is 1 wt.% With respect to the total mass of the resistive layer. Ions are washed as described above and an appropriate reducing agent is added. The reducing agent is added at a rate such that the ions can be fully reduced. The low proportion of ions and the absence of ions in the electroconductive polymer used in accordance with the present invention keep the resistive layer subjected to the current to a stable state for a long term. Since the electrolysis reaction causes spontaneous breakdown of the resistive layer, it is evident that the polymer containing the higher percentage of ions has a lower aging resistance when subjected to the action of an electric current. The electroconductive polymers used in accordance with the invention are resistant to aging due to their low ion concentration, even under the action of extended currents. The reducing agent for the above-described process of preparing the electrically conductive polymer used in accordance with the present invention is to thermally decompose during processing so that it does not form ions such as hydrazine, but chemically reacts with a reducing agent such as hypophosphite or the polymer itself such as formaldehyde. The excess product or reaction product here is easily washed off and removed. Preferred metals or semimetals are silver, arsenic, nickel, graphite or molybdenum. Particular preference is given to metals or semimetal compounds which form metals or semimetals without breaking the reaction product only by thermal decomposition. Arsenic hydroxide and nickel carbonanyl are known to be particularly advantageous. The electroconductive polymer used according to the invention can be produced by adding to the polymer a premix prepared according to one of the following compositions in an amount of 1 to 10 wt.%.

Example 1 1470 parts (55% solids in water) by weight of fluorohydrocarbon polymer dispersion, 1 part by weight of wetting agent, 28 parts by weight of 10% silver nitrate solution, 8 parts by weight of ammonia, carbon 20 parts by weight of black, 214 parts by weight of graphite, 11 parts by weight of hydrazine hydroxide.

Example 2 1380 parts by weight of 60% acrylic resin dispersed in water, 1 part by weight of wetting agent, 32 parts by weight of 10% silver nitrate solution, 10 parts by weight of chalk, 12 parts by weight of ammonia, 6 parts by weight of carbon black, 310 parts by weight of graphite, 14 parts by weight of hydrazine hydroxide.

Example 3 2200 parts by weight of distilled water, 1000 parts by weight of styrene (monomer), 600 parts by weight of amphoteric soap (15%), 2 parts by weight of sodium phosphate, 2 parts by weight of potassium persulfate , 60 parts by weight of nickel sulfate, 60 parts by weight of sodium hypophosphite, 30 parts by weight of adipic acid, 240 parts by weight of graphite.

Claims (76)

A planar heating element (1) consisting of a thin resistive layer (2) containing intrinsic electroconductive polymer and at least two planar electrodes (3,4) disposed on one side of the resistive layer (2) spaced apart from each other. 2. Heating element according to claim 1, characterized in that the flat flotation electrode (5) is arranged on the side of the resistive layer (2) opposite the two flat electrodes (3,4). 3. The electrode according to one of the preceding claims, characterized in that the electrodes (3, 4, 5) are made of a material having a specific electrical resistance of 10 ⁻⁴ kPa · cm or less, 10 ⁻⁵ kPa · cm or less. Heating element. Heating element according to claim 1, wherein the electrodes have a thickness of 50 to 150 μm, preferably 75 to 100 μm. The heating element of claim 1, wherein the resistive layer has a thickness of 0.1 to 2 mm, preferably 1 mm. Heating element according to one of the preceding claims, characterized in that the resistive layer (2) has a positive temperature coefficient of electrical resistance. Heating element according to one of the preceding claims, characterized in that the resistive layer (2) is metallized at the surfaces facing the electrodes (3,4) and the supporting electrode (5). The heating element of claim 1 wherein the intrinsically conductive polymer is doped. 9. The heating element of claim 8 wherein the doping is metal doping or semimetal doping. 10. The dopant of claim 8 or 9, wherein the dopant is added to the polymer in an amount within a range of 1: 1, preferably 2: 1 to 10: 1, of the dopant for doping. Heating element, characterized in that. Heating element according to one of the preceding claims, characterized in that the resistive layer (2) comprises graphite particles. 12. Heating element according to claim 11, wherein the graphite particles are imparted in an amount of 20 vol.%, Preferably 5 vol.%, Based on the total volume of the resistive layer, and have an average diameter of 0.1 mu m. The heating element of claim 1 wherein the content of free ions in the resistive layer is 1 wt.% Relative to the total weight of the resistive layer. The heating element of claim 1, wherein the intrinsically conductive polymer comprises polyamide, acrylic, epoxide or polyurethane. Heating element according to one of the preceding claims, characterized in that the resistive layer (2) comprises a support material. 15. The heating element of claim 14 wherein the support material is a flat porous, electrical insulator. On the outer side the inner pipe 11 is a thin resistive layer 12 containing an intrinsic electroconductive polymer, which is partially covered by or directly through the intermediate layer 15 and on the outer side of the resistive layer 12. 12. Heatable pipe 10, characterized in that two planar electrodes 13, 14 partially covering 12) are spaced apart from each other. 18. Pipe according to claim 17, characterized in that an intermediate layer (15) made of a material having a high electrical conductivity is disposed between the inner pipe (11) and the resistive layer (12). 18. Pipe according to claim 17, characterized in that the resistive layer (12) is arranged directly on the inner pipe (11) and the inner pipe (11) is made of a material having a high electrical conductivity. 20. The resistive layer according to any one of claims 17 to 19, wherein the resistive layer (12) and the electrodes (13, 14) disposed thereon extend longitudinally in the axial direction and the electrodes (13, 14) are spaced apart on the outer circumference. A pipe, characterized in that arranged in (12). 21. Pipe according to claim 20, characterized in that the resistive layer (12) extends longitudinally in the axial direction covering only a portion of the outer circumference of the inner pipe (11). 22. The electrode according to one of claims 17 to 21, wherein the electrodes 13 and 14 and the intermediate layer 15 are made of a material having a specific electrical resistance of 10 ^-4 kPa · cm or less, preferably 10 ^-5 kPa · cm or less. A pipe, characterized in that configured. 23. Pipe according to one of the claims 17 to 22, characterized in that the electrodes (13, 14) and the intermediate layer (15) have a thickness in the range of 50 to 150 micrometers, preferably 75 to 100 micrometers. Pipe according to one of claims 17 to 23, characterized in that the resistive layer (12) has a thickness of 0.1 to 2 mm, preferably 1 mm. 25. Pipe according to one of the claims 17 to 24, characterized in that the resistive layer (12) has a positive temperature coefficient of electrical resistance. 26. Pipe according to one of the claims 17 to 25, characterized in that the resistive layer (12) is metallized at the surface facing the electrodes (13, 14) and the intermediate layer (15). 27. Pipe according to one of the claims 17 to 26, characterized in that the intrinsic electroconductive polymer is doped. 28. The pipe of claim 27, wherein the doping is metal or semimetal doping. 29. The dopant of claim 27 or 28, wherein the dopant is added to the polymer such that the ratio between the number of atoms of the dopant and the number of polymer molecules is in the range of 1: 1, preferably 2: 1 to 10: 1 for doping. Pipe. 30. Pipe according to one of the claims 17 to 29, characterized in that the resistive layer (12) comprises graphite particles. 31. The pipe according to claim 30, wherein the graphite particles are given at 20 vol.%, Preferably 5 vol.%, Based on the total volume of the resistive layer and have an average diameter of 0.1 μm. 32. The pipe according to any one of claims 17 to 31, wherein the content of free ions in the resistive layer is 1 wt.% Relative to the total volume of the resistive layer. 33. A pipe according to any one of claims 17 to 32, wherein the intrinsically electrically conductive polymer comprises polyamide, acrylic, epoxide or polyurethane. 34. Pipe according to one of the claims 17 to 33, characterized in that the resistive layer (12) comprises a support material. 35. The pipe of claim 34, wherein the support material is a flat porous, electrical insulator. On the outer side of the resistive layer 22, at least two electrodes 23, 24 partially covering the resistive layer are spaced apart from each other and on the outside the container 21 is a thin resistive layer 22 comprising a unique electrically conductive polymer, directly Or a container (21) for receiving a medium covered through the intermediate layer (25). 37. A transport apparatus according to claim 36, wherein an intermediate layer (25) made of a material having a high electrical conductivity is disposed between the container (21) and the resistive layer (22). 38. A transport apparatus according to claim 37, wherein the resistive layer (22) is disposed directly in the container (21) and the container (21) is made of a material having a high electrical conductivity. 39. A transport apparatus according to any one of claims 36 to 38, wherein the container (21) has a cylindrical shape. 38. The method of claim 37 wherein the resistive layer 12 and the electrodes 13, 14 disposed thereon extend longitudinally in the axial direction and the electrodes 13, 14 are spaced apart on the outer periphery and placed on the resistive layer 12. Characterized in that the transport device. The transport apparatus according to claim 38, wherein the resistive layer (12) extends longitudinally in the axial direction and covers only a part of the outer circumference of the inner pipe (11). The transport apparatus according to any one of claims 36 to 41, wherein the electrodes 23 and 24 are made of a material having a specific electrical resistance of 10 ⁻⁴ kPa · cm or less and 10 ⁻⁵ kPa · cm or less. . 43. A transport apparatus according to any one of claims 36 to 42, wherein the electrodes (23, 24) have a thickness in the range from 50 to 150 [mu] m, preferably 75 to 100 [mu] m. 44. A transport apparatus according to any one of claims 36 to 43, wherein the resistive layer (22) has a thickness of 0.1 to 2 mm. 45. A transport apparatus according to any one of claims 36 to 44, wherein the resistive layer (22) has a positive temperature coefficient of electrical resistance. 46. A transport apparatus according to any one of claims 36 to 45, wherein the resistive layer (22) is metallized at the surface facing the electrodes (23, 24) and the intermediate layer (25). 47. A transport apparatus according to any one of claims 36 to 46, wherein the intrinsically conductive polymer is doped. 48. The transport apparatus of claim 47, wherein the doping is metal or semimetal doping. 49. The polymer of claim 47 or 48, wherein the dopant is polymerized in an amount such that the ratio of the number of atoms of the dopant to the number of polymer molecules relative to the doping is 1: 1, preferably in the range 2: 1 to 10: 1. A transport apparatus, characterized in that added to. 50. The transport apparatus according to any one of claims 36 to 49, wherein the resistive layer (22) comprises graphite particles. 51. A transport apparatus according to claim 50, wherein the graphite particles are imparted in an amount of 20 vol.%, Preferably 5 vol.%, With an average diameter of 0.1 [mu] m relative to the total volume of the resistive layer. 52. A transport apparatus according to any one of claims 36 to 51, wherein the content of free ions in the resistive layer is 1 wt.% Relative to the total volume of the resistive layer. 53. The transport apparatus of any one of claims 36 to 52, wherein the intrinsically conductive polymer comprises polyamide, acrylic, epoxide or polyurethane. 53. A transport apparatus according to any one of claims 36 to 52, wherein the resistive layer (22) comprises a support material. 56. The transport apparatus of claim 55, wherein the support material is a flat porous, electrical insulator. 59. Power according to one of the claims 36 to 58, which extends outward of the container 21 in the axial direction with respect to the entire length of the container 21 and is connected to the respective electrodes 23, 24 at two or more contact points. A transport device comprising a supply device (29). One or more flat resistive heating elements and roller shells 31 disposed on the inner side of the roller shell 31, wherein the resistance-heating element comprises a thin resistive layer 32 containing an intrinsically conductive polymer and two or more flat electrodes. Heating roller 30, consisting of (33,34). 58. The heating roller of claim 57 wherein a resistive layer (32) is disposed between the planar electrodes (33,34) and the electrodes (33,34) partially cover the layer. 59. A heating roller according to claim 57 or 58, characterized in that the at least two planar electrodes (33,34) are arranged on the side of the resistive layer (32) facing away from each other and away from the roller shell (31). 60. The heating roller according to claim 59, wherein an intermediate layer (35) composed of a material having a high electrical conductivity is disposed between the resistive layer (32) and the roller shell (31). 61. A heating roller according to one of the claims 59 and 60, characterized in that the electrodes (33,34) extend about the entire circumference and are spaced apart in the axial direction. 62. The heating roller according to one of claims 57 to 61, characterized in that the resistive layer (32) comprises a structure in which a resistive material having different specific electrical resistances is present in the layer. 63. The electrode according to any of claims 57 to 62, wherein the electrodes 33 and 34 and the intermediate layer 35 have a specific electrical resistance of 10 ⁻⁴ kPa · cm or less, preferably 10 ⁻⁵ kPa · cm or less. Heating roller, characterized in that made of a substance. The heating roller according to one of claims 57 to 63, characterized in that the electrodes (33, 34) and the intermediate layer (35) have a thickness in the range of 50 to 150 μm, preferably 75 to 100 μm. The heating roller of claim 57, wherein the resistive layer has a thickness of 0.1 to 2 mm, preferably 1 mm. 66. The heating roller according to one of claims 57 to 65, wherein the resistance layer (32) has a positive temperature coefficient of electrical resistance. 67. The heating roller according to one of claims 57 to 66, wherein the resistive layer (32) is metallized at the surface facing the electrodes (33,34) and the intermediate layer (35). 68. The heating roller of claim 57 wherein the intrinsically conductive polymer is doped. 69. The heating roller of claim 68 wherein the doping is metal or semimetal doping. 70. An amount of the dopant according to any one of claims 68 or 69 in an amount such that the ratio of the number of atoms of the dopant to the number of polymer molecules for doping is 1: 1, preferably in the range of 2: 1 to 10: 1. A heating roller, which is added to the polymer. The heating roller of claim 57, wherein the resistive layer comprises graphite particles. 72. The heating roller of claim 71 wherein the graphite particles are present in an amount of 20 vol.%, Preferably 5 vol.%, Based on the total volume of the resistive layer, and have an average diameter of 0.1 μm. The heating roller of claim 57, wherein the content of free ions in the resistive layer is 1 wt.% Relative to the total volume of the resistive layer. 75. The heating roller of claim 57, wherein the intrinsically conductive polymer comprises polyamide, acrylic, epoxide or polyurethane. 75. The heating roller according to one of claims 57 to 74, wherein the resistive layer (32) comprises a support material. 76. The heating roller of claim 75 wherein the support material is a flat porous, insulating material.