DE2655543A1 - HEATING ELEMENTS - Google Patents

Description

300 Constitution Drive, Menlo Park, California 9 ^ 025 (U.S.A.)

Heating learner

The invention relates to heating elements which contain or consist of conductive polymers.

It is well known that polymers can be made electrically conductive by dispersing therein appropriate amounts of finely divided conductive fillers. It is also well known that certain polymeric articles can be made heat recoverable. It has already been suggested fsh. GBtPS 1.265.19 ^) to produce a heat-resilient object which has a first part made of a conductive polymer and a second electrically non-conductive, heat-resilient part, and to restore this object by passing an electric current through it lets the first part flow. However, research by the applicant has shown that such articles suffer from certain disadvantages. If one of the dimensions of the part by more o. "_ S 30 is changed so particular, it was found that the electrical properties of the polymer part excessively star> change, which is less than is ÜR wäVmerückstellfähige objects generally desirable **. Next increases the presence of the conductive

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[MSPECiED

Polymer layer provides the force required to deform the object and can, to the contrary ^: affect the recovery. It was also found that when the electricity! from one end to the other of the conductive polymer part i, as ^{suggested in GB-PS 1.265.19 2} *, the part is often not heated uniformly, as would be desirable for satisfactory shrinkage and to avoid local overheating.

It has now been found that it is possible to produce an easily expandable and / or contractable product with significantly improved electrical properties if a laminar conductive polymer part sandwiched between I a pair of laminar flexible electrodes j

and suitable openings in the laminate obtained

forms are. j

The invention therefore relates primarily to a heating element ^ that includes:

(λ) A layer of a material which contains an organic polymer and electrically conductive particles dispersed therein in an amount sufficient for conversion to the conductive state i and which has a specific ι contradiction of more than 1.0 ohm · cm at room temperature I and ^!

(B) a pair of laminar flexible electrodes that (i) direct '. or indirectly connected to opposite faces of said layer; (ii) the essentially coplar; -a. · to this, layer are arranged; and the (iii) made of a material with a specific resistance of less than 10 ohm-cm, preferably less than 1 ohm * cm ' exist at r.raumteraoeratur and the (iv) for a connection are set up with an external energy source for the purpose of current flow through the polymer layer,

wherein the above layer and the layer electrodes are one

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Have a plurality of perforations or slots through their thickness which have such a size, shape and distribution that at least one of the dimensions of the element in the plane of the element or at the melting point of the polymer can be changed by at least 30% without a Complete breakage of the electrode occurs at one point, the dimensional change being absorbed or compensated for by a change in the shape of the perforations.

The phrase "without a complete breakage of an electrode a dot "means that each electrode retains a current path completely surrounding each perforation; the electrode can therefore partially but not completely break or tear at any point. "Melting point of the polymer" for crystalline thermoplastic polymers means the temperature at which the crystalline material melts and for other polymers, e.g. elastomers and non-crystalline thermoplastic polymers, the softening point of the polymer.

These new heating elements are useful in situations where a heating device is desired that can easily at least; can change any of its dimensions in the plane without undue change in its electrical properties. Preferably, as mentioned above, the element is deformable by a percentage of at least 50% , for example at least 70, in particular at least 100 % and for some purposes at least 250 %. It has surprisingly been found that the resistance of the element, even when deformed by a high percentage, generally does not exceed 20 % \

increases, which is very valuable. '

The holes or slots have to change their ^; Shape to be able to accommodate the change in planar dimension; of at least 30% (or preferably more) to include or to ^{compensate for 1} , but with changes of greater percent

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suppose the possibility of some stretching or contraction of the element material itself is not precluded. >

The term "perforations" or "slots" is used below to designate slots which, for example, are used in the expansion of the element result in diamond-shaped openings. In general, the holes are in the undeformed one Construct the element in such a way that a substantial deformation of the element in the plane is only possible by stretching, i.e. the element is expandable and the invention is primarily described in this way. However, the invention includes E.g. also elements that are expandable or contractable in one direction when not deformed, as well as elements with such holes that the element can be stretched in two directions at the same time.

The choice of perforations or slots depends on the degree of

i required expandability and ductility of the electrodes and of part A. The perforations must be elongated and overlapping, however a wide variety of perforations to meet these requirements can be used. The perforations can therefore be regular or irregular and, for example, have the shape of straight or wave-shaped slots or notches, oval or diamond-shaped holes. It is generally expedient if the perforations are regularly spaced from one another and have the same size and shape. In general, it is desirable that the perforations are such that the element has extensions in its plane through responsive symmetrical through its thickness, in order to avoid buckling of the element. Good results have been obtained with elements in which the distance between the edges of adjacent perforations is 1/10 to 1/2 inch (0.25 to 1.25 cm). Preferably \ pass the perforations of a plurality of identical Ge-I raden slots in parallel rows equally spaced! the slots in adjacent rows overlapping each other;

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the length of the slots is preferably at least 1/2 inch (1.25 cm), more preferably 5 to 20 times the distance between adjacent rows of slots. In this way you can Elements are obtained which can be stretched by at least 3 times their original length.

In a preferred embodiment, the part A ^of:. A material which belongs to the small proportion of conductive polymers, the so-called PTC (positive temperature coefficient) behavior show that a rapid increase in resistivity at a particular temperature or over a special temperature range. The term "switching temperature" (usually abbreviated T) is used to denote the temperature at which the ^rapid: takes place increase. If the rise takes place over a temperature range (as is often the case), T expediently denotes the temperature at which the extensions of the essentially even portions of the log- _; intersect the arithmic resistance-temperature curve (above and below the range).

PTC materials used in conjunction with layer A generally have a T above ^r on 53 *, often above 100 ° C, and a resistivity at a temperature below T of about 25 to about 10

Ohm · cm. It is also desirable that the increase in resistance above T be sufficiently high that layer A effectively transforms an electrical conductor into an electrical insulator through a relatively limited range; rose in temperature is converted. This requirement is expressed in the fact that the material should have an R ^ value of at least 2.5 or an _R.Q0 value of at least 10 and preferably an R, _Q value of at least 6, where R «2i is the ratio of the specific resistances at the end and at the beginning of the 14 ° C range with the sharpest increase in the specific resistance, Ri ₀₀ the corresponding ratio

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nis of the 100 ° C range, and R, _Q represents the ratio of the resistivities of the corresponding 30 ⁰ C range. ^;

Find a general overview of conductive polymers! in "Conductive Rubbers and Plastics" by R.H.Nc-r.an, j Hlsevier Publishing Company (1970). PTC masses are in "Polymer Engineering and Science", November 1973 * JJv »No. 6, Pages 462-468, and in U.S. Patents 2,978,665, 3,243,753,! 7. ^: 2.358, 3.59I.526, 3-793.716, 3.823.217 and 3.914.363 J described. The latest developments in this area are: ? s5 43; 38.9 as well as P 26 34 999-5 and the US Annel j fertilize 601.427 and 601.5 ^ 9 corresponding applications described.

The use of a PTC material for the layered part A prevents this part from being heated to a temperature above its T_. The T _{0 of} the PTC material is j

S S

usually very much dependent on its tensile strength. In ! Ar / .; esessness of perforations would be the T of part A.

- Usually change if its planar dimensions are changed} ..hould be. It has been found, however, that the total value of * 7 _e of part A does not change significantly by expansion or contraction, although parts of A are under considerable span-j. j

The electrodes can be made of any suitable material, for example Ke ⁴ . all or a highly conductive polymer and can contain sections in the manner of a busbar, which have no soldering points and which run at right angles to the Rieh-, Ζ'ΛΤ-s: the main change in dimension. Metals are generally preferred because they have high conductivity coupled with strains that are generally sufficiently high for most purposes; Metals with ductility at least equal to that of aluminum are preferred. The tendency of the metal foil electrode to tear can

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Reduced (and at the same time increased "flexibility") are achieved by corrugating the foil, for example to the extent that the foil is shortened by about 15% . Suitable metals are copper, lead and aluminum.

One of the problems that arise especially when using metal electrodes J and / or diamond-shaped openings |

is the possibility of short circuits between electrodes of opposite polarity on the edges of the element or when the element is partially broken. This problem can be caused by coating the exposed surfaces of the Electrodes with an insulating material, for example a polymer, in particular a crosslinked polymer, with a softening temperature be mitigated above a temperature ever reached by the electrodes. It is desirable to j that both the edges and the flat surfaces of the electrodes are coated, so that slot-shaped openings prior to coating by expansion of the element 1

ι should be expanded. Suitable coating techniques include electroplating, electrostatic spraying ΐ as well as immersion in a suitable powdery insulator, followed by curing of the coating by means of heat. are i Alternatively, the short slope, by using \ perforations, such as slits or ovals reduced, the 'a considerable width even have, when the element is fully contracted. Another solution is to use two electrodes of the same size, which are made of conductive polymers and are therefore less prone to short-circuit formation than metal electrodes, whereby if necessary or desired, satisfactory electrical properties are achieved through the use of additional metal electrodes that do not overlap, be achieved; Such an arrangement also leads to changed electrical properties because of the non-uniform flow of current.

In general, the electrodes are the same size

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like part A. However, this is not essential provided that, in operation, the current flows essentially all the way through part A and causes sufficient heating.

Particularly useful heating elements are those whose part A has PTC properties and which furthermore at least; one Interlayer containing (a) constant wattage (as defined below) at temperatures below T_ of part A shows; which (b) consists of a material which an organic polymer and disperses therein contains electrically conductive particles in an amount sufficient for electrical conductivity; the (c) a j . has a resistivity greater than 10 ohm · cm; !

and the (d) disposed between part A and an electrode.

net is. Preferably, such an intermediate layer on each _is arranged side of the part A. The expression "constant watt output" means that the resistance of the layer is less than 6 times in each JO C range below the T ·

of part A and preferably between room temperature and the T_ of part A increases. \

Preferably, the constant wattage layers i have a resistance at room temperature that is greater than the j resistance of part A in order to be able to control the amount of current applied when the heating element is initially connected to a power source. It is also preferred that the intermediate layers have PTC properties at temperatures above j

half of the T_ of part A, ie .with a higher T ♦: ss

This is useful in avoiding overheating of the interlayer which would otherwise occur if the electrode were completely broken at any point, causing current to flow through the interlayer to bridge the break. This can cause severe overheating if the intermediate layer does not switch itself off at a suitable temperature.

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The conductive particles in layer A and in each intermediate layer preferably consist of ¹ μB, especially when PTC properties are required. Layered electrodes, which contain conductive polymers, are more conductive; Particles preferably made of carbon black or a metal. The? E! .Lcn -.- r. can haoen any shape, including fibers, iici ^ cip.e suitable masses bark into the above. Publications. The PTC compounds are preferably based on "Crlctallineri polymers" and "Haber". -a T ani or near the crystal point of the polymer, which can be crosslinked above T for the purpose of improved stability. A preferred M & cse door

Layer A is a mixture containing high density polyethylene (45% by weight ), ethylene / propylene rubber (5% by weight) and Ru3 (50% by weight), "the one T ! of about 20 ⁰ C is preferred composition for an intermediate layer of constant wattage consists of an ethylene / Ytiv / lacetat copolymers Sine. (61 wt -.%) and carbon black (39 wt .- ^).

When formulating the compounds for the various layers it is of course necessary to consider both the physical and electrical properties of these layers. For example, the flexibility to observe the adhesion z \ x cer-z ^ n.:. Ii'terr layers and the resistance to flies at operating temperatures). However, the person skilled in the art does not have any difficulties in selecting a suitable composition. The element is preferably constructed symmetrically.

The new heating elements can be produced by assembling the various layers, connecting the layers with the help of distortion and pressure, whereupon the holes are made. Suitable conductive K'-eb ^r ; -. O: ':' e, for example carbonaceous hot melt glue, are incorporated into the layers, in particular ^ v.-ischen metal electrodes and adjacent polymer layers, in order to ensure sufficient adhesion between the layers. A suitable adhesive contains about 65 wt .- # of an ethylene / acrylic

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BAD ÖftiiäiNAL

acid copolymers and about 35 % carbon.

Of course, if the polymer of layer A and any other polymer layer is desired to be crosslinked, as is preferred, the polymers initially used must be crosslinkable. Networking is preferred after! the joining step, but performed before the holes are created, for example using ionizing radiation of a sufficient dose, for example 5 to 20 kegarads. ^: Alternatively, a chemical crosslinking agent can be incorporated into the poly-1 me-en and the crosslinking during the ^! Combination or in a separate heating step after the combination, but before the openings are created. i

Slots are generally easier to produce in the element than oval-shaped or groove-shaped openings. \ Slots can be cut easily using a sharp blade, for example by means of a plurality of staggered · cutting, so that the slots are produced a Rei-ι he at the same time. By using ^! a wiper pad, the element can be prevented from tearing by the cutting edge when it is withdrawn. On the other hand, the openings must be punched out.

The new heating elements are particularly useful as conroons; 'he. v ~ n objects that are a (after- ^:. * Vl {-. end defined) plate-shaped material that is sensitive ^{to heat and adjacent!} ζ; one surface of this plate contain a heating element as defined above. The heating element can be in direct contact with the sheet-like material, for example connected by an adhesive, or it can be separated therefrom by an intermediate layer, provided that there is sufficient heat transfer between the heating element and the sheet material. The article is preferably flexible at least at the temperature at which the sheet material responds. '

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INSPECTED

The expression: "responsive to heat" means : ia.ß c: 3s: iatteri-shaped material, when heated to a suitable temperature, either a spontaneous change; in v.er. omitted at least one dimension of its plane and / '.. II. r is subject to another change, e.g. a * softening {-ei: ': ": hl: e: 3-lioh of the flow), which the au sera " v ^ i>. ί ::.?>. ran ^ ellen forces), which z'j .: ' ' -η Depending on at least one dimension of the plate material in ic: Piatten-? ~ ene erTc: - 'sriich. The plate material contains bevcr -..-: ei :; . organic polymer, such as a polymer film, l-ic .. ^ r 'is er'iekstellflhig or made heat-recoverable part capable • λ- ·; ".:, iann-., an adhesive (eg hot melt adhesive egg-elr.on? riitzeaktivierbaren glue 'or eir.en Kitt It "err..? ent, since, in such articles dax heating element in Vaohoarschaft vu the plate material to be so ^ he V.'eise Toggle £ i j :: lnez should that in the case of the heater: of the object it changes its dimensions in the required V, ^r ei; .e.

The objects according to the invention have Im a ~ Ipr-.rs- \ rt-n crti \ heating element and a plate-shaped material, air " ¹ , far, 'oioch more than one heating element and / cd he contain more than one plate, For example, they can contain an _elen: ent sandv-ich-ar-tif. enclosed by two plate materials or a plate material sancwi ^ h-like enclosed by two elements.

VY-r.ri ias plate-shaped material a polymer f'i ..: .. is ", which is"Uckst'il! Capable or can be heat-resilient.g cera ^^. T, this plate material preferably contains ., a crystalline-crosslinked polymer Suitable polymers for v; less advan- • Erick part capable -Plattenmaterialien sin: ¹ fcekanr good. ". 'vg ;. r.]. *; 3- ~ 3 .'-. 0 °>.2'i2) and include folyrere of one ode: · Tehre-: vr define unc / or one or more ethylenically unsaturated clayerners, which contain polar groups.

Ger · = ·· -: stands that have a v / är- "ier-'ick ?." ^ l; capable polymer film

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SAD

• hold, can by deforming a Ge ^ οι.ϊ, χ -.:·. k .; he: yestelLt that (a) a film that ^{can be thought of as warm back 11: "':} lhi _t ", and (b) attached to a · ". ·; · y. ·;? he of the Filr .s, contains a heating element (which has preferably not been substantially deformed in its plane), the deformation being carried out at a temperature above the crystal melting trace.; -: ts of the polymer in the sheet material, followed by cooling of the object, while in the partially deformed state. Suitable techniques are known in the art (see e.g. US Pat. No. 5,086,242). Such articles can also be made by assembling a warmer heat-resistant sheet material and a heating element which has preferably been deformed in its plane in a direction opposite to the direction of heat recovery of the sheet material.

As already mentioned, the plate material, in al] _e stones with deir. The heating element is curled by means of an adhesive. The adhesive does not need to be very strong, it generally changes the dimensions of the heating element slightly ''.-Er-de-ri. This is an important advantage over ähnlicnen ^f ': ..- ef is nständen, the au one heating element without perforations. ^f v. ^: siser. and which generally require a very strong adhesive so that the element satisfactorily follows the dimensional changes of the sheet material. An adhesive is preferably used which, at the operating temperature, ie the back temperature of the object, allows sliding between the heating element and plate material, but does not flow into the openings of the heating element and thereby interfere with its dimensional change. Suitable adhesives are for example in the. Gl-PS 1. '440.810 described; other adhesives contain labile ionic bonds. Preferably, the adhesive has a Schreizounkt r.aoh Vicat and a softening point (ring and ball method) uncerhalo its operating temperature. Particularly preferred adhesives are thixotropic at the operating temperature, ie the reset temperature »

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BAD ORiGiNAL

Plate material and heating element can for example be connected to one another be joined by placing between them a layer of a suitable hot melt or heat activated adhesive Adhesive and then this arrangement is heated under pressure, e.g. from a pair of rollers. When the plate material Made heat-recoverable before assembly and the assembly was done using a temperature above the reset temperature Measures are taken to prevent complete recovery of the plate material.

If the heating element forms a surface of the object, it may be desirable for at least one of the openings to have a mass that flows at the operating temperature of the object, e.g. a solder or putty or a hot melt adhesive. This is particularly useful when the article is heat recoverable, such as a heat shrinkable one Representing sleeve with a heating element on the inside, and the return of the object the heating element in contact brings with a substrate to be enveloped and thereby pushes the mass out of the openings. The presence Such a mass can also reduce the heat transfer from heating element to plate-shaped! Improve material. «

The objects according to the invention can have any shape and form part of a larger object. The invention therefore encompasses articles having one or more portions which are articles according to the invention. Particularly useful objects are sleeves, ie hollow bodies of closed cross-section with at least one open end, for example tubular objects of circular or other cross-section, in particular those sleeves which, when heated to a smaller one. Contract diameter .. If the heating element is on the inside, such sleeves can conveniently be made by expanding a sleeve-shaped heating element ,

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• / ή.

in the. this is nlaziert over a mandrel, einerr the exterior of the element with a suitable adhesive (eg preformed Kohr of adhesive, is surrounded by the A \ i. ierr Z face of the adhesive with a sleeve made of plate-shaped, ü'-TERIAL surrounded is? , which in the V.'ärr.e sohrurrpft to a smaller diameter than the outer diameter of the element, the entire assembly is heated for the purpose of shrinkage, the sleeve and connection to the element via adhesive, the said assembly is cooled and the mandrel is removed. V.'enn the! heating element is located on the outer side, know conveniently be prepared such 1 sleeves by a potentially 'heat-resilient sleeve in the interior of a heating element is arranged with an intermediate layer of adhesive, heating the arrival \ order and pneumatically external against a The shape is exonated, cooling the assembly while it is held in the expanded state.

A tubular heating element can expediently be manufactured by cutting the opposite edges of a panel through a strip of insulating material such as a organic polymers, by using the edges a suitable adhesive with the insulating strip Kleot. ι

A particularly valuable application of the heating elements according to the invention is the new cable splice described in US application 658,687. '_

DIF invention includes processes in which an object duron connection of the electrodes of the above-defined object T.it an external power source Uird prepared 3tr'cr 'lu.-: effected by the layer A and at least one Τ <ίί * ~ ur rlitse provides, which is necessary for heating the Tjlatteni'örrr.i ^ eri 'material ajf its response temperature, ..' orauf the plate material is subject to a Pimensionänierung in its plane at this temperature

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or is forced to do so. The method is particularly useful when a substrate is to be wrapped in which the article is placed in the vicinity of the substrate and
the electrodes are connected so that the heated plate material undergoes a dimensional change such that ^: sica the object conforms to the surface of the substrate.
If desired, the article can surround the substrate
or interact with another coating component in the vicinity of the substrate. The external source of power
for these methods typically consists of a DC power ^{source of about 12 volts (battery 1} ) or a V / AC power source of about 115 or about 220 volts from a main line. It may be desirable to continue heating the object ("by continuing the flow of current through the heating element in some other way) after its
pL.anarer. Have changed dimensions, e.g. heating a substrate brought into contact with it in order to ensure adequate adhesion between the object and substrate by means of a heat-activated adhesive or in some other way. I.

The invention is illustrated by the attached drawing,
Figure 3 is an isometric view of part of the heating element: according to the invention. The element has a layer 12 which is composed of a conductive polymer with PTC behavior. Layers IJa and 13b with constant wattage, which consist of a conductive polymer and deviate PTC behavior with a T!

s j

higher than that of layer 12. The layers IJa 'and 13b are by means of adhesive 14a and. IAb on corrugated resp.
corrugated metal foil layers 15a and 15b attached. One
A plurality of slots are arranged in rows 17 offset in parallel. The slots are generally a little longer than shown in the drawing. The edge areas of the plate parallel to the perforations do not contain any perforations.
When these edge areas are separated, diamond-shaped openings are obtained.

"^ BlGiHAL US3PECTEÜ

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The invention is further illustrated by the following example, in which the percentages relate to weight.

Example '

Layered parts of the composition given below. and thickness are assembled in the order shown:

(1) lead; 4 mils (0.01 cm) thick.

(2) mixture of ethylene / acrylic acid copolymer (65 %) and carbon black ( $ 35); 5 mils (0.0125 cm) thick.

(3) Mixture of ethylene / vinyl acetate copolymer (61 #) and carbon black (39 %) x> 10 mils (0.025 cm) thick.

(4) Mixture of high density polyethylene (45 %) , an ι ethylene / propylene rubber (5%) and carbon black (50 %); 20 mils (0.051 cm) thick. ,

(5) As a layer part (3).

(6) As a layer part (2).

(7) As a layer part (1).

These layers are bonded together using heat and pressure and then ionizing radiation of 6 megarads exposed. An expandable heating element is made by inserting slots of a ' 0.5 "(1.25 cm) long in parallel but staggered rows 0.025" (0.06 cm) apart will; the slots in a row are 0.10 inches (0.25 cm) apart. A heat-resilient plate Polymeric material is obtained as follows: A plate 0.08 inch (0.2 cm) thick is made from a mixture of Ethy-

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len / ethyl acrylate copolymers (88.4 %) (DPD olP ", Hor ^ -. eller Union Carbide), a dispersion of 1 part of carbon black in"-; Parts of ethylene / vinyl acetate copolymer (9 %) (Colorant CC 004 \ finely divided silica gel (3 %) (Carbosil) and an antioxidant (0.6 %) are extruded; the plate is crosslinked with radiation of 12 megarads; a sample of a Size 10 χ 4 inches (25 χ 10 cm) is cut from the plate, reinforced to 20 inches: (50 err.) And in this condition until cooled
held. A section of a heating element made as described above about 10 χ 4 inches (25 χ 10 cm) is connected to a 24 volt power source and heated and stretched to 20 inches (50 cn). The heating element is hot
Condition bonded to the sample of the recoverable plate with a 5 mil (0.0125 cm) thick layer of adhesive that softens but does not flow at about 100 ° C. ■ The V / arm generated by the heating element softens the adhesive;
by applying pressure, the heating element is fused with the heat-resistant plate. The thermally adjustable plate is held in the clamped state in order to prevent it from being restored. The resulting article is cooled to room temperature and the restraint is removed
will. The heating element is then connected to a 24 volt power source. The heat-recovering part and the heating element return to their original dimensions within 2 minutes. The heater reached its control temperature of 115 C in about 1 minute. Shrinkage of the heat-restoring part and heater took place
smooth.

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Claims (1)

Patent applica s ρ r U che 1) jHeating element, containing a pair of electrodes and a, layer-shaped part, which is an organic polymer and electrically conductive particles dispersed in it in! i contains an amount which gives the layered part a specific resistance of greater than 10 Ohm.cm at room temperature, characterized in that the j electrodes are in the form of flexible layers which ¹ (i) overlay with free.erv ' Faces of the layered Telia are connected; (Ii ") are disposed substantially coplanar to this layer part; (iil) the a \ as ^a; material of a resistivity of less than 10 Ohm.cm are constructed at room temperature and (iv): for a connection with an external power source for the purpose of generating a current flow through the layer part are incorporated; and further characterized in that the layer-like part and the layer-like electrodes have a plurality of perforations through their thickness, which (a) in the case of a heating element not deformed in its plane, have a size, shape and distribution which enable at least one of the dimensions of the element in its plane at the melting point of the polymer by a percentage of at least 0 % , ^: based on the original dimension, without complete breakage of the electrode at one point, j α can be changed, the dimensional change being absorbed or compensated for by changing the shape of the perforations or (b) in the case of a heating element deformed in its plane have been obtained by deformation of perforations of such size, shape and distribution that one Change at least one dimension of the element in 709825/0706 its level at Schrnelztyunxt des ^ o.jr.f. r-en arr -ilneri percentage of at least 30 <a, related. a \ .i 'the original dimension, without the electrode leaking out at a point, without the vcllnt'.r.-digir pruoh of the electrode,' Aoboi the D ir.e ns ion change by a ^ rrl-vrurig the For.Ti der Perforations are added or compensated. 2) heating element according to claim 1, characterized in that da3 the schicht.'örmige part made of a material with P "C behavior is constructed. 3) heating element according to claim 2, characterized in that the sc "nic
having. the sc "non- _{shaped part has an R-. 0} -fourth of at least 6 h) heating element according to claims. 1 to 3 »characterized in that the electrodes consist of a material - ,, rich an organic polymer and dispersed therein contains electrically conductive particles and the electrodes have the same extent as the layered part. 5 ^ heating element according to claim 4, characterized. That the sheet-like part obtained from a material with? TC-7 consists and the electrodes are made of a material with PTC behavior at a switching temperature above the switching temperature of the layered part exist. 6) heating element according to claims 1 to 6, characterized ge <cennzeleh net, that the electrodes are made of a metal with a resistivity of less than 1 ounce cm at room temperature and a ductility of at least that of aluminum. 7) Heating element according to claim 6, characterized in that the metal is lead, aluminum or Kuofer. 709825/0706 ⁰ ^ INAL INSPBCTEQ 8) Heating element according to one of claims 6 or 7, characterized in that: characterized in that the electrodes are corrugated. 9) heating element according to one of claims 1 to 8, characterized ge-j indicates that the j Electrode surfaces are coated with an insulating material. 10) Heating element according to claims 1 to 9 »characterized in that the layer-shaped part has PTC behavior 'and the element contains at least one intermediate layer which (a) constant wattage at temperatures below] Shows switching temperature of the layered part; (b) consists of a material which is an organic polymer and dispersed therein electrically conductive Contains particles in an amount sufficient for electrical conductivity; (c) which have a specific resistance of more than 10 Ohm.cm has; (d) the between the layer-shaped part and an elec-! trode is arranged and · j (e) the PTC behavior with a switching temperature above the switching temperature of the layer-shaped part. 11) heating element according to claims 1 to 10, characterized in that the perforations from a plurality of identical evenly spaced straight slots in parallel rows with overlapping slots in adjacent rows exist or correspond to such. 12) Heating element according to claim 11, characterized in that the distance between the edges of adjacent slots 0.25 to 1.25 cm, the length of each slot at least 1.25 cm and the length of each slot 5 to 20 times the distance between adjacent rows of slots. - - - - - 709 8 2 5/0706 13) heating element according to claims 1 to 12, characterized in that that the electrodes have essentially the same extent as the layer-shaped part. 14) heating element according to one of claims 1 to l ~ 5, characterized in that at least one dimension of the Sie- ', ment can be changed by at least 100 % and the cons; stood at room temperature by no more than 20 % changes. j 15) Object sensitive to the effects of heat, thereby in that it comprises a thermally responsive plate-j tenförmiges material and adjacent to an area DIE \ ses material, a heating element according to claims 1 to 14 j. ! Ib) object according to claim 15 »characterized in that the plate material is composed of an adhesive, a cement, a heat-backing capable FoLymerfiln or a polymer film which can be converted into the heat-restoring state. 1 ") The article of ANSN-ucti Iv or 16, daiaroh et ;; that the plate, ateri -il and the heating element by means of a in the K: rweichunr; _', er.peravar of Piatter / raterials thixotropic adhesive ni" each other verounder: become. 1S ^N Gef.'fr.otand according to Ansorüc-ien I5 to 1 ", characterized in that" the heating element ^ ine surface of the Ge ^ eristands cilciet -JiTiZ at least some of the perforations a mass flowing at the Er-Keiehang temperature of the plate material ent .-. old. 19) object according to claim 16, characterized in that that it has the shape of a heat shrinkable sleeve with the; Heize ", tj.r.ent on the inner surface, with the in- 709825/0706 inner surface has a coating of a putty and an adhesive. 20) A method for producing an article, Ge _{characterized:} indicates that an object according to claims I5
to 19 with an external energy source that connects
causes a current flow through the laminar part and
at least a part of the heat required to heat the plate material to its response temperature is provided and the dimensional change of the plate material in the plane of the plate at this temperature is made possible or enforced. ; 21) A method for coating a base, characterized in that an object according to claims 15 to 19 is arranged in the vicinity of the base, the electrodes of this object are connected to an external energy source, the current flow through the
layered part hosted and at least a part! which provides the necessary heat to heat the plate material to its response temperature and which
Dimensional change of the plate material in its plane; at this temperature enables or forces in such a way
that the object is attached to the surface of the base. 709825/0706