IL48165A

IL48165A - Flexible electric area heating elements and their manufacture

Info

Publication number: IL48165A
Application number: IL48165A
Authority: IL
Original assignee: Reuter Maschinen
Priority date: 1971-09-27
Filing date: 1972-09-27
Publication date: 1977-10-31
Also published as: IL48165A0; ZA726586B; JPS534237A; DE2148191B2; BR7206668D0; DE2148191A1; DE2148191C3

Abstract

The heating element is completely flexible as it does not have any heating resistance wires inside it. It comprises a layer of fabric laminated on one side and with a plastic layer on the non-laminated side so that prior to addition of the plastic layer, the non-laminated side is treated with an aq. plastic dispersion contg. electrically conductive particles and provided with flexible electrodes and terminals. Pref. the plastic dispersion is polyisobutylene and the plastic layer can be a soft, elastic, closed pore, polyurethane foam, pad. [DE2148191A1]

Description

Flexible electric area heating elements and their manufacture GmbH 45711 The invention relates flexible electric area elements virtue of their elastic and flexible properties are intended particularly for pliable electrical heating electric and the In the case of conventionally used electric heat electrical energy is converted by resistance following Joule s laws into current the heat produced being passed from the resistance wire through an to the actual effective These heat conductor which consist for example of nickelin or rheotan and easily break under mechanical by virtue of fatigue The disadvantages connected therewith are It will be understood that pliant heat generators constructed according to this system are sensitive to any kind of mechanical strain and ought not to be described either as flexible or For pliable electrical heating appliances the recommend imprinting the words not In general in the household and in flexible heat generators are if complicated contours have be heated or if deflections are such as is desirable for example in the case of a heating cushion pad which adapts to the contours of the there have been various attempts to replace the resistance wires by another material which has substantially better mechanical Thus i is known to a flexible carrier material with conductive graphite and for the resultant heating element to be used for beatabl bed covers the The carrier material may fee inorganic fibre material Patent organic for example cotton Patent rubber Patent or even plastics material Patent A heating element of reinforced conducting polysiloxane elastomer suitable for incorporation in seats of motor vehicles is known from British Patent Specification In this known heating element the reinforcing substrate may be in the form of a film or a or fabric made from polyethylene a synthetic or This substrate is covered with a layer organopolysiloxaae is hardened at a temperature of about The electrically conductive surface which is provided with electrodes before or after the application of the polysiloxane layer is then for electrical into a cotton Where these known heating elements are the danger of conductor breakage is eliminated above in the ease of organic Despite this they have not however become established in The reason for this probably resides in the fact that the carrier materials as well as the conductive do not withstand the desired mechanical stresses as soon as tractio or compressive forces come into Also known are for example flexible heating elements made from textile which obtain their conductivity by being coated or impregnated with a graphite The term textile fabric in this case denotes a mechanical combination of weft and warp The graphite coating applied to the textile threads by means of a dispersion lies on the weft and warp threads and joins This slight tractive loading on a single warp or thread causes the graphite coating to even if additional binders such as synthetic are intended to enhance the If this conductive fabric is then lined with an electrically insulating cover or is otherwise mechanically then by virtue of the movements the electrical values change to values which cannot be The abject of the inventio therefore was to provide flexible area heating elements not exhibit the disadvantages of the prior ar and which in particular have a high and electrical stability as well as reproduceable electrical values and improved properties during the heating The problem according to the invention is resolved in that an electrically conductive film provided appropriate and electrical connections covere with a relatively thick is applied onto a unilaterally woven abric The object the invention is thus an electrically beatable flexible area heating element without electrieal of the type consisting of a flexible or elastic woven layer of fabric covered with plastics material and provided with electrically conductive film to which are connected wherein the flexible or elastic woven is lined on one side and covered on the other with an electrically conductive obtained by application of a aqueous dispersion of a plastics material containing electrically conductive and a layer of polyurethane foam is foamed onto the electrically conductive The electrically conductive film hereinafter referred to as the of the area heating according to the invention is preferably such a film has been obtained by applying a plasties dispersion which contains electrically conductive electrically conductive particles relates thereby preferably to other metals or substances coated with rar or carbo black or carbon black is particularly Particularly preferred is an acetylene carbon black such as is for example in the of an aqueous For the further construction of a heating according to the at least two electrodes are also The purpose of the electrodes is establish a resistance value betwee the electrodes which is regular over the entire conductive When an electric voltage is applied to the then by virtue of film resistance an homogenous voltage potential forms between The electrodes be made from flexible metal stri or for example plastics so long as the electrodes are not mechanically For flexible such as heatable car heated heated blankets and the a flexible to a certai extent elastic electrode is required the heating elements are loaded over their entire area with and bending In addition fulfilling these mechanical the electrodes in flexible area elements must have very good electrical conductivity which corresponds approximatel the According to the has been found that electrodes with elastic and readily conductive such as are manufactured as particularly suitable for flexibl area heating As a conductive substanc commercially available copper powder is The powder has a particle size of approximately 180 Other metal powders apart from those coated with rare cannot be used this copper powder with a particle diameter of approximately 180 is stirred for example a added for the mixture to be just the relatively large particles of metal powder alongside the tangential contact relativel large a aqueous carbon dispersio is stirred into the existing dispersion readily conductive acetylen carbo black content millicrons particle fills previously empty interstices completely with particles of carbon black after the carrier liquid has dried the resistance of metal particles is considerably According to the these readily conductiv films have a resistance of about after a drying tim of about 1 hour at room they exhibit a satisfactory flexible and elastic The thicker may consist of any homogenous or foamed plastics material which corresponds to the required the coating is Fo flexible heating this coating particularly consists of a softly polyurethane foam which can be particularly easily foamed directly onto the layer of manufacture of the soft polyurethaae foam is known to a man skilled in the Further details of the electrically hea able area heating elements according to the invention will become manifest from the ensuing the of embodiment and in 1 shows a thin layer 1 in form of a a textil on one 2 shows a thin layer 1 provided with electrodes 3 and connection points 3 shows the same object as in with a subsequently applied heating 4 shows a thin unilaterally lined fabric layer 1 provided with the heating film together with a 6 for producing a layer of and 5 shows an area heating element according to the consisting of the woven fabric 7 lined on side and treated with plastics dispersio containing electrically conductive particles and the foam padding 8 and connecting lead The fact that wove fabric used flexible area heating elements is lined on one side that freedom of movement of the individual threads which occurs in conventional area heating elements which have a disadvantage effect for the reasons already is For the purpose of the inventio it is possible i principle to use any woven fabrics which are lined on one the woven fabric consisting off organic or inorganic absorbent fabrics are since when these woven fabrics treated with hereinafter described aqueous a better adhesion of the heating film which is to be formed can The use of woven abrics is naturally also namely if the heating films which are be adhere sufficiently the woven As a textile it to use made from those unilaterally lined fabrics wherein the plastics coating is approximately which have proved particularly According to the particular preference is given to those textile fabrics which are lined on one side with flexible plastics for example those which are available commercially under the trade names Vistram when using lined fabrics of wove it is possible also to produce rigid heating wall or celling heating when for example a polyur thane rigid foam ca be applied to the unlined side of the For such the fabric will naturally also be with rigid plastics For the manufacture of and elastic wireless area heating elements according to particularly suitable plastics dispersions which are blended the electrically conductive particles prior to application onto the woven are any plastics dispersions which form an elastic ageing resistant According to the preferably a aqueous dispersio of polyisobutene is In order to produce the aqueous electrically conductive plastics an aqueous dispersion of polyisobutene is for exampl blended aqueous dispersion of carbon viscosity of the plastics dispersion being so adjusted by the blending with th carbo black that a readily brushable mi ture is This mixture then fo example to the fabric side of the unilaterally lined textile onto the textile fabric which then rapidly absorbs the mixture which forms the The film forms within 30 minutes at room The the according to the thickness of the applied is artificially aged for a few hours at The is necessary to stabilise because the plastics particles previously present in the plastics exhibit shrinking due to The shrinking has the effect that the contact between the conductive particles adhering to the plastics particles becomes somewhat so that the electrical resistance of the film is somewhat The dispersion forming the heating film consists preferably of an plastics dispersion by the admixture of an aqueous carbon black adjusted to the desired values with respect to conductivity and A completed foil with the heating film applied to the reverse side is flexible and exhibits surprisingly good elastic The area heating elements according to the which are prof lined on the back with a coating of polyurethane are universally In addition to their ready workability into soft polyurethane materials are particularly characterised by excellent thermal insulating The heating elements according to the invention particularly exhibit three The heat generated is given only through the effective so that minimal conduction losses By virtue of the low heat losses and construction of the heating the times are very short even in the case of heating elements measuring square metres By virtue of the fact that the polyurethane reverse side The weight of a one square metre large and 20 mm thick heating area with a coating of polyurethane foam is approximately 1000 The side consists a material which can be supplied in the most widely diverse In order to eliminate risks caused for example by knocking nails into the heating these heating elements preferably operate on low According to the field of the heating elements are adjusted to the most widely diverse temperature ranges can be designed for any working If by virtue of poor heat an upper temperature limit has to be then a or some other temperature limiting means can be connected directly in or on the heating film For heating elements according to the with low working only the mixture has to be somewhat modified in that the resistance is reduced according to the desired values by the additio of The area heating element according to the invention is completely waterproof and resistant to temperatures down to below The area heating element can furthermore used for working temperatures of up to It is mostly arranged for voltages of or 110 If by virtu of som special application of the area heating no layer of foam is then the heating like the can also be coated with epoxide in which an area heating elemen is obtained which as has a thin layer instead of the thicker heat insulating In any the heating film should be protected The following example explains the invention without however restricting its le Manufacture of a flexible heating cushion A textile fabric lined on one side with plastics material is provided on the side with flexible elastic electrodes The electrodes applied by means of a template mm 270 and are at a reciprocal distance of 370 The electrode mixture consists of 80 parts by weight of a dispersion of a copolymer of aer vinyl acetate and acrylic parts b weight of copper powder and 100 parts by weight of a acetylene using a frame template x 370 the actual heating film is In order to produce the heating an aqueous dispersion of polyisobutene while being black thoroughl blended with a aqueous acetylene The easily brushable mixture is evenly applied to the woven The electrodes are completely by the heating the film is By means of plastics a contact plate and cable shoe are to each electrode in order to allow connection to a voltage The entire heating film can if necessary be sealed with an electrically insulating The of a softly elastic polyurethane foam padding o the heating film is now The polyurethane foam is foamed on in known manner and therefore need not be described in greater mould with for example sides 40 mm is so placed on the heating foil that on at a minimum distance of 15 The reaction mixture forming the is poured into the mould mould cover is placed on the and applied in order to avoid of the foaming mould frame can be after 10 On its reverse the heating element now shows the elastic foam pad When a voltage is the heat generated is now radiated only from the lined insufficientOCRQuality

Claims

CLAIMS Electrically beatable flexible area heating element without electrical of the type consisting of a flexible or elastic woven layer of fabric covered with plasties xrtaterial and with a electrically conductive film to which are connecte wherein flexible or woven fabric is lined on one side and on the lined with a electrically conductive film obtained by applicatio of an aqueous dispersion of a plastics containing electrically conductive and a layer of is onto conductiv Area heating element according wherein the electrically conductive particles consist of rare other metals or substances coated with rare or or carbon black being particularly Area elemen according to

1. Claim 1 and chacterised in that the dispersed material is insufficientOCRQuality