DE1794255B2 - Slightly conductive mixture of thermoplastics or elastomers - Google Patents

Description

The magnetite powder is chemically a parallel connection of an infinite number of resistance temperatures, even at high temperatures particularly resistant, d. H. elements can be represented. At constant voltage is resistant to aging. Another advantage for from the amperage proportional to the conduction against such Mixtures produced moldings is the stand or the line length. With falling lyre reachable Flexibility. 60 line length the amperage decreases, and with increasing

Both thermoplastics can be used, the length of the line increases and thus decreases in each case Polyethylene, or elastomers, such as ethylene-pro-given performance again. To a low resistance pylene terpolymer rubber can be used. Voltage source can thus provide any heating power For example, a butyl rubber mixture can be connected with line lengths without the need for about 70 to 95 percent by weight magnetite powder, 65 short heating cable lengths the risk of overso one obtains specific resistances that are an order of magnitude in heating or with long heating cables of pure magnetite. Likewise, a decrease in the heat output to be expected is to be expected it is possible to use an ethylene instead of butyl rubber.

About the outer conductor 1 b, which may also be corrugated spiral to increase the flexibility of the heating cable or stranded with a Parallelwellung, the outer shell 3 of a heat resistant insulating material, for example arranged Buiylkautschuk.

Notwithstanding that in FIG. The embodiment shown in FIG. 1 is the end termination in FIG a high-voltage cable described in which the conductor 1 with the insulation 2 made of polyethylene is surrounded, which has been applied to the conductor in an extruder, not shown. From the end of the high voltage conductor is the massive, z. B. molded rotational body trained Shot club 3 made of polyethylene shot up. Several foils 4 are inserted into this end lobe 3 made of a weakly conductive mixture, for example butyl rubber with magnetite powder, embedded. the End lobe 3 can also be made by wrapping with polyethylene tape, with between the layers of polyethylene tape are arranged from the weakly conductive mixture. the Number of layers of foils from the weakly conductive mixture depends on? the amount of too controlling electric field.

In addition, a weakly conductive mixture according to the invention can also be used as emptying be used to reduce high field strengths, or find their way into technology everywhere, where previously the known conductive thermoplastic Plastics, for example, as protection against radiation or for making earth-sensitive Communication or power cables have been used.

1 sheet of drawings

Claims (2)

Use vinyl acetate copolymer (EVA), which will be "i" i., "": "™ iH / pr hftioeeeben. Patent claims: TÄSÄ according to the invention 1. Weakly conductive mixture of thermal insulation can ^ "^^^^ J5SS
plastic plastics or elastomers and 5 between two ,, at a distance juemander ^ ord
Iron oxides, characterized by the ladders of a heating line approaching ^ 8? « that the iron oxide magnetite powder with a heating cable designed in this way * ^rt ™ £ * ^^ Grain size is less than 100 _m old. Performance in which the person is connected to an alternating 2. Use of a mixture according to arrival n ™ gsquelle be placed and conductive by de kitfahige to claim 1. HeLellung layers, - the mixture currents flow as ^M "^ ^rms, for example in the form of strips in the structure can find application as η Vereisungsscnutz elegiac cable or cable sets and terrarium heating and the like. In this way, heating cables can solve almost any heating problem, be it through Change in cable length - even with short ones 15 heating cable lengths is the risk of overheating not given - or by changing the specific resistance by mixing different ones poorly conductive minerals, whereby the The invention relates to a weakly conductive mixed mineral if possible only to a toe mixture from thermoplastic plastics or »° nerpotenz differ in their resistance values Elastomers and iron oxides. It is known should. Elastomers or Thermoplastics The invention is not just about application To add carbon in the form of soot, limited by heating conductors, but it exists To change the properties of these materials. A possibility of surface heating, whereby a plate, Soot addition causes z. B. an extensive lack of sensitivity, for example, from this weak conductivity against solar radiation, an increase schung, through their ohmic heating with Stromder Slidability as well as an improvement in the overflow emits heat. surface quality. Since carbon belongs to the group of semi- Another possible application arises If the ladder belongs, the conductivity of this also increases in the area of the high-voltage cables to the control Mixtures with the addition of carbon. For 3 ° and for the reduction of the electric field. For cable voices Purposes, however, for example to release end closures are for example foils or of heating problems, a carbon black containing tape is made from the conductive mixture that Mixture not suitable due to its relatively low end specific resistance in the layer structure of a wound. But also a degree in the known way was brought in In cable technology, it can often be an advantage to use the 35 den. But also for radiation protection or the as radiation protection or, if necessary, as core shielding to limit the electrical Shielding as well as a field for field-controlling purposes are such weakly conductive masses, be it Set carbon black-containing materials by means of a layer other than sprayed on, as a film or foil, suitable Replace materials. suitable. It is also known that plastic mixtures 40 are used for a more detailed explanation of the invention in to increase the resistance to ozone and ^ - F i g. 1 and 2 two application examples on-ionization anhydrous oxides, for example the leads. Iron, admit it. The iron oxide used is dried. 1 shows a cross section through a heating Rust (Fe ₂ Oj ₁ ) is used, whereby the electrical line, in which the two conductors ϊ α and 1 b, which are made of copper, for example, not or only slightly changed 45, become concentric (GB-PS 9 98 499). are arranged differently. The space between The invention is based on the object of making a material 2, for example a mixture, that conducts the two conductors 1 α and 1 b with a plastic mixture containing weak iron oxide. made of an ethylene-vinyl acetate copolymer and This object is achieved in that the iron 5 ° gnetite powder with a grain size below 100 μπι geoxid Magnetite powder with a grain size of fills. If you connect the two conductors la and Ib is less than 100 μπι. Compared to the soot-containing alternating voltage, currents flow through the Mixtures, the mixtures according to the invention have a weakly conductive mixture 2, so that it heats up tion has the advantage of a much higher specificity. Such a structure results in swimming Resistance. 55 loaned a heating cable, its total resistance through