DE2138155A1 - PROCESS FOR MANUFACTURING HEATING DUCTS AND HEATING DUCTS MANUFACTURED BY THIS PROCESS - Google Patents

Description

FARB ¥ ERKE HOECHST AIiTIEXGESELLSCHAFT formerly Master Lucius & Brüning

File number: - HOE? 1 / P 192

Date: July 29, 1971 - Dr.BK / Ba

Yerfaliren for making, of heating conductors and after this Process manufactured heating conductors

The invention relates to a method for producing heating conductors from non-combustible material and heating conductors, which are produced by this process. The heating conductors according to the invention consist of inorganically bound molding compounds, as a binder z. B. Portland cement, gypsum, anhydrite or water glass.

In recent times, surface heating conductors have found increasing interest. They can easily be adapted to the object to be heated Due to their homogeneous structure, they deliver uniform surface temperatures even over larger areas. In practice, plastic foils or fabrics made of synthetic or glass fibers have been used as surface heating conductors with electrically conductive pigmented PTFE dispersions are coated. Their applicability is limited by the thermal load capacity of the plastics used, which does not allow temperatures above about 30 ° C. When using as radiators in floors, streets, driveways and the like, place the heating conductors opposite the one used Building material represent foreign bodies that do not bond with the building material, and the other coefficient of expansion have than the surrounding building material. Finally, the attachment of the electrical leads causes difficulties.

20988670621

HOE 7T / F 1 92

It has now been found that you can heat conductors with high thermal Resistance and mechanical strength are obtained if an inorganic binder and, if appropriate, are added to a molding composition contains conventional additives, an electrically conductive pigment, in particular carbon black, adds during the shaping process embeds metallic leads in the mass and allows the mass to harden.

Thus, the heat conductor according to the invention consist of a hardened molding material, containing an inorganic binder, and optionally conventional additives, two metallic leads are in the at least W embedded, and is pigmented conductive. . ·

As an inorganic binder, which-for the production dex; Heating conductor come into question, hydraulically setting materials such. B. Portland cement, gypsum and anhydrite, where "The choice of the binder is not least due to the demand thermal resistance is determined. So plaster of paris and anhydrite are only suitable for moderate temperatures. Special thermal resistance show masses, lax those as Binder water glass is used. Is used.

k In addition to the binding agent, the molding compounds can contain the usual aggregates, for example sand or grit. Inrasserglas-bound masses can, for. B. also barite, quartz powder, titanium dioxide, etc. may be included.

Carbon in the form of graphite or soot is used as a conductive pigment. For reasons of strength, above all the pigmentation should not be too high in cement-bound masses. It has therefore proven to be particularly useful to use as conductive pigment carbon black, which was obtained by pressureless thermal cracking of acetylene. Brine Carbon black is sold under the name * 'Acetogen carbon black. He results in high electrical conductivity even with a small amount added. -

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It is advisable to order the electrical leads made of -metal- fabric tapes. Have ribbons made of fine-mesh copper mesh sicli particularly proven.

The heating conductors according to the invention are suitable, for example as underfloor heating. They become useful in this application designed as part of a cement or anhydrite screed, for example in such a way that a leveling layer of unpigmented screed material is first laid, then * the heat conductor layer with the electrical leads and finally a cover layer made of unpigmented Material is laid. This is the same for all layers apart from the conductive pigmentation of the heating conductor layer If screed material is used, one essentially obtains one Monolithic screed, in which the unpigmented Lagsi also provide electrical insulation.

The heating conductors according to the invention can be shaped accordingly as a radiator, e.g. B. serve in iron and ¥ arm holder plates. For example, they can also be shaped into tubes will. The electrical insulation can each consist of the The same molding compound exist as the heating conductor itself, only the conductive pigmentation being omitted. ■

Examples of compounds composed according to the invention are given below Molding compounds specified for the production of heating conductors:

In all cases, carbon black is used as the conductive pigment pressureless thermal cracking of acetylene was obtained.

T. molding compounds with Portland cement as a binder.

a) Portland cement is mixed with water without additives. The specified square resistances are obtained with the following amounts of soot:

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$ Soot related to cement Quadra ^ resistance "one

10 mm thick plate StL

3 100

h 62

5 52

b) The basic mixture of I50 GT sand, 50 pbw of Portland cement and 20 parts water is added to carbon black in the form of a paste, which fit by dispersing of 8 wt .- ^ carbon black in an internally veichgemachte dispersion of a vinyl acetate CapolATnerisat, solids content: about 50 was obtained

Paste GT corresponds to fi carbon black based on the square resistance of a total solid. 10 mm thick plate

80 2.7 · 120

60, 2.1 164

4o 1.45 '520

c) With an asbestos cement of the basic composition 150 GT Portland cement, 25 GT asbestos fibers, 130 GT water were used The following square resistances were determined on 10 mm thick panels

Soot GT <p based on solid square resistance

5.2 3,260

7 4 .125

8.7 5 61

d) With the same basic composition as in c), but with an addition of 17 ^ 5 pbw of a vinyl acetate copolymer dispersion (corresponding to 5 ° plastic dry matter based on solids), the following values were measured

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Carbon black GT $ based on solid square resistance SB.

5.5 3 425

7.4 4 143

9.2 5 113

e) A concrete suitable as a heating conductor results in the following mixture, for example

I.6OO GT sand, 1,200 GT grit, 400 GT Portland cement,

(r)

320 GT of a copolymeric vinyl acetate dispersion (* 'Moviton M 300), 240 GT! Barrels, 60 GT soot.

The square resistance of a 10 mm thick plate is 180

II. A 10 mm thick plate made of a mixture of 200 parts by weight of gypsum, 130 parts by weight of water and 6 parts by weight of carbon black (= $ 3 based on gypsum) had a square resistance of 920 5i after curing.

III. A commercial water glass putty was pigmented with soot, The molding compound consisted of 1,280 parts by weight of a commercially available cement flour made of inert filler and hardener, 400 parts by weight of potassium silicate, 135 GT water and 24 GT carbon black. One made from it After curing, the 10 mm thick plate had a square resistance of 210 Si.

2 09886/06? 1

Claims (4)

71 / F 192 Patent claims: j / Process for the production of heating conductors, characterized in, that a molding compound made of an inorganic binder and optionally conventional additives with an electrically conductive pigment is added so that metal leads into the molding compound during molding be embedded, and the mass is hardened. 2. The method according to claim 1, characterized in that the molding composition is added as electrically conductive pigment carbon black which was obtained by thermal cracking of pressureless AcetyXen. 3. Heating conductor, consisting of a hardened molding compound made of an inorganic binder, if necessary additives, an electrically conductive pigment and embedded in the mass metallic supply lines. 4. Heating conductor according to claim k, characterized in that the electrically conductive pigment is carbon black, which was obtained by pressureless thermal decomposition of acetylene.