FR2709590A1 - Electrically conductive fluid or pasty material - Google Patents

Abstract

Fluid or pasty material intended to cover a surface, the said material being electrically conductive and containing a binder; the said material furthermore contains copper (Cu) and an additive containing a double oxide of tin and antimony (Sn/Sb)O2. Use of the said fluid or pasty material, especially a paint, as an electrically conductive coating (8) intended, for example, for heating a component using radiation.

Description

 Electrically conductive fluid or pasty material.

DESCRIPTION
The invention relates to a fluid or pasty material intended to cover a surface, said material being electrically conductive for heating by radiation, and containing a binder.

 The technical field of the invention is that of coating compositions, for example such as paints, varnishes, varnishes, thick coatings, plasters.

 A main application of the invention is the production of a substance for producing temperature differences. Such substances are used more particularly to be applied to supports, so as to obtain radiant panels for radiation heating, and electric heating systems using resistance heating.

We already know, from the Bulgarian Author's Certificate BG 15934, an electrically resistant material which is applied in the form of a paint or a paste, on an insulating surface or on the walls of rooms and rooms to be heated. This material is used for radiant heating and includes
- gray or black graphite, at a rate of 100 parts by weight
- a neutral filler, at a rate of 0 to 50 parts by weight
- a black fire varnish, at a rate of 75 to 150 parts by weight
- and coresilin, at a rate of 60 to 120 parts by weight.

 This material has the advantage of allowing the heating of a room at low temperature, on very large exchange surfaces, by consuming less energy than traditional systems, of the central heating type which, from an area point overheated, use the local air as a thermal vehicle.

 While having advantages, this material has the disadvantage of using gray or black graphite, and black fire varnish as a binder. The heating elements made of gray or black graphite and black fire varnish, require mechanical treatment in order to acquire the necessary electrical parameters. The black fire varnish has a relatively low mechanical resistance, cracks very quickly, and destroyed, it becomes unusable.

 Also known, from French patent application FR-A-2 593 185 filed on October 30, 1986, an electrically resistant material for radiation heating which comprises amorphous graphite, polyvinyl acetate, denatured alcohol , and a diluting agent consisting of coresilin.

 While having the advantage of having a high mechanical resistance, this material also has drawbacks. For example, the measurement of the resistance of graphitized paint shows a significant resistance, which allows the passage only of a very low current intensity, for a voltage applied to the terminals of such a coating of the order of 50 volts.

 The present invention aims to provide a fluid or pasty material of the aforementioned type, not having the drawbacks indicated above and which allows to reduce the electrical resistance of the corresponding coating, so that the voltages to be applied to the terminals such a coating, are relatively weak for obtaining a sufficient current intensity.

 According to the invention, this objective is achieved because the aforementioned fluid or pasty material also contains copper Cu and an additive containing a double oxide of tin and antimony (Sn / Sb) 02, more precisely Snx Sby 02, x and y satisfying the valence of oxygen.

 The fluid or pasty and electrically conductive material designed in accordance with the invention has a number of advantages.

 The electrically conductive fluid or pasty material according to the invention makes it possible to decrease the value of the corresponding resistance, in order to increase the intensity of the current transmitted, while applying the lowest possible voltage. It can be applied to both small and large areas, allowing uniform and pleasant heating of the rooms. It can be applied to different electrically insulating substrates, such as concrete, marble slabs, etc., by simple application using a brush, paint sprayer, flat brush, spatula, or using a coating machine just like ordinary paint.

 In addition, it is possible to obtain the desired electrical resistance by modifying the width of the application of the fluid or pasty material to the support, and by modifying the distance between the terminals intended to apply the potential difference.

 The dose of copper Cu added varies, preferably between 17 and 33% by weight approximately, and the dose of mixture of tin dioxide and antimony dioxide (Sn / Sb) 02 also varies, preferably between 17 and 33% by weight approximately, the dose of the copper and (Sn / Sb) 02 unit varying, preferably between 40 and 60% by weight approximately.

 Said additive preferably also contains at least one non-conductive oxide, for example silica (SiO2) and / or titanium dioxide Tir2.

 Said binder preferably contains a polar solvent, for example isobutyl alcohol. The presence of such a polar solvent facilitates the polarization of the conductive or semiconductor elements and increases the cohesion.

 The binder generally used is a varnish based on pliolite and can be replaced by any binder in the aqueous phase or dissolved in a solvent, such as binders based on polymer, for example acrylic solvents, chlorinated rubber, cyclized rubber, or all types of vinyl emulsions, pure acrylic, acrylic styrene, etc.

 Alternatively, an odorless paint in aqueous phase is obtained. An aliphatic solvent and / or an anti-sedimentation agent such as bentone are preferably added.

 The present invention is illustrated by the example below.

Example
Composition of the binder: for example a varnish V known under the brand EC1:
50 parts by weight of pliolite known under the brand Plioway EC1;
300 parts by weight of 5% aliphatic solvent
10 parts by weight of isobutyl alcohol.

Composition and characteristics of the additive A used, known under the brand name MINATEC CM and manufactured by the company MERCK
Minatec 30 CM opaque, of resistance less than 100 Q per cm of density substantially equal to 3.6 g / cm3; particle size less than 15 microns; composed of (Sn / Sb) 02, mica, Ti02, Six2.

 Minatec 31 CM transparent, with a resistance of less than 150 Q per cm; with a density substantially equal to 3.6 g / cm3; particle size less than 15 microns; composed of (Sn / Sb) 02, mica and SiO2.

Composition of electrically conductive material
Table I
Weight (g)% by weight Mass Volume
volume (cm3)
(g / cm3)
Varnish (V) 120.7 22.95 0.82 27.98
Additive (A) 131.1 24.92 3.6 6.92
Cu 125.3 23.82 8.9 2.67
Bentone 2.6 0.49 1.6 0.30
Solvent 146.3 27.82 0.78 35.66
aliphatic ~~~~~~ ~~~~~~ ~~~~~~~
526 100 73.53
Dry extract by weight: 49.23%.

 Density of material or paint: 1.36.

 Dry extract by volume: 18.56%.

 The thickness of the paint layer is 18.5 microns (18.5 10-6 m) per 100 microns (100 10-6 m) deposited wet.

 The following results have been obtained for a conductive layer deposited on a wooden support, a variable potential difference being applied to two terminals spaced by a variable distance d and in contact with the conductive layer.

Temperature in degrees Celsius measured
Table II
Difference of 40 70 ioo 130 160 180 200 220 potential (volts) d = 10 cm R = 3000 a 24 25 27 30 33 37 46 d = 20 cm R = 5800 Q 23 24 26 27 29 - 30 32
Resistance in Q measured as a function of the distance between the terminals to which a voltage of 220 volts is applied
Table III d (cm) 10 20 30 40 50 60
R (Q) 3000 5800 6300 8300 9000 10000
The present invention relates not only to the new electrically conductive fluid or pasty material, but also to the method of using said material comprising the following steps
- Placement on a support of at least two tensioning means, spaced a predetermined distance
- Application of a layer of said material between said tensioning means, so that said layer conducts electricity during tensioning.

The following advantageous arrangements are also preferably adopted
Said electrically conductive layer is applied in an elongated shape, so as to substantially reproduce a conductive wire, for example along a sinuous line or in the form of a frame
said layer is applied uniformly between the two tensioning means, so as to cover a large area
said method further comprises applying on said support an insulating primary layer
the tensioning means are elongated conductive elements, for example copper bars.

 The invention will be better understood and other characteristics and their advantages will appear on reading the description of the methods of use given below by way of example.

Reference will be made to the accompanying drawings, in which
Figure 1 is a perspective view of an experimental implementation of the method of the invention;
Figure 2 is a partial perspective view illustrating a first embodiment of the method of the invention in a room
Figure 3 is a partial elevational view illustrating a second embodiment of the method on a panel.

 Reference is first made to FIG. 1 of the drawings; the support 1 which is represented there, for example in laminated wood, is coated with a layer of insulating primary paint 9 previously applied, and containing radiant particles making it possible to reflect the heat towards the outside.

 Two tensioning means 4, 5 themselves connected to terminals 6, 7 to which a variable potential difference is applied, are placed on the support 1, more precisely on the insulating layer 9, spaced apart by a variable distance d .

 Alternatively, the tensioning means 4, 5 are copper bars arranged transversely to the layer of electrically conductive material 8.

 Reference is then made to FIG. 2 of the drawings; the room shown there has two walls 1, 2 and a floor 3. Compared to the embodiment of Figure 1, it should be noted that the electrically conductive layer 8 is applied in an elongated shape, more particularly in the form of a frame . The tensioning means 4, 5, consist of copper bars, alternately conductive cords, which frame the layer of conductive material according to the invention.

 Alternatively, the electrically conductive layer 8 is applied along a sinuous line, so as to reproduce the electrical resistances of known type, for example arranged in a zigzag.

 Preferably, a decorative finishing layer containing radiant particles is applied so as to mask all of the conductive elements.

 Finally, reference is made to FIG. 3 of the drawings; the panel which is represented has two electrically conductive layers 8 ′ applied uniformly, in order to cover two extended surfaces between two pairs of tensioning means 4, 5, the tensioning means being alternated and mounted in bypass.

 This arrangement increases the temperature obtained in the room.

 The three embodiments described above make it possible to regulate the temperature obtained by virtue of the presence of a voltage variator at the terminals of an alternative source, for example.

 Although the use of the fluid or pasty material according to the invention has been described in its application to an electrically conductive coating intended for radiant heating of a room, it should be noted that the invention has more general applications . The electrically conductive material according to the invention can be used simply for removing moisture from a wall, for the insecticidal nature of the presence of an electric current on a surface, to be applied to a container so as to maintain the certain liquids or food, or as a simple electrical conductor, for example in the manner of an electric wire connected to a light source.

 The method of using the invention can be applied to an electrically conductive fluid or pasty material of composition different from that of the electrically conductive material of the invention.

 Of course, various modifications can be made by those skilled in the art to the composition of the electrically conductive material and to its use which have just been described only by way of nonlimiting example without departing from the protective framework defined by the appended claims.

Claims (10)

 1. Fluid or pasty material intended to cover a surface, said material being electrically conductive for radiation heating, and containing a binder, characterized in that said material also contains copper (Cu), and an additive containing a double oxide tin and antimony (Sn / Sb) 02.  2. Fluid or pasty material according to claim 1, characterized in that the copper (Cu) is added in an amount of 17 to 33% by weight approximately, and the mixture of tin dioxide and antimony dioxide (Sn / Sb) 02 is added in an amount of approximately 17 to 33% by weight, the copper (Cu) and mixture of tin dioxide and antimony dioxide (Sn / Sb) 02 being present in an amount of 40 to 60 % by weight approximately.  3. Fluid or pasty material according to any one of claims 1 or 2, characterized in that said additive further contains at least one non-conductive oxide, for example silica (SiO2) and / or titanium dioxide TiO2.  4. Fluid or pasty material according to any one of claims 1 to 3, characterized in that said binder contains at least one polar solvent, for example isobutyl alcohol.  5. Use of the fluid or pasty material according to any one of claims 1 to 4 as an electrically conductive coating intended for heating by radiation.  6. A method of using the fluid or pasty material according to any one of claims 1 to 4, comprising at least the following steps  - placement on a support (1) of at least two tensioning means (4, 5), spaced by a predetermined distance (d)  - application of a layer (8, 8 ') of said material between said tensioning means (4, 5), so that said layer (8, 8') conducts electricity during tensioning .  7. Method according to claim 6, characterized in that said electrically conductive layer (8) is applied in an elongated shape, so as to substantially reproduce a conductive wire, for example along a sinuous line or in the form of a frame.  8. Method according to claim 6, characterized in that said electrically conductive layer (8 ') is applied uniformly between the two tensioning means (4, 5), so as to cover an extended surface.  9. Method according to any one of claims 1 to 8, characterized in that said method further comprises the application on said support (1) of an insulating primary layer (9).  10. Method according to any one of claims 1 to 9, characterized in that the tensioning means (4, 5) are elongated conductive elements, for example copper bars.