Compositions – Electrically conductive or emissive compositions – Metal compound containing
Patent
1997-08-26
1999-10-19
Kopec, Mark
Compositions
Electrically conductive or emissive compositions
Metal compound containing
2525181, 25251933, 2525213, 264450, 219209, 219213, 427 58, 4271263, 392407, H01B 120, H05B 100, B05D 512
Patent
active
059684208
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a fluid or semifluid material for covering a surface, and containing a binder; said material being electrically conductive, and particularly suitable for radiant heating.
The technical field of the invention is that of surface-covering compositions, for example such as paints, varnishes, lacquers, thick coverings, rendering.
A main application of the invention is to obtain a substance for producing temperature differences. Such substances are used more particularly for applying to supports in order to obtain radiant panels for radiant heating, and electrical heating systems making use of resistance heating.
Bulgarian author's certificate BG 15934 discloses an electrically resistive material which is applied in the form of a paint or a paste on an insulating surface, such as on the walls of rooms and/or premises to be heated. The material is used for radiant heating and it comprises:
That material has the advantage of enabling low temperature premises to be heated over very large heat exchange areas, thereby consuming less energy than traditional systems of the central heating type which start from a small overheated zone and make use of the air in the premises to carry heat.
That material suffers from the drawback of using gray or black graphite, and fireblack varnish as its binder. Heater elements made of gray or black graphite and fireblack varnish require mechanical treatment in order to acquire the necessary electrical parameters. Fireblack varnish has relatively low mechanical strength, crazes very quickly, and once destroyed, becomes unusable . . . .
Also known, from French patent application FR-A-2 593 185, filed Oct. 30, 1986, is an electrically resistive material for radiant heating and comprising amorphous graphite, vinyl polyacetate, denatured alcohol, and a diluant constituted by coresiline.
While having the advantage of presenting high mechanical strength, that material also suffers from drawbacks. For example, the measured resistance of the graphite-containing paint is high, which means that it can pass only a very low current, even when the voltage applied to the terminals of such a covering is about 50 volts.
Paints are also sold that contain a small percentage by weight (generally about 3%) of conductive fillers. Such fillers are incorporated in said paints for the purpose of improving application thereof, by making them electrostatic. Given the low level of filler that they contain, such paints are not electrically conductive.
An object of the present invention is to propose a fluid or semifluid material of the type described in the above BG and FR documents, while avoiding the drawbacks mentioned above and enabling the electrical resistance of the corresponding covering to be reduced so that the voltages that need to be applied to the terminals of such a covering are relatively low while obtaining sufficiently high current.
According to the invention, this object is achieved by the fact that the fluid or semifluid material contains, in a surface covering binder, 20% to 80% by weight of conductive filler constituted by a flaky inorganic medium coated in a powder based on a double oxide or on a mixture of double oxides, said double oxide(s) satisfying the following formula: Pb; Bi; and
The present invention thus provides an electrically conductive fluid or semifluid material for covering a surface and that is particularly suitable for radiant heating. The invention is mainly described with reference to such heating. Nevertheless, the person skilled in the art will readily understand on reading the following description that said fluid or semifluid material as presently claimed has other applications. In particular, it can be used for the following purposes: surface; receptacle; and connected to a light source).
In characteristic manner, said material contains in a binder 20% to 80% by weight of specific fillers.
Said fillers must be present in sufficient quantity (.gtoreq.20%) for obtaining the expected result: the resulting material in which they are dispersed is
REFERENCES:
patent: 4857384 (1989-08-01), Mio et al.
patent: 5529720 (1996-06-01), Hayashi et al.
patent: 5536770 (1996-07-01), Glausch et al.
Sinigaglia Jean-Claude
Thuny Gilles
Kopec Mark
Renaudin
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