EP0035968B1 - Apparatus for forming, on a glass-sheet raised to a high temperature, a plurality of resistive tracks - Google Patents

Description

As is known, most heated glazing, such as that forming the rear window of motor vehicles, includes one or more networks of wires or conductive tapes incorporated into the glass of the telescope or applied to its surface, these wires or ribbons constituting as many electrical resistors intended to be attached to the terminals of the vehicle battery and thus produce the heat necessary for the melting of the frost covering the telescope in order to restore its original transparency.

Various types of heated glazing have also been proposed in which the conductive wires and ribbons have been replaced by areas of a transparent resistive coating extending over the surface of the glazing in the form of horizontal or vertical strips of only part of interest. of this surface, or even all, in certain cases, these resistive pads being, also, intended to be supplied with electric current to produce the defrosting of the glazing.

Among the numerous prior documents illustrating the state of the art relating to such glazing, mention will be made, by way of example, the patents FR-A-2,075,352, 1,116,234, 1,165,645 and 1,531,506, as well as patents US-A-3,475,588, 2,833,902 and 2,564,677 or even patent application EP -A-0.023.471 of the applicant.

Some of these documents also deal with processes used to obtain heated glazing, in which the resistive elements consist of conductive coatings, generally coatings of metal oxides, such as tin oxide. , deposited by vaporization, as for example in patents US-A-2,564,677 and 2,833,902, or also by the technique called CVD, as in the case of patent FR-A-1,165,645 or European application EP-A-0.023.471 already cited.

The technique of depositing such coatings by CVD is, moreover, well known and is illustrated by a relatively large number of publications of all stripes. In addition to the above documents, it is in particular the subject of patent FR-A-2,210,675, of patent GB-A-1,516,032, of patent application DE-A-2,123,274 or of patent DD -A-109.033.

As will be seen below, it is these last two documents which constitute the most representative state of the art in the context of the present invention. These documents indeed illustrate installations for covering a substrate brought to high temperature, for example a glass plate, with a coating of metal oxide, in this case Sn0 _{2 ′} in which coaxial nozzles directed towards the substrate and intended to spray reagents onto this substrate, the combination of which generates the formation of the desired coating. Means make it possible to relatively move the substrate and the nozzles so as to obtain the covering, with SnO ₂ , of the entire surface of the substrate. In addition, patent DD-A-109,033 envisages the evacuation, by aspiration, of the gaseous products resulting from the combination reaction occurring near the substrate.

In certain applications of the processes mentioned, by vaporization or by CVD, the deposited metallic coating is protected, the glazing being in the form of a “sandwich” structure, this coating being covered by one or more sheets of transparent material, while, in others, the coating remains bare. Thus, in the case of coatings of Sn0 ₂ obtained by CVD, these coatings have, at the same time, high transparency, high mechanical hardness and sufficient flexibility to allow the production of glazing of various shapes, without continuity solution for the layer of Sn0 _{2 '}

The object of the present invention is to allow the production of heated glazing units having a plurality of resistive pads intended to be connected to a source of supply current and each consisting of a coating of Sn0 _{2 '} deposited by CVD on at least one face. of a glass plate brought to high temperature, glazing whose ranges have, in section, dimensions remaining both particularly precise and constant, despite the particularly high speed at which such manufacture must be able to be carried out, while guaranteeing the 'Obtaining conductive pads of sufficiently low resistivity so that the glazings thus obtained can, in use, be defrosted fairly quickly by feeding from energy sources of limited power, such as the batteries with which motor vehicles are usually fitted.

To this end, the invention proposes to make use of a device intended for the formation of said resistive pads on a glass plate, including a series of nozzles each comprising, as in the device described in patent DD-A-109,033, two coaxial nozzles directed towards the face of the glazing to be coated by said areas and intended to be supplied by separate reagents, from nozzle to nozzle, the combination of which generates the formation of said coating, means for relatively moving the glass plate and the nozzles so that each coating is formed on renewed areas of said face of the plate, thereby creating said resistive areas, and a device for the evacuation, by suction, of gases from the combination of said reagents, comprising a suction head of these gases, arranged near each nozzle and connected to a network for removing said gases.

The device according to the invention is characterized, however, from this prior art, in that each suction head is constituted by a tubular bell surrounding the respective nozzle, coaxial therewith, and opening at a level corresponding substantially to that of the opening of the nozzles of this nozzle, the opening of said bell having a diameter of value substantially equal to the desired width for the range resistive to form by the nozzle considered so that the reaction for forming the coating of Sn0 ₂ takes place exclusively in the region of the glass plate limited, at all times, by the periphery of the opening of the bell of each nozzle .

Advantageously, the implementation of such a device makes it possible to obtain a particularly efficient heating glazing of the type mentioned above, which is characterized in that the thickness of the coating constituting each range is 2.5 μm, that its resistivity is 10- ³ ohm.cm and the extent of the part of the glazing covered by the resistive pads is 4 times less than the extent of the rest of this glazing.

• sur la fig. 1, une vue en élévation des éléments constructifs d'un dispositif selon l'invention et,
• sur la fig. 2, une vue en perspective d'un fragment d'un vitrage chauffant obtenu par la mise en oeuvre du dispositif de la figure 1.

The attached drawing shows, schematically and by way of example:

• in fig. 1, an elevational view of the constructive elements of a device according to the invention and,
• in fig. 2, a perspective view of a fragment of a heated glazing obtained by the implementation of the device of FIG. 1.

The device visible in fig. 1 comprises three nozzles 1, 2 and 3, each comprising two concentric nozzles designated respectively by the letters a and b. The set of central nozzles marked a is connected by a general piping 4, distribution, to a bubbler container 5 containing one of the reagents 6 allowing the formation of the transparent conductive layer; in this case, this reagent is SnCl ₄ . The nozzles b are connected by a distribution circuit 7 to a container 8 containing a second reagent 9, in this case aqueous methanol. Furthermore, the device also comprises conduits for supplying a carrier gas, respectively 10 and 11, immersed in the reactive liquids, this gas being intended to vaporize a part of these. Evacuation chambers, respectively 12, 13 and 14, collect the by-products of the coating reaction, in this case HCI, and direct them towards a chimney 15. The device described is intended to coat the upper face d 'a glass plate 16 by a layer of SnO ₂ , this plate being supported by rollers 17 so as to ensure its displacement perpendicular to the flow of gas flows. As indicated in the drawing, the enclosures 12, 13 and 14 closely surround the nozzles 1, 2 and 3, respectively, and their size, as well as the suction depression which prevails therein, determine the field of dispersion on the plate 16 of gases from said nozzles and, thereby, the width of said conductive areas.

le Sno₂ se déposant sur la plaque 16 sous forme de trois rubans 18 (fig. 2) et le HCI formé étant entraîné de manière contrôlée, en compagnie du gaz porteur et des produits n'ayant pas réagi dans la cheminée d'évacuation 15. En raison de la position concentrique des enceintes d'évacuation autour des buses, les gaz en contact avec la plaque 16 ne peuvent s'étaler librement sur la plaque au delà des limites imposées par les dimensions de l'embouchure desdites enceintes qui les capture. Il résulte de cette disposition la formation de dépôts (A) de Sno₂ dont l'empreinte est bien marquée et les bords nets et francs avec un minimum de diffusion sur les zones (B) (fig. 2).The device described operates as follows: the glass sheet 16 is heated to a relatively high temperature, for example 500 to 600 ° C., by means of an oven not shown in the drawing, and is progressively conveyed, by rollers 17, in look at the outlet of the nozzles 1, 2 and 3. Via the conduits 10 and 11, a carrier gas, for example an H _{2 /} N ₂ mixture, is introduced at a predetermined rate, so that, by bubbling, this gas entrains, in the form of vapors, the reactants 6 and 9, these simultaneously opening out orifices a and b of each of the nozzles. These gases are projected onto the plate and, in contact with it, they react according to the well-known reaction

the Sno ₂ being deposited on the plate 16 in the form of three ribbons 18 (fig. 2) and the HCI formed being driven in a controlled manner, along with the carrier gas and unreacted products in the exhaust chimney 15 Due to the concentric position of the discharge chambers around the nozzles, the gases in contact with the plate 16 cannot spread freely on the plate beyond the limits imposed by the dimensions of the mouth of the said chambers which captures them. . The result of this arrangement is the formation of deposits (A) of Sno ₂ , the imprint of which is well marked and the edges sharp and clean with a minimum of diffusion over the areas (B) (fig. 2).

In a single pass as described above, are formed ribbons Sn0 ₂ of about 0.5 to 0.8 _f lm thick. To produce the glazing according to the invention, several passes will therefore be made, for example by ironing the plate, backwards, then again forward, the number of times necessary for the conductive strips (18) to acquire the thickness and the conductivity chosen.

Of course, as a variant, it is possible to work continuously provided that there are several nozzles ramps placed, one after the other, in the direction of movement of the plate to be coated. Such an arrangement, although not shown in the drawing, is easily understood, by imagining two or more sets of devices, such as that of the drawing, placed side by side so that the deposit of each of the successive nozzles is superimposed on the deposit provided by the nozzle which precedes it. Or, in other words, an equivalent result is obtained by passing the plate four times opposite the drawing device or by passing it once opposite a battery of four similar units, these being arranged so that the trace of each unit is superimposed on that of the others.

By way of example, an industrial embodiment of the device according to the invention will be described below, making it possible to obtain particularly efficient heating glazing.

• a) SnCI₄ (tuyères intérieures (a); gaz porteur N_2/H₂ (60:40) au débit de 2001/h; débit de SnCI₄ 2 ml/min.
• b) solution aqueuse à 1% de HF (tuyères extérieures (b); gaz porteur N_2/H₂ (60:40), débit 3001/h; débit du réactif 1 ml/min. Les différents débits étaient réglés par des vannes placées sur les conduites d'amenées des gaz porteurs.

This device, which is similar to that shown in the drawing, included 8 nozzles, spaced 5 cm apart per row, and 5 successive rows of nozzles. The nozzle orifices, all placed in the same plane, had a diameter of 5 mm, the lower nozzle (a) having an opening of 2 mm in diameter. Each of the nozzles was surrounded by a cylindrical suction enclosure arranged coaxially with the respective nozzle and having an opening with a diameter of 12 mm. These enclosures, whose lower mouth protruded about 1 mm from the nozzle orifice, abou woven, at their opposite end, to the exhaust chimney which was equipped with conventional suction fans (not shown in the drawing). The nozzles were supplied, also as shown diagrammatically in the drawing, with the following reagents:

• a) SnCI ₄ (internal nozzles (a); carrier gas N _{2 /} H ₂ (60:40) at the flow rate of 2001 / h; flow of SnCI ₄ 2 ml / min.
• b) 1% HF aqueous solution (external nozzles (b); carrier gas N _{2 /} H ₂ (60:40), flow rate 3001 / h; flow rate of reagent 1 ml / min. The different flow rates were regulated by valves placed on the carrier gas supply lines.

We proceeded to deposit the Sno ₂ on a glass plate 4 cm thick, heated to 600 ° C and moving at 8.5 m / min. opposite and parallel to the nozzle opening plane. The deposition conditions were as follows: nozzle temperature; 130 ° C; suction speed of the trained HCI; 500 l / h.

The following results were obtained: width of the rectilinear areas 15 mm; thickness of the deposit 2.5 μm; resistivity = 10- ³ ohm.cm; overall resistance of the glazing R _o = 0.4 ohm.

There was thus obtained a glazing of approximately 30 cm in height having 5 conductive strips of overall surface representing approximately ¼ of the total surface of the glass.

After applying a strip of conductive paint to its lateral ends, a plate of this glazing (60 x 30 cm) was subjected to a standard icing and defrosting test as follows: At -15 ° C, we sprayed water on the plate, so as to cover it with a thick and absolutely opaque layer of frost. Then the lateral conductive paint strips were connected to the terminals of a 12 V direct current source and it was found that, at the temperature of -15 ° C, the conductive areas became clear in approximately 1 min. which allowed to have a good general vision through the glazing.

Claims (2)

1. Apparatus for forming on a glass plate (16) heated to high temperature a plurality of resistive areas (A) to be connected to a current supply source, each area (A) being constituted by a Sn0₂ coating (18) deposited by CVD on at least one of the faces of the glass plate (16), this apparatus including a series of nozzles (1, 2, 3) each comprising two coaxial tuyeres (a, b) oriented toward said face of the plate (16) and intented to be fed with discrete reactants (6, 9), from tuyere to tuyere, whose combination causes the formation of said coating (18), means (17) for displacing said glass plate (16) relative to said series of nozzle (1, 2, 3) so that each coating is formed on renewed zones on said face of plate (16) thus providing said resistive areas (A), a device for eliminating by aspiration gases issued from the combination of said reactants, comprising a suction head for these gases (12, 13, 14) located next to each nozzle (1, 2, 3) and connected to a network (15) for evacuating said gases, characterized in that each suction head (12, 13, 14) is constituted by a tabular bell surrounding its respective nozzle coaxially thereto and whose opening is at a level corresponding substantially to that of the nozzle opening (a, b) of this nozzle, the opening of said bell (12, 13, 14) having a diameter substantially equal to the desired width for the resistive area (A) to be formed by the nozzle under consideration, so that the formation of the Sn0₂ coating takes place exclusively in the area of the glass plate (16) defined, at each moment, by the periphery of the bell opening (12, 13, 14) of each nozzle (1,2,3).

2. Heating glass-pane obtained by bringing into play the apparatus according to claim 1 of which at least one face is coated with a plurality of transparent area (A), distant to one another, each constituted by a resistive coating of Sn0₂ deposited by CVD on the glass-pane and intended to be connected to a current supply source, characterized in that the coating thickness constituting each area is 2.5 _flm, that its resistivity is 10^-3 ohm · cm and that the extent of the portion of the glass-pane covered by said areas (A) is four times lower than the extent of the remainder (B) of said glass-pane.

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