FR2708591A1 - Window pane provided with at least one conductive layer with improved properties - Google Patents

Abstract

Monolithic or laminated window pane consisting of at least one sheet of glass and/or of plastic comprising at least one conductive layer and an essentially organic coating based on a polymer or copolymer deposited on at least a part of at least one of the faces of the sheet forming part of the constitution of the window pane. The part of the face of the glass sheet covered with the coating is situated in alignment with the conductive layer.

Description

GLAZING PROVIDED WITH AT LEAST ONE CONDUCTIVE LAYER
WITH IMPROVED PROPERTIES
The invention relates to a monolithic or laminated glazing comprising at least one conductive layer.

 There are several types of glazing requiring a conductive layer. These are, for example, heated, de-icing glazing, with remote-controlled optical properties or glazing having sensors, an antenna, etc.

 Whatever the type of glazing, it is sometimes necessary to protect this conductive layer from the external environment.

 The conductive layer is usually a metallic layer, generally deposited by screen printing, from a paste containing at least one glass frit and metallic particles.

 The remainder of the description relates, more specifically, to a glazing used in the automotive field. It can also be a glazing used for another transport vehicle or in the building sector.

 I1 is known to cover at least part of the conductive layer with a layer of enamel. The protective enamel layer has the advantage of having excellent mechanical strength as well as a strong adhesive power with respect to the glass and the conductive layer. Its composition contains at least one glass frit capable of being vitrified at high temperature, thus intimately binding the enamel to its support.

 Furthermore, the enameled protective layer thus deposited on at least part of the conductive layer can make it possible to camouflage the presence of conductive layers, which are not very attractive. It is then usually black.

 To make the enameled layer, the enamel composition is preferably deposited on the substrate, the wet layer formed is then dried until this layer has sufficient adhesion and resistance to prevent the appearance of traces on the layer formed-when handling the glazing.

 Of course, different layers can thus be deposited. The enameled layer or layers are then treated by a high temperature heat treatment, of the order of 6000 ° C., in order to vitrify 11 enamel and obtain the enamel layer itself.

 However, enamel thus deposited on a conductive layer requires a high temperature treatment which can sometimes risk damaging the conductive layer supporting it. Furthermore, this enameled layer often has a non-uniform surface appearance due to the presence of micro-pores. On the other hand, the presence of these micropores makes the enamelled layer permeable to air and / or to other fluids. The conductive layer can then deteriorate by oxidation and / or corrosion.

 In order to protect the conductive layer from oxidation and / or corrosion, a seal can be provided between the bodywork and the glazing. This seal protects the conductive layer from attack by agents external to the vehicle. However, the size of the joint can sometimes be annoying. Furthermore, some vehicle models do not allow the presence of this seal so that it ensures, in particular, the sealing of the conductive layer.

 The invention overcomes the aforementioned drawbacks.

 The object of the invention is to provide a glazing unit comprising at least one conductive layer which is sheltered from the risks of corrosion and of oxidation, in particular when it is not protected by a seal.

The conductive layer according to the invention is, moreover, protected from attacks due both to agents external to the vehicle, such as air, aqueous solutions, detergents, etc., and to the air and humidity prevailing in the 'passenger compartment.

 The invention also aims to provide a glazing whose conductive layers can be hidden from view.

 The present invention relates to a monolithic or laminated glazing consisting of at least one glass and / or plastic sheet, said glazing comprising a conductive layer and a coating, essentially organic, based on a polymer or a copolymer, deposited on at least part of at least one face of the sheet forming part of the glazing. The part of the face of the glass sheet covered with the coating is located in alignment with the conductive layer.

 Your sheet capable of being coated with a coating according to the invention can be made of glass obtained, for example, by the "float glass" process. It can also be a glass support having undergone thermal or chemical toughening or a plastic support. It may be a sheet forming part of a laminated glazing, an outer sheet or an interlayer, for example, made of polyvinyl butyral or polyurethane.

The support can also be previously coated, at least partially, with a mineral coating, for example an enameled layer or a conductive layer. The enamel can be a conductive enamel, for example an enamel constituting a conductive strip or an enamel, for example black, in order to camouflage certain parts of the glazing.

 According to a preferred variant of the invention, at least part of the coating is deposited on at least part of a conductive layer. The coating according to the invention advantageously replaces the enamel deposited on the conductive layer thus making it possible to dispense with a heat treatment at high temperature capable, moreover, of damaging the substrate.

 The conductive layer covered by the coating can be located within the sealing zone, that is to say in the zone limited by a sealing joint situated between the bodywork bay and the glazing. The coating advantageously constitutes the outer layer.

 The coating then has sufficient mechanical strength so that the conductive layer is protected from scratches, shocks, abrasion or the like. Advantageously, the layer consisting of the coating is not deteriorated by these mechanical stresses, thereby improving the aesthetics of the glazing as well as, if necessary, the optical qualities of the glazing. The coating based on polymer or copolymer according to the invention has a resistance to scratching, measured according to the so-called "pencil line" test. The coating according to the invention is not damaged by a pencil line, the hardness of which is between H and F, despite the essentially organic composition of the coating. Furthermore, the coating according to the invention can have adequate dielectric properties. The dielectric strength of the coating can reach values as high as 5.101 Ohms. It is preferably between 3.10c Ohms and 5.101 Ohms. Furthermore, the coating according to the invention has a nice surface appearance, in particular a smooth surface and a uniform thickness. The coating can also protect the conductive layer from any pollution liable to damage it. I1 can be, for example, pollution due to the presence of an element covering the conductive layer, for example a primer, an adhesive joint, mounting, sealing ... The conductive layer covered with coating according to the invention can, for example, be covered with the mounting gasket thus making it possible to reduce the bulk at the periphery of glazing.

 Preferably, the coating is opaque, thus camouflaging the conductive layer from view. It can also be semi-transparent or transparent, in particular when it is used in the so-called "vision" zone of the glazing.

 The coating can be colorless, black, white or any other color. It preferably has the property of stabilizing the color of the substrate on which it is deposited.

It is thus possible to avoid deterioration of the color of a conductive layer based, for example, on silver paste, deterioration which usually takes place during use.

 The coating can also be applied to a layer of enamel in the form of touch-ups, for example. It thus gives a beautiful surface appearance on a previously enamelled support while giving it, if necessary, additional properties such as good dielectric strength, coloring effects ...

 The conductive layer coated with the coating can be located, according to an advantageous variant, outside the sealing zone. In addition to the properties already described of the coating, the latter then confers on the conductive layer resistance to oxidation, corrosion and fluids.

 The coating can also be applied to a face which does not support the conductive layer. It may be the face opposite to the face supporting the conductive layer of a glass sheet constituting a monolithic or laminated glazing.

 It can also be any side of a laminated glazing, consisting of at least two sheets of glass and a sheet of flexible plastic, when the conductive layer is embedded in the plastic.

The conductive layer is then usually a foil strip. The coating can be applied to the face of a glass sheet and / or to the face of the plastic sheet.

 According to a preferred variant, the laminated glazing consists of at least two glass sheets between which a plastic sheet is interposed. The coating is advantageously located at the interface formed by the face of the plastic sheet and the face of the glass sheet whose face opposite this interface is an outer face.

 The part of this face supporting the coating can possibly be covered with an enameled layer or another type of layer. The coating then camouflages the presence of such a conductive layer from view. It can also have other functions such as resistance to ultraviolet rays, thus protecting, for example, the glue used to fix the glazing to the bodywork bay.

 The material constituting the coating of the invention is advantageously a resin chosen from the following resins: polyurethane, acrylic or cationic resin.

 The term “resin” means a polymer or a copolymer. The copolymer can be formed from a monomer chosen from polyurethane, an acrylic or cationic monomer in combination with one or more other monomer (s).

It can also comprise at least two monomers chosen from polyurethane, an acrylic or cationic monomer, optionally in combination with one or more other monomer (s).

 By cationic resin is meant a resin in which the monomer has at least one polar group capable of reacting with an acid, during the polymerization. The cationic resins advantageously used according to the invention are ether-vinyl, vinyl or, preferably, epoxy resins. The epoxy resins may optionally contain hydroxyl groups such as diols, triols, and / or optionally diluents.

 The preferred epoxy resins according to the invention are resins essentially containing the following epoxy groups, alone or in combination: 3, 4-epoxycyclohexyl methyl-3,4-epoxycyclohexane carboxylate or bis (3,4-epoxycyclohexyl) adipate. The epoxy resin according to the invention can also contain a mixture of cyclo-aliphatic epoxies, the main epoxy of which is 3,4epoxycyclohexyl methyl-3,4-epoxycyclohexane carboxylate.

The epoxy resins according to the invention preferably contain a photoinitiator which is advantageously either an antimony salt or a phosphate salt.

 Preferably, the resins used according to the invention are photopolymerizable. Preferably, they are crosslinkable under the action of ultraviolet radiation. This advantageously improves the mechanical strength of the coating. In order to further improve this mechanical resistance, drying by heat and / or by infrared radiation may possibly follow exposure to ultraviolet radiation.

 The coating of the invention may optionally include silane groups in order to improve its adhesion to the glass or the conductive layer. Preferably, a primer comprising silane groups is applied beforehand to the substrate to be coated.

 The coating can be applied by spraying, immersion, screen printing, pad printing or by a micro-feather or micro-roller or any other means.

 The coating method according to the invention may consist, for example, of carefully cleaning the surface to be coated, optionally applying an adhesion primer and then depositing the coating at the desired location. The coating is then left for a few minutes at room temperature or is advantageously subjected to infrared radiation. It is then subjected to ultraviolet radiation for a period of 3 to 5 min at a power of 300 to 600 Watts.

Optionally, an additional step may be provided, comprising, for example, cooking and / or exposure to infrared radiation.

The following description relates, in more detail, to the glazing according to the invention with reference to the figures in which
FIG. 1 represents a schematic longitudinal section of a glazing unit according to the invention,
FIG. 2 represents a schematic longitudinal section of a second variant of a glazing according to the invention,
FIG. 3 represents a schematic longitudinal section of a third variant of a glazing according to the invention,
FIG. 4 represents a schematic longitudinal section of a fourth variant of a glazing according to the invention,
FIG. 5 represents a schematic longitudinal section of a fifth variant of a glazing according to the invention,
FIG. 6 represents a schematic view of a heated glazing according to the invention,
FIG. 7 represents a cross section of the left part of the glazing represented in FIG. 6.

In the following description, the examples illustrate
iTexample 1: the corrosion resistance of the coating according to the invention,
Example 2: the dielectric properties of the coating according to the invention,
Example 3: the mechanical strength properties of the coating according to the invention,
Example 4: the optical properties of a glazing unit coated with the coating according to the invention.

 Figure 1 shows a longitudinal section of a glazing according to the invention. It may be a monolithic glazing, as shown, or a glass sheet used in the constitution of laminated glazing. The glass sheet 1 is partially covered with an enamel layer 2 on which is deposited a conductive layer 3. The layer 2 can also be another type of layer other than an enamel layer. Of course, the conductive layer can also be located directly on the glass sheet 1. The conductive layer is, for example, a layer based on silver paste. This conductive layer is covered with a coating 4 according to the invention.

In this figure, the face 5 of the glass sheet I constitutes the outer face, while the layer based on the coating 4 faces the passenger compartment.

 The thickness of the coating layer is uniform. It is, for example, between 5 and 50 μm.

According to this figure, the conductive layer is camouflaged both to people located outside, by the presence of the enameled layer 2, and to people located in the passenger compartment, by the presence of the coating 4. This the latter is then preferably opaque, for example black.

The coating can also be of another color, transparent or semi-transparent in order, for example, to modify the initial color of the conductive layer. In addition to its coloring functions, the coating can also have protective functions such as electrical insulation, resistance to corrosion, to oxidation, to ultra-violet radiation, depending on the applications envisaged.

 The coating can also be applied to at least part of the glass and of the enameled surface, as illustrated in FIG. 2. It can also coat the conductive layer and part of the glass or else the conductive layer and part of the layer. enameled. The part of the glass covered by the coating can be located in the viewing area of the glazing. In this case, the coating is preferably colorless and transparent. It does not harm the light transmission of the glazing. Of course, for reasons of understanding, Figure 2 does not respect the scales.

 FIG. 3 represents another variant of the invention according to which the conductive layer 3 is covered by an enameled layer 6. This enameled layer 6 includes plaster keys, not shown, in order to improve its surface appearance. The coating can also be applied in the form of a film in order to additionally impart additional properties to the enamel layer. This arrangement can be useful for repairing already existing glazing, for example.

 FIG. 4 represents another variant of the invention according to which at least part of the coating is applied to at least one face which does not support the conductive layer 3. The coating 4 then hides from view the presence of this layer conductive. It can also constitute a screen vis-à-vis ultraviolet radiation.

 Laminated glazing is shown in Figure 5.

 I1 consists of two sheets of glass 7 and 8 between which there is a plastic interlayer 9. A conductive layer 10 is for example embedded in the plastic 9. These are, for example, strips of copper foil 0.05 mm thick and 5 mm wide, covered with low-melting tin solder. The face 11 of the glass sheet 7 is turned towards the passenger compartment or the bodywork bay, while the face 12 of the glass sheet 8 is turned towards the outside. A plaster-based layer 13 is applied to the face 14 of the glass sheet 8 so as to hide the conductive strip 10 from view.

 The coating according to the invention then resists the conditions for joining the sheets 7, 8 and 9 by the combined action of temperature and pressure. These parameters can reach values as high as 1000C and 12 bars respectively.

 The layer 13 based on the coating according to the invention can also be deposited on the face 15 of the plastic sheet 9. It is then opaque in order to camouflage the conductive layer 10.

 FIG. 6 represents a heated glazing, in particular a heated rear window. In this figure, it is a monolithic glazing comprising a network of fine electrical resistance heating wires 16. Each heating wire 16 is electrically connected to two collecting strips 17 and 18. They are, for example, made of silver, deposited by screen printing.

 Once the glazing is mounted in the bodywork bay, the collecting strip 17 is isolated from attacks due to agents external to the vehicle by the presence of the seal, represented by the dotted line 19. This seal is usually glued to the bay of bodywork.

 The conductive strip 17 is located in the sealing zone delimited by the seal 19.

 The left part of the glazing represents another variant of the invention according to which the conductive strip 18 is not protected from attacks due to agents external to the vehicle, by the position of the seal represented by a dotted line 20. This seal is usually glued to the body bay.

 The heating wires 16 and / or the collecting strip 17 or 18 can be covered with a coating according to the invention. The entire so-called viewing area of the glazing 21 can also be covered with a coating according to the invention, as well as, possibly, the frame 22 of the glazing, which can be glazed.

 A cross section of the left part of Figure 6 is shown in Figure 7. Reference 23 represents the body bay. The coating 4 makes it possible to protect the collecting strip 18 from attacks due to external agents. It is, for example, an opening rag.

EXAMPLE 1
A series of glass plates is covered with an enameled layer on which a conductive layer is deposited. A coating is deposited on the conductive layer previously coated with a silane-based primer. The patches obtained conform to those described in Figure 1.

 The conductive layer has a thickness of about 15 μm and is made up of 70 to 75% by weight of silver, 4% by weight of glass frits, the rest being made up of an organic medium.

 The coating consists of an acrylic resin, a hardener based on polyurethane.

 The samples thus prepared are exposed to a saline solution containing 5% by weight of sodium chloride and at a temperature of 35 "C.

 The samples do not undergo any deterioration after an exposure of 400 hours under these conditions.

 This example illustrates the corrosion and oxidation resistance of the coating according to the invention.

EXAMPLE 2
The same series of plates as those described in Example 1 is used. Two metal lugs are placed, on the one hand, on the coating and, on the other hand, on the conductive layer. A direct current is passed through the conductive layer while varying the voltage.

 We observe a breakdown, that is to say the passage of current between the two terminals for a voltage of 2000 V.

 A second series of plates, identical to that described in Example 1, is tested with a view to measuring their electrical insulation resistance. The same assembly is used as that described above.

 The electrical insulation resistance measured is 5.10Lo Ohms at 500 V.

 This example illustrates the excellent dielectric properties of the coating according to the invention.

EXAMPLE 3
Two sets of plates are prepared.

 The series 1 comprises glass plates covered with an enameled layer, themselves covered with a conductive layer based on silver paste. The silver paste comprises, as in Example 1, from 70 to 75% by weight of silver and 4% by weight of glass frits, these solid particles being dispersed in an organic medium.

 Ea series 2 comprises, in addition to the enameled layer and the conductive layer, a coating. Series 2 is identical to the series described in Example 1.

 A plate from each series is successively interposed between a light source and a receiver capable of measuring the light transmission of the glazing.

 There is no difference in the light transmission between a plate of series l and a plate of series 2.

 This example illustrates the fact that the coating of the invention does not modify the light transmission of the glazing.

EXAMPLE 4
The abrasion resistance of two series of plates, identical to those described in Example 1, is tested.

 The first series is subjected to a test simulating the abrasion due to the mineral charges contained in a seal conventionally used for a car trunk, when the trunk is closed. A pressure simulating the closing of the trunk is applied to this rubber seal so that it is crushed. This seal is, moreover, in direct contact with the coating.

 No deterioration of the coating is observed after 30,000 cycles simulating 30,000 trunk closings.

 The second series is subjected to a test simulating abrasion due to the mineral charges contained in a seal conventionally used for a car trunk, abrasion due to vibrations when the engine is running.

 The seal is also applied against the plaster under pressure such that it is crushed.

 The joint is subjected to vibrations with a frequency of 24 Hz, the amplitude being 5 mm.

 No deterioration of the coating is observed.

 This example illustrates the excellent mechanical strength of the coating according to the invention.

Claims (10)

 1. Monolithic or laminated glazing consisting of at least one glass and / or plastic sheet comprising at least one conductive layer and an essentially organic coating based on a polymer or a copolymer deposited on at least part 'At least one of the faces of the sheet forming part of the glazing, the part of the face of the glass sheet covered by the coating is located in alignment with the conductive layer.  2. Monolithic or laminated glazing according to claim 1, characterized in that the polymer or copolymer constituting the coating is a resin chosen from the following resins: polyurethane, acrylic or cationic.  3. Monolithic or laminated glazing according to claim 2, characterized in that the cationic resin is chosen from the following resins: epoxy resin, vinyl resin, vinyl ether resin.  4. Monolithic or laminated glazing according to claim 2, characterized in that the resin is photopolymerizable.  5. Monolithic or laminated glazing according to claim 1, characterized in that at least part of the coating is deposited on at least part of the conductive layer.  6. Monolithic or laminated glazing according to claim 1 or claim 5, characterized in that at least part of the coating is deposited on at least part of an enameled layer.  7. Monolithic or laminated glazing according to claim 1, characterized in that the conductive layer is a layer capable of heating the glazing.  8. Monolithic or laminated glazing according to claim 1, characterized in that the coating is deposited on at least part of at least one face of a sheet entering into the constitution of the glazing, face not supporting the conductive layer.  9. Laminated glazing according to claim 7 consisting of at least two sheets of glass and a sheet of flexible plastic, characterized in that the coating is applied to at least part of at least one side of a sheet of glass or plastic and in that the conductive layer is embedded in the plastic.  10. Laminated glazing according to claim 9, characterized in that the plastic sheet is interposed between the two glass sheets and in that the coating is located at the interface formed by the face of the plastic sheet and of the face of the glass sheet, the face opposite to this interface is the outside face.