ENAMELED GLAZING

Abstract

The present invention concerns a method to produce a bent and/or tempered glazing offering improved thermal comfort, comprising the following steps (a) Providing a glass sheet having an outer-side surface and an interior-side surface, (b) Applying a thermal radiation reflective coating over at least a layer of the surface of the interior-side surface of the glass sheet, (c) Applying a black ceramic layer on at least a portion of at least the interior-side surface of the glass sheet, the black ceramic layer covering at least partially the thermal radiation reflective coating and/or running alongside the area covered by the thermal radiation reflective coating, (d) Hot bending and/or tempering the glass sheet. According to the present invention, the black ceramic layer has a pattern that mitigates the contrast in emissivity during the step d. between the area where the thermal radiation reflective coating is not covered by the black layer and the area where the black ceramic layer covers at least partially the thermal radiation reflective coating and/or the black ceramic layer runs alongside the area covered by the thermal radiation reflective coating.

Claims

1. A method to produce a bent and/or tempered glazing offering improved thermal comfort, comprising: a. providing a glass sheet having an outer-side surface and an interior-side surface; b. applying a thermal radiation reflective coating over at least a layer of the surface of the interior-side surface of the glass sheet, c. applying a black ceramic layer on at least a portion of at least the interior-side surface of the glass sheet, the black ceramic layer covering at least partially the thermal radiation reflective coating and/or running alongside the area covered by the thermal radiation reflective coating; and d. hot bending and/or tempering the glass sheet, wherein the black ceramic layer has a pattern that mitigates the contrast in emissivity during d. between an area where the thermal radiation reflective coating is not covered by the black layer, and wherein the area where the black ceramic layer covers at least partially the thermal radiation reflective coating and/or the black ceramic layer runs alongside the area covered by the thermal radiation reflective coating.

2. A method to produce a laminated glazed roof offering improved thermal comfort, comprising: a. providing an outer glass sheet having an outer-side surface and an interior-side surface; b. providing an inner glass sheet having an outer-side surface and an interior-side surface, c. applying a thermal radiation reflective coating over at least a layer of the surface of the interior-side surface of the inner glass sheet; d. applying a black ceramic layer along at least a layer of the perimeter of at least the interior-side surface of the inner glass sheet, the black ceramic layer covering at least partially the thermal radiation reflective coating; e. hot bending the outer and the inner glass sheet separately or together, the said inner glass sheet having a black ceramic layer along its perimeter and a low-E coated over at least a layer of the surface of the interior-side surface; and f. laminating the outer and the inner glass sheets with a thermoplastic intermediate layer that joins the interior-side surface of the outer glass sheet to the outer-side surface of the inner glass sheet, wherein the black ceramic layer has a pattern that mitigates the contrast in emissivity during d. between an area where the thermal radiation reflective coating is not covered by the black layer, and wherein the area where the black ceramic layer covers at least partially the thermal radiation reflective coating and/or the black ceramic layer runs alongside an area covered by the thermal radiation reflective coating.

3. The method according to claim 2, wherein the glazing is a vehicle laminated glazed roof.

4. The method according to claim 1, wherein the black ceramic layer has a pattern of alternating zones provided with and free of black ceramic layer.

5. A method to produce a bent and/or tempered glazing offering improved thermal comfort, comprising: a. providing a glass sheet having an outer-side surface and an interior-side surface; b. applying a thermal radiation reflective coating over the surface of the interior-side surface of the glass sheet, c. applying a de-coating technique to locally remove the thermal radiation reflective coating and locally applying a black ceramic layer or locally applying the black ceramic layer over the thermal radiation reflective coating; and d. hot bending and/or tempering the glass sheet, wherein the decoating pattern mitigates a thermal radiation reflective effect of the coating in areas where more heat uptake is needed to facilitate shaping of the glazing.

6. The method to produce a bent and/or tempered glazing roof according to claim 5, wherein the decoating has a pattern of alternating zones provided with and free of thermal radiation reflective coating.

7. The method to produce a vehicle laminated glazed roof according to claim 3, wherein the thermal radiation reflective coating is a low-e coating.

8. A laminated and glazed vehicle roof offering improved thermal comfort produced according to claim 1.

9. The vehicle laminated glazed roof of claim 3, further comprising a low-emissivity coating system wherein the low-emissivity coating system has an emissivity that is no higher than 0.5.

10. The vehicle laminated glazed roof of claim 9, wherein the low-emissivity coating system comprises at least one layer of a transparent conductive oxide or a layer of low-emissive nitride or a layer of a metallic compound.

11. The vehicle laminated glazed roof of claim 3, further comprising a low-emissivity coating system wherein the low-emissivity coating system has an emissivity that is no higher than 0.3.

12. The vehicle laminated glazed roof of claim 3, further comprising a low-emissivity coating system wherein the low-emissivity coating system has an emissivity that is no higher than 0.2.

Description

DRAWINGS

[0066] In the following, the invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings do not restrict the invention.

[0067] FIG. 1 shows a laminated glazed roof according to prior art;

[0068] FIG. 2 shows a glazing unit according to one embodiment of the present invention;

[0069] FIGS. 3a to 3c show examples of pattern of the black ceramic band;

[0070] FIG. 4 shows a glazing unit according to one embodiment of the present invention;

[0071] FIG. 5 shows a glazing unit according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0072] Even if the following description is oriented to a vehicle laminated glazed roof, the present invention may be applicable to a vehicle single glazing or a glazing for building.

[0073] The assembly of elements in FIG. 1 is a laminated glazed roof according to prior art. More particularly the FIG. 1 is a top view of a laminated glazed roof. The face visible on the drawing is the inner-side of the glazing toward the passenger compartment.

[0074] The sheets shown in FIG. 1 are not curved, for the sake of clarity. In practice roofs, whether glazed or not, have curvatures that are ordinarily more accentuated at their edges in the place where they join with the body of the car for a fit, chosen for its design, aerodynamics and its flush appearance, corresponding to a good surface continuity between the contiguous elements.

[0075] The glazing unit 100 in FIG. 1 comprises two glass sheets, an external glass sheet 1 and an internal glass sheet 2. Most frequently, these two glass sheets are made of highly absorbent colored glass, such that the light transmission is limited only by the effect of these two glass sheets, for example to less than 50%, and in a configuration of this type preferably to less than 30%.

[0076] The glasses used for these sheets are for example gray glasses or the green-tinted gray glasses. In one example, the glass sheets 1 and 2 have respectively a thickness between 1.6 mm and 2.6 mm

[0077] In FIG. 1, the glass sheets are shown with the enamel patterns 3 (as a black ceramic band) that are conventionally used to mask the edges of glazing units. As shown in FIG. 1, a large layer is provided in the area 4, the area 4 being the area close to the windshield once installed with the car body. Enamels of this type could for example be placed on the internal face of sheet 1, therefore in position 2, concealing all of the adhesive joints and localized connections at the edge of the glazing unit. The masking enamels may also be located in position 4, in other words on that face of the glazing unit which is exposed to the interior of the passenger compartment. However, in this position, for an observation from the exterior of the vehicle, they do not mask elements contained in the laminate. It is also possible to place the masks in position 2 and in position 4 as illustrated in FIG. 1.

[0078] A system 10 of low-E layers, as a thermal radiation reflective coating, is applied over the surface of the internal glass sheet 2 on the face turned toward the passenger compartment before applying the enamel pattern according to prior art. Then, the glass sheet is hot bent according to the requirement of the car manufacturer to fit with the design of the car body. The bending process occurred at a temperature comprised between 500? C. and 700? C. In case of a laminated glazed roof, the inner and the outer glass sheet may be bent separately or together according to well-known technologies. Unfortunately, due to the difference of thermal behavior of the coating and the black ceramic band, a reverse curvature is created during the heating up of the glass sheet, leading to a tub shape or U-shape that is an unacceptable non-smooth shape by the car manufacturers. The same non-homogeneous heating up of the glass sheet is creating critical issue during flat glass conveying in sheet by sheet process, as glass may no more remain flat on the rollers and could achieve wrong positioning in the pressing area or be marked on the contact surface with many defects. Car manufacturers require progressive/smooth shape instead of the U shape for aesthetical reason and/or functional reason such as the wipe ability. Thus, the glazing of the prior art provided with a low-E coating, and more generally with a thermal radiation reflective coating, are not easily bendable.

[0079] The manner to apply the thermal radiation reflective coating and the black ceramic layer on the internal glass sheet 2 on the face turned toward the passenger compartment are well known and are not described in details. Generally, the thermal radiation reflective coating and more particularly the low-E coating is first provided over all or partially on the surface of the internal glass sheet 2 on the face turned toward the passenger compartment and then the black ceramic layer is applied along the periphery of the glass sheet with or without full (or partial) overlapping on the coating. The black layer is larger in the area 4 close to the windshield and wherein inner some items such as upholsteries or rear mirror, cameras may be fixed on, in the face of the roof toward the car's compartment.

[0080] This low-E coating system 10 of is not shown in FIG. 1 for sake of clarity but is in fact not dissociable from the sheet under which it is deposited.

[0081] Once the inner and the outer glass sheets (in case of laminated roof) are bent, they are joined together thanks to at least one thermoplastic interlayer sheet (not shown).

[0082] FIG. 2 shows one embodiment according to the present invention. As for FIG. 1, a laminated glazed roof 100 is represented. An outer 1 and an inner 2 glass sheets are joined together thanks to at least one thermoplastic interlayer layer sheet (not shown). Before laminating the outer 1 and the inner 2 glass sheets together, a low-E coating system 10, as a thermal radiation reflective coating 10, is applied over of the inner glass sheet 2 on the face turned (position 4) toward the passenger compartment.

[0083] The black ceramic layer 3 is applied along the periphery of the inner glass sheet 2 on the face turned (position 4) toward the passenger compartment. The black ceramic layer 3 is provided with a larger enamel pattern 4 in the upper layer of the glazing that will be in contact with the car body close to the windshield. An enamel pattern 6 that mitigates the contrast in emissivity during the step of heating up of the bending and/or tempering process between the area where the thermal radiation reflective coating is provided in a central area 5 of the larger enamel pattern 4. The pattern 6 according to the embodiment described in FIG. 2 has successive rectangular shapes with sizes decreasing progressively from the upper layer of the glass sheet to the layer toward the center of the glazed roof. Thus, an area of the low-E coating 10 is not covered (or partially covered) by the black ceramic band. it is understood that the pattern of the black ceramic layer 6 according to the present invention is designed to mitigates the contrast in emissivity during the step of heating up of the bending and/or tempering process between the area where the thermal radiation reflective coating.

[0084] According to the present invention, the black ceramic layer 3 has a pattern 6 that mitigates the contrast in temperature increase during the heating up step between the area of the glass covered by black ceramic layer and the area of the glass coated with thermal radiation reflective coating and that generates a smooth temperature profile across the area where the black ceramic layer covers at least partially the thermal radiation reflective coating (more particularly a low-E coating) and the area where the thermal radiation reflective coating is not covered by the black band.

[0085] According to the present invention, the pattern 6 is designed in the area wherein the black ceramic layer is applied and wherein there is a need to, have a smooth temperature profile to have a final good shape after the bending according to car's manufacturer requirement, or to keep a flat shape behavior during the conveying operation inside the heating tunnel for sheet by sheet process technology.

[0086] Thus, the pattern in the black ceramic layer 6 may be provided in the large area 4 close to the windshield and wherein inner some items such as interior trim or rear mirror, cameras may be fixed on, in the face of the roof toward the car's compartment. The design may be only provided in the central area of the black band. The position and the design of the pattern will depend on the zone wherein an U-shape and/or a reverse curvature has to be controlled or corrected to correctly bend the glass sheet to obtain the requested shape of the glass sheet and finally the good shape of the roof or homogeneous heating up during the conveying in sheet by sheet process

[0087] According to the embodiment shown in the FIG. 2, the black ceramic layer 4 (also called enamel band) is provided in the central area 5 with a pattern 6 alternating enameled zone and zones free of enamel. The pattern according to the embodiment of the present invention is a zebra pattern. The width of bands with enamel or free of enamel is determined depending on the requested shape of the glass sheet and the difference of thermal behavior of the enamel and the low-E coating and more generally the thermal radiation reflective coating 10.

[0088] As shown in FIG. 3a to 3c, different patterns may be applied to the black ceramic layer 6 such as zebra pattern as shown in FIG. 3a, checkerboard as shown in FIG. 3b, or dots pattern as shown in FIG. 3c. The zebra length can be along the full width of the glass layer. The width of the line as well as The space between lines may go from few millimeters to several centimeters and is driven by the layer design as well as the issue faced during the heating up operation (bending or conveying). The chase layer or the dots pattern can also have many different designs according to the achievement to be reached on the glass (size can move from several millimeters to several centimeters). The geometry can also be really different according the case we will be faced and be not only lines or squares or dots but possibly ellipsoid, parallelepipedal, . . . .

[0089] The size of the design of black enamel 6 as well as its position inside the black layer 3 have to be tuned according to the geometrical defect to deal with or to compensate.

[0090] Further to the black ceramic part 3, some part of black ceramic part 11 may be provided on the inner-side of the inner glass to allow gluing or masking some fixing parts.

[0091] According to another embodiment of the present invention, the pattern 6 of in the black layer 3 may be a single enamel-free zone, for example along each lateral edge 8 of the layer, as depicted in FIG. 4.

[0092] Some glazing configurations might not require to print any kind of enamel or high emissive material on top of the thermal radiation reflective coating and more particularly the low-E coating. In those cases, the whole surface of the coated glass is reflecting the thermal radiation of the furnace and there might be a need for bringing more heat locally than what the furnace equipment may allow.

[0093] One solution according to the present invention is to remove the thermal radiation reflective coating and more particularly the low-E coating locally in areas where additional heat is needed and fill the areas with a black enamel. In this way, the un-coated or de-coated areas would have high emissivity and would allow more efficient heat uptake from all radiative sources in the furnace.

[0094] This coating removal could also be done with a pattern adapted to both aspects of aesthetical design and heat up-take efficiency of the treated area by mitigating the thermal radiation reflective effect of the coating in areas where more heat uptake is needed to facilitate the shaping of the glazing. The decoating pattern may have alternating zones provided with and free of thermal radiation reflective coating such as a zebra pattern as depicted in fig z but many other types of patterns can be usefully applied, like dot patterns, for example.

[0095] Localized coating removal can be obtained by masking or patterning the glass prior to the coating process or coating ablation after coating process by mechanical, chemical or laser treatment, for examples.

[0096] Another embodiment of the present invention is shown in FIG. 6. a black enamel 3 with a pattern 6 according to the present invention may be provided for example by printing black enamel on top of the thermal radiation reflective coating 10 and more particularly the low-E coating only in the area where the emissivity should be controlled to allow more efficient heat uptake from all radiative sources in the furnace.

[0097] In the case of a laminated glazed roof, the enamel pattern 6 according to the present invention as well as the thermal radiation reflective coating 10 are provided in the inner-side face (position 4) of the inner glass sheet 2.

[0098] It is understood than in case of a single glass sheet the enamel pattern 6 and the thermal radiation reflective coating 10 are provided on the inner-side face (position 2) of the glass sheet.

[0099] The glass sheet provided over a major layer of its surface with the thermal radiation reflective coating and more particularly the low-E coating and with at least a layer of the periphery of the glass sheet provided with a black ceramic layer and overlapping a layer of the coating is provided with a pattern according to the present invention, is then hot bent at a temperature comprised between 50? and 700? C. to shape the glass sheet as requested by the car's manufacturer.

[0100] The U-shape or reverse bending of the zone covered by the black layer alongside the zone coated with the thermal radiation reflective coating, the black layer optionally overlapping the low-E coated layer of the glass, may be avoided during the bending process or during the glass conveying (sheet by sheet case) when the glass sheet is submitted to temperatures comprised between 500? C. and 700? C.

[0101] According to the present invention, in case of a laminated glazing, the glass sheet provided with the thermal radiation reflective coating and more particularly the low-E coating and the black ceramic layer provided with a pattern to compensate during the bending step the emissivity of the thermal radiation reflective coating and/or the heat absorption of the black ceramic layer and to have a smooth temperature profile in the area where the black ceramic layer covers at least partially the thermal radiation reflective coating (more particularly a low-E), is the inner glass sheet, the coating and the black ceramic layer being provided on its inner face (position 4).

[0102] Masking enamel is located in position 4, in other words on that face of the glazing unit which is exposed to the interior of the passenger compartment. However, in this position, for an observation from the exterior of the vehicle, they do not mask elements contained in the laminate. It is also possible to place the masks in position 2 and in position 4. The masking patterned enamel according to the present invention is preferably only provided on position 4. Thus, the masking enamel in position 4 is masked from outside by the enamel in position 2. The enamel provided on position 4 is then masked/covered by the upholsteries.

[0103] In case of a laminated glazing, the outer glass sheet and more particularly the inner face (position 2) of the outer glass sheet is provided along its periphery with a black ceramic layer to protect components to be fixed on the glazing from UV and/or for aesthetical reasons.

[0104] The inner and the outer glass sheets may be bent separately or together according to well-known technologies. After bending, the inner and the outer glass sheets are joined together thanks to at least one thermoplastic interlayer according to well-known technologies.

[0105] According to one embodiment of the present invention, the glazing and in particular the glazed roof is made of one a single tempered glass sheet. In that case, the black ceramic layer and the thermal radiation reflective coating and more particularly the low-E coating are provided on the inner face ie the face exposed to the interior of the passenger compartment. Such as glass sheet is typically used for sliding roofs.

[0106] According to another embodiment of the present invention and as shown in FIG. 5, the black layer may be provided in a central zone of the glazing and over the low-E coating. The glazing is preferably a laminated glazed roof. The black layer may be provided with zone free of enamel. The free zones of enamel may have a rectangular or any shape suitable to mitigate the contrast in emissivity between the area where the thermal radiation reflective coating is not covered by the black layer during the step of bending or tempering.

[0107] One example low-E system having the desired properties consists of a 320 nm-thick layer of tin oxide doped with 2 at % fluorine. This layer is deposited on a layer making contact with the glass, said layer being 75 nm-thick and composed of silicon oxycarbide. The two layers are deposited by CVD. This system leads to an emissivity of about 0.16.

[0108] Other low-E coating systems may be produced using a cathode sputtering technique while preserving a satisfactory mechanical resistance. Systems of this type are for example. Comprising transparent conductive oxides, especially doped Indium, Zinc or Tin oxides or comprising low-emissivity nitrides like Ti nitride.

[0109] By way of yet another example, a usable system comprises a metal layer of Chromium, Niobium, Tantalum, Molybdenum or Zirconium and mixtures thereof. To protect this metal layer deposited by cathode sputtering, it could be sandwiched between two layers of silicon nitride. This assembly also leads to a satisfactory emissivity with a decrease in the light transmission that may reach 10%, decrease that for the use in question does not constitute a drawback.

[0110] The use of these low-E systems considerably improves how comfortable the passenger compartment feels during cold periods and may make the use of a screen superfluous.