LAMINATED GLASS

Abstract

A laminated glass includes a first glass sheet, an electrically powered functional film, a reflective element to reflect infrared radiation, disposed between the first glass sheet and the functional film, at least one first thermoplastic interlayer disposed between the reflecting element and the functional film, and a second glass sheet. The laminated glass includes at least one interlayer including a zone that is opaque to radiation in the visible wavelength.

Claims

1. A laminated glazing comprising: a. a first glass sheet, b. an electrically powered functional film, c. means for reflecting infrared radiation positioned between the first glass sheet and the functional film, d. at least one first thermoplastic interlayer positioned between the means for reflecting infrared radiation and the functional film, e. a second glass sheet, wherein the at least interlayer comprises a zone that is opaque to visible wavelength radiation.

2. The laminated glazing as claimed in claim 1, wherein the opaque zone extends over the periphery of at least one of the first and second glass sheets.

3. The laminated glazing as claimed in claim 1, wherein the opaque zone extends over the periphery of the internal face of the first glass sheet.

4. The laminated glazing as claimed in claim 1, wherein the energy reflection is less than 60% and the reflection in the infrared region is greater than 70% and the light transmission is less than 5%, these values being measured in the opaque zone.

5. The laminated glazing as claimed in claim 1, wherein the functional film can be detrimentally affected at a high temperature of greater than 60° C.

6. The laminated glazing as claimed in claim 1, wherein the at least one first thermoplastic interlayer is positioned substantially on the surface of the glazing.

7. The laminated glazing as claimed in claim 1, wherein the at least one first interlayer is formed by an opaque zone, the light transmission of which is less than 5% of the incident light.

8. The laminated glazing as claimed in claim 1, wherein the at least one first interlayer is formed from an opaque frame positioned around a nonopaque zone.

9. The laminated glazing as claimed in claim 1, wherein the at least one first thermoplastic interlayer is a sheet of polyvinyl butyral or of ethylene/vinyl acetate.

10. The laminated glazing as claimed in claim 1, wherein the opaque zone is obtained by a bulk coloring of the periphery of the interlayer.

11. The laminated glazing as claimed in claim 1, wherein the functional film is a film having liquid crystals or a film having particles dispersed in suspension.

12. The laminated glazing as claimed in claim 1, wherein the means for reflecting infrared radiation consists of an assembly of thin silver-based layers.

13. The laminated glazing as claimed in claim 1, wherein the glazing is a glazed roof for a motor vehicle.

14. A method of using an interlayer film comprising a zone that is opaque to visible wavelength radiation, the method comprising: protecting from heat a functional film which can be detrimentally affected at high temperatures, said film being comprised between at least two glass sheets.

15. The method as claimed in claim 14, wherein the film is a glazing for a motor vehicle.

16. The method as claimed in claim 15, wherein the first glass sheet is the sheet directed toward the outside of the vehicle and the second glass sheet is the glass sheet directed toward the inside of the vehicle, the thermoplastic interlayer comprising an opaque zone extending over the entire periphery of said interlayer sheet then being placed on the side of the internal face of the glass sheet directed toward the outside and the functional film then being positioned between the at least one first interlayer and the second glass sheet.

Description

[0100] For a better understanding, the present invention will now be described in more detail as nonlimiting example, with reference to the following figures, in which:

[0101] FIG. 1 shows a schematic plan view of a known glazing 10 of the prior art comprising a PDLC film laminated between 2 glass sheets.

[0102] FIG. 2 shows a schematic plan view of a thermoplastic interlayer 20 comprising a zone 21 that is opaque to visible wavelength radiation, said opaque zone framing a nonopaque zone 22.

[0103] FIG. 3 shows a schematic plan view of a glazing 10 according to the invention comprising a PDLC film laminated between 2 glass sheets and a thermoplastic interlayer comprising a zone that is opaque to zones that are opaque to visible wavelength radiation.

[0104] FIG. 1 shows a known laminated glazing of the prior art, in the form of a glazed roof for a motor vehicle 10, comprising a functional film in the form of a polymer dispersed liquid crystal film 12 fitted inside the laminated structure. FIG. 1 does not show the curvatures of the sheets, for the sake of clarity. In practice, roofs, whether or not they are glazed, exhibit curvatures which are ordinarily more accentuated at the edges in the place where they join with the body for a fit chosen for its design, the aerodynamics and the flush appearance corresponding to a good surface continuity between the contiguous elements.

[0105] The functional film is a film of LC type consisting of a polymer containing the liquid crystals sensitive to the application of the electric voltage. The film is of PDLC (polymer dispersed liquid crystal) type. This laminated structure additionally comprises a sensor sensitive to the application of the electric voltage so as to activate the PDLC film (not shown), it being possible for such a sensor to be placed between the PDLC and the second glass sheet.

[0106] The polymer dispersed liquid crystal (PDLC) film 12 is represented as being positioned close to the edges of the glass sheets 11 and 16 of the glazing 10 but they might be positioned anywhere inside the glazing, for example at the center. However, in order to protect the PDLC film inside the laminated glazing, it is preferable for the edges of the film not to reach the edges of the glass sheets 11 and 16.

[0107] The PDLC film is “framed” by a PVB frame 17 (corresponding to the second thermoplastic interlayer described above) and is laminated between two thermoplastic interlayers 17 and 18 (respectively corresponding to the first and third thermoplastic interlayers); this assembly is itself laminated between an external glass sheet 11 and an external glass sheet 16. The thermoplastic interlayer 18 is added so as to ensure sufficient adhesion between the PDLC film 12 and the exterior window glass sheet 16. It is known to use a design in which a “frame” frames the functional film, itself laminated between two thermoplastic interlayers, in order to laminate a functional film within a glazing. According to a specific embodiment of the invention and as illustrated by FIGS. 1 and 3, the thermoplastic interlayers 17 and 18 are made of PVB but, of course, they can be in any other material capable of making possible the lamination of the functional film between two glass sheets. The thermoplastic interlayers 17 and 18 are coextensive with the glass sheets 11 and 16. The PDLC film exhibits a thickness of 0.38 mm.

[0108] Around the periphery of the glazed roof for a motor vehicle 10 is positioned, on faces 2 and 4, an occultation strip 101 and 102, more specifically an enamel layer, the role of which is, on one hand, to conceal and protect the tightness material (not represented) which is used to attach the window in a vehicle (not represented) and, on the other hand, to conceal the electrical connections (busbars, and the like) which provide electrical energy to the polymer dispersed liquid crystal film 12. The layer reflecting infrared radiation 13 of silver metal layer type makes it possible to reflect the infrared radiation 104 originating from the PDLC film. According to a specific embodiment of the invention, the means for reflecting infrared radiation 13 can consist of multiple alternating layers of silver and of indium oxide. Alternatively, the film reflecting infrared radiation 13 can be a nonmetallic film, composed of several layers. However, due to the presence of the enamel layer 101 at the periphery of the glass sheet on face 2, the infrared radiation originating from the outside of the glazing, for example originating from the lamination process or also from solar radiation, is absorbed by the external glass sheet 11. The heat is then conducted 106 through the external glass sheet 12, the first thermoplastic interlayer 16 and the thermoplastic interlayer frame 17 to be finally captured by the PDLC film, then resulting in its deterioration. The temperature of the PDLC can then reach a temperature of greater than 100° C., a high temperature which in the long run damages the PDLC film. If the laminated glazing is subjected to prolonged exposure to heat, the zone located at the edge of the functional film (PDLC, SPD, and the like) can be damaged and result in a detrimental change in the switching function, for example. In addition, other thermoplastic interlayers may be placed between the PDLC film and the second glass sheet 16 so as to ensure the assembling of the laminate.

[0109] The glass sheets 11 and 16 as illustrated in FIGS. 1 and 3 are glasses of soda-lime-silica type. One or both glass sheets can be sheets of clear glass of soda-lime-silica type with the following composition (by weight): SiO.sub.2 68-75%; Al.sub.2O.sub.3 at 0-5%; Na.sub.2O 10-18%; K.sub.2O at 0-5%; MgO 0-10%; CaO 5 to 15%; SO.sub.3 0-2%. The glass can also contain other additives, such as, for example, refining adjuvants, in an amount ranging up to 2%.

[0110] According to a specific embodiment of the invention, one or both glass sheets 11, 16 can be sheets of strongly absorbing colored glass, so that the light transmission is limited by the effect alone of these two glass sheets, for example to less than 50%, and in a configuration of this type preferably to less than 30%.

[0111] Glasses used for these sheets are, for example, gray glasses, such as described in the patent FR 2 738 238 or in the patent EP 1 680 371, or green-hued gray glasses, such as described in EP 887 320, or blue-hued gray glasses, as in EP 1 140 718.

[0112] In one example, the glass sheets 11 and 16 are respectively 1.6 mm and 2.6 mm in thickness. According to a specific embodiment of the invention, the internal glass sheet of the laminated glazing can be made of glass colored throughout, the composition of which can comprise one or more of the following colorants: iron oxide, cobalt oxide, selenium, chromium oxide, titanium oxide, manganese oxide, copper oxide, vanadium oxide or nickel oxide. It is understood that the two glass sheets can be made of clear glass. One or the glass sheets can be made of tempered glass. The glass sheets can be flat or curved. Each glass sheet can have a thickness of between 0.5 and 25 mm in thickness, preferably between 1 and 5 mm. The total thickness of the motor vehicle glazing can thus be between 1.5 and 100 mm, preferably between 2 and 50 mm and more preferably between 2.5 and 20 mm. Preferably, the glazing has a transmission of visible light (measured with the CIE illuminant A) of greater than 70% and more preferably of greater than 75% when the two glass sheets and the layers of thermoplastic interlayer film are substantially clear. If the glazing overall exhibits a color (because either the internal glass sheet of the glazing is colored throughout or one or more folds of the intermediate layer material is colored), it preferably has a visible light transmission (measured by the CIE Illuminant A) of less than 40%, more preferably of less than 30% and preferably of less than 25%, and a total energy transmission (Parry Moon, Air Mass 1.5) of less than 30%, more preferably of less than 25% and preferably of less than 20%.

[0113] FIG. 2 shows the at least first thermoplastic film according to a specific embodiment of the invention. The thermoplastic interlayer 20 comprising an opaque zone 21 is found at the periphery of the thermoplastic interlayer 20. The interlayer film 20 is slightly greater in size than the glass sheets 11 and 16, so that it extends over the entire surface of the glass sheets. The opaque zone 21 according to this specific embodiment takes the form of a frame produced from a colored thermoplastic interlayer, the light transmission of which is 0%. In particular, the frame is produced from a black PVB surrounding the nonopaque zone 22 which it consists of a transparent PVB which screens out UV radiation, allowing only a very small proportion of the latter to pass. For PVB films with a thickness of 0.38 mm, more than 95% of the UV radiation is suppressed. This proportion can exceed 99%. Polymers based on ethylene/vinyl acetate (EVA) are also proposed which include components conferring on them a very low transmission of UV radiation. It is understood that any thermoplastic interlayer exhibiting these characteristics, namely a transmission of less than 5% and preferably equal to 0%, can be used to form this opaque zone. The dimensions of the opaque zone are generally equivalent to those normally used for the occultation strip. These dimensions will depend in particular on the zone to be concealed. Thus, the at least first thermoplastic interlayer as represented by FIG. 2 is formed of a frame of PVB colored throughout positioned on the circumference/periphery of a transparent PVB, so as to form the thermoplastic interlayer according to the invention. It is understood that this frame can be formed by different strips positioned so as to form said frame, these strips fusing during the stoving so as to form a single piece. However, it can be made up and applied using any other known means. The interlayer is subsequently provided on at least the face 2-1la—of the external glass sheet. It can, of course, also be provided on the face 4. FIG. 3 shows a glazing according to the invention, in the form of a glazed roof for a motor vehicle 10, comprising a functional film in the form of a polymer dispersed liquid crystal film 12 fitted inside the laminated structure. The description of the glazing represented by FIG. 1 applies generally to that represented by FIG. 3, except for the fact that, in FIG. 3, a thermoplastic interlayer comprising a zone that is opaque to visible wavelength radiation is provided on the face 2-11a—of the glass sheet 11 (that is to say on the internal surface of the exterior window 11) between the means for reflecting infrared radiation and the PDLC film.

[0114] The polymer dispersed liquid crystal (PDLC) film 12 is represented as being positioned close to the edges of the glass sheets 11 et 16 of the glazing 10. The PDLC film does not cover the whole of the glazing, in order for the edges of the LC film not to come into contact with the exterior atmosphere, in particular in order to protect the crystals from moisture. In order to prevent any contact with the atmosphere, the PDLC film 12 is entirely enveloped in the different thermoplastic interlayers. The PDLC film is enveloped at its periphery by a PVB film 17 having a thickness similar to that of the PDLC film which exhibits an appropriate cutout in which the PDLC film will be housed (corresponding to the second thermoplastic interlayer described above) and is laminated between a first thermoplastic interlayer 20 and a third thermoplastic interlayer 18. In addition, other thermoplastic interlayers may be placed between the PDLC film and the second glass sheet 16 so as to ensure the assembling of the laminate. In one exemplary embodiment, the interlayers are PVBs, each with a thickness of 0.38 mm. The first thermoplastic interlayer 20 is positioned between the means for reflecting infrared radiation 13, itself deposited on the face 2-11a—of the external glass sheet 11, and the PDLC film 12. The thermoplastic interlayer 20 as represented by FIG. 2 comprises a zone 21 that is opaque to visible wavelength radiation and a nonopaque zone 22. In this example, the nonopaque zone 22 is formed of a transparent

[0115] PVB film of 0.76 mm which screens out UV radiation. The zone 21 that is opaque to visible wavelength radiation for its part is formed by a “frame” of PVB film black in color (PVB colored throughout) which surrounds the nonopaque zone. Thus, the thermoplastic interlayer 20 is formed by a PVB frame black in color surrounding the nonopaque zone of transparent conventional PVB, so as to form an integrated PVB sheet which extends over the entire surface of the external glass sheet 11. The dimensions of the opaque zone are generally equivalent to those normally used for the occultation strip. These dimensions will depend in particular on the zone to be concealed.

[0116] In contrast to FIG. 1, the face 2-11a—of the external glass sheet is devoid of an enamel layer.

[0117] As indicated above, the components of the PDLC films may be sensitive to aging. In order to confer the desired aging on them, the film is normally protected by a means reflecting infrared radiation originating in particular from solar radiation. Such a means is positioned between the glass sheet 11 and the PDLC film 12. In this embodiment, the means reflecting infrared radiation acts well by reflecting, outside the glazing, the infrared radiation (104), thus protecting the PDLC from internal heating.

[0118] The infrared radiation originating from outside the glazing, for example originating from the lamination process or also from solar radiation, is then very slightly or not absorbed 105 by the opaque zone 21 of the first thermoplastic interlayer 20, thus preventing the PDLC film from being subjected to high temperatures. The heat conducted 106 by the glass sheet, then the opaque zone 21 of the thermoplastic interlayer 20 and then finally the thermoplastic film 17, in order to be captured by the PDLC film, is greatly reduced in comparison with the glazing of the prior art, as shown in FIG. 1. In addition, as shown in FIG. 3, an enamel layer may be present on the face 4 of the glazing, so as to conceal the connections, such as busbars and the connectors which provide electrical energy to the polymer dispersed liquid crystal film 11, or also the glue making it possible to glue these elements, and the like.

[0119] The means for reflecting infrared radiation 13 is identical to that represented in FIG. 2, namely a silver metal layer. According to a specific embodiment of the invention, the film reflecting infrared radiation 13 can consist of multiple alternating layers of silver and of indium oxide. Alternatively, the film reflecting infrared radiation 13 can be a nonmetallic film, composed of several layers.

[0120] The opto-energetic values, seen from the outside of the vehicle, in the opaque zone (black PVB) of the laminated glazing according to the invention, were measured. Thus, the energy reflection (ER) measured was 48.8%, the reflection in infrared radiation (RIR) was 89% and the light transmission (LT) was 0%.

[0121] These properties make it possible to guarantee good attractiveness of the exterior of the vehicle (hides connections, and the like) and, at the same time, to prevent overheating of the roof due to the solar radiation in this zone.

[0122] By way of example, a glazing according to the invention exhibits the following structure, from the outside toward the inside: [0123] clear (indeed even extra-clear) glass sheet with a thickness of 2.1 mm [0124] a silver layer as means reflecting infrared radiation [0125] clear PVB sheet which screens out UV radiation with a thickness of 0.76 mm, surrounded by a PVB frame of black coloring which is opaque to visible wavelengths [0126] gray PVB sheet of 0.38 mm [0127] PDLC film (with the means making it possible to power it electrically) [0128] a minimum of two thermoplastic interlayers including in particular the means for activation of the PDLC film [0129] clear glass sheet of 3.15 mm, coated with a system of low-e layers composed, as indicated above, of a silica layer covered with a doped tin oxide layer [0130] an enamel occultation strip.

[0131] The PDLC film is powered by AC current of 50 Hz and under a potential difference which rises to 110 V.

[0132] A laminated glazing according to the invention can be fitted into any window of a vehicle.

[0133] It can particularly and preferably be used as a motor vehicle glazed roof.

[0134] Furthermore, a laminated glazing according to the invention can be provided with an additional functionality, by inclusion of appropriate elements, such as a hydrophilic or hydrophobic coating on face 1 or face 4. For example, laminated glazings, as used as windshield or rear window of a motor vehicle, comprise numerous functionalities, such as: layer reflecting solar radiation, thus making it possible to lower the temperature of the dashboard and the ambient temperature in the passenger compartment, the interior rear-view mirror support, busbars making it possible to convey an electric current, a network of heating wires, an upper strip screening out solar radiation, having a possibly shaded coloring, a rain detector, and the like.