CA3030379C - Laminated glazing with very thin internal glass sheet in a retracted position - Google Patents

Abstract

The laminated glazing comprises two sheets of glass (1,3) and one polymer interlayer (2) arranged between them. The first sheet of glass (1) is thicker than the second sheet of glass (3), the thickness of which is less than 1.2 mm. The rim (3a) of the second sheet of glass (3) is in a retracted position (DI) relative to the rim (1a) of the first sheet of glass (1) over all or part of the periphery of the glazing (10), which helps protect the second more fragile sheet of glass (3) from mechanical impacts against the edge of the glazing.

Description

5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 PCT/EP2017/067573 1 LAMINATED GLAZING WITH A VERY THIN INNER GLASS IN A RECESSED LAYER The present invention relates to the field of laminated glazing, particularly for automotive applications. Laminated glazing is commonly used in the automotive, aerospace, and building sectors. It generally consists of an outer glass sheet and an inner glass sheet with a thermoplastic interlayer—for example, polyvinyl butyral (PVB)—between them to ensure adhesion. In the automotive industry, laminated glass has long been used as "safety" glass for windshields due to its ability to hold the glass fragments together if the glass sheets break following a mechanical impact on the windshield surface. Today, it is also used for side windows, roof windows, and rear windows of motor vehicles for reasons of acoustic comfort and safety. The outer glass sheet is generally thicker than the inner glass sheet to provide adequate resistance to stone chips and potential mechanical impacts on its surface. The current trend is to use increasingly thinner inner glass sheets in order to reduce the overall weight of the glazing. While outer glass sheets are generally 1.4 mm to 2.1 mm thick, very thin inner glass sheets are preferred, with a thickness of 1.2 mm or less, or even 1 mm or less, or even 0.7 mm or less. These very thin inner glass sheets are inherently very fragile and extremely sensitive to mechanical shocks. Therefore, they are handled with care during the manufacturing stages of laminated glass. Once the laminated glass is produced, they are protected from mechanical shocks applied to their surface due to their bonding with the thermoplastic interlayer and the outer glass sheet. Furthermore, the mechanical strength of the inner glass sheets can be improved by chemical tempering. Within the scope of the present invention, the applicant has identified a particular, previously unknown problem concerning these laminated glass panes with very thin inner glass sheets. Indeed, it appears that these very thin glass sheets are particularly fragile with regard to mechanical shocks or other mechanical stresses applied to their edges. Furthermore, while chemical tempering significantly improves resistance to mechanical shocks applied against the main surface of the glass sheet, this is not the case for mechanical shocks applied against its edges. Therefore, a knife-cutting operation—manual or robotic—of the excess thermoplastic film protruding around the edge of the glazing after the glass and thermoplastic sheets have been assembled is difficult, if not impossible, because it carries a risk of the knife striking the edge of the inner glass sheet. It is possible to use pre-cut thermoplastic films of the appropriate dimensions to avoid such a cutting operation, but this has the drawback of requiring precise pre-cutting and positioning during assembly with the glass sheets. Furthermore, another difficulty concerns glazing with an exposed edge after installation on the vehicle, which has an opaque band along the edge of the glass. This is usually the case for windshields and automotive glazing other than sliding side windows in the doors. This opaque band generally serves to conceal the vehicle's bodywork beneath the edge of the glazing and to protect the adhesive sealant used to attach the glazing to the body from ultraviolet radiation. In such cases, it is preferable to use a technique for eliminating edge gloss other than texturing the edge of the thermoplastic film by abrading the excess film after the glazing has been autoclaved. The edge gloss effect results from the reflection of incident sunlight off the mirrored surface of the thermoplastic film's edge, which then propagates through the screen-printed area at the edge of the glazing used to create the aforementioned opaque band. The edge gloss phenomenon is clearly illustrated in Figure 2, which shows a local cross-section through the edge of laminated glass: the outer glass pane is labeled 1, the inner glass pane 3, the thermoplastic film 2, and the opaque strip 4. Also shown is an incident light ray I, which produces a reflected light ray R contributing to the edge gloss effect. The fact that the edge of the PVB or similar thermoplastic film is reflective is due to the fact that in the autoclave, the thermoplastic material softens and the edge tends to self-smooth, or to the fact that it was cut with a knife after being in the autoclave. In practice, for aesthetic reasons, it is desirable to avoid the edge gloss effect manifesting as one or more shiny segments along the edge of the glass that are visible to an observer. This case is illustrated in Figure 1, showing a front view of laminated glass: the shiny segments are symbolized by thicker lines and referenced S.5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 PCT/EP2017/067573 3. The generally preferred solution for eliminating or limiting this drawback is to make the edge of the thermoplastic film diffusive by giving it a fine texture through abrasion. To achieve this, the thermoplastic film has an excess extending beyond the edge of the glass sheets along the periphery of the glazing before passing through the autoclave, and this excess is also present after passing through the autoclave: see Figure 3, showing a local section similar to Figure 2, but where the thermoplastic film has an excess before abrasion. The glazing is then handled by a robot that presents its periphery to abrasive strips – see Figure 4, where one abrasive strip is labeled B – which remove the excess thermoplastic film while giving its edge a matte, light-diffusing appearance: see Figure 5, similar to Figure 2, but where the edge of the thermoplastic film diffuses the incident light ray I instead of reflecting it. However, this solution is not suitable for laminated glazing with a very thin inner glass pane, as this would break upon contact with the abrasive strip. Other solutions are possible, such as applying the opaque strip right to the edge of the glazing (which then blocks incoming light rays) or leaving the thermoplastic film recessed between the two panes of glass (in which case the incoming rays can be reflected directly off the inner pane, producing a uniform reflection along the edge of the glazing, thus avoiding a discontinuous and unsightly appearance). However, these solutions also have drawbacks: the first considerably complicates the screen-printing application of the opaque strip, while the second allows, after the glazing is installed on the vehicle, the accumulation of dirt and the growth of mold in the peripheral groove of the glazing between the two panes of glass, thus making its appearance unsightly. But above all, the plaintiff realized that the problem of the inner glass pane's fragility with regard to mechanical shocks applied to its edge persists even after the laminated glass has been manufactured, unlike the case of shocks applied to its main surface. Indeed, if the laminated glass is subjected to a mechanical shock on its edge, this shock can also be sustained by the edge of the inner glass pane, given that the edges of the outer and inner glass panes are usually juxtaposed at the same level. However, laminated glass is susceptible to impacts centered on its edge even once installed in its final application. For example, on a motor vehicle, this could be the case with opening side windows that are not guided on their visible part, fixed side windows with exposed edges, or even in the case of opening rear windows.5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 4 PCT/EP2017/067573 The aim of the present invention is to at least partially overcome the aforementioned drawbacks. In one aspect, the invention aims more particularly to limit the risk of breakage of laminated glass with very thin sheets of glass due to possible mechanical shocks to the edges of the glass. To this end, the present invention proposes a laminated glazing, in particular a laminated glazing for automotive applications, comprising a first sheet of glass and a second sheet of glass, and an interlayer polymer layer disposed between the first and second sheets of glass. The second sheet of glass has a thickness of less than 1.2 mm and the first sheet of glass has a thickness greater than that of the second sheet of glass. The edge of the second sheet of glass is recessed relative to the edge of the first sheet of glass along at least a portion of the glazing's perimeter. In the area around the perimeter of the glazing where the edge of the second pane of glass is recessed relative to the edge of the first pane, mechanical impacts against the edge of the glazing are not applied to the edge of the second pane, which is therefore protected. This contrasts with the case of the front section where the edges of the thick and thin panes of glass are usually flush. In this case, the impacts are absorbed by the edge of the first pane of glass, which is more resistant than the second pane due to its greater thickness. This recess can be limited to one or more portions of the perimeter of the glazing. It is preferably implemented in those areas most exposed to the risk of impacts on the edge of the glazing after installation in its final application. For example, in the case of automotive glazing, shrinkage can be applied to the edge(s) of the glazing where the edge remains visible and accessible after installation on the vehicle—and therefore susceptible to impact during the vehicle's lifespan—while it would not be applied to the other edge(s) where the edge of the glazing is protected from impact, for example, by the vehicle's body. This is applicable mutatis mutandis if only a portion of the edge of a peripheral side of the glazing remains exposed to impact after installation in its final application. Of course, it is preferable to apply shrinkage to the entire perimeter of the glazing if the entire perimeter remains exposed to edge impact after installation in its final application. However, it is advantageous to generalize edge shrinkage around the entire perimeter of the glazing, even when the edge is partially or fully protected after installation in its final application. This measure protects the glazing against mechanical impacts on its edge throughout its entire lifecycle, from the glazing assembly operation to installation in its final application. During this period, the glazing is subjected to handling or operations such as conveying, palletizing, transport, storage, and installation in its final application, during which the risk of impact to its edge cannot be eliminated. Furthermore, this design allows for the advantageous use of a knife-cutting operation – manual or robotic – to trim the excess thermoplastic film that would otherwise protrude around the perimeter of the glazing after the glass and thermoplastic sheets have been assembled, without the risk of the knife striking the edge of the second glass sheet. When such glazing is used in an automotive application, it is understood that the first glass sheet constitutes the outer glass sheet of the glazing, while the second glass sheet constitutes the glass sheet on the interior side of the vehicle's passenger compartment. As already mentioned in the previous section, the edges of the inner and outer glass sheets are usually aligned at the same level, that is, on the same perpendicular to the main surface of the glass sheets. By way of exception, laminated glazing in which the edge of one glass sheet is recessed relative to that of another glass sheet has already been described, but not with the aim of protecting the edge of a very thin glass sheet against impacts. This is the case for EP 0 418 123 Al and EP 0 600 766 Al, which disclose laminated glazing in which all the constituent glass sheets are thick, unlike the laminated glazing according to this aspect of the invention, which comprises a glass sheet with a thickness of 1.2 mm or less. Due to the significant thickness of the constituent glass sheets and the resulting laminated glazing, the shrinkage is disclosed in these documents to thin the glazing around its perimeter and thus allow the edge of the glazing to be fitted into the guiding and mounting elements of car doors that were designed for previous monolithic glazing. WO 00/61366 Al discloses partially laminated glazing for the integration of non-transparent elements such as photovoltaic cells. The constituent glass sheets are also thick, and therefore the shrinkage at the edge of the glazing is disclosed to avoid level differences around the perimeter of the glazing where it rests on the bodywork for assembly and sealing purposes. WO 2014/029605 Al deals with the fixing of mechanical parts in holes made in laminated glass, which poses problems both in making the holes and in loosening the fixing due to the pressure exerted on the glass by the fixing system.5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 6 PCT/EP2017/067573 This is the case for side windows mounted sliding in car doors and having a hole in the lower part used to fix the window drive parts, and also for rear windows having a hole for fixing a wiper system. To avoid these problems, this document teaches how to make the fixing hole in an area of the glazing where the outer pane of glass is not covered by the inner pane. More specifically, it discloses a side glazing unit having four peripheral sides and an area along the lower peripheral side of the glazing where the outer pane of glass is not covered by the inner pane. The fixing hole for the glazing drive components is made in this area of the outer pane of glass before tempering and assembly with the other glazing components. In contrast, the invention according to the aspect described above is independent of any shaping of the glass panes for fixing any mechanical devices. Thus, a distinctive characteristic of laminated glazing lies in the fact that it has a peripheral edge where the entire region of the first glass pane not covered by the second glass pane, which is contiguous to this peripheral edge of the glazing, is free of any holes. It will be understood that this region is free of any holes, whether through or blind. The laminated glazing according to the invention is further distinguished from the teachings of this prior art document by various preferential characteristics. It will be understood that each of these preferential characteristics can also be implemented independently of the aforementioned distinctive characteristic, either individually or in combination with one or more others. One such preferential characteristic is that the edge of the second pane of glass is set back from the edge of the first pane of glass for at least 30% of the glazing perimeter, more preferably for at least 50% of the perimeter, and more advantageously for at least 70% of the perimeter, or even more advantageously for the entire perimeter. The perimeter of the glazing is understood to mean the outer edge of the glazing. Another preferential characteristic is that the glazing has a peripheral side for which the setback distance is less than or equal to 10 mm for the entire portion—continuous or discontinuous—of that peripheral side where the edge of the second pane of glass is set back from the edge of the first pane of glass. According to yet another of these preferred characteristics, the glazing further comprises, at least for said portion of the glazing's perimeter, an opaque band running at a distance from the edge of the first pane of glass. This distance is preferably less than or equal to 2 mm. 5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 PCT/EP2017/067573 According to yet another of these preferred characteristics, the glazing has a peripheral side for which the entire region of the first pane of glass not covered by the second pane of glass which is contiguous to this peripheral side of the glazing is free from any framing for fixing any mechanical device whatsoever. The laminated glazing according to the invention may further comprise one or more of the following preferential features, each of which may also be implemented independently of the aforementioned distinctive features: the thickness of the first sheet of glass is at least 0.2 mm greater than that of the second sheet of glass, the first sheet of glass preferably having a thickness of at least 1 mm and more preferably of at least 1.4 mm and the second sheet of glass preferably having a thickness less than or equal to 1 mm and more preferably less than or equal to 0.7 mm; the retraction distance is at least 1 mm, preferably at least 2 mm and more preferably at least 3 mm; - for said part of the perimeter of the glazing (i.e. for which the edge of the second sheet of glass is recessed relative to the edge of the first sheet of glass), the edge of the second sheet of glass is recessed relative to the edge of the polymer layer; - the recess of the edge of the second sheet of glass relative to the edge of the polymer layer is greater than 1 mm and more preferably greater than or equal to 1.5 mm; the recess of the edge of the second sheet of glass relative to the edge of the polymer layer is less than 10 mm and more preferably less than 5 mm; The portion of the polymer layer that extends beyond the edge of the second glass pane must not be thicker than the portion of the polymer layer sandwiched between the first and second glass panes, or must be thicker than a maximum of one-third, more preferably a maximum of one-quarter, and even more preferably a maximum of one-tenth of the thickness of the second glass pane. Furthermore, it is preferable that this extra thickness be less than or equal to one-tenth of the thickness of the portion of the polymer layer sandwiched between the two glass panes. - for said part of the glazing perimeter, the edge of the polymer layer extends obliquely from the edge of the first glass pane at an acute angle with the main internal surface of the first glass pane, the edge of the second glass pane being set back from the edge of the polymer layer; 5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 PCT/EP2017/067573 8 said angle is, on the one hand, greater than 20°, preferably greater than 30°, and, on the other hand, less than 80°, preferably less than 60°; - for said part of the glazing perimeter, the edge of the polymer layer is textured to diffuse light, preferably by an abrasion treatment; - for said part of the glazing perimeter, the fact that the edge of the polymer layer extends diagonally from the edge of the first glass pane at an acute angle with the main internal surface of the first glass pane is preferably achieved by an abrasion treatment applied to the edge of the polymer layer; where appropriate, the edge of the polymer layer is textured to diffuse light by this same abrasion treatment; - for said part of the glazing perimeter, the edge of the polymer layer is recessed relative to the edge of the first glass pane; - for said part of the glazing perimeter, the opaque strip is arranged between the first glass pane and the second glass pane, the edge of the second glass pane being located at an intermediate level between the outer edge and the inner edge of the opaque strip; - for said part of the glazing perimeter, the opaque strip is arranged between the first sheet of glass and the polymer layer, the edge of the polymer layer being located at an intermediate level between the outer edge and the inner edge of the opaque strip; the glazing includes a seal fixedly arranged at least on said part of the glazing perimeter; the second sheet of glass has been treated by chemical tempering; the glazing is glazing for motor vehicles, in particular; o a windscreen; or o a fixed side window preferably with a visible edge and accessible when mounted in the motor vehicle; or a side window intended to be mounted sliding in a door of a motor vehicle in which case said part of the perimeter of the window (for which the edge of the second sheet of glass is set back from the edge of the first sheet of glass) preferably includes at least partially - and more advantageously totally - the part of the edge of the window which becomes visible and accessible when the window is moved between its closed position and its open position in the door; or a rear window, and in particular a rear window with an exposed edge accessible in the state mounted in the motor vehicle and/or having four peripheral sides with said part of the perimeter of the glazing including at least partially - preferably totally - two peripheral sides of the glazing, more preferably three peripheral sides and more advantageously all four peripheral sides; or a fixed glazing for the roof of a motor vehicle having preferably at least a part of its edge which is exposed and accessible in the state mounted on the roof of the vehicle; or a sliding roof glazing for a motor vehicle, in which case said portion of the glazing perimeter (for which the edge of the second pane of glass is recessed relative to the edge of the first pane of glass) preferably includes at least partially—and more advantageously, completely—the portion of the glazing edge that becomes visible and accessible when the glazing is moved between its closed and open positions in the roof. In another aspect, the invention relates to the use of such laminated glazing for an automotive application. In yet another aspect, the invention relates to a motor vehicle comprising such laminated glazing. According to yet another aspect, the invention relates to a method for manufacturing laminated glazing, comprising: - a first step consisting of pre-assembling the glazing by placing and holding together a sheet forming a polymer layer between a first sheet of glass and a second sheet of glass in such a way that, at least in a part of the perimeter of the glazing thus pre-assembled: o the edge of the second sheet of glass is set back from the edge of the first sheet of glass, the dimensions of the second sheet of glass being smaller than those of the first sheet of glass, o the edge of the polymer layer is set back from the edge of the first sheet of glass, and o the edge of the second sheet of glass is flush with or set back from the edge of the polymer layer; Then, a second step involves treating the pre-assembled glazing in an autoclave to ensure the physicochemical bonding of the glass panes to each other thanks to the polymer layer. In this step, the dimensions of the polymer layer's constituent sheet are chosen relative to the dimensions of the glass panes so that, during the first step, in the aforementioned part of the glazing perimeter or the edge of the second glass pane, which is recessed relative to the edge of the first glass pane, the polymer layer is either flush with or extends beyond the edge of the second glass pane but without extending beyond the edge of the first glass pane, taking into account the relative positioning tolerance between the constituent sheet of the layer. The polymer layer and the two glass panes are bonded together. The process ensures that the edge of the polymer layer is never recessed relative to the edges of the two glass panes, thus preventing the creation of a groove between the two glass panes. This groove is undesirable when the glazing is not equipped with a perimeter seal, both in terms of protecting the edge of the second glass pane from impacts and in terms of the risk of soiling such a groove. It will be understood that this process can be implemented to obtain glazing according to the invention described above, which may, where applicable, have one or more of the preferred features mentioned above or which are mentioned in the following description of preferred embodiments of the invention, provided, of course, that they are not incompatible with the process. Other aspects, features, and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example and with reference to the accompanying drawing. Figure 1 schematically represents a front view of a motor vehicle windshield and illustrates the undesirable phenomenon of edge gloss in the form of several shiny segments at the edge of laminated glass. Figure 2 is a local cross-section of the edge of laminated glass and explains the edge gloss phenomenon. Figures 3 to 5 are local cross-sections of the edge of laminated glass that illustrate a solution to avoid the edge gloss phenomenon. Figures 6 and 7 schematically represent, for a windscreen for a motor vehicle according to a first embodiment of the invention, a local section through the edge of the laminated glass along the section line A-A shown in Figure 1 respectively before and after the edge treatment of the polymer layer by abrasion to remove the edge gloss effect. Figure 8 illustrates a technique for abrading the edge of the polymer layer of the glazing to obtain the edge profile of the glazing shown in Figure 7. Figure 9 schematically represents a local section taken through the edge of the laminated glazing along the section line A-A shown in Figure 1, but which is according to a second embodiment of the invention. Figure 10 represents a local section similar to Figure 9, but which corresponds to a variant of the relative arrangement of the edges of the different constituent components of the laminated glazing. Figures 11 and 12 illustrate a local section taken through the edge of the laminated glazing according to a third embodiment. We will describe below a first embodiment of a windshield for a motor vehicle according to the invention with reference to Figures 6 to 8. The general view of the windshield is that of the windshield 10 in Figure 1, which shows it in its mounting position on the motor vehicle. It comprises four peripheral sides, namely: a lower side 11, two lateral sides 12, 14, and an upper side 13. Alternatively, it may be a laminated glass for a motor vehicle other than a windshield, for example, a side window, whether intended to be fixed to the vehicle or sliding in a door, a rear window, or even a roof window for the vehicle, whether opening or fixed. Generally, all these glazing units, viewed from the front, have a roughly polygonal outline—albeit with curved segments—which very often has four peripheral sides, but their overall shape differs. In the case of side glazing units, some have only three peripheral sides. In these applications, the glazing is generally curved, but it can also be flat. More generally, glazing can also be designed for applications other than motor vehicles, notably for aeronautics, in which case it can have a disc shape—which amounts to having only one peripheral side in the sense of the present invention—or for buildings. The following description is applicable mutatis mutandis regardless of the overall shape of the glazing and its final application. As can be seen in Figure 6, the glazing is a double-layered system: it comprises a first sheet of glass 1, which forms the outer pane of the windshield 10, and a second sheet of glass 3, which forms the inner pane. The outer and inner panes 1 and 3 can be of conventional type. Since this is lightweight glazing, the outer pane 1 preferably has a thickness in the range of 1.4 mm to 2.1 mm. It can be thicker, for example up to 3.5 mm or even more, for specific applications where increased mechanical strength is desirable. Conversely, the thickness of the outer glass pane 1 may be less than 1.4 mm for certain special applications where lower mechanical resistance is acceptable, but it is preferably greater than or equal to 1 mm.5 10 15 20 25 30 35 CA 03030379 2019-01-09 WO 2018/011278 PCT/EP2017/067573 12 For the purpose of reducing the weight of the glazing, the inner glass pane 3 has a thickness of less than 1.2 mm and more preferably less than or equal to 1 mm and more advantageously less than or equal to 0.7 mm. The outer glass sheet 1 can either be subjected to a treatment increasing its surface mechanical resistance using, for example, a conventional heat treatment of quenching or hardening, or of the annealing type, that is to say without significant compression of its surfaces as is most often the case with laminated windshields for automobiles. Nevertheless, in both of the aforementioned cases, it is advantageous for the edge of the glass sheet to be mechanically reinforced by the application of edge compression membrane stresses during its fabrication. The inner glass sheet 3 is preferably subjected to a treatment that increases its mechanical strength. Given its thinness, chemical tempering is preferred, as this creates a surface zone of the glass that is under compression while a central zone is under tensile stress. The chemical tempering technique is well known: one may refer, for example, to the article: Ion exchange for glass strengthening, Rene Gy in Materials Science & Engineering: B, Vol. 149 No. 2, 25/03/2008, Elsevier, ISSN: 0921-5107, pp. 159-165. Naturally, the composition of the glass sheets 1 and 3 is chosen to suit the treatments applied to them. As is known, an interlayer polymer 2 is placed between the two glass sheets 1 and 3 and serves to hold them together by adhesion. This is typically a 0.76 mm thick polyvinyl butyral (PVB) sheet. Alternatively, it can be any other suitable material such as an ethylene-vinyl acetate (EVA) or polyurethane sheet. Depending on the glazing application, it may also be a resin poured between the glass sheets 1 and 3, which is then polymerized. The thickness of the polymer layer 2 can vary. It can also consist of several superimposed polymer sheets made of the same material or different materials. The outer edge 3a of the inner glass sheet 3 is recessed relative to the outer edge la of the outer glass sheet 1 by a non-zero distance denoted DI. It is advantageous to maintain such a recess around the entire perimeter of the glazing 10 because the entire periphery of the inner glass sheet 3 is then protected from impacts against the edge of the laminated glass. The recess distance DI can be small. However, it is preferably at least 1 mm and more preferably at least 2 mm, or even at least 3 mm, which facilitates the recessed positioning of the inner glass pane 3 relative to the outer glass pane 1 during their assembly, taking into account the positioning tolerances. The recess distance DI can be constant around the entire perimeter of the glazing 10, but can also vary, for example, be different depending on the side of the glazing. In the case of a windshield, the glazing includes an opaque band 4 – typically black, but which can be different – running close to the periphery of the glazing 10, as illustrated in Figure 1. The conventional function of this band 4 is to conceal the vehicle body beneath the edge of the glazing 10 and to protect the adhesive joint used to fix the glazing 10 to the body from ultraviolet radiation. Conventionally, it can be applied by screen printing, depositing enamel, ink, or paint onto one or the other of the glass sheets. It is preferably applied to the inner surface of the outer glass sheet 1. Alternatively, the opaque band 4 is applied to one of the surfaces of the intermediate polymer layer 2, for example, by ink deposition as taught by WO 95/00329A1. For ease of applying the enamel, ink, or paint that makes up strip 4, the strip extends slightly back—by a distance denoted D2—from the edge of the outer glass sheet 1. For aesthetic reasons, the distance D2 is preferably less than or equal to 2 mm. It is advantageous for the edge 3a of the lower glass sheet 3 to be located at an intermediate level between the outer edge 4a and the inner edge 4b of strip 4. This improves the aesthetics of the glazing because edge 3a is not visible to the user through the screen-printing area at the edge of the glazing. Therefore, it is preferable that the retraction distance DI be less than or equal to 10 mm around the entire perimeter of the glazing 1, or at least on the lateral sides 12, 14 and the top side 13, where the opaque band 4 is generally the narrowest. Regardless of this consideration, it is preferable that the retraction distance DI be less than or equal to at least 10 mm around the entire perimeter of the glazing where its main surface is exposed to impacts, in order to maximize the benefits of the laminated glass. During the assembly of the glazing, the outer edge 2a’ of the interlayer polymer layer 2 does not show any retraction relative to the edge la of the outer glass sheet 1. After final assembly of the glazing 10 - that is to say in this case after treatment in the autoclave to ensure the physico-chemical bonding of the glass sheets together thanks to the polymer layer 2 -, the edge 2a’ of the polymer layer 2 is subjected to an abrasion treatment illustrated in figure 8. This abrasion treatment serves to texture the edge of the polymer layer 2 to make it diffusive of light instead of reflective, which makes it possible to eliminate or significantly reduce the edge gloss effect. The abrasion operation is made possible because the edge 3a of the lower glass pane 3 is set back from both the edge 1a of the outer glass pane 1 and the edge 2a’ of the polymer layer 2. The abrasion operation can be carried out as follows. The glazing 10 is manipulated by a robotic arm R so that the edge 2a’ contacts a moving abrasive belt B. The contact between the abrasive belt B and the edge 2a’ is inclined so as to exclude, or at least limit, contact 1 with the outer glass sheet 1. This abrasion treatment can be carried out by successive application of several abrasive belts with progressively finer grits. The movement of the abrasive belt B is in the direction from the polymer layer 2 towards the outer glass sheet 1, which avoids the risk of delamination of the polymer layer 2 from the outer glass sheet 1. After this abrasion treatment, the textured edge of the polymer layer 2 – reference 2a in Figure 7 – presents an acute angle – reference a – with respect to the main internal surface li of the first glass sheet 1. Generally, it is preferable for the angle a to be greater than 20°, or even greater than 30°. On the contrary, it is preferable that it be less than 80°, or even less than 60°. More generally, however, angle α is chosen so that edge 3a of the inner glass sheet 3 is set back from edge 2a of the polymer layer 2 in order to avoid the risk of the abrasive belt B contacting edge 3a of the inner glass sheet 3 during the abrasion operation. The fact that edge 2a extends at this angle is advantageous compared to the case where it would be perpendicular—that is, if angle α were 90° as in Part 1—because the risk of delamination of the polymer layer 2 of the outer glass sheet 1 after the glazing is manufactured is minimized, and the effect of reducing or eliminating the edge gloss effect is increased. A second embodiment of laminated glazing is now described with reference to Figure 9. It is based on the first embodiment—the same reference numerals are used to designate the same elements—and its entire description is applicable, with the following exceptions. In this embodiment, the edge 2a of the polymer layer 2 is set back—by a non-zero distance denoted D3—from the edge 1a of the outer glass sheet 1 in the finished glazing 10. This setback, in itself, limits the risk of edge glare, regardless of any treatment of the edge 2a to make it non-reflective. Such a treatment of the edge 2a can therefore be omitted in this embodiment. It is preferable that the setback distance D3 be less than the setback distance DI of the edge 3a. This prevents a groove from being defined between the glass sheets 1 and 3 on the edge of the glazing, which could become soiled once the glazing is installed on the motor vehicle. The setback of edge 3a of the inner glass sheet 3 relative to edge 2a of the polymer layer 2 – in other words (DI - D3) – is preferably greater than 1 mm, or even greater than or equal to 1.5 mm. Conversely, it is preferable that this shrinkage (D1-D3) be less than 10 mm, or even less than 5 mm, which limits the size of the free surface of the polymer layer 2 that is exposed to aging and which can also exhibit a troublesome stickiness. It will be understood that, by convention, this shrinkage is measured by taking as a reference point for edge 2a of the polymer layer 2 its highest point – that is, the point furthest – from edge 3a of the inner glass sheet 3, bearing in mind that edge 2a is generally angled and curved towards edge 3a of the inner glass sheet 3 due to the softening of the polymer layer 2 during treatment in the autoclave. In practice, the highest point of the edge 2a of the polymer layer 2 is usually the point where the edge 2a of the polymer layer 2 meets the inner surface of the outer glass sheet: see this point which serves as a reference for the distance D3 in Figure 9. In any case, when manufacturing glazing with a polymer layer 2 supplied in sheet form, it is preferable that the dimensions of the sheet constituting the polymer layer 2 be chosen to be larger than the inner glass sheet 3 so that, after assembly of the glazing, the polymer layer 2 is always flush with or protrudes from the edge of the inner glass sheet 3, taking into account the relative positioning tolerance between the sheet constituting the polymer layer 2 and the inner glass sheet 3. This positioning tolerance is usually +/- 1 mm. Therefore, from a theoretical point of view, it is advantageous to define an overhang of the polymer layer 2 of at least 1 mm – but more preferably at least 1.5 mm – relative to the edge 3a of the inner glass sheet 3. This ensures that the inner glass sheet 3 effectively exhibits a shrinkage (D1-D3) greater than or equal to 0 mm, or greater than or equal to 0.5 mm respectively, taking into account the positioning tolerances. However, as mentioned previously, it is possible to achieve an even greater effective shrinkage (D1-D3), namely at least 1 mm, or even more than 1.5 mm. In this second embodiment, it is particularly advantageous that the shrinkage D3 of the edge 2a of the polymer layer 2 is greater than the shrinkage D2 of the outer edge 4a of the opaque strip 4. This case is illustrated by Figure 10. More precisely, the edge 2a of the polymer layer 2 is located at an intermediate level between the outer edge 4a and the inner edge 4b of the strip 4, which is also the case for the inner glass sheet 3 as already mentioned above regarding the first embodiment. As a result, the risk of edge glare is completely eliminated and the aesthetics of the glazing are improved, since neither the edge 3a of the inner glass sheet 3, nor the edge 2a of the polymer layer, are visible to the user through the screen-printed area at the periphery of the glazing. Figure 11 illustrates a third embodiment according to the invention. It is based on the second embodiment, in which the edge 2a of the polymer layer 2 is also recessed relative to the edge la of the outer glass sheet 1, regardless of whether it is the variant shown in Figure 9 or that shown in Figure 10. This third embodiment differs from the previous one only in that the glazing is provided with a gasket 5 fixedly attached to its periphery, for example by extrusion or bonding. It is preferably arranged around the entire perimeter of the glazing 10. The gasket 5 eliminates the edge glare effect and ensures a perfect aesthetic finish at the edge of the glazing as seen from the side of the inner glass sheet 3, since the edges 2a and 3a are concealed. It can advantageously be made of rubber or elastomer or another material capable of absorbing mechanical shocks, in which case it also protects the edge 3a of the inner glass sheet 3 against mechanical shocks. As illustrated, the seal 5 can encapsulate the edge 2a of the polymer layer and the edge 3a of the inner glass sheet 3. It can also be designed to cover all or part of the edge la of the outer glass sheet 1, in which case it will also protect this edge against mechanical shocks. Figure 12 illustrates a variant of the arrangement of Figure 11 in which the seal – referenced 5’ – is also in contact with the edge 3a of the inner glass sheet, but is flush with the outer face 3e of the inner glass sheet 3. In other words, the seal 5’ does not extend onto the outer face 3e, unlike the case of seal 5 in Figure 11. In the third embodiment, the edge 2a of the polymer layer 2 can be recessed relative to the edge 3a of the inner glass sheet 3, thus creating a peripheral groove to improve the adhesion of the seal 5 or 5’. Bringing a 5 or 5’ joint by extrusion or bonding onto the edge of the glazing as described for this third embodiment is preferable in the case where a bead intended to provide all or part of the functions mentioned for the 5 or 5’ joint was made on the edge 3a of the inner glass sheet by an excess of material from the polymer layer 2 accumulating at this place during the glazing manufacturing process. Indeed, it is particularly difficult to control the creation of such a bead during the manufacturing process, and there is a risk of insufficient or excessive material in locally forming the bead, which can compromise the protective function of the inner pane of glass and the desired aesthetic. In contrast, applying a seal by bonding or extrusion to the edge of the glazing does not present these difficulties. Due to the aforementioned difficulties, it is preferable to avoid the formation of such a ridge by the polymer layer 2. However, in the case of the polymer layer 2 being in the form of a sheet, it softens during treatment in the autoclave to ensure the physico-chemical bonding of the glass sheets together thanks to the polymer layer 2, and can therefore flow and present a slight excess thickness in the part protruding from the edge 3a of the inner glass sheet 3. Thus, both in the second embodiment described in relation to Figures 9 and 10 – that is, in the absence of a 5 or 5' added gasket – and in the third embodiment described in relation to Figures 11 and 12 – that is, where the glazing is provided with a 5 or 5' added peripheral gasket – it is preferable that, after treatment in the autoclave, the portion of the polymer layer 2 that extends, where applicable, beyond the edge 3a of the inner glass pane 3 does not have an excess thickness compared to the portion of the polymer layer 2 located between the outer glass pane 1 and the inner glass pane 3, or at least that this excess thickness is limited to a maximum of one-third, more preferably a maximum of one-quarter, and even more preferably a maximum of one-tenth. of the thickness of the inner glass pane 3. Furthermore, it is preferable that this additional thickness be less than or equal to one-tenth of the thickness of the portion of the polymer layer between the outer glass pane 1 and the inner glass pane 3. It will be understood that the local sections shown in the figures for the different embodiments can be applied to all or part of the perimeter of the laminated glazing. In addition, the retraction distances DI, D2, D3 and the angle α – as applicable – can be identical or different for the various peripheral dimensions of the glazing concerned, while respecting the relative ratio mentioned above. Of course, the present invention is not limited to the examples and embodiment described and represented, but is susceptible to numerous variants accessible to the person skilled in the art. It will be understood in particular that the laminated glazing according to the invention does not necessarily include an opaque band 4, for example in the case of a movable side window of a motor vehicle door or for applications in fields other than motor vehicles.

Claims (22)

5 10 15 20 25 Date Received 2024-06-06 18 CLAIMS 1. Laminated glazing, comprising: - a first sheet of glass (1) and a second sheet of glass (3), and - an intercalated polymer layer (2) disposed between the first sheet of glass and the second sheet of glass, wherein: - the second sheet of glass (3) has a thickness less than 1.2 mm, - the first sheet of glass (1) has a thickness greater than that of the second sheet of glass (3), - the edge (3a) of the second sheet of glass (3) is set back by a setback distance (DI) from the edge (la) of the first sheet of glass (1) over at least a portion of the perimeter of the glazing (10), - for said portion of the around the glazing, the edge (2a) of the polymer layer (2) extends obliquely from the edge (la) of the first sheet of glass (1) making an acute angle (a) with the main internal surface (li) of the first sheet of glass (1), the edge (3a) of the second sheet of glass (3) being set back from the edge (2a) of the polymer layer (2), and - the glazing has a peripheral side (11; 12; 13; 14) for which the whole region of the first sheet of glass (1) not covered by the second sheet of glass (2) which is contiguous to this peripheral side of the glazing is free of holes. 2. Glazing according to claim 1, wherein the thickness of the first sheet of glass (1) is at least 0.2 mm greater than that of the second sheet of glass (3), the first sheet of glass (1) having a thickness of at least 1 mm and the second sheet of glass (3) having a thickness less than or equal to 1 mm. 3. The glazing according to claim 2, in which the first sheet of glass (1) has a thickness of at least 1.4 mm. 4. The glazing according to any one of claims 2 or 3, wherein the second pane of glass (3) has a thickness less than or equal to 0.7 mm. 5 10 15 20 25 Date Received 2024-06-06 19 5. Village according to any one of claims 1 to 4, in which the edge (3a) of the second sheet of glass (3) is set back from the edge (la) of the first sheet of glass (1) over at least 30% of the perimeter of the glazing. 6. The glazing according to claim 5, wherein the edge (3a) of the second sheet of glass (3) is set back from the edge (la) of the first sheet of glass (1) over at least 50% of the perimeter of the glazing. 7. The glazing according to any one of claims 5 or 6, wherein the edge (3a) of the second glass pane (3) is recessed relative to the edge (la) of the first glass pane (1) over at least 70% of the perimeter of the glazing 8. The glazing according to any one of claims 5 to 7, wherein the edge (3a) of the second sheet of glass (3) is set back from the edge (la) of the first sheet of glass (1) all around the perimeter of the glazing. 9. Glazing according to any one of claims 1 to 8, wherein the retraction distance (DI) is at least 1 mm. 10. The glazing according to claim 9, wherein the retraction distance (DI) is at least 2 mm. 11. The glazing according to any one of claims 9 to 11, wherein the retraction distance (DI) is at least 3 mm. 12. Glazing according to any one of claims 1 to 11, which has a peripheral side (12; 13; 14) for which the setback distance (DI) is less than or equal to 10 mm for the whole part of this peripheral side for which the edge (3a) of the second sheet of glass (3) is set back from the edge (la) of the first sheet of glass (1). 13. Village according to any one of claims 1 to 12, wherein, for said portion of the glazing perimeter, the edge (3a) of the second glass pane (3) is recessed relative to the edge (2a) of the polymer layer (2). 5 10 15 20 25 Date Recue/Date Received 2024-06-06 20 14. Village according to any one of claims 1 to 13, in which said acute angle (a) is, on the one hand, greater than 20°, and, on the other hand, less than 80°. 15. The glazing according to claim 14, wherein said acute angle (a) is greater than 30°. 16. The glazing according to any one of claims 14 or 15, wherein said acute angle (a) is less than 60°. 17. Glazing according to any one of claims 1 to 16, wherein, for said part of the periphery of the glazing, the edge (2a) of the polymer layer (2) is textured to diffuse light. 18. Glazing according to any one of claims 1 to 17 comprising at least for said part of the perimeter of the glazing, an opaque band (4) running at a distance along the edge (la) of the first sheet of glass (2). 19. Glazing according to claim 18, wherein, for said part of the perimeter of the glazing, the opaque strip (4) is arranged between the first sheet of glass (1) and the second sheet of glass (3), the edge (3a) of the second sheet of glass (3) being situated at an intermediate level between the outer edge (4a) and the inner edge (4b) of the opaque strip (4). 20. Glazing according to any one of claims 18 or 19, wherein, for said part of the glazing perimeter, the opaque band (4) is arranged between the first sheet of glass (1) and the polymer layer (2), the edge (2a) of the polymer layer (2) being located at an intermediate level between the outer edge (4a) and the inner edge (4b) of the opaque band (4). 21. Glazing according to any one of claims 1 to 20, comprising a seal (5; 5') fixedly arranged at least on said part of the perimeter of the glazing. 22. Glazing according to any one of claims 1 to 21, wherein the second sheet of glass (3) has been treated by chemical tempering.