laminated glass with protective treatment

Abstract

The present invention relates to vehicle glazing comprising: - a first sheet of glass (1) and a second sheet of glass (3), and - an interlayer polymeric layer (2) disposed between the first sheet of glass and the second sheet of glass, - characterized in that said glazing comprises at least one protective barrier (20) in the form of at least one demarcation line (22) separating the first sheet of glass into at least two portions, said demarcation line comprising a multitude of points, each point consisting of a local modification of the material. Fig 5

Description

Title of the invention: Laminated glazing with protective treatment

[0001] The invention relates to the field of laminated glazing and in particular to laminated glazing used in the transport sector, such as the automotive sector. Prior art

[0002] Side windows for vehicles, such as cars, buses, or trucks, are generally mounted so that they can be raised and lowered as needed. To achieve this, the structure in which the window is mounted includes a window movement system. This window movement system comprises a motor that drives a linkage. This linkage includes a support that attaches to the window.

[0003] Automotive side windows are currently produced using a process called the "BT process," which is protected by various SG patents. These conventional side windows are monolithic panes of glass heated to 650°C and then rapidly cooled to temper them and give them a toroidal shape. This tempered glass has the dual advantage of being more resistant to mechanical stress and shattering into a multitude of small pieces if broken.

[0004] This fine fragmentation is called "Securit fragmentation." It protects vehicle occupants from serious cuts in the event of an accident and broken glass. This fragmentation meets the very precise specifications of the international standard R-43.

[0005] On a single-pane glass, the support is fixed to the glass by holes made in said glass. These holes are made by drilling before tempering said glass.

[0006] There is also the possibility of using so-called laminated glazing. Laminated sidelights (LSL) are essentially a sandwich of two glass panes that have been formed and hardened (in the sense that they are rapidly cooled) bonded together by a PVB elastomer interlayer. In reality, the glass panes composing these sandwiches do not reach the stress levels of tempered glazing. Indeed, their thickness is too small to create, during cooling, a sufficient thermal gradient to generate the stresses necessary to achieve Securit fragmentation. These panes are therefore described as "hardened" or "semi-tempered."

[0007] This last point does not pose a safety problem, because the PVB interlayer ensures the cohesion of the assembly in the event of an accident and thus prevents the projection of potentially harmful glass fragments. These LSLs are therefore used for three purposes:

[0008] • Improved acoustic comfort thanks to the absorption properties of the PVB interleaf;

[0009] • Improved resistance to burglary;

[0010] • New properties for blocking UV radiation from the sun;

[0011] Nevertheless, these LSLs have a particular construction with respect to the side windows classic monolithic hardened.

[0012] Indeed, the current solution for fixing these laminated side panels within a door is achieved by means of a plastic part added after manufacturing and glued onto the glazing, called a holder. This solution complicates the process with an additional step.

[0013] Another solution is to drill holes in separate sheets of glass and then glue them together. However, this solution is complex because it requires aligning the holes in the two sheets of glass during assembly. While this alignment is already complex for flat sheets of glass, the complexity increases with curved sheets of glass.

[0014] Another existing solution for drilling holes in the glazing is to have one sheet of glass larger than the other and to drill the holes in this larger sheet. However, this area with the holes is crucial for securing the glazing to the vehicle, and it is essential to ensure the cohesion of the holed area in the event of an impact and therefore breakage. It is possible to add reinforcement, but this complicates the glazing. Summary of the invention

[0015] The present invention therefore seeks to solve the problems of the prior art by providing a means of protecting the sensitive areas of laminated glazing during an impact.

[0016] To this end, the present invention relates to vehicle glazing comprising:

[0017] - a first sheet of glass and a second sheet of glass, and

[0018] - an intercalated polymeric layer disposed between the first glass sheet and the second sheet of glass,

[0019] characterized in that said glazing comprises a protective barrier in the form of at least one demarcation line separating the first sheet of glass into at least two portions, said demarcation line comprising a multitude of points, each point consisting of a local modification of the material.

[0020] According to one example, the local modification of the material consists of a microchannel.

[0021] According to an example, two adjacent points are separated by a distance of between 1 and 50pm.

[0022] According to one example, the microchannel extends over at least 80% of the thickness of the glass sheet, preferably 100% of the thickness.

[0023] According to one example, the edge of the second sheet of glass is set back from the edge of the first sheet of glass over at least part of the perimeter of the glazing.

[0024] According to one example, the first sheet of glass includes at least one hole for fixing said glazing to a structure.

[0025] According to one example, the demarcation line extends over the area of ​​the first sheet of glass not covered by the second sheet of glass.

[0026] According to one example, the demarcation line extends over the area of ​​the first sheet of glass covered by the second sheet of glass.

[0027] According to one example, the demarcation line extends opposite the edge of the second sheet of glass.

[0028] According to one example, at least one demarcation line surrounds said at least one hole.

[0029] According to one example, the second sheet includes a specific area at which an accessory is fixed, said demarcation line surrounding said specific area.

[0030] According to one example, the second sheet includes an opening forming the specific area.

[0031] The invention further relates to a structure comprising an opening in which glazing according to one of the preceding characteristics is arranged.

[0032] According to one example, the glazing is glued into the opening.

[0033] According to one example, the structure is arranged to allow said glazing to slide in said structure, said structure comprising a movement system to allow said glazing to slide. Brief description of the figures

[0034] Other features and advantages will become clear from the description given below, by way of example and in no way limiting, with reference to the attached drawings, in which:

[0035] - Figures 1 and 2 are schematic representations of a glazing;

[0036] - [Fig.3] is a schematic representation of a glazing with one sheet of glass larger than the other according to a first configuration;

[0037] - Figures 4 and 5 are schematic representations of glazing equipped with a treatment according to the invention;

[0038] - Figures 6 and 7 are schematic representations of a laser beam used to obtain the glazing according to the invention;

[0039] - [Fig.8] is a schematic representation of the impact points forming the protective barrier;

[0040] - Figures 9 to 13 are schematic representations of the positioning of the protective barrier.

[0041] - Figures 14 and 15 are schematic representations of a second glazing configuration.

[0042] Detailed description.

[0043] We will describe below a first embodiment of glazing, particularly for a motor vehicle, according to the invention. The general view is that of glazing 10 in [Fig. 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.

[0044] Alternatively, it may be laminated glazing for a motor vehicle other than side glazing, for example a windshield, a rear window, or even glazing for the vehicle's roof, whether opening or fixed. The glazing 10 is mounted in a structure, which is a door, or directly on the vehicle itself for a windshield or roof. Generally, all these glazings, viewed from the front, have a substantially polygonal outline—albeit with curved segments—which very often has four peripheral sides, but their overall shape differs. In the case of side glazing, 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 be disc-shaped – which amounts to having only one peripheral edge within the meaning of the present invention – or for buildings. The following description is applicable mutatis mutandis regardless of the general shape of the glazing and its final application.

[0045] As can be seen in [Fig.2], the glazing 10 is laminated: it comprises a first sheet of glass 1 which constitutes the outer sheet of glass of the glazing 10 and a second sheet of glass 3 which constitutes the inner sheet of glass.

[0046] The outer and inner glass panes 1, 3 may be of conventional type. In the case of lightweight glazing, the outer glass pane 1 preferably has a thickness in the range of 1.4 mm to 2.1 mm. It may 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 specific applications where lower mechanical strength is acceptable, but it is preferably greater than or equal to 1 mm.

[0047] For the purpose of reducing the weight of the glazing, the inner glass sheet 3 has a thickness of less than 1.2 mm and more preferably less than or equal to 1 mm and even more advantageously less than or equal to 0.7 mm.

[0048] The outer glass sheet 1 can be subjected either to a treatment increasing its surface mechanical strength, for example by conventional heat treatment such as quenching or hardening, or by annealing, i.e., without significant compression of its surfaces, as is most often the case with laminated automotive windshields. However, 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 manufacturing.

[0049] The inner glass sheet 3 is preferably subjected to a treatment that increases its mechanical strength. This treatment may be a thermal hardening treatment (called semi-tempering). In the case of thinner glass sheets, 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: see, for example, the article: Ion exchange for glass strengthening, René 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 be compatible with the treatments applied to them.

[0050] In a manner known per se, an interlayer polymeric layer 2 is disposed between the two glass sheets 1, 3 and serves to hold them together by adhesion, as shown in [Fig. 2]. This can conventionally be 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 can also be a resin poured between the glass sheets 1, 3 and then polymerized. The thickness of the polymeric layer 2 can vary. It can also consist of several superimposed polymeric sheets made of the same material or of different materials.

[0051] In a first configuration, the glazing 10 is such that the outer edge 3a of the inner glass pane 3 or second glass pane is recessed relative to the outer edge la of the outer glass pane 1 or first glass pane by a non-zero distance referred to as DI. Depending on the application, it is possible to provide such a recess around the entire perimeter of the glazing 10.

[0052] The retraction distance DI can be small. But it is preferably at least 1 mm and more preferably at least 2 mm, or even at least 3 mm, which facilitates the retraction of the inner glass pane 3 relative to to the outer pane of glass 1 during assembly, taking into account positioning tolerances. The retraction distance DI may be constant around all or part of the perimeter of the glazing 10, but may also vary, for example, be different depending on the side of the glazing. Indeed, in the case of a side window 10 for automobiles, the outer pane of glass 1 includes holes 40 for attaching the raising / lowering mechanism. These holes 40 are located in the area of ​​the outer pane of glass that is not covered by the inner pane of glass.

[0053] In this first configuration, the area of ​​the outer glass sheet that is not covered by the inner glass sheet has a greater fragility and cannot maintain its cohesion in case of breakage because it is not held together by the sandwich formed with the interlayer and the inner glass.

[0054] In a second configuration, the laminated glass comprises two sheets having the same dimensions, i.e., without any indentation. The laminated glass includes a specific area 3b. This specific area is used for mounting an accessory 5, such as a camera or radar, as seen in [Fig. 14]. The specific area is then at least as large as the camera's field of view at the distance from the outer sheet. The accessory is bonded to the inner glass sheet 3 or to the outer glass sheet 1. For this purpose, the inner glass sheet 3 is drilled to accommodate the accessory.

[0055] In this second configuration, the outer glass sheet must remain intact because cracks would lead to poor image quality at the camera and therefore a malfunction of the camera function.

[0056] According to the invention, the outer glass sheet 1 comprises a protective barrier 20. This protective barrier 20 consists of a demarcation line 22 as seen in Figures 4 and 5. This demarcation line is created using a laser device 10 that generates a laser beam F as seen in [Fig. 6]. The generated laser beam F is such that it makes it possible to create this demarcation line 22.

[0057] In order to enable the creation of such a demarcation line, a laser device 10 is used and designed, arranged to shape the laser beam to obtain a Bessel beam.

[0058] Such a Bessel beam F, visible in [Fig. 6], is characterized by a cross-sectional profile comprising a central point Pc and at least one ring A or corona whose center is said central point. This central point Pc is the area where the beam intensity is highest.

[0059] The laser beam F used is also characterized by a wavelength. More specifically, the laser device is such that it emits in a wavelength range for which both the glass and the interlayer are transparent - typically in the visible or near-infrared range. As such, the wavelength is within a range of 400 to 1100nm.

[0060] In order to create the demarcation line, the laser beam is shaped so that its length is at least equal to the thickness of the panel. The length LB of a Bessel beam is shown in [Fig. 7].

[0061] To shape this beam to the desired length, a device and parameters such as those presented in the article Meyer et al. Appl. Phys. Lett. 114, 201105 (2019) are used.

[0062] This allows us to have a Bessel beam whose length LB is at least equal to 80% of the thickness of the outer glass sheet 1, preferably over the entire thickness of the treated glass sheet.

[0063] Said beam F also exhibits power and operating frequency characteristics, the latter being characteristic of the time between each pulse. Indeed, the laser beam F comprises a natural frequency related to its wavelength but also an operating frequency. The operating frequency is related to the fact that the laser beam F is pulsed and that the pulses are generated at a certain frequency, called the operating frequency.

[0064] The laser beam treatment consists of locally modifying the material of the outer glass sheet. This modification is a local embrittlement of the material that propagates throughout the glazing. This embrittlement takes the form of microchannels, each channel extending over 80% or the entire thickness of the glass. These microchannels form a barrier that prevents cracks from propagating.

[0065] The demarcation line is thus created by a relative displacement between the laminated glass panel P and the laser beam F so that the line T can be produced. Preferably, the laser device 10 is mounted to move relative to the glass panel.

[0066] According to the invention, the demarcation line consists of a plurality of points PI, each point corresponding to an impact of the laser beam. The distance d between each point, called impact point PI, is such that it allows each point PI to treat an area of ​​the panel P without impacting a contiguous point, as seen in [Fig. 8].

[0067] Indeed, the laser beam F is such that it creates a stress in each of the glass sheets 1, 2 and micro-channels in the intermediate film 3.

[0068] However, if two impact points Plj and PIj+1 are too close, then the impact point Plj+1 influences the preceding impact point Plj. This influence can be seen in the fact that the stresses induced by the beam's impact on point PIj+1 lead to a reduction or modification of the stresses due to the beam's impact on point PL. Thus, it is possible that the microchannels created by the beam's impact on point Plj may close upon the beam's impact on point PIj+1. Thus, the consequence would be that using the beam at point PIj+1 would render point Plj inoperative and therefore the cutting line would be useless.

[0069] The invention therefore proposes to define a distance d between two points of impact allowing this problem to be avoided.

[0070] For this purpose, the distance d between two points of contact is chosen to depend on the dimensions of the laser beam. More specifically, the diameter of the Bessel beam, and in particular the width of the central lobe in the focusing zone, is used. Indeed, the central lobe is the most energetic area of ​​the beam, that is to say, the area that impacts the laminated glass panel the most; it is therefore the area to be used as a reference.

[0071] In this case, a distance d between two points of impact is chosen to be equal to a value between two and seven times the diameter of the central lobe Pc. It is understood that the distance between two points will be between 1 and 50 pm.

[0072] To achieve this distance, two parameters of the laser device are taken into account. These parameters are the relative speed of movement between the glass panel P and the laser device 10 and the operating frequency.

[0073] Indeed, the relative speed of movement is representative of the difference in speed of movement that can exist between the glass panel P placed on a support and the laser device, namely that the glass panel P and / or the laser device 10 can move. This speed of movement can also be called the scanning speed.

[0074] The working frequency is the frequency at which the pulses are generated.

[0075] These two quantities are therefore linked such that the scanning speed and the operating frequency allow us to define the maximum step between two impact points. Indeed, the operating frequency is expressed in Hertz, i.e., in s⁻¹, while the scanning speed is expressed in m / s or mm / s; the ratio between the two allows us to obtain a value in m or mm.

[0076] In this case, it is necessary that the ratio between the slew rate and the operating frequency be equal to a value between two and seven times the diameter of the central lobe. This allows the values ​​of the frequency and slew rate used to be determined.

[0077] The operating frequency is between 1 and 1000kHz.

[0078] The laser beam is also characterized by its energy per pulse / group of pulses. This varies from 10 to 1000 J.

[0079] The pulses of the laser beam also exhibit characteristics such as a duration characteristic. Indeed, the amount of energy depends on the intensity of the pulse but also on its duration.

[0080] In the context of the present invention, the pulses have a duration of between 0.1 and 100ps, or even between 0.1 and 10 ps.

[0081] In one embodiment, each pulse of the laser beam is such that it is composed of at least two sub-pulses. It is understood from this that the laser device is such that each pulse is in fact a train of pulses. These pulses also have a duration of between 0.1 and 100 ps, ​​or even between 0.1 and 10 ps.

[0082] The pulse frequency, related to the duration between two pulses of the same pulse train, is higher than the operating frequency. The frequencies between two pulses of the same pulse train are at least an order of magnitude higher than the operating frequency.

[0083] The demarcation line 22 makes it possible to create a barrier which prevents fracturing extending from the outer glazing from extending onto the outer sheet of glass on the other side of the demarcation line 22.

[0084] Thus, this barrier protects the part of the outer glass sheet 1 which is not covered by the inner glass sheet 3 because the micro-channels prevent the propagation of cracks.

[0085] In the first glazing configuration, the protective barrier 20 extends to completely separate the area of ​​the outer glass sheet 1 that is not covered by the inner glass sheet 3.

[0086] This protective barrier 20 is arranged, in a first embodiment, on the part of the outer glass sheet 1 which is not covered by the inner glass sheet 3 as seen in [Fig.9].

[0087] In a second embodiment, the protective barrier 20 is arranged opposite the edge of the inner glass sheet as seen in [Fig. 10].

[0088] In a third embodiment, the protective barrier 20 is arranged on the part of the outer glass sheet 1 which is covered by the inner glass sheet 3 as seen in [Fig. 11].

[0089] In a second embodiment, the protective barrier 20 is arranged to isolate areas as shown in Figures 12 and 13. This second embodiment is used to isolate defined areas. These areas are, for example, the holes in the outer glass panel used for attaching the lifting / lowering system. The protective barrier then takes the form of a circular demarcation line around the hole(s). It is understood that each hole can be surrounded by a demarcation line or that the holes are surrounded by a single demarcation line.

[0090] In the second glazing configuration, the protective barrier 20 extends to protect the specific area. It is understood from this that the demarcation line 22 encircles the specific area as seen in [Fig. 15].

[0091] In this configuration, the demarcation line 22 is arranged so that at a minimum the area defined by said demarcation line 22 is identical to the surface of the specific area, i.e. the field of vision of the accessory at the distance from the outer glass sheet 1.

[0092] In this second configuration, the specific area is preferably coated with an opaque layer of the enamel type. This opaque layer, deposited on one or the other of the glass sheets, makes it possible to mask the demarcation line 22.

[0093] The glazing 10 is intended to be mounted in a structure. This structure is a roof, a vehicle door, or the vehicle itself. The structure housing the glazing is considered to have an opening, and the glazing is sized to be larger than the opening. In a preferred embodiment, the positioning of at least one demarcation line 22 depends on the mounting of the glazing 10 in the structure. This is because the laser treatment is likely to be visible. To prevent the demarcation line 22 from being visible to the user, the demarcation line 22 is positioned so that it is hidden when the glazing is mounted.

[0094] Of course, the present invention is not limited to the illustrated example but is susceptible to various variants and modifications which will become apparent to those skilled in the art.

[0095] Thus, it is possible for the glazing to be configured to have one pane recessed relative to the other and at least one specific area. In this case, it is evident that said glazing is likely to include at least two demarcation lines according to the invention to protect each part of the glazing that needs to be protected.

Claims

Demands

1. : Glazing, particularly for vehicles, comprising: - a first sheet of glass (1) and a second sheet of glass (3), and - an interlayer polymeric layer (2) disposed between the first sheet of glass and the second sheet of glass, - characterized in that said glazing comprises at least one protective barrier (20) in the form of at least one demarcation line (22) separating the first sheet of glass into at least two portions, said demarcation line comprising a multitude of points, each point consisting of a local modification of the material.

2. Glazing according to the preceding claim, wherein the local modification of the material consists of a microchannel.

3. Glazing according to any one of claims 1 or 2, wherein two adjacent points are separated by a distance of between 1 and 50pm.

4. Glazing according to any one of claims 2 or 3, wherein the microchannel extends over at least 80% of the thickness of the glass sheet, preferably 100% of the thickness.

5. Glazing according to any one of the preceding claims, 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 part of the perimeter of the glazing (10).

6. Glazing according to claim 5, wherein the first sheet of glass (1) includes at least one hole (40) for fixing said glazing to a structure.

7. Glazing according to claim 5, wherein the demarcation line (22) extends over the area of ​​the first sheet of glass (1) not covered by the second sheet of glass (3).

8. Glazing according to claim 5, wherein the dividing line extends over the area of ​​the first sheet of glass covered by the second sheet of glass.

9. Glazing according to claim 7, wherein the demarcation line extends opposite the edge (3a) of the second sheet of glass (3).

10. Glazing according to any one of claims 6 to 8, wherein at least one demarcation line (22) surrounds said at least one hole.

11. Glazing according to any one of claims 1 to 10, wherein the second sheet comprises a specific area (3b) at which an accessory is fixed, said demarcation line (22) surrounding said specific area.

12. Glazing according to the preceding claim, wherein the second sheet includes an opening forming the specific area.

13. Structure includes an opening in which glazing according to one of the preceding claims is arranged.

14. Structure according to the preceding claim, wherein the glazing is glued into the opening.

15. Structure according to claim 13, wherein the structure is arranged to allow said glazing to slide in said structure, said structure comprising a movement system to allow said glazing to slide.

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