Asymmetric laminated glazing, associated manufacturing method

Abstract

The invention relates to a laminated glazing (100) comprising a first glass sheet (110) and a second glass sheet (120) separated by an interlayer (130), the first glass sheet (110) being heat strengthened and having a thickness greater than 1.8 mm, the second glass sheet (120) being untempered and having a thickness less than 1.6 mm. The glazing (100) has at least one first curved curvature defining a surface arc and a chord supporting said arc, in order to be associated with a first curvature ratio between a length of said chord and a depth of curvature between said arc and said chord. Moreover, the glazing (100) is shaped so that a flatness factor, which is at least equal to said first curvature ratio, is greater than 250.

Description

Existing technology

[0001] This invention belongs to the general field of glass assembly production.

[0002] This invention relates more particularly to asymmetric laminated glass and a method for manufacturing such asymmetric laminated glass. This invention is particularly advantageous in the manufacture of laminated glass (roof, side windows, windshield, rear window) for use in the automotive industry, but is by no means limiting.

[0003] The technology used for assembling glass in the manufacture of motor vehicles has undergone significant changes, depending on various design standards.

[0004] Therefore, automotive glass, especially side glass, was initially designed using a heat-tempered, one-piece construction. This method resulted in excellent strength properties.

[0005] Subsequently, a design was proposed for laminated assembled glass with glass sheets of uniform thickness. This laminated assembled glass also achieved very high durability while providing various additional features, such as sound attenuation. Furthermore, this lamination principle, combined with the heat tempering or semi-tempering of the glass sheets, further enhanced the durability of the manufactured assembled glass, especially against external impacts (particularly during break-in and potentially against grit impacts) or internal impacts (laminated assembled glass helps retain passengers in the passenger compartment in the event of an accident or vehicle rollover; thus preventing permanent damage when passengers are partially ejected from the vehicle).

[0006] However, such laminated glazing is not without its drawbacks. In particular, they are exceptionally heavy and bulky components. Therefore, design practice has continued to evolve towards producing laminated glazing with reduced weight and floor space. Recently, the production of so-called "asymmetric" laminated glazing has been proposed, where the two assembled glass sheets have different thicknesses. In practice, this glazing comprises a very thin sheet, typically on the order of millimeters, usually facing the interior environment (e.g., the interior of a vehicle). On the other hand, the thicker sheet is typically positioned facing the exterior environment (e.g., the exterior of a vehicle).

[0007] The fact that one glass sheet is much thinner than the other can lead to reduced stiffness, which in turn can result in poorer impact resistance. To compensate for this disadvantage, manufacturers have systematically selected and implemented treatments to harden the thinnest glass sheet, particularly through chemical tempering.

[0008] This method has many drawbacks. Chemical tempering is an expensive, time-consuming, and complex process that requires holding glass slides in various alkaline salt baths at high temperatures for several hours to achieve the appropriate surface stress levels. This results in very poor yields, with numerous breakages occurring during operations before or after chemical tempering, during washing, and during the tempering process itself. Furthermore, from an environmental perspective, it represents an unfavorable solution because the treated products are difficult to recycle.

[0009] It is important to point out that although the aforementioned features have been disclosed in the context of motor vehicles, they still apply in other application areas, such as residential, aviation, maritime and rail transportation. Invention Overview The present invention aims to partially or completely overcome the shortcomings of the prior art, especially those disclosed above, by proposing a solution that allows for the production of asymmetrical laminated glass with a slightly curved appearance through a simpler and more environmentally friendly production method than that used in the prior art.

[0011] Therefore, and according to a first aspect, the present invention relates to laminated assembled glass comprising a first glass sheet and a second glass sheet separated by an interlayer, the first glass sheet being heat-strengthened and having a thickness greater than 1.8 mm, the second glass sheet being untempered and having a thickness less than 1.6 mm, the assembled glass having at least one first curvature that defines a curvature depth between a surface arc and a chord supporting the arc, in order to be associated with a first curvature ratio between the length of the chord and the curvature depth, the assembled glass being further shaped such that a flatness factor at least equal to the first curvature ratio is greater than 250.

[0012] In its general principle, the laminated glass according to the invention corresponds to an asymmetric laminated glass and is configured in a manner that avoids the inherent disadvantages of chemical tempering, based on results obtained by the inventors after simulation and testing activities.

[0013] More specifically, considering the fact that an increasing number of laminated assembly glasses are manufactured with substantially flat geometries (especially, but not limited to, in the automotive industry), the inventors have managed to characterize the acceptable curvature of asymmetric laminated assembly glasses so that it is not necessary to subject all or part of the glass sheets used in their composition to tempering, while ensuring a low stress level within the thinnest glass sheet (i.e., the second glass sheet in this case), and based on the understanding that asymmetric laminated assembly glasses have excellent strength once assembled (due to sufficient stress levels within the thickest glass sheet and the presence of intermediate layers).

[0014] Therefore, the solution proposed in this invention lies in asymmetric laminated glass assembly, wherein the thinner glass sheet is not tempered. In other words, the second glass sheet is not subjected to any heat strengthening (semi-tempering or tempering) or chemical tempering, and is therefore formed directly from flat glass supplied by the float glass production line.

[0015] Furthermore, in order to compensate for the lack of tempering treatment of the second glass sheet and to minimize the risk of breakage of the sheet, the assembled glass according to the invention has a substantially flat geometry, characterized by a value that can be represented by the flatness coefficient.

[0016] This essentially flat geometry is achieved within the limits that allows it to achieve excellent robustness while avoiding the need for tempering a second glass sheet.

[0017] In a particular implementation, the laminated assembled glass may further include several of the following features, either individually or in any technically feasible combination.

[0018] In a particular embodiment, the assembled glass has a second curvature in a direction substantially perpendicular to the first curvature, so as to be associated with a second curvature ratio, the flatness factor being equal to the sum of the first and second curvature ratios.

[0019] In certain implementations, the flatness factor is greater than 500.

[0020] In a particular embodiment, the thickness of the second glass sheet is less than 1.2 mm, for example, less than 1 mm.

[0021] In a particular embodiment, the thickness of the first glass sheet is greater than 2.1 mm, or greater than 2.6 mm, or greater than 2.85 mm, or greater than 3.15 mm, or greater than 3.5 mm, or greater than 3.85 mm.

[0022] In a particular embodiment, the intermediate layer comprises a polymer material comprising a polyvinyl butyral layer having a loss factor tan(δ) greater than 0.8 and a shear modulus G' less than 20 MPa at a frequency between 500 Hz and 5000 Hz at a temperature of 20°C.

[0023] In a particular implementation, the intermediate layer comprises a transparent “OCA” type adhesive material, such as latex.

[0024] In a particular embodiment, the intermediate layer is made of ethylene-vinyl acetate.

[0025] According to a second aspect, the present invention relates to the use of the assembled glass according to the invention in residential or road, air, sea or rail transport vehicles, preferably as window assembled glass in motor vehicles, particularly as windshield, rear window assembled glass, side assembled glass or roof assembled glass.

[0026] According to a third aspect, the present invention relates to a motor vehicle comprising a mounting glass according to the invention.

[0027] According to a fourth aspect, the present invention relates to a method for manufacturing assembled glass according to the invention, the method comprising the following steps: - Obtain a first glass slide in a flat state and a second glass slide in a flat state. - The first glass sheet is thermally bent based on the aforementioned flatness coefficient. - Heat-strengthened first glass plate, - Assemble a first glass sheet and a second glass sheet into a laminated glass assembly, with an intermediate layer placed between the first and second glass sheets. The assembly includes cold bending the second glass sheet against the first glass sheet. - Extract the air contained in the assembled laminated glass assembly.

[0028] The manufacturing method according to the invention is particularly advantageous because it enables the production of robust asymmetric laminated glass, which is simpler and more environmentally friendly than prior art asymmetric laminated glass, taking into account the absence of tempering treatment for the thinnest glass sheet.

[0029] In a particular implementation, the manufacturing method may further include one or more of the following features, either individually or in any technically possible combination.

[0030] In a particular implementation, the evacuation step is performed by rolling the laminated assembled glass.

[0031] In certain embodiments where the assembled glass includes a PVB interlayer, particularly acoustic PVB, the method further involves an autoclaving step of the assembled laminated glass following a evacuation step.

[0032] In a particular implementation, the assembly step involves holding the stack formed by the glass sheet and the intermediate layer in place after cold bending the second glass sheet. Brief description of the attached diagram Other features and advantages of the invention will become apparent from the following non-limiting description given with reference to the accompanying drawings, which illustrate exemplary embodiments thereof. In the drawings: - [ Figure 1 A specific embodiment of the asymmetric laminated glass according to the present invention is schematically depicted; - [ Figure 2 ] schematically depict [ Figure 1 The two curvatures of the asymmetric laminated glass shown in the image; - [ Figure 3 ] is an example in [ Figure 1 The table shows the surface stress values ​​measured on the thinnest glass sheet of the asymmetric laminated glass assembly shown in the figure. - [ Figure 4 The main steps of the method for manufacturing asymmetric assembled glass according to the present invention are described in the form of a flowchart. Invention Details [ Figure 1 A particular embodiment of the laminated assembled glass according to the present invention is schematically depicted.

[0035] For the remainder of this specification, it is understood, but not limited to, that the laminated glass (100) is intended for use in motor vehicles, such as automobiles. More specifically, this refers to side windows of automobiles, but does not exclude the possibility of rear window windows, windshields, or roof windows.

[0036] However, it should be noted that considering this type of glazing and such applications using this glazing constitute only one alternative embodiment of the invention. Generally, there are no limitations on the uses that the glazing 100 can be used for. For example, it can be used in residential buildings (room partitions, wall glazing, etc.) or in all types of transportation (road, air, sea, or rail).

[0037] like[ Figure 1 As illustrated in the figure, the assembled glass 100 includes a first glass sheet 110 and a second glass sheet 120 assembled via an intermediate layer 130.

[0038] "Glass sheet" is understood to refer to a plate formed of a transparent material. For example, the transparent material can be mineral glass, such as soda-lime glass, aluminosilicate glass, or borosilicate glass. Alternatively, the transparent material can be plexiglass, such as stretched polymethyl methacrylate (stretched PMMA), unstretched polymethyl methacrylate, polycarbonate (PC), polyethylene terephthalate (PET), or polyurethane (PU). It should be noted that the two glass sheets 110 and 120 can be made of different transparent materials.

[0039] Furthermore, one or both of the glass plates 110 and 120 may be colored (colored glass is glass containing desired inorganic pigments, such as iron oxide, cobalt oxide, chromium oxide, etc.). It should also be noted that the two glass plates 110 and 120 may have different hues.

[0040] The intermediate layer 130 is made of a polymeric material, such as PVB (polyvinyl butyral). More specifically, in this embodiment, this polymeric material is of the "acoustic" type, i.e., it has the function of reducing sound passing through the assembled glass 100. To be classified as acoustic, such a polymeric material comprises at least one layer of polymeric material (typically made of PVB) having a loss factor greater than 0.8 and a shear modulus G' less than 20 MPa at frequencies between 500 Hz and 5000 Hz at a temperature of 20°C. These viscoelastic properties are evaluated, for example, by those skilled in the art using a viscosity analyzer such as a Metravib 01dB Metravib VA4000 to measure the plane shear according to standard ISO 6721 (determination of dynamic mechanical properties).

[0041] When using such an acoustic polymer material layer, it can be the sole layer of the intermediate layer 130, or it can be juxtaposed with at least one other polymer material layer. The acoustically-based intermediate layer 130 can be produced, in particular, by assembling at least three PVB layers, where the innermost layer is softer than the other two surrounding it. Typically, acoustic polymer materials result in a slight loss of rigidity in laminated glass compared to conventional polymer materials. Therefore, conventional polymer materials are more suitable for laminated glass where high rigidity is primarily desired. Conventional polymer materials typically have a shear modulus G' greater than 100 MPa and a tan(δ) loss factor less than 0.4 at a temperature of 20°C and frequencies between 500 Hz and 5000 Hz.

[0042] It should also be noted that considering only PVB polymer materials, especially acoustic polymer materials, as the intermediate layer 130 is merely one alternative embodiment of the invention. This does not preclude the possibility of other embodiments in which the intermediate layer 130 comprises a transparent adhesive material of the "OCA" (Optically Transparent Adhesive) type, such as latex glue, and more particularly acoustic latex glue (with a glue thickness of, for example, less than 100 μm, ideally 30 μm), in combination with or as a substitute for PVB polymer materials. As an alternative to these models, other models are also conceivable, in which the intermediate layer 130 is made of EVA (ethylene vinyl acetate).

[0043] The assembled glass 100 is more specifically an asymmetric laminated assembled glass. Therefore, the first glass sheet and the second glass sheets 110, 120 have different thicknesses. More specifically, in reference [ Figure 1 In the embodiment described herein, the first glass sheet 110 has a thickness greater than 1.8 mm, while the second glass sheet 120 has a thickness less than 1.6 mm.

[0044] Considering the intended use of the mounting glass 100, the first glass pane 110 (more specifically, surface 1 of the mounting glass 100, according to conventional practice in the mounting glass industry) is configured to face the external environment of the vehicle. The second glass pane 120 (more specifically, surface 4 of the mounting glass 100) is configured to face the internal environment of the vehicle (i.e., the passenger compartment).

[0045] It should be noted that the respective thickness values ​​of the first and second glass sheets 110 and 120 considered in this embodiment are not limitations on the invention. Therefore, other configurations are conceivable, wherein the thickness of the second glass sheet 120 is less than 1.2 mm, for example less than 1 mm, and / or the thickness of the first glass sheet 110 is greater than 2.1 mm, or greater than 2.6 mm, or greater than 2.85 mm, or greater than 3.15 mm, or greater than 3.5 mm, or greater than 3.85 mm.

[0046] The first glass sheet 110, which is the thicker of the two glass sheets in the assembled glass 100, is heat-strengthened. In other words, the first glass sheet 110 is partially tempered or tempered.

[0047] Heat strengthening is typically performed by tempering immediately after the glass is bent (by rapidly cooling the glass from the bending temperature by blowing air on both sides) and before the laminated glass 100 is assembled.

[0048] In itself, semi-tempered glass (also known as "thermally toughened" glass) is manufactured on the same equipment used for thermally tempered glass. Although the heating conditions are the same, the cooling air supply is less powerful.

[0049] It is known that very thin glass sheets, such as the second glass sheet 120, can be cold-bent during the manufacturing process of laminated assembled glass. Cold bending is preferred for this type of glass sheet because thermal bending (i.e., hot bending) generally affects its optical quality.

[0050] The term "cold bending" is traditionally used to refer to a deformation process that occurs within the elastic range of glass. Conversely, hot bending refers to bending glass at its deformation temperature so that it is permanently deformed after it returns to ambient temperature. Hot bending is particularly carried out at temperatures above the glass transition temperature of the glass, and typically at temperatures above 550°C.

[0051] While preferred, cold bending has limitations, namely that it does not allow the glass to achieve a significant curvature without significantly increasing the risk of breakage. To limit this risk, existing technology shows that thin glass sheets used in the manufacture of asymmetric laminated assemblies are systematically strengthened by chemical tempering.

[0052] The general principle of this invention aims to avoid the inherent drawbacks of chemical tempering based on results obtained by the inventors after simulation and testing activities. More specifically, considering the increasing prevalence of laminated assembly glass manufactured with substantially flat geometries (especially, but not limited to, in the automotive industry), the inventors have managed to characterize acceptable curvature for asymmetric laminated assembly glass so that it is unnecessary to subject the assembly glass to such chemical tempering, while ensuring low stress levels within the thinnest glass sheet, and based on the understanding that asymmetric laminated assembly glass possesses excellent strength once assembled (due to sufficient stress levels within the thickest glass sheet and the presence of the intermediate layer).

[0053] For these reasons, the second glass sheet 120, the thinner of the two glass sheets in the assembly glass 100, is not tempered. In other words, the second glass sheet 120 is not subjected to any heat strengthening (semi-tempering or tempering) or chemical tempering, and is therefore formed directly from the flat glass supplied by the float glass production line.

[0054] In addition, to compensate for the lack of tempering treatment of the second glass sheet 120, the assembled glass 100 in this embodiment has two curvatures, the characteristics of which will now be described.

[0055] It is known that glass sheets can be bent in one or more directions, each associated with a bending curvature (i.e., radius of curvature). Each bending curve allows for a defined bending depth between a surface arc (i.e., an arc extending across the surface of the glass sheet) and a chord supporting said arc. Since these characteristics are applied in a similar manner to each glass sheet used in the composition of a laminated assembled glass, the overall bending curvature of the laminated assembled glass can thus be referenced.

[0056] [ Figure 2 ]Schematic depiction [ Figure 1 The two curvatures of the asymmetric laminated glass 100 shown in the figure.

[0057] like[ Figure 2As illustrated in the illustration, the mounting glass 100 has a first curvature associated with the curvature depth of the longest arc ARC_F extending across the surface of the mounting glass 100 (corresponding to the most significant curvature in this example). This curvature depth of the first curvature is also referred to as "sag F", and more specifically corresponds to a segment whose ends are the midpoint of the arc ARC_F and the midpoint of the chord C_F extending below the arc ARC_F.

[0058] In this embodiment, the assembled glass 100 also has a second curvature in a direction substantially perpendicular to the first curvature. This second curvature, also referred to as "lateral curvature," is generally less significant than the first curvature. It is also associated with the curvature depth of the arc ARC_DB, which is substantially perpendicular to the longest arc ARC_F. This curvature depth of the first curvature is also referred to as "lateral curvature DB," and more specifically corresponds to a segment whose end is the midpoint of the arc ARC_DB and the midpoint of the chord C_DB extending below the arc ARC_DB.

[0059] Due to these arrangements, the asymmetric laminated glass 100 can be associated with the following: - A first bending ratio R_F between the length of the string C_F and the bending depth (i.e., R_F = C_F / F); - A second bending ratio R_DB between the length of the chord C_DB and the bending depth DB (i.e., R_DB = C_DB / DB).

[0060] As mentioned above, the asymmetric laminated assembly glass 100 has a substantially flat geometry that advantageously enables it to achieve excellent robustness while avoiding the need for tempering of the second glass sheet 120. Specifically, in this embodiment, the assembly glass 100 is shaped such that the flatness coefficient COEF_FLAT, which is equal to the sum of the first curvature ratio R_F and the second curvature ratio R_DB, is greater than 250.

[0061] [ Figure 3 [ ] is a table illustrating the surface stress values ​​measured on the second glass plate 120.

[0062] More specifically, in order to obtain [ Figure 3 The values ​​in the table in [ ] represent the asymmetric laminated glass 100, where the thickness of the first glass sheet 110 (and correspondingly the second glass sheet 120) is 2.1 mm (correspondingly equal to 1.1 mm). The intermediate layer 130 is a PVB layer with a thickness of 0.76 mm.

[0063] exist[ Figure 3In the table, the values ​​of parameters C_F, F, R_F, C_DB, DB, and R_DB are expressed in millimeters. The first column, marked "%", corresponds to the flatness ratio of the assembly glass 100 compared to a nominal configuration of the same assembly glass 100 (flatness here is intended to represent a reduction in curvature depths F and DB). The nominal configuration corresponds in terms of curvature to a geometry that would typically be pursued in the prior art (i.e., if chemical treatment of the second glass sheet 120 is permitted) and is associated with values ​​F and DB equal to 8.39 mm and 19.45 mm, respectively. This nominal configuration is shown in the table as row 0%. For example, for the row corresponding to a flatness ratio of 20%, F = 8.39 x (1 - 20%) = 6.71 mm.

[0064] In addition, in [ Figure 3 In the table, the column labeled “CO_F4” includes the surface stress values ​​measured at surface 4 of the assembled glass 100 (i.e., the surface of the second glass sheet 120 facing inwards towards the carrier). These values ​​are expressed in MPa and are negative, taking into account the chosen measurement convention and the fact that these are compressive surface stresses (it should be understood that normal stresses with the same values ​​can be measured symmetrically on surface 3, and these normal stresses therefore correspond to tensile surface stresses).

[0065] Conventionally, these surface stresses correspond to residual mechanical stresses resulting from the assembly of the laminated asymmetric assembled glass 100. Specifically, these residual stresses arise particularly from the thermal bending and thermal strengthening of the first glass sheet 110, and the cold bending of the second glass sheet 120. In the case of the second glass sheet 120, the surface stresses are located substantially at the periphery, typically at the edge of the largest dimension.

[0066] In the context of this application, surface stress is measured using a device that operates according to the principle of polarizing mirror inspection, such as the Scalp-04 polarizing mirror sold by GlasStress Ltd, Tallin 10912 Estonia.

[0067] Similarly, as from [ Figure 3 As can be seen from the table, for flatness ratios of 40%, 60%, and 80%, the flatness coefficient COEFF_FLAT is greater than 250. This specifically corresponds to surface stresses of less than 20 MPa (absolute value), which, as observed by the inventors, is a stress level that significantly reduces the risk of breakage of the second glass sheet 120.

[0068] In other words, by proposing a geometry that is flatter than that of the prior art (COEFF_FLAT>250), a very robust asymmetric laminated assembly glass 100 can be obtained, in which it is not necessary to temper the second glass sheet 120.

[0069] The inventors were also able to measure that, in [ Figure 3 In the example considered, the asymmetric laminated assembled glass 100 has a surface stress level greater than 40 MPa or greater than 80 MPa at the first glass sheet 110, depending on whether the glass sheet has undergone hot semi-tempering or tempering, respectively. This stress level on the first glass sheet 110 supports the conclusion that the resulting assembled glass 100 is extremely robust.

[0070] Asymmetric laminated glass 100 has been described to date as having a flatness factor COEFF_FLAT of at least 250. However, this does not preclude the possibility of envisioning more stringent constraints on flatness, such as a flatness factor COEFF_FLAT of at least 500.

[0071] The asymmetric laminated glass 100 has also been described based on the flatness coefficient COEFF_FLAT corresponding to the sum of the first curvature ratio R_F and the second curvature ratio R_DB. This is only one alternative embodiment of the invention and does not preclude the flatness coefficient COEFF_FLAT from being equal to only one of the two curvature ratios R_F and R_DB.

[0072] This invention also relates to a method of manufacturing [ Figure 1 A method for asymmetric lamination assembly of glass 100. The method is carried out using forming equipment conforming to features known to those skilled in the art. Therefore, the forming equipment typically includes a glass sheet heating device (e.g., a kiln), a hot bending device for the glass sheet, a cold bending device for the glass sheet, and a hot strengthening device for the glass sheet. According to a particular embodiment, the steps of the manufacturing method are illustrated in […]. Figure 4 ]middle.

[0073] like[ Figure 4 As shown in the diagram, the manufacturing method begins in step H10 to obtain a first glass sheet 110 in a flat state and a second glass sheet 120 in a flat state. Typically, the first and second glass sheets 110 and 120 are cut from a piece of float glass. The first and second glass sheets 110 and 120 may have the same profile before bending. They may be further shaped at their edges after cutting.

[0074] Typically, the term "obtain" can encompass all or some of the intermediate stages in the production of flat glass sheets (cutting, shaping, etc.), or it can simply refer to the fact that a glass sheet has undergone all of the aforementioned production operations.

[0075] Once the first glass sheet 110 has been obtained in a flat state, it is hot-bent in step H20 of the manufacturing method. The hot bending is performed according to the flatness coefficient COEFF_FLAT, that is, so that once the first glass sheet 110 is bent, it has a flatness coefficient of at least greater than 250, and even at least greater than 500, as described above.

[0076] Therefore, once completed, the bending of the first glass sheet 110 determines the bending of the asymmetric laminated assembly glass 100. Suitable bending methods for the glass sheet include, for example, the type of "bending simultaneously while conveying between two rollers" (as disclosed in WO2005047198 or WO2004033381), or the type of "bending by pressing" (as disclosed in WO0206170 or WO2017178733).

[0077] Then, in step H30 of the manufacturing method, the first glass sheet 110 is heat-strengthened (tempered or semi-tempered).

[0078] The manufacturing method then includes step H40, which involves assembling a first glass sheet and second glass sheets 110, 120 into the laminated assembled glass 100, wherein an interlayer 130 is disposed between the first glass sheet and the second glass sheets 110, 120. In particular, the assembly includes cold bending the second glass sheet 120 against the first glass sheet 110.

[0079] In practice, the assembly of the asymmetric laminated glass 100 from the first and second glass sheets 110, 120 and the intermediate layer 130 can be performed using any method known to those skilled in the art. Typically, such assembly involves pre-assembly, in which the intermediate layer 130 is deposited on one face of the first glass sheet 110 or the second glass sheet 120. More specifically, when the intermediate layer 130 is made of PVB or EVA, it is typically deposited on face 2 of the first glass sheet 110. Alternatively, if the intermediate layer 130 comprises an OCA material, particularly a liquid OCA material, the latter is deposited on face 3 of the second glass sheet 120. A suitable device is then pressed onto face 4 of the second glass sheet 120, for example, in the central region of the second glass sheet 120, to cold deform it and press it onto the first glass sheet 110. It should be noted that if an OCA material, particularly a liquid OCA material, is used, assembly step H40 may also involve drying the stack formed by the sheets 110, 120 and the intermediate layer 130.

[0080] In a more specific embodiment, assembly step H40 may also involve holding the stack formed by the first and second glass sheets 110, 120 and the intermediate layer 130 in place after cold bending the second glass sheet 120. Advantageously, holding the stack in place in this way stabilizes it and minimizes the risk of misalignment between the first glass sheet 110 and the second glass sheet 120. This holding can be achieved by any method known to those skilled in the art, such as by means of clamps or by creating hot spots between the glass sheets 110, 120.

[0081] In reference [ Figure 4 In the disclosed embodiments, the manufacturing method further includes a step H50 for extracting air contained in the assembled asymmetric laminated glass 100. When the interlayer 130 comprises an OCA material, particularly a liquid OCA material, this extraction or "degassing" step H50 is performed, for example, simultaneously with the drying of the assembled asymmetric laminated glass 100.

[0082] This evacuation step H50 is performed, for example, by a rolled and assembled asymmetric laminated glass 100.

[0083] However, considering the calendering of the assembled asymmetric laminated glass 100 is merely one alternative embodiment of the invention. Generally, any evacuation method known to those skilled in the art, such as the vacuum bag method (e.g., encapsulating the assembled glass 100 in a vacuum bag), can be contemplated.

[0084] It should be noted that when the asymmetric laminated assembled glass 100 includes a PVB interlayer, particularly, for example, acoustic PVB, the manufacturing method may also include a heat treatment step of the assembled assembled glass 100 after assembly step H40 (in [… Figure 4 (Not shown in the image).

Claims

1. A laminated assembled glass (100) comprising a first glass sheet and a second glass sheet assembled from an intermediate layer (130), the first glass sheet (110) being heat-strengthened and having a thickness greater than 1.8 mm, the second glass sheet (120) being untempered and having a thickness less than 1.6 mm, the assembled glass having at least one first curvature that defines a bending depth (F, DB) between a surface arc (ARC_F, ARC_DB) and a chord (C_F, C_DB) supporting the arc, in relation to a first curvature ratio (R_F, R_DB) between the length of the chord and the bending depth, the assembled glass being further shaped such that a flatness factor (COEFF_FLAT) at least equal to the first curvature ratio is greater than 250.

2. The assembled glass (100) according to claim 1, wherein the assembled glass has a second curvature in a direction substantially perpendicular to the first curvature, so as to be associated with a second curvature ratio (R_F, R_DB), wherein the flatness factor (COEFF_FLAT) is equal to the sum of the first curvature ratio and the second curvature ratio.

3. The assembled glass (100) according to any one of claims 1 to 2, wherein the flatness factor (COEFF_FLAT) is greater than 500.

4. The assembled glass (100) according to any one of claims 1 to 3, wherein the thickness of the second glass sheet (120) is less than 1.2 mm, for example less than 1 mm.

5. The assembled glass (100) according to any one of claims 1 to 4, wherein the thickness of the first glass sheet (110) is greater than 2.1 mm, or greater than 2.6 mm, or greater than 2.85 mm, or greater than 3.15 mm, or greater than 3.5 mm, or greater than 3.85 mm.

6. The assembled glass (100) according to any one of claims 1 to 5, wherein the intermediate layer (130) comprises a polymer material comprising a polyvinyl butyral layer having a loss factor tan(δ) greater than 0.8 and a shear modulus G' less than 20 MPa at a frequency between 500 Hz and 5000 Hz at a temperature of 20°C.

7. The assembled glass (100) according to any one of claims 1 to 6, wherein the intermediate layer (130) comprises a transparent adhesive material of the "OCA" type, such as a latex adhesive.

8. The assembled glass (100) according to any one of claims 1 to 5, wherein the intermediate layer (130) is made of ethylene-vinyl acetate.

9. Use of the mounting glass (100) according to any one of claims 1 to 8 in residential or road, air, sea or rail transport vehicles, preferably as window mounting glass in motor vehicles, particularly as windshield, rear window mounting glass, side mounting glass or roof mounting glass.

10. A motor vehicle comprising a mounting glass (100) according to any one of claims 1 to 8.

11. A method for manufacturing an assembled glass (100) according to any one of claims 1 to 8, the method comprising the following steps: - Obtain a first glass plate (110) in a flat state (H10) and a second glass plate (120) in a flat state. - The first glass sheet is thermally bent (H2O) based on the flatness factor (CEOFF_FLAT). - The first glass sheet is heat-strengthened (H30). - Assemble the first glass sheet and the second glass sheet (H40) into a laminated glass assembly, with an intermediate layer (130) disposed between the first glass sheet and the second glass sheet, the assembly including cold bending the second glass sheet against the first glass sheet. - Extract the air contained in the assembled (H50) asymmetric laminated glass.

12. The method of claim 11, wherein the evacuation step is performed by rolling the laminated assembled glass.

13. The method according to any one of claims 11 to 12, wherein the laminated assembled glass to be manufactured conforms to any one of claims 6 to 7, and the method further involves a step of heat-pressing the assembled laminated assembled glass after the evacuation step.

14. The method according to any one of claims 11 to 13, wherein the assembly step involves holding the stack formed by the glass sheet and the intermediate layer in place after cold bending the second glass sheet.

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