Illuminatable vehicle glazing and manufacturing process for such glazing

Abstract

Vehicle glazing (1) illuminable, comprising at least one sheet (2, 2') of glass with at least one layer (3) of opaque enamel of thickness (E1) of no more than 20 µm, the enamel layer (3) comprising a fused glass frit, pigments and with at least one mask (4) forming a pattern, the enamel layer (3) having a minimum optical density of 5 and a roughness parameter Ra of less than 0.3 µm over a measurement length of 10 mm with a 0.8 mm Gaussian filter. Figure for the abbreviation: Figure 1

Description

Title of the invention: Illuminatable vehicle glazing and method for manufacturing such glazing

[0001] The present invention relates to the field of vehicle glazing.

[0002] More specifically, the invention relates to vehicle glazing, particularly for automobiles, incorporating illuminated signage. Such glazing finds a particular, but not exclusive, application in the field of motor vehicles.

[0003] In the field of motor vehicles, it is known to supplement certain signal lights, such as taillights, turn signals, brake lights, or reversing lights, with light sources synchronized with these signal lights and of the same color. These light sources can be located inside the passenger compartment, generally near the rear window, as described, for example, in application EP1234752. In the glazing described in this document, light-emitting diodes (LEDs) are positioned opposite an inner main face of the window, visible through a window in the frame enamel. They are housed in a casing located at the edge of the inner face.

[0004] However, these additional signal lights are not entirely satisfactory in terms of visual comfort, size, and aesthetics. Furthermore, they do not allow for the simple display of patterns, such as signage, particularly for the driver.

[0005] It has been proposed to create illuminated signage by applying an opaque masking layer to the glazing, in which discontinuities or recesses are formed. The discontinuities can form signs, such as pictograms, particularly for the driver. A lighting device, such as OLEDs, is placed behind the discontinuities so as to illuminate one or more pictograms on command. The masking layer is generally an enamel or ink, applied to the glazing by screen printing, inkjet or laser printing, spraying, roller application, etc. Document WO2017 / 103427 gives an example of such an embodiment, in which the masking layer containing the discontinuities is applied to an exterior surface of the glazing, facing the interior of the vehicle.

[0006] Document WO2020089288 also proposes the application of an opaque layer, forming a masking frame along the periphery of a glazing, which includes discontinuities forming a pattern. A lighting device includes Light-emitting diodes (LEDs) are combined with a light guide that includes a diffusing pattern of the same shape as the pattern formed by the discontinuities in the masking frame. The light guide is applied against the masking frame so that the two patterns align. Thus, when the light source emits light, the pattern in the masking frame is illuminated.

[0007] However, these solutions are not entirely satisfactory. Indeed, the light emitted through the discontinuities in the opaque masking layer can be partially diffused through the opaque layer. Consequently, the contours of the discontinuities appear blurred when illuminated. Furthermore, the opaque masking layer can have a grainy appearance, adding an impression of irregularities to the contours of the discontinuities and reinforcing the impression of blurriness. Visual comfort and aesthetics are thus degraded. The driver's ability to read and interpret the signage may be affected.

[0008] The invention aims in particular to provide a solution to the aforementioned drawbacks.

[0009] Thus, according to a first aspect, the invention relates to an illuminable vehicle glazing comprising at least one sheet of glass with at least one opaque enamel layer of thickness El of at most 20 µm and preferably of at most 18 or 15 µm, comprising a fused glass frit, pigments with at least one masking pattern, the enamel layer having an optical density of at least 5 and even at least 5.5 and a roughness parameter Ra (arithmetic roughness) of less than 0.3 µm, preferably less than 0.25 µm, and preferably even less than 0.2 µm. The roughness is notably measured over a measurement length of 10 mm, with a 0.8 mm Gaussian filter, in particular by a roughness tester (tactile profilometer).

[0010] In particular, the enamel layer is obtained by inkjet printing, also known as digital printing, on the sheet of glass.

[0011] The thickness is advantageously at most 18pm and even at most 15pm (and in particular at least 8 or 10pm) and preferably the optical density is at least 5.5 even at least 6.

[0012] The term "removal" here refers to a discontinuity or a set of discontinuities in the otherwise continuous enamel layer. More precisely, the enamel layer extends over one face of the glass sheet in a substantially homogeneous manner, and the removal leaves the face in question exposed. For example, the removal has a characteristic dimension of at least 0.1 mm (millimeter) and at most 5 cm (centimeters), preferably at most 2 cm. The removal may extend to an edge of the enamel layer, but not necessarily. The removal may form a convex or non-convex pattern.

[0013] Optical density D here and in what follows refers to the ability of a material to block, that is to say not to transmit, the light rays that reach it. Optical density is obtained from the transmittance denoted T, or transmission coefficient, which is the ratio between the intensity I of the light transmitted through the material and the intensity Io of the incident light:

[0014] Tt- *0

[0015] The optical density D is then calculated as follows:

[0016] D=-lognT

[0017] Thus, it is possible to provide for the installation of a lighting device emitting visible light radiation so as to illuminate at least one compartment. The compartment forms a motif, in particular to provide information or an indication, such as signage, decoration, or a warning. This could be, for example, a message, the compartment forming, for instance, several letters of the alphabet, a symbol, a pictogram, a drawing, a decorative geometric pattern, or a combination thereof. The lighting device visually highlights the information or indication conveyed by the compartment. Thanks in particular to the optical density achieved, the information or indication stands out visually clearly and legibly to a human observer.

[0018] Depending on different aspects, it is possible to foresee one and / or the other of the characteristics below taken alone or in combination.

[0019] According to one embodiment, the opaque enamel layer comprises a pore content of less than 15% by volume. Alternatively or cumulatively, the opaque enamel layer comprises a crystallite content of less than 20% by volume. These content levels are, for example, measured within the thickness of the enamel layer from a scanning electron microscope (SEM) image of the layer in cross-section over a surface area of ​​1 Opm². If necessary, the image can be processed by digital analysis, for example, using Matlab software. More generally, from these measurements of the crystallite content and the pore content, a ratio between the crystallite content Te and the pore content Tp (content in % by volume) in the enamel layer can be defined, which, according to the invention, can be less than 3:

[0020] 7 p

[0021] According to one embodiment, the enamel layer has a colorimetry L*a*b* with a parameter L* of value less than 10, preferably less than 8, preferably even less than 5, and parameters a* and b* of value less than 1. The color of the enamel layer perceived by the human eye is thus black, so as to make the relief stand out particularly when it is illuminated.

[0022] According to one embodiment, the glazing may include a lighting device emitting visible light radiation, so as to illuminate the storage area. Said lighting device includes at least one light source arranged opposite of said savings. It is arranged in such a way that at least part of the emitted light, and preferably all of the emitted light, passes through the glass sheet. The lighting device is attached to the glass sheet by a main face F2 or F4 of the glass sheet which is intended to face the interior of the vehicle.

[0023] More specifically, the lighting device may include a light source arranged opposite the storage area, preferably, for example, an array of LEDs. More specifically, the light source may be chosen from miniLEDs, microLEDs, or nanoLEDs.

[0024] According to one embodiment, the lighting device may include at least one diffuser disposed between the source and the shield, in order to obtain a soft light and limit glare. The aesthetic effect when the shield 4 is illuminated by the lighting device is enhanced.

[0025] According to one embodiment, the opaque enamel layer is made on all or part of a peripheral edge of the glass sheet.

[0026] According to one embodiment, the glazing is intended to be installed as fixed side glazing, in particular quarter window, or rear window or windscreen of the vehicle.

[0027] According to a second aspect, the invention relates to a method for manufacturing illuminable glazing, particularly for vehicles, as described above. The enamel layer is produced by a step of depositing an enamelable liquid composition onto the glass sheet, including particles comprising a glass frit and pigments, followed by a firing step. The method further comprises the following steps: • The deposition by inkjet onto the glass sheet of the enamelable liquid composition comprising not more than 80% (percent) by mass of inorganic, mineral solid material, including particles containing a glass frit and pigments, and comprising not more than 50%, preferably not more than 45%, and preferably a further 40% by mass of liquid material, including organic material. The liquid material may include, for example, a solvent and / or a resin and / or one or more stabilizers, and / or a rheological agent. The liquid composition is deposited to a thickness E0 at the time of deposition of not more than 100 µm (micrometers), preferably not more than 90 µm, and preferably not more than 60 µm, and preferably at least 15 µm. The liquid composition also exhibits a viscosity of at least 5 mPa.s (milliPascal second) at a shear rate of 100s (per second) at room temperature and even at most 30 mPa.s or at most 25 mPa.s or 20 mPa.s.the enamelable liquid composition also exhibits a particle size distribution. D90 less than 2.5pm, preferably less than 2pm, preferably even less than 1.5pm and at least 1pm and even greater than 1pm; • a drying process that removes all or part of the organic matter. The drying is carried out for example by infrared waves with heat flux, for a temperature of at least 120°C, preferably at least 130°C, and at most 200°C, and preferably at most 180°C, for a duration of at least 30 s, preferably at least 40 s and preferably even more at least 2 min (minutes); • Firing the glass sheet with the formation of the opaque enamel layer comprising at least one illuminable area, from the liquid enamel composition. Firing can be carried out, for example, at a firing temperature of at least 500°C.

[0028] The opaque enamel layer, once fired, thus has an optical density D of at least 5 for a maximum thickness of 20 pm and in particular of at least 5 pm and a roughness parameter Ra (arithmetic mean roughness) of less than 0.3.

[0029] According to one embodiment, the deposition and drying are carried out by continuously moving the glass horizontally. For example, the moving speed is at most 12 m / min (meters per minute), for example 9 m / min, and preferably 6 m / min. Such a moving speed is particularly suitable for the manufacture of glazing for motor vehicles.

[0030] According to one embodiment, the enamelable liquid composition comprises 55% to 65% by mass of inorganic solid matter.

[0031] According to one embodiment, the thickness E0 of the liquid composition at the deposit is greater than 50 pm.

[0032] According to one embodiment, the viscosity of the enamelable liquid composition is greater than 10 mPa.s at 100s 1 at room temperature.

[0033] According to one embodiment, the inkjet deposition is carried out by a technique called "drops on demand" in which drops of the liquid enamelable composition are deposited on the glass sheet according to the pattern of the relief.

[0034] According to one embodiment, the process further comprises a bending operation during which a radius of curvature is imparted to the glass sheet, the firing being carried out simultaneously with the bending operation. The bending is therefore carried out after the application of the liquid enamelable composition.

[0035] Embodiments of the invention will be described below with reference to the drawings, briefly described below:

[0036] [Fig-1] is a diagram representing a cross-sectional view of an illuminable glazing comprising a layer of enamel on an inner face of a sheet of a laminated glass panel according to an example of an embodiment;

[0037] [Fig.2a] represents a schematic front view of an external side of an illuminable glazing, according to a first embodiment of the invention, comprising a lighting device in an illuminated state;

[0038] [Fig.2b] represents a schematic view similar to that of [Fig.2a], the lighting device being in an off state, according to the first embodiment;

[0039] [Fig.3] is a diagram illustrating an arrangement of a light source in relation to a glazing according to an example of an embodiment;

[0040] [Fig.4] is a diagram representing a cross-sectional view of an illuminable glazing comprising an enamel layer on an outer face of a glass panel comprising a single sheet of glass;

[0041] [Fig.3] is a diagram representing a cross-sectional view of an illuminable glazing comprising an enamel layer on an outer face of a sheet of a laminated glass panel;

[0042] [Fig.5] is a diagram representing a cross-sectional view of an illuminable glazing comprising an enamel layer on an inner face of a sheet of a laminated glass panel;

[0043] [Fig.6] is a diagram representing a cross-sectional view of a sheet of glass on which a composition of an enamelable liquid is being deposited according to an embodiment of the invention;

[0044] [Fig.7] is a diagram representing the deposition of an enamelable liquid composition on a sheet of glass according to an embodiment;

[0045] [Fig.8a] illustrates a cross-sectional view under a scanning electron microscope of the enamel layer of an illuminable glazing according to the invention;

[0046] [Fig.8b] illustrates a scanning electron microscope top view of the screen-printed enamel layer of a reference illuminable glazing;

[0047] [Fig.9a] illustrates the surface roughness profile of an enamel layer deposited by screen printing.

[0048] [Fig.9b] illustrates the roughness profile of an enamel layer according to the invention.

[0049] [Fig. 10a] represents a schematic front view of an exterior side of a motor vehicle comprising an illuminable glazing as a windscreen, according to a second embodiment of the invention;

[0050] [Fig. 10b] is a detail view of [Fig. 10a] along circle Xb at the level of a space on the illuminable glazing;

[0051] [Fig. 1a] represents a schematic front view of an exterior side of a vehicle automobile comprising an illuminable glazing as a windscreen, according to a third embodiment of the invention;

[0052] [Fig. 11b] is a detail view of [Fig. 11a] along circle Xlb

[0053] [Fig. 12] represents a schematic exterior side view of a vehicle comprising illuminable glazing, according to a fourth embodiment of the invention;

[0054] [Fig. 13] represents a schematic exterior side view of a vehicle comprising illuminable glazing, according to a fifth embodiment of the invention;

[0055] [Fig. 14] represents a schematic external and partial perspective view of top of a vehicle comprising illuminable glazing, according to a sixth embodiment of the invention.

[0056] In the drawings, identical reference numerals designate identical or similar objects. The diagrams and schematic views are not to scale.

[0057] The invention relates to a so-called illuminable glazing 1, that is to say, one intended to be associated with a lighting device, as will be explained later. Such illuminable glazing has particular applications in the automotive field, examples of which are given below. However, it may also find applications in other fields, notably the building sector.

[0058] The glazing 1 may, in particular, be a glazing of a motor vehicle, such as a car, truck, or bus, for example. The glazing 1 is preferably fixed, that is to say, it is not intended to be movable relative to the chassis of the part of the vehicle on which it is mounted. Examples include the windshield, a fixed side glazing such as a quarter window, or a rear window.

[0059] The glazing 1 includes, in particular, at least one transparent glass sheet 2, comprising a first principal face, referred to as Fl, intended to face outwards from the vehicle, a second principal face, referred to as F2, substantially parallel to face Fl and intended to face inwards from the vehicle, and an edge. The glass sheet 2 is at least translucent in that it allows at least some visible light to pass through (i.e., light whose wavelengths are in the spectrum visible to the human eye). In practice, the glass sheet 2 is transparent in that it does not significantly block visible light to the human eye, allowing a person on one side of the glass sheet 2 to clearly distinguish objects on the other side. The glass sheet 2 is, for example, tempered glass. It is, for example, a PLANICLEAR® glass sheet from Saint-Gobain.

[0060] The glazing 1 further comprises at least one layer 3 of opaque enamel comprising a fused frit and pigments, and extending over at least a portion of face F2, and generally over strictly only a portion of face F2. According to the embodiment presented, the enamel layer 3 extends along the peripheral edge of the The glass sheet 2 is covered, leaving the center of face F2 free. More precisely, the enamel layer 3 forms a band whose width, i.e., the dimension from a peripheral edge of the glass sheet 2, is, for example, between 2 cm and 10 cm. The enamel layer 3 is opaque, meaning it transmits less visible light than the glass sheet 2. More precisely, the enamel layer 3 has a thickness El of at most 15 µm, and an optical density of at least 5 (five), or even 6 (six). At least one mask 4 is formed on the enamel layer 3.

[0061] Optical density is measured for example according to DIN 4512-8, using a COLORLITE SD350 densitometer, in which the light source is a D65 type illuminant with a measurement range of 3.2 nm and the angle of incidence of the light rays from the light source is 2°.

[0062] According to one feature of the invention, the enamel layer 3 has a roughness parameter, called arithmetic roughness and denoted Ra, of less than 0.3 pm. The roughness parameter Ra can be measured by any known method, allowing the determination of the average gap between the peaks and the pits on the surface of the enamel layer 3.

[0063] For example, the Ra roughness parameter is measured according to ISO4287, by a Perthometer Taylor Hobson Talysurf roughness meter, using a measurement distance of 10mm and a Gaussian filter of 0.8 mm.

[0064] The spacer 4 on the glazing 1 thus makes it possible, in particular when illuminated by a lighting device 5 for the glazing 1, to clearly show the pattern of the spacer 4. The optical density of at least 5 and the roughness Ra less than 0.3 pm of the enamel layer 3 make it possible to avoid all or part of the disadvantages of the prior art, in particular by limiting the blurring effect.

[0065] The lighting device 5 includes, in particular, at least one light source 51 and at least one support 52. The source 51 emits visible light and is preferably direct, such as an LED. The support 52 is arranged so that at least a portion of the light rays from the source 51 reach at least a portion of the recess 4. In practice, the lighting device 5 includes several light sources or a light source sufficiently large to illuminate the entire recess 4. The luminance of the lighting device 5, and more specifically of the source or plurality of sources, can be chosen to meet regulatory requirements depending on the nature of the pattern formed by the recess 4 and the information or indication conveyed by the recess 4.The light emitted by the lighting device 5 is preferably homogeneous and evenly distributed to avoid glare and ensure good visibility.

[0066] The enamel layer 3 can be any color, preferably dark in color to make the recess 4 stand out by contrast when illuminated. The color can be characterized by the L*a*b* or CIELAB parameter system, in which L* is Clarity, a* represents the value on a green-red axis and b* represents the value on a blue-yellow axis. According to one embodiment, the color of the enamel layer perceived by the human eye is black, with the parameter L* which is less than 10, preferably less than 8, and preferably even less than 5, and with the absolute values ​​of parameters a* and b* which are less than 1.

[0067] The light source 51 may be of the LED type, for example, chosen from among miniLEDs, i.e., with a diameter of less than 1 mm, microLEDs, with a diameter on the order of a few micrometers, for example 1 Opm, or nanoLEDs, with a typical diameter of a few nanometers. LEDs with a diameter generally between 3 mm and 5 mm may also be suitable as a light source. In what follows, the term "LEDs" will be used to refer to an LED-type light source.

[0068] Figure 1 schematically illustrates a cross-sectional view of an example of the illuminable glazing 1 comprising a laminated glass panel which includes a first sheet 2 with face F1 facing outwards and face F2 facing inwards. The panel includes a second sheet 2' of glass, a first principal face of which, referred to as F3, faces face F2 of the first sheet 2; the second sheet 2' similarly includes a second principal face, referred to as F4, facing inwards. An interlayer 30, for example of a polymer, preferably PVB (polyvinyl butyral), is between face F2 of the first sheet 2 and face F3 of the second sheet 2'. The enamel layer 3 is preferably deposited on face F2 of the first sheet 2 and / or on face F3 of the second sheet 2'. The lighting device 5 is assembled on face F4 of the second sheet 2' so as to illuminate the pocket 4.Thus, the saving 4 is visible in particular when the lighting device 5 is switched on for a person located on the side of face Fl, through the first sheet 2 and the second sheet 2'.

[0069] More specifically, according to the embodiment illustrated in [Fig. 1], the lighting device 5 comprises a light source 51, for example direct, of the LED type, mounted on a support 52 fixed to the chassis of the part of the vehicle on which the glazing 1 is mounted. The source 51 comprises an LED 53 arranged opposite the recess 4, i.e., the LED 53 is substantially centered with respect to the recess 4 in a given cross-sectional plane. In practice, the source 51 may be in the form of an LED strip. The lighting device 5 further comprises one or more spacers 54 bearing on the support 52 on one side and on a face F2 or F4 of the glazing 1 on the other, in this case face F4 according to the present embodiment, in order to maintain a fixed distance between the source 51 and face F2 or F4. The spacers 54 are for example fixed by gluing onto face F4.

[0070] A diffuser 55 can be arranged between the source 51 and the spacer 4. More precisely, the diffuser 55 is positioned in the path of at least a portion of the light rays from the source 51 to the spacer 4, and in such a way as to diffuse the light rays passing through the diffuser 55. Preferably, the diffuser 55 diffuses all, or at least 90%, of the light emitted by the source(s) 51, i.e., at least 90% of the intensity of the emitted light is diffused. The glare phenomenon is thus limited. Moreover, thanks in particular to the diffuser 55, the source(s) 51 are not visible through the diffuser 55. This results in a homogeneity of illumination satisfactory to the human eye.

[0071] Figures 2a and 2b show an illuminable glazing unit 1 according to a first embodiment. More specifically, Figures 2a and 2b respectively represent an outer face Fl of the illuminable glazing unit 1 comprising a lighting device in an on and off state, respectively. The design of the cutout 4 includes the letters "LOGO" visible through the glass.

[0072] According to the example in Figures 2a and 2b, the relief 4 is positioned in a lower corner of sheet 2. The relief 4 has a characteristic dimension of at least 0.1 mm. The characteristic dimension here refers to a dimension that is limiting for the formation of the relief 4. This characteristic dimension may correspond to the thickness of the lines forming the relief 4, such as the thickness of the letters LOGO. The characteristic dimension is at most 5 cm, and preferably at most 2 cm. For example, the letters LOGO may be 2 cm high by 1 cm wide.

[0073] The position and dimensions of the LEDs 53 of the source 51 can be chosen according to the pattern and dimensions of the recess 4. In particular, the diameter of the LEDs may correspond to the characteristic dimension of the recess for cost reasons. However, the optical density of the enamel layer 3 allows the use of LEDs with a diameter greater than the characteristic dimension of the recess 4, without compromising the legibility and / or visibility of the pattern in the recess 4. In particular, the LEDs may be of standard sizes, without restricting the minimum characteristic dimension of the recess 4.

[0074] The characteristics of the light source 51 are chosen to provide uniform and homogeneous illumination of the entire area 4. These characteristics may include, in particular, the diameter of the LEDs, their distribution, and the diameter of the light cone of each LED. Figure 3 illustrates an example of the diameter of LEDs 53 in relation to the thickness W of the stroke of the letter L in the "LOGO" motif. According to this example, the lighting device 5 comprises a plurality of LEDs 53 distributed according to the shape of the letter L, but with a diameter D greater than the thickness of the stroke of the area 4.

[0075] Preferably, the lighting device 5 is not visible to a person inside the vehicle. For example, the lighting device 5 is masked, in whole or in part, by a trim panel in the vehicle's interior.

[0076] We will now describe several examples of illuminable glazing 1. The elements identical to those in [Fig. 1] and already described are not described again.

[0077] Figure 4 schematically illustrates a cross-sectional view of an example of the glazing 1. An illuminable panel comprising a glass panel formed from a single sheet 2 of glass, with face Fl of sheet 2 on the exterior side and face F2 of sheet 2 onto which the enamel layer 3 is applied. Sheet 2, in this example, is made of tempered glass. The recessed area 4 shown has two characteristic dimensions, denoted W1 and W2, one characteristic dimension W1 being larger than the other characteristic dimension W2. The lighting device 5 comprises a source 51 formed from two LEDs 53 of the same diameter D. The lighting device 5 further comprises a diffuser 55 common to the two LEDs 53. The diameter D of the LEDs 53 is, for example, chosen to be substantially greater than or equal to W1. Thus, the recessed area 4 is particularly visible when the lighting device 5 is switched on for a person located on the side of face Fl, through sheet 2.

[0078] Figure 5 schematically illustrates a cross-sectional view of another example of the illuminable glazing 1 comprising a laminated glass panel, with two sheets 2, 2', having the four faces F1, F2, F3, F4 already described with reference to Figure 1. As before, the recess 4 shown has two characteristic dimensions, denoted W1 and W2, one characteristic dimension W1 being larger than the other characteristic dimension W2. The lighting device 5 comprises a source 51 formed of three LEDs 53 of the same diameter D. The lighting device 5 further comprises a separate diffuser 55 for each of the three LEDs 53. The diameter D of the LEDs 53 is chosen independently of the dimensions W1 and W2. However, the diameter D and / or the distribution of the LEDs 53 are chosen so that the entire saving 4 is reached by light rays from the LEDs 53, for a homogeneous rendering when the lighting device 5 is switched on.

[0079] Figure 6 illustrates a cross-sectional view of another example of the illuminable glazing 1 comprising a laminated glass panel, with two sheets 2, 2', having the four faces F1, F2, F3, F4 already described with reference to Figure 1. As before, the recess 4 shown has two characteristic dimensions denoted W1 and W2, one characteristic dimension W1 being larger than the other characteristic dimension W2. The lighting device 5 comprises a source 51 formed of two LEDs 53, each with a different diameter denoted DI and D2, the diameter DI being larger than the diameter D2. A diffuser 55 common to the two LEDs 53 is arranged on the path of the light rays. The diameters DI and D2 and the distribution of the LEDs 53 are chosen so that the entire storage area 4 is illuminated by the LEDs 53.

[0080] The illuminable glazing 1 may correspond to any variant or combination of the examples shown. In particular, the number of LEDs 53, their size, their distribution and the diffuser(s) 55 are determined so as to ensure uniform and homogeneous illumination of the entire storage area 4.

[0081] We will now describe a manufacturing process for such illuminable glazing 1.

[0082] A liquid enamelable composition is chosen, comprising at most 80% by mass of inorganic solid matter, preferably between 55% and 65% by mass of inorganic solid matter. This solid matter includes, in particular, particles containing a glass frit and pigments. The glazeable liquid composition comprises at most 50% by mass of liquid matter. For example, the glass frit in the liquid composition contains particles of bismuth (Bi) and / or zinc (Zn) and / or borosilicate. Preferably, the liquid composition does not contain lead (Pb). The particle size distribution of the glazeable liquid composition, denoted D90, or maximum D90 particle size, is less than 2.5 µm, meaning that 98% of the particles in the glazeable liquid composition are smaller than 2.5 µm. Preferably, the D90 particle size is less than 2 µm, or even less than 1.5 µm, and greater than 1 µm.

[0083] The particle size distribution of the glazeable liquid composition can be measured with a laser diffraction particle size analyzer. For example, a sample of the glazeable liquid composition is taken and mixed with a suitable solvent to dilute the liquid medium and suspend the particles in the liquid phase. The mixture is homogenized, and drops taken with a pipette are placed in the particle size analyzer. For example, approximately 30 mg of the glazeable liquid composition is taken and placed in a beaker or other container. The solvent used could, for example, be a TCG 11537 M reference rinsing solution. Approximately 20 mL are placed in the beaker with the glazeable liquid composition. The particle size analyzer used is, for example, a MALVERN MASTERSIZER MS2000 or MS3000; the darkening level can be set between 5% and 10%, and the refractive index can be set to 1.43.

[0084] TECGLASS company ink compositions 1A024 and 1A007 may be suitable.

[0085] The liquid enamelable composition is deposited on one side of the glass sheet 2, 2' using the inkjet printing technique. Inkjet printing consists of depositing a layer 6 of the enamelable composition by ejecting the composition through at least one print head 7, and directing the print head(s) towards the areas where the enamel layer 3 is to be formed. The print head(s) are mounted on a a machine tool with at least three axes to move the printing head 6 over the entire surface of the sheet 2 on which the enamel layer is to be formed, in this case face F2 in the example of [Fig. 5]. The deposition can however be carried out on face F2 of the first sheet 2 or on face F3 of the second sheet 2', or on face F4 of the second 2', or on a combination of two or three of these faces F2, F3, and F4, by matching the pattern of each relief 4.

[0086] For this printing process the print head(s) can be in a fixed position and it is the glass sheet that moves under the print head(s).

[0087] According to one embodiment, the average relative speed of the print head with respect to the glass sheet is between 6 and 12 m / min*, preferably between 8 and 10 m / min¹ and, for example, 7 m / min². The distance between the print head exit 7 and the face F2, F3, or F4 of the sheet 2, 2' on which the deposit is made is preferably at least 0.5 mm to avoid any risk of collision with the sheet 2, 2'. The maximum distance is, for example, 2.5 mm, and preferably 1.5 mm.

[0088] More specifically, according to one embodiment, the enamelable liquid composition is deposited by inkjet printing using one or more print heads 7, located above the glass sheet 2 at a distance of between 0.5 and 4 mm. Each print head 7 generates droplets 71 with a volume of between 6 and 120 pL (picoliters) on demand. The glass sheet 2, 2' is presented substantially horizontally, with the face F2, F3, or F4 on which the enamel layer 3 is to be formed facing upwards. The sheet 2, 2' may be in continuous motion during the deposition step, and the print head(s) 7 may remain fixed in a reference frame external to the sheet 2, 2, or stationary, in which case the print head(s) 7 move above the sheet 2, 2'. For application to the automotive field, the deposition method is called "single pass", meaning that the enamelable liquid composition is deposited in a single pass.More specifically, the glass sheet 2, 2' travels continuously without stopping, at a speed between 6 and 18 m / min*, relative to the print head(s) 7. The movement of the print head(s) 7 is determined in the frame of reference linked to the sheet 2, 2'. The ejection of the droplets 71 by each print head 7 is controlled by a computer system that takes into account the pattern or design of the relief 4 to be formed, as well as the dimensions, position, and, where applicable, the travel speed of the glass sheet 2, 2'. The computer system, having knowledge of all this information, can synchronize the ejection of the droplets 71 so that each droplet of the enamelable liquid composition lands at the required position on the glass sheet 2, 2'. The printing method is called "drop on demand" or "Drop On Demand" (DOD): only. The droplets 71 strictly necessary for the formation of the pattern of the spacer 4 are generated. These droplets 71 then fall by gravity onto the sheet 2, 2' of glass so as to form the desired pattern.

[0089] According to one embodiment, the volume of each droplet of enamelable liquid composition can be adapted according to the final position of the droplet on the resist design. In particular, to avoid the formation of a ridge due to the migration phenomenon at the edge of the deposited layer, the volume of the droplets at the edge of the enamel layer 3 can be less than the volume of the droplets elsewhere on the enamel layer 3. The term "edge of the enamel layer 3" here refers to a boundary between an area that, once the enamelable liquid composition is fired, will include the opaque enamel layer 3 and an area devoid of the enamel layer 3, for example, the boundary between the enamel layer 3 and the resist design 4, as well as the outline of the enamel layer 3.The migration phenomenon partially compensates for the volume reduction. The reduction in thickness of the enamel layer 3 that might occur at the level of the smaller droplets means that the opacity and optical density of the enamel layer 3 are not affected. Furthermore, by reducing the volume of the droplets at the edge of the deposited layer, the deposition of the liquid enamel composition is carried out with greater precision, resulting in a sharper design of the relief pattern 4.

[0090] In order to control the thickness E1 of the enamel layer 3 of the glazing, the enamelable liquid composition has a viscosity of at most 30 mPa·s at a shear rate of 100 s⁻¹. Preferably, the viscosity is at most 25 mPa·s, and preferably between 20 mPa·s and 100 s⁻¹, at a shear rate of 100 s⁻¹ at room temperature. According to one embodiment, the viscosity of the enamelable liquid composition is greater than 100 mPa·s at a shear rate of 100 s⁻¹ at room temperature. The enamelable liquid composition is then deposited to a thickness E0 of at most 100 pm, preferably at most 90 pm, and preferably even more preferably at most 70 pm. The deposit thickness E0 of the enamelable liquid composition is at least 15 pm, and preferably greater than 50 pm.

[0091] The deposition step may lead to the uncontrolled ejection of droplets into the area intended to form the relief 4. However, such droplets may be acceptable depending on their size and number, particularly if they are not detectable by the human eye, and / or they do not significantly degrade the pattern of the relief 4 to the point of rendering it illegible. For example, such droplets may fall into the area intended to form the relief, but near the edge of the enamel layer 3, so as to partially blend with the droplets that fell into the area of The enamel layer 3, giving an irregular appearance to the edge of the enamel layer 3. An example of irregular edges is illustrated in [Fig. 1 1b], described further below.

[0092] The process also includes a drying step to remove all or part of the organic matter from the liquid enamel composition, in order to obtain an enamel layer 3 with high mechanical strength. More specifically, the drying allows the temperature of the liquid enamel composition to be gradually increased without melting the solid particles, so that the majority of the organic liquid components, such as solvents and / or resins, evaporate gently during drying, preventing the formation of bubbles and giving the enamel layer 3 a homogeneous appearance. In one embodiment, the drying is carried out by IR (infrared) heating with a heat flow, using an infrared tunnel or furnace.The drying temperature is at least 120°C, or even 130°C, and at most 200°C, or even 180°C, for a duration of at least 30s, or even 40s, and preferably at least 2 min.

[0093] Once the drying step is complete, the process includes a firing step of the glass sheet 2 coated with the liquid enamelable composition. The firing is carried out at a temperature of at least 500°C in order to obtain the enamel layer 3 and the resist layer 4. The firing may be followed by rapid and sudden cooling in order to thermally temper the glass sheet 2, 2'.

[0094] In the case of the laminated glass panel in which the enamel layer 3 is applied to face F4 of the second sheet 2', the firing step is carried out on the two sheets 2, 2' previously matched on a skeleton to achieve the curvature. After firing, the two sheets 2, 2' are optionally cooled, washed and dried, and if necessary, the interlayer layer 30 is inserted between the two sheets 2, 2' to achieve the lamination.

[0095] In the case of the laminated glass panel in which the enamel layer 3 is between the two glass sheets 2, 2', the deposition step is carried out on face F2 of the first sheet 2 and / or on face F3 of the second sheet 2'. The firing step is carried out as before, on the two sheets 2, 2' previously paired on a skeleton. After firing, the process further includes the application of the interlayer layer 30 and the lamination of the two sheets 2, 2'.

[0096] According to one embodiment, the glazing 1 is curved, that is, it has a non-zero radius of curvature. In practice, the radius of curvature is positive on the side intended to face the interior of the vehicle, i.e., on the side of F2 and / or F4. To this end, the process may include a curvature step, which is carried out simultaneously with the baking step, after the deposition of the liquid enamelable composition. The curvature step is implemented in particular when the glazing is intended for the automotive sector.

[0097] According to one embodiment, the process is carried out at least partially in continuous conveying. More specifically, the glass sheet(s) 2, 2' are transported substantially horizontally, for example flat on face Fl, and at least the deposition and drying steps are carried out continuously, that is, without stopping during and between these steps. The firing step can also be carried out in continuous conveying, or with the conveyor stopped.

[0098] The enamel layer 3 thus obtained on the resulting glazing is illustrated in Figure 8a. Figure 8b illustrates a typical enamel layer 3' obtained by a screen-printing process. These images are taken within the thickness of the enamel layer after firing. They are obtained by scanning electron microscopy (SEM) of a cross-section of the enamel layer over an area of ​​10 µm². In the two images, 8a and 8b respectively, one can distinguish darker areas and / or areas with irregular outlines forming pores, 9 and 9' respectively, and lighter areas and / or areas with regular outlines forming crystallites, 10 and 10' respectively. Thus, one can distinguish, for example, pores 9 and 9', the maximum diameter of pores 9' in the enamel layer 3' obtained by screen printing being greater than that of pores 9 in the enamel layer 3 according to the invention. Various measurements can then be taken on these images, particularly through image processing techniques.For example, if necessary, the images can be processed by digital analysis, for example using Matlab software. In particular, the following measurements can be performed: • the pore count Tp by volume, that is to say the quantity of pores detected on a volumetric portion of the cross-section of the 3,3' layer of enamel; • the volume fraction of crystallites Te, that is, the quantity of crystallites detected on a volume portion of the cross-section of the enamel layer 3, 3'; • the maximum radius of the pores (pore max radius).

[0099] The table below presents the measurements of crystallite content (Te) and pore content (Tp) obtained for eight samples of enamel 3 according to the invention, numbered #1 to #8 in the table below, and three samples of enamel 3' obtained by screen printing, numbered Ref 1 to Ref 3 in the table below. For each sample, the firing temperature T, the initial thickness E0 before firing, the final thickness El after firing, and the optical density D are specified. The ratio is also calculated. Tc(% ) Tp (%) Max radius pores (pm) T c / Tp ratio T (°C ) E0 (pm) El (pm) D #1 6.8 5.1 0.55 1.34 600 60 12.5 to 13.5 >6.1 #2 7.6 3.2 0.65 2.34 600 60 12.5 to 13.5 >6.1 #3 8.0 6.1 0.75 1.30 600 60 12.5 to 13.5 >6.1 #4 6.4 5.3 0.65 1.20 600 60 12.5 to 13.5 >6.1 #5 13.6 7.5 0.65 1.83 620 60 12.5 to 13.5 >6.1 #6 14.7 8.5 1 1.72 620 60 12.5 to 13.5 >6.1 #7 14.0 10.0 1.2 1.40 620 60 12.5 to 13.5 >6.1 #8 11.4 7.6 1 1.50 620 60 12.5 to 13.5 >6.1 Ref 1 13.2 2.5 1.25 5.19 600 25 12 to 14 4 Ref 2 17.2 4.8 1.4 3.57 600 25 12 to 14 4.1 Ref 3 17.7 3.1 1 5.80 620 25 12 to 14 4.3

[0100] Thus, the 2L ratio for samples #1 to #8 of enamel 3 according to the invention is less than 3, and for example greater than 1, and the pore size (Tp) is preferably less than 15%. The ratio for screen-printed samples Ref 1 to Ref 3 is greater than 3.

[0101] Figures 9a and 9b illustrate the roughness profile Ra measured respectively on a screen-printed enamel layer and an enamel layer according to the invention, using a Taylor Hobson roughness tester. The roughness profile of the screen-printed enamel layer ([Fig. 9a]) exhibits a repeating pattern: peaks and valleys can be identified that repeat at a frequency of approximately 4 to 5 peaks per millimeter, with a maximum roughness (Rz) greater than 5 µm and a total height (Rt) greater than 8 µm. Such a pattern is typical of the screen mesh used in screen printing. By comparison, the roughness profile of the enamel layer according to the invention ([Fig. 9b]) does not exhibit such a pattern, but rather a noise profile, with a maximum roughness (Rz) less than 1.5 µm.

[0102] Thanks in particular to the deposition by inkjet of the enamelable liquid composition to Thanks to the aforementioned characteristics, the pattern of the 4-inch pocket can be produced with increased precision, resulting in sharp outlines. The blurring effect for the human eye is then very limited, or even nonexistent. Comfort is improved.

[0103] The illuminable glazing 1 can thus be used for both informational and purely decorative purposes.

[0104] According to one embodiment, the color of the light emitted by the lighting device 5 can follow the color code of the vehicle's lights, such as red for braking, white for reversing, amber for indications relating to the operation of the vehicle intended for the driver, red for the rear lights.

[0105] Thus, according to one embodiment, the recess 4 complements the vehicle's lights, such as brake lights, front or rear turn signals, reversing lights, fog lights, etc. For example, the glazing 1, comprising the enamel layer 3 and the recess 4, can be used as a rear window of a vehicle. The design of the recess 4 can then be chosen to provide a reminder to following vehicles, such as a turn signal or reversing reminder, or additional information such as a malfunction or being too close. The lighting device 5 can be controlled in the same way, and / or simultaneously, with the vehicle's lights.

[0106] Figure 10a shows a schematic front view of an exterior side of a motor vehicle 100 comprising an illuminable glazing 1 in a second embodiment of the invention, wherein the illuminable glazing 1 is the windshield 101 of the vehicle. The windshield 101 includes, in a lower corner on the right side when the vehicle is viewed from the front as in Figure 10a, a symbol formed by an enamel layer 3 comprising a recess 4 as shown above, a detailed view of which is given in Figure 10b. According to the example, the enamel layer 3 and the recess 4 form an arrow, which is visible from the outside. The arrow can then form a turn signal indicator: the arrow can be illuminated steadily or flashingly, to indicate the intention to turn, like a turn signal.

[0107] Generally, the windshield 101 has a frit forming a black frame 102 around all or part of its periphery. The enamel layer 3 can then blend into the black frame 102, so as to give an impression of continuity of the black frame 102. The enamel layer 3 and the masking 4 can, however, be made anywhere on the windshield 101, provided that the visibility requirements for the driver are met. The black frame 102 can be made in the same way as the enamel layer 3, i.e., by the same inkjet deposition process of the liquid enamelable composition described above, or by other techniques using other materials.

[0108] Figure 1a shows a schematic front view of an exterior side of a motor vehicle 100 comprising an illuminable glazing 1 in a third embodiment of the invention, in which the illuminable glazing 1 is the windshield 101 of the vehicle. The windshield 101 comprises, as before, a black frame 102, of which an upper edge 103 is said to be degraded, formed by the enamel layer 3 and the relief 4 so as to draw a plurality of distinct point elements, for example, substantially square and / or rectangular shapes 4a which alternate with square and / or rectangular shapes 3a of enamel layers 3, for a decorative purpose, as illustrated in the detail view of [Fig. 11b]. According to this example, the relief 4 is open, in that it does not have a contour closed by the enamel layer 3.

[0109] Figure 12 represents in a fourth embodiment according to the invention a schematic external, side view of a vehicle 110 comprising illuminable glazing 1, which is fixed, and which is in particular side glazing 111 such as the fixed glazing of the front doors and the quarter windows, the glazing 112 of the rear window and the windscreen 113. The glazing 111, 112 and 113 may have a clear glass 114 and on a face F2 or F4 a black frame 115 in which the enamel layer 3 comprising the resist 4 is fused.

[0110] Fig. 13 represents in a fifth embodiment according to the invention a schematic external, side view of a vehicle 120 of the mobile home or van type comprising glazing 1 illuminable on fixed side glazing 121 and on the windscreen 122, comprising the enamel layer 3 and the shielding 4.

[0111] Fig. 14 represents in a sixth embodiment according to the invention a schematic external and partial top perspective view of a vehicle 130 comprising a glazing 1 illuminable on the glazing of the roof pavilion 131.

Claims

Demands

1. Vehicle glazing (1) illuminable, comprising at least one sheet (2, 2') of glass with at least one layer (3) of opaque enamel of thickness (El) of not more than 20 pm, the enamel layer (3) comprising a fused glass frit, pigments and with at least one relief (4) drawing a pattern, the enamel layer (3) having an optical density of at least 5 and a roughness parameter Ra less than 0.3 pm over a measurement length of 10mm with a 0.8mm Gaussian filter.

2. Glazing (1) according to the preceding claim wherein the thickness is at most 18pm and even at most 15pm and preferably the optical density is at least 5.

5.

3. Glazing according to claim 1 or claim 2, wherein the opaque enamel layer (3) comprises crystallites (10) and pores (9) and has a ratio between a crystallite content Te by volume and a pore content Tp by volume that is less than 3, preferably with a pore content of less than 15% by volume.

4. Glazing any one of the preceding claims, wherein the opaque enamel layer (3) has a colorimetry L*a*b* with an L* value less than 10, and parameters a* and b* with a value less than 1.

5. Glazing (1) according to any one of the preceding claims, comprising a lighting device (5) emitting visible light radiation suitable for illuminating the storage area (4), said lighting device (5) comprising at least one light source (51) disposed opposite said storage area (4), and in which the lighting device (5) is assembled to the glass sheet (2, 2') by a face F2 or F4 of the glass sheet (2, 2') which is intended to be turned towards the interior of the vehicle.

6. Glazing (1) according to the preceding claim, wherein the light source (51) is selected from miniLEDs, microLEDs or nanoLEDs.

7. Glazing (1) according to claim 5 or 6, wherein the lighting device (5) comprises at least one diffuser (55) disposed between the light source (51) and the spacer (4).

8. Glazing according to any one of the preceding claims, wherein the opaque enamel layer (3) is made on all or part along a peripheral edge of the glass sheet (2, 2') and in particular forming a band of width in a range from 2 to 10 cm.

9. Glazing (1) according to any one of the preceding claims, wherein the glazing (1) is intended to be installed as fixed side glazing, in particular quarter window, or rear window or windscreen of the vehicle.

10. A method for manufacturing an illuminable glazing (1) in particular for a vehicle according to any one of the preceding claims, the enamel layer (3) being produced by a step of deposition on the glass sheet (2, 2') of an enamelable liquid composition including particles comprising a glass frit and pigments, followed by a baking step, the method being characterized in that it comprises: • the deposition by inkjet onto the glass sheet (2, 2') of the enamelable liquid composition comprising at most 80% by mass of inorganic solid matter including particles comprising a glass frit and pigments, and comprising at most 50% by mass of liquid matter, the liquid composition being deposited to a thickness (E0) at deposition of at most 100pm and at least 15pm, having a viscosity of at least 5mPa.s at a shear rate of 100s 1 at room temperature, and having a particle diameter distribution D90 less than 2.5pm and at least 1 pm; • a drying removing all or part of the organic matter; • the firing of the glass sheet (2, 2') for the formation of said opaque enamel layer (3) comprising said at least one illuminable spatter (4) from the enamelable liquid composition.

11. Method according to the preceding claim, wherein the deposition and drying are carried out by continuously, horizontally moving the glazing (1).

12. A method according to claim 10 or claim 11, wherein the thickness (E0) at the deposition of the liquid composition is greater than 50 pm.

13. A method according to any one of claims 10 to 12, wherein the inkjet deposition is carried out by a so-called "drops on demand" technique in which drops of the enamelable liquid composition are deposited on the glass sheet (2, 2') according to the pattern of the relief (4).

14. A method according to any one of claims 10 to 13, wherein the drying is by heating with infrared waves with heat flux, and is carried out at a temperature of at least 120°C and at most 200°C for at least 30s.

15. A method according to any one of claims 10 to 14, comprising assembling a lighting device (5) with said at least one sheet (2, 2') of glass by a face F2 or F4 of the sheet of glass (2, 2') which is intended to be turned towards the interior of the vehicle, the lighting device (5) comprising at least one light source (51) and a support (52), the light source (51) being arranged opposite the spacer (4).

Images