ROOF GLAZING FOR MOTOR VEHICLES

Description

[0001] The present invention relates to a motor vehicle roof (hereinafter referred to more simply as "automobile roof"), incorporating glazing and its manufacturing method.

[0002] Many comfort features exist in motor vehicles, in particular features integrated into the passenger compartment of vehicles, such as sunroofs, which may or may not be glazed. These specific roof sections, when glazed, allow more light into the vehicle, provide passengers with a pleasant view of the sky, and, if necessary, allow fresh air to enter, without the disadvantages of a simple opening in the roof. The glazing used for these glazed sunroofs is traditionally transparent for aesthetic and comfort reasons and to allow a pleasant exterior view, and may also be made of tinted glass, in particular to protect users from solar radiation.

[0003] Where appropriate, these automotive roof glazings may be fitted at their periphery with an opacifying frame, generally made of enamel, in order to cover in particular the structure of the passenger compartment on which the glazing is mounted (for example to hide a bead of glue), this frame (or this peripheral strip) being usually of small dimensions so as not to impair the desired clear view and vision, and of classically black color. Alternatively, fine prints of white enamel can also be used to allow the diffusion of light produced by diodes fixed in the edge of a laminated glass. All these localized enamel prints are traditionally produced by screen printing, using screens or screen printing templates appropriate and specific to each size of glazing.

[0004] FR 2 705 335 A1, WO 2019 / 239055 A1, FR 2 703 043 A1, and EP 0 636 588 A2 disclose glazing units comprising a glass sheet, in which the glass sheet is coated with an enamel layer. Said enamel layer is applied to the glass substrate by screen printing. Furthermore, none of these documents relates to vehicle roof glazing units.

[0005] The purpose of document WO 2022 / 123161 A1 is to improve the mechanical strength of a glazing unit provided with enamel, electrically conductive patterns and a connector welded using a solder alloy. This application discloses a method for obtaining a glazing unit comprising the steps of depositing an enamel coating by inkjet printing and an electrically conductive layer forming patterns.

[0006] The present invention sought to develop new automobile roofs expanding the range of existing products while being compatible with the requirements of the automobile market and the manufacturing constraints in this field, and in particular new glazing for automobile roofs offering more varied possibilities of customization on demand while guaranteeing good comfort for the user, the obtaining of these new glazings remaining sufficiently simple and compatible with the constraints of industrial processes for automobiles.

[0007] This objective has been achieved by means of a method for manufacturing a motor vehicle roof incorporating glazing, in which at least one opacifying layer of ink(s), in particular at least one layer of colored ink(s), is applied by digital printing, in particular by inkjet, to at least 40% of the surface of one of the faces of at least one glass sheet, such that the composition of said ink(s) comprises at least one glass frit, and where appropriate one or more inorganic pigment(s), with a D90 value of the particle size distribution of less than 2 µm, and such that said ink(s) have a viscosity of between 1 and 50 mPa.s, said ink(s) further comprising an anti-adhesive agent and / or component and / or at least one anti-adhesive agent and / or at least one anti-adhesive layer being further applied to at least one layer ink(s) and / or on at least one sheet of glass.The method according to the invention can be characterized in that the printing is carried out using a single-pass printing machine. The method according to the invention can be characterized in that the printer used is equipped with six sets of print heads to enable printing with a set of six colors. The method according to the invention can be characterized in that the surface tension of the ink is between 20 and 40 mN / m.

[0008] A product obtained by said process also made it possible to achieve this objective, this product being a motor vehicle roof capable of being obtained by said process, said vehicle roof incorporating glazing comprising: one or more sheets of glass, at least one sheet of glass being coated on at least 40% of the surface of at least one face with at least one opacifying layer of ink(s), such that the composition of said ink(s) comprises at least one glass frit, and at least one layer of ink(s) and / or at least one sheet of glass being coated with at least one anti-adhesive agent and / or at least one anti-adhesive layer, and / or at least one layer of ink(s) comprising at least one anti-adhesive agent and / or component. The motor vehicle roof according to the invention may be characterized in that the opacifying layer of ink(s) is at least one layer of colored ink(s). The motor vehicle roof according to the invention may be characterized in that the composition of said ink(s) comprises one or more inorganic pigment(s). The motor vehicle roof according to the invention may be characterized in that said glazing is a monolithic glazing formed from a single sheet of glass, said sheet being coated with at least one layer of said ink(s) on one face, in particular face F2, or characterized in that said glazing is preferably a laminated glazing formed from at least two sheets of glass and an interlayer, at least one of said sheets of glass being coated with at least one layer of said ink(s) on one face, in particular face F2, F3, or F4. 9. The motor vehicle roof according to the invention may be characterized in that said glazing has a light transmission TL of less than 10%, in particular less than or equal to 0.1%, or an optical density greater than or equal to 1, in particular greater than or equal to 3. The motor vehicle roof according to the invention may be characterized in that two different decorations are printed, for a different effect on the outside and inside of the passenger compartment. The motor vehicle roof according to the invention may be characterized in that several layers of ink are superimposed on the same face in order to produce a double image, for example a first layer or print forming a first image, a second layer or print being a layer of white, and a third layer or print forming a. second image. The motor vehicle roof according to the invention may be characterized in that said glazing is provided, on the same face and / or on at least two different faces of glass sheet(s) of the glazing, with at least two different coatings or two different layers including at least one layer of said ink(s), the second layer or second coating being either a second mineral layer formed of digital printing ink(s), or a layer with a decorative effect different from said layer(s) of ink(s), or a layer or coating or film or sheet with an additional functional effect, in particular in terms of thermal comfort, such as a low-emissivity coating or solar control.

[0009] The present invention has made it possible to develop a decoration solution compatible with automotive production lines and expanding the range of existing automotive roof products by making it possible to produce a whole new variety of decorations on demand, and in particular decorations in color(s), these decorations being obtained in a simple and economical manner. Depending on the face(s) on which one or more layers of ink are deposited (in particular and advantageously one or more colored ink layers), one or more decorations can be produced giving different appearances depending on whether the glazing is observed from one side or the other.The invention makes it possible, for example, to obtain an opaque glass roof retaining the aesthetics of the glass and its brilliance on the exterior of the vehicle, and a personalized decoration on the interior, decoration imitating, for example, a landscape, a sunny sky or a starry night, or materials (for example a carbon, wood or leather effect), depending on the customer and / or the interior decoration of the vehicle, etc., or conversely to have an opaque glass rendering on the interior of the vehicle and a personalized decoration on the exterior, or even two identical or different personalized decorations on the interior and exterior.

[0010] Digital printing (this technique for printing documents directly from computer data) used according to the invention offers infinite decoration possibilities, starting in particular from any photo having a good resolution, for example greater than or equal to 700 dpi (or "ppi" or "pixels per inch"), or from a vector file. In addition to the varied decoration possibilities, the method can also be used to obtain technical effects, such as anti-reflective effects (the printed layer being for example selected to be matte) or anti-fingerprint effects, or a functional coating, for example allowing interactions with light, or having conductive tracks, etc.

[0011] In addition to allowing the production of high-quality, high-resolution (photographic-type) prints at high speed, on, where appropriate, small series or by customizing to the piece without requiring expensive equipment or complex equipment changes, digital printing is adaptable to the geometric constraints of the products (contactless method) and allows a wide variety of decorations to be obtained with few difficulties compared to the screen printing methods currently used in the automotive industry. The image to be printed can be stored digitally, avoiding the need for screens, engravings, etc., unlike screen printing methods which require a specific screen for each decoration and each product to be coated.It allows the printing of large areas and offers a wide gamut of reproducible colors using a reduced set of primary colors, whereas screen printing methods require different screens for each color. The design can be printed very flexibly from computer-generated image files and the printing technique can be interfaced with image processing devices allowing easy and rapid modification of template images to further vary the prints and offer great freedom of design. No stops or cleaning are necessary between different designs and ink waste is avoided, as ink is only deposited where needed.

[0012] A disadvantage of digital printing, however, being the small size of the nozzles of the print heads, the present invention has also selected inks allowing the desired printing for the desired application without worries, in particular, of nozzle obstruction.

[0013] It should be noted that the deposition of inks has already been attempted on glass, mainly for the decoration of architectural glass, however the solutions developed so far have proven to be poorly suited for the decoration of automotive glazing due in particular to problems linked to the requirements of automotive manufacturing (such as the high speed of production lines) or even problems of adhesion to the forming dies of automotive glass. Furthermore, the formulations usually used for screen printing deposition in the automotive industry cannot be used directly in digital printing methods such as inkjet, these formulations, in particular viscous and with a particle size greater than 5 µm, being likely to clog the printing nozzles.

[0014] In particular, the multi-pass printers used until now for architectural glass have shown too low productivities incompatible with the cycle times typical of the automotive markets (the coating steps must generally not exceed 60 s per glass). In addition, since the glazing used for automobile roofs is generally curved, it was not possible to apply coatings over a large surface, in particular on parts that had to be brought into contact with other glass or forming or bending dies, due to the sticking problems that could arise during forming or bending or folding or bending.

[0015] Until the present invention, there was therefore no technique allowing the easy and economical decoration of automobile roof glazing, while respecting the constraints, in particular thermal and mechanical, specific to this application, and while offering great flexibility and numerous possible variations of decoration.

[0016] The motor vehicle roof incorporating the glazing according to the invention may comprise one or more sheets of (or "made of") glass. In particular, it may be a monolithic glazing unit, consisting of a single sheet of tempered or reinforced (thermally or chemically) glass, or it may be a laminated glazing unit, consisting of at least two sheets of glass assembled by means of an interlayer, as detailed below.

[0017] The glass sheets (or "panes" or "glass plates" or "glass substrates" or "glasses") are advantageously sheets of soda-lime glass (advantageously mineral), and may be transparent and colorless (in particular clear or "extra clear" glass, i.e. with a light transmission TL greater than 90%) or may be colored or tinted (generally in the mass). They are usually of geometric shape, in particular quadrilateral or rectangular or square, and may be flat or curved / bent. Preferably, they are curved, their shape in particular following the curvature of the roof. They are also generally smooth, i.e. without textures.

[0018] The glass sheets preferably have a thickness (for each) between 0.7 mm and 6 mm, in particular between 1 mm and 4 mm, for example a standard thickness of 1.6 mm or 2.1 mm. The total thickness of the glazing is preferably less than 5 mm.

[0019] Preferably, the automobile roof glazing according to the invention is a laminated glazing comprising at least two sheets of glass, said sheets being bonded together adhesively by means of a lamination interlayer, this glazing comprising more precisely: a first sheet of glass, called "external" i.e. intended to be positioned outside the passenger compartment of the vehicle, and having two main faces (larger faces) called respectively face 1 (or F1), face to be turned towards the outside, and face 2 (or F2), face to be turned towards the interlayer, a lamination interlayer (or interlayer or interlayer film or interlayer or intermediate sheet), a second sheet of glass, called "internal" i.e. intended to be positioned inside the passenger compartment, and having two main faces called respectively face 3 (or F3), this face being turned towards the interlayer, and face 4 (or F4), this face being turned towards the passenger compartment.

[0020] It should be noted that the terms "first" or "second" above are only used to distinguish between the various sheets and do not refer to an order of filing or arrangement.

[0021] In the case of laminated glass, the outer glass sheet is generally no more than 2.1 mm thick, the inner sheet being able to be of the same thickness or less than that of the outer sheet, one and / or the other glass being able to be, or not, chemically or thermally toughened (for safety reasons).

[0022] If necessary, one and / or the other glass can be tinted, depending on the positioning and the choice of decoration, and / or the lamination interlayer can be colored, to limit the penetration of heat into the passenger compartment by absorbing infrared rays.

[0023] The lamination interlayer is in the form of one or more sheets or films or sheets, hot-melt and adhesive, made of polymeric material, in particular formed from at least one thermoplastic polymer or copolymer, such as ethylene-vinyl acetate (EVA), polyvinyl butyral (PVB) or polyurethane (PU), or mixtures or copolymers or derivatives thereof, the interlayer most generally being made of PVB. It can also be composite (for example a composite of PVB and a polyester film or a polyethylene terephthalate film or a plasticizer for vibro-acoustic damping properties). The total thickness of this interlayer (whether in one or more sheets) is generally less than 1 mm, in particular 0.7 mm or 0.3 mm, this interlayer being able to be transparent, clear, extra-clear or possibly tinted.

[0024] As indicated according to the invention, the layer of ink(s) deposited or the coating comprising said layer of ink(s) (or the layers of ink(s) deposited one on the other when there are several superimposed), covers at least one of the main faces of a glass sheet of the glazing according to the invention over at least 40% of its surface, preferably at least 50% of its surface, and particularly preferably at least 75% of its surface, or even over its entire surface.

[0025] By layer of ink(s), it is meant that the layer may be formed from one or more inks (each advantageously meeting the definition given in the invention) where appropriate mixed and / or superimposed, simultaneously (simultaneous deposits for example during the same inkjet printer pass) and / or possibly consecutively (several passes forming said layer). In particular, several primary color inks may be superimposed to form the layer, the printed image thus being formed from a large number of small spots or drops of juxtaposed inks.

[0026] The thickness of each layer of ink(s) is in particular between 3 and 8 microns. If necessary, several layers of ink(s) may be deposited one on top of the other, each deposition then being followed by drying, as described later, the total thickness of the coating formed in this case being preferably between 3 and 20 microns. By thickness of a layer is meant the geometric thickness (also called physical or real), this thickness being measured once the ink has been heat-treated to remove the solvent and any other organic part(s) from the composition.

[0027] The inks used according to the invention are essentially mineral inks (formed solely from inorganic / mineral components with the exception of the solvent and additives that are removed during the glazing forming or ink baking process) and are in particular so-called “ceramic” inks, having an enamel-based formulation selected to be compatible with the desired printing. They are in particular formed from at least one glass frit (or a mixture of glass frits), intended to melt during the subsequent heat treatment to form a vitreous matrix that will bond to the substrate. The composition of the inks according to the invention may also comprise one or more pigments that are fixed to the substrate by the frit, the pigment(s) advantageously being inorganic / mineral pigments (unlike conventional inkjet formulations that generally comprise organic pigments).Said pigments have in particular an average diameter of less than 500 nm, more preferably an average diameter of between 100 and 300 nm. The average diameter can be measured using a scanning electron microscope (SEM). Said pigments have the advantage of not being altered during the process, in particular after drying and baking of the inks. In addition to this solid fraction, the composition of the inks also initially comprises a liquid fraction, formed of at least one solvent and, where appropriate, one or more additives.

[0028] The glass frit is preferably based on bismuth borosilicate, and / or optionally based on zinc borosilicate. The mass (or weight) fraction (or percentage) of the glass frit in the mineral ink is preferably between 10 and 50%, in particular between 15 and 50%. The pigments may be any known mineral pigment or any mixture of known mineral pigments, and are in particular based on one or more compounds or oxides such as chromium oxide, titanium dioxide, iron oxide, cobalt titanate, cobalt chromate, cobalt silicate, tin chromate, iron zirconate-silicate, manganese chromate, cobalt phosphate, etc. The mass fraction of the pigment(s) in the mineral ink is preferably between 1 and 25%.

[0029] The mass fraction of the solid fraction (frit and pigments) in the mineral ink is preferably between 10 and 60%, the relative percentages of pigment(s) and frit(s) in the solid fraction making it possible in particular to adjust the optical density and opacity of the ink.

[0030] The liquid fraction (generally representing 40 to 90% by weight of the ink) is generally formed from at least one solvent or dispersion medium, and one or more additives, including for example at least one resin acting as a binder and making it possible to maintain the properties of the ink and the structure of the deposits until their heat treatment, the level of additive(s) generally not exceeding 10% by weight.

[0031] As a solvent (generally representing at least 30% by weight of the ink, and in particular 30 to 50%), it is possible to use, for example, one or more alcohols, glycol ethers, lactates, glycol ether acetates, aldehydes, ketones, oils, aromatic hydrocarbons, etc., or more simply water.

[0032] As additives (representing less than 10% by weight of the ink), it is possible to use in particular a binder (for example one or more acrylic or akyde resins), one or more additives making it possible to adjust the physical properties of the ink such as one or more dispersing agents (such as those marketed by the company Byk under the reference Disperbyk making it possible to prevent flocculation and / or sedimentation of the solid phase, one or more surfactants (such as those marketed by the company Byk under the reference 301, 302 or 337), leveling agents (such as those marketed by the company Evonik under the reference Tego), one or more antifoams (such as those marketed under the reference 51, 52, 53 by the company Byk), one or more rheology agents, etc.

[0033] The size of the grains or particles constituting the mineral solid phase (including in particular the frit(s) and pigment(s)) of the inks is chosen in accordance with the invention such that the D90 value of their particle size distribution is less than 2 µm, preferably less than 1 µm, more particularly less than 0.9 µm.

[0034] In the present invention, the particle size distribution is evaluated using the D90 percentile, meaning that 90% of the particles in the set of particles considered have a size less than D90. The size or dimension of a particle is called its equivalent diameter, i.e. the diameter of the sphere which would behave identically during the particle size analysis of the particles (or the powder formed from said particles) forming (initially) the mineral solid phase considered, the particle size distribution (set of particle sizes) being measured in particular by laser particle size analysis according to ISO 13320:2009. The desired particle size is in particular obtained by grinding.

[0035] As indicated according to the invention, the deposition viscosity of the inks used is also between 1 and 50 mPa.s, in particular between 5 and 20 mPa.s, the viscosity being measured at the application temperature of the ink envisaged (generally between 30 and 40°C). Advantageously also, the surface tension (or surface tension) of the ink is between 20 and 40 mN / m.

[0036] As previously defined, the solution according to the invention also combines, with the use of inkjet type digital printing and the selection of inks to carry out a colored opacifying coating on demand over a large surface, the selection of anti-adhesive (or "anti-stick") characteristics for the ink(s) (in particular their frit(s)) and / or the addition of materials (in the form of anti-adhesive agent(s) / additive(s) or, where appropriate, anti-adhesive layer(s)) in the composition of the ink or on the ink or the glass to avoid sticking during any forming step.

[0037] The “non-stick” properties or characteristics according to the invention mean non-adhesion of the ink layer(s) to a glass other than that on which they are deposited or to a pressing tool during a bending or forming operation. These properties are evaluated by carrying out gravity bending of a glass coated with the ink layer(s) to be tested for 10 minutes at 640°C and by verifying that no transfer or sticking of the layer has taken place on the test glass.These properties are obtained in particular by the choice of the ink(s), then comprising an anti-adhesive agent / additive or component, that is to say in particular capable of crystallizing at least partially so as not to adhere to the various elements with which the ink(s) may be in contact, the crystallization in question being obtained in particular by carrying out a heating and cooling phase of the layer, in particular before the other heat treatment operations linked to bending or forming, these heating then cooling phases allowing the crystallization, at least partial, of the layer. Alternatively, or even cumulatively, these properties can also be obtained by applying at least one anti-adhesive agent and / or at least one anti-adhesive layer to at least one sheet of glass (which must in particular be brought into contact with the glass coated with inks) and / or to said layer(s) of ink(s).

[0038] In a first embodiment, the non-stick properties are thus obtained by the choice of the ink(s) (comprising an agent / additive or component capable of crystallizing at least partially). In particular, the ink, in particular in its solid fraction, may contain one or more nucleation additives, at a rate for example of at least 0.05% in this case and not exceeding in particular 10% by weight of the ink, this (these) nucleation additive(s) being chosen for example from zinc silicates, aluminum silicates, zinc borates, zinc titanates, bismuth silicates, bismuth oxides, bismuth titanates, refractory products having melting points above 650°, or combinations thereof.

[0039] In another embodiment making it possible to avoid adhesion problems, at least one glass sheet or at least one layer of ink(s) according to the invention is further coated with at least one anti-adhesive agent, for example sprayed or sprinkled on its surface, or at least one anti-adhesive layer, for example deposited on its surface by spraying, digital printing, curtain, roller or screen printing, for example a layer of anti-adhesive enamel marketed by the company Prince Minerals under the reference DV788380, or a layer of anti-adhesive enamel marketed by the company Johnson Matthey under the reference 1L6030, or a layer of anti-adhesive ink marketed by the company Prince Minerals under the reference DJ70474.

[0040] These different modes according to the invention can be alternative or even used in combination. Thanks to the non-stick properties obtained, the printed decorations can be deposited on surfaces which are inside a laminated glazing (F2 face or F3 face), which makes it possible to use inks without being limited by the durability specifications (mechanical and chemical resistances) required for the automotive application, the decorations being protected. These properties are also advantageous for a toughened monolithic glazing whose printed surface can be brought into contact with a pressing mold or for a laminate also having a decorated external face.

[0041] The fact of using, in the method according to the invention, a release ink or a release agent or a release layer thus makes it possible to avoid, following the heat treatment of the sheets, in particular when they are laminated, problems of ink sticking, in particular during the forming or bending steps used in the automotive glass industry. When the ink layer is in contact with another surface, for example a mold surface, the article can be molded and baked at the same time without problems of transfer or sticking of the inks. The same is true when the ink layer is in contact with a second glass during a bending operation. The bending or forming operations are thus not hindered by the sticking phenomenon mentioned above, and the applied decorations can retain their integrity.

[0042] The ink layers or compositions chosen according to the invention are also opacifying (this is the case in particular for compositions partially crystallizing during baking which already form a more or less opaque finish), the opacity being able in particular to be adjusted by varying the thickness of the layers. By "opacifying", it is meant that the coating reduces the light transmission TL of the glazing or increases its optical density, compared to the same glazing not provided with said coating, in particular reduces the light transmission TL of the glazing to a value less than or equal to 10% or increases its optical density to a value greater than or equal to 1, in particular greater than or equal to 3, the opacifying character having in particular advantages in terms of solar protection or advantages in terms of privacy inside the vehicle.

[0043] Advantageously, the motor vehicle roof incorporating the (coated) glazing according to the invention is thus more or less opaque and has a light transmission TL less than or equal to 10%, and in particular less than or equal to 0.1%, or an optical density greater than or equal to 1, and in particular greater than or equal to 3, whereas intrinsically (i.e. without coating), the glazing generally has a light transmission TL greater than 70% or an optical density of the order of 0.05 or less. The light transmission TL is measured according to standard EN 410 using illuminant A (standardized lamp), the measurement being carried out for example using a spectrophotometer, and the optical density is measured using a densitometer (for example a reference densitometer 331C marketed by the company X-rite).

[0044] The mineral inks chosen according to the invention are particularly suitable for deposition by digital inkjet printing on glass substrates for automobile roofs, for example by choosing sets of primary colors making it possible to achieve extended color gamuts. Each primary color can in particular be formulated using mineral ink according to the invention by selecting a suitable mineral pigment. The production of the gamut can then be carried out using several colors, for example by a set of four (CMYK model: cyan, magenta, yellow black) or six colors (BGWORK system: blue, green, white, orange, red, black) the set of six colors being preferred. The desired color is for example defined by a ratio between the different colors, and is advantageously obtained by superimposing or simultaneously depositing the inks of each of the colors in the ratios (or ratios or proportions) chosen.There is no need to prepare a solution with the correct ratios in advance; for example, the ratios are simply entered into the printer's management software at the time of printing. They can therefore be adjusted very easily depending on the desired decorations, with the resulting color having good uniformity.

[0045] As specified above, the decoration is preferably printed with a set of six colors according to the BGWORK model on one or even two sides, two different decorations being able, if necessary, to be printed on one side of a sheet and on another opposite side (one facing outwards and the other inwards), or even on the same side by superimposing at least two different layers as indicated later, for a different effect depending on whether one is placed outside or inside the passenger compartment.

[0046] As mentioned previously, the motor vehicle roof incorporating the glazing according to the invention may be a monolithic glazing, formed from a single sheet of glass; in this case said sheet is coated with at least one layer of ink(s) on at least one face, in particular the face intended to be turned towards the interior of the passenger compartment (or face F2 of a monolithic).

[0047] More generally and preferably, the glazing is a laminated glazing formed from at least two sheets of glass and an interlayer, at least one of the sheets of glass being coated with at least one layer of ink(s) on at least one face, in particular on a face inside the laminate (facing the interlayer - face F2 or F3) in order to protect this layer from bad weather or abrasion, or on the face of the laminate which must be on the inside of the passenger compartment (face F4).

[0048] If necessary, several layers of inks can be superimposed on the same face in order to produce a double image (different on the two opposite sides). For example and advantageously, at least two and in particular three layers or prints can be produced, with intermediate drying after each print, the first layer or print forming a first image (for example a carbon effect), the second layer or print being an opaque layer, in particular white, and the third layer or print forming a second image (for example a sunny or starry sky). The glazing is then formed from the following stack of layers, going from the side intended to be turned outwards to that intended to be turned towards the interior of the passenger compartment, or vice versa: glass / PVB / glass / layer 1 / layer 2 / layer 3. Alternatively, the stack layer 1 / layer 2 / layer 3 can be on a face inside the laminate (or PVB side) such as one of the faces F2 or F3.For example, the glass on the outside is tinted and the glass facing inwards is clear, extra clear or tinted.

[0049] According to a preferred embodiment, the motor vehicle roof incorporating the glazing according to the invention is provided, on the same face and / or on at least two different faces of glass sheet(s) (on the same sheet or two different glass sheets of the glazing), with at least two different coatings or different layers including at least one layer of said ink(s) according to the invention, the second layer or the second coating being either another layer of digital printing ink(s) according to the invention as already indicated previously, or a layer with a decorative effect different from a layer of ink(s) according to the invention, or a layer or a coating or a film or sheet with an additional functional effect, in particular in terms of thermal comfort.

[0050] For example and advantageously, the ink layer(s) according to the invention are combined with a coating making it possible to reflect and / or absorb solar radiation and / or heat (such as a so-called "low-emissivity" or "solar control" coating) to provide increased thermal comfort inside the vehicle, this coating, in the case of laminated glazing, being for example on face F2, F3 or F4, this coating being in particular in the form of thin layer(s) (from a few nanometers to a few tens of nanometers thick each).

[0051] For example and without limitation, the roof of a motor vehicle incorporating glazing can be designed with an infrared radiation reflection function in order in particular to preserve thermal comfort inside the vehicle in summer, obtained for example: by an infrared reflective layer, in particular based on silver, obtained in particular by magnetron sputtering, and deposited for example on the F2 or F3 face in the case of a laminate, and / or by a film (or sheet) having infrared reflective properties by laminating it with the glass sheet(s) (such as, and in addition to, the interlayer in the case of laminated glazing), for example a polymeric film based on polyethylene teraphthalate (PET), and / or the glazing may be equipped with a heat reflection function in order in particular to preserve thermal comfort inside the vehicle in winter, obtained for example: by a low-emissive coating, obtained in particular by magnetron sputtering, and deposited, for example and in the case of a laminate, on one of the faces F2, F3 or F4, and / or by a thermo-reflective coating consisting of superimposing layers with high and low refractive indices and adjusting the interference filter obtained (called a "Bragg filter"), obtained in particular by sol-gel method, for example on the face F2, F3 or F4 in the case of a laminate, etc.

[0052] More particularly, to obtain these thermal comfort properties, at least one functional layer is used, in particular an electrically conductive functional layer, this layer preferably being comprised between two thin dielectric layers, this electrically conductive functional layer being for example chosen from metallic layers, in particular silver or niobium, or even gold, and layers of a transparent conductive oxide (called TCO layer), in particular chosen from indium and tin oxide (called ITO layer), doped tin oxides (for example with fluorine or antimony), doped zinc oxides (for example with aluminum or gallium), these different functional layers being able to be used in combination (it being for example possible to put one or more silver layers on face F2 or F3 and a TCO layer on face F4 in particular).In the case where one or more silver layers are used (in particular in a stack of layers), the thickness of the silver layer or where appropriate the sum of the thicknesses of the silver layers is preferably between 2 and 50 nm, in particular between 3 and 40 nm, and in the case where the stack of thin layers comprises at least one layer of indium and tin oxide, its thickness is preferably between 30 and 200 nm, in particular between 40 and 150 nm.

[0053] In order to protect the electrically conductive layer(s), each of these layers is preferably framed by at least two dielectric layers, these dielectric layers being in particular based on oxide(s), nitride(s) and / or oxynitride(s) of at least one element chosen from silicon, aluminum, titanium, zinc, zirconium, tin, the stack preferably comprising in particular at least one layer based on a nitride, in particular a silicon nitride, the nitride-based layers having in particular blocking properties making it possible to prevent oxidation of the functional layers and having low emissivity, the thickness of each dielectric layer being for example between 2 and 100 nm.

[0054] This type of stacking has in particular properties of electricity conduction or infrared reflection useful for enabling, as required, thermal insulation of the passenger compartment and / or heating, current leads can also be coupled, such as strips of silver paste deposited by screen printing on the stack of thin layers, at two opposite edges of the glass sheet.

[0055] The layers of the aforementioned stack can be deposited by various known techniques, in particular by chemical vapor deposition (CVD), or more advantageously by cathode sputtering, in particular assisted by a magnetic field (magnetron process).

[0056] In a non-limiting embodiment making it possible to obtain a motor vehicle roof incorporating laminated glazing according to the invention having, in addition to the layer(s) of ink according to the invention, good thermal comfort, the glass on the exterior side can for example be clear and coated with an infrared-reflecting layer and the glass facing inwards can be tinted and coated with a low-emissivity layer which makes it possible to retain heat inside the vehicle in winter.

[0057] In the case of thermo-reflective coatings or coatings having solar control properties, the coating may also essentially consist of a stack of dielectric layers alternating with low and high refractive indices (without necessarily the presence of a functional layer as mentioned above), for example layers with an index respectively greater than 1.7 and less than 1.5, the refractive indices of the layers being measured for example with an ellipsometer. This type of stack using an arrangement based on constructive optical interference alternating layers with high and low refractive indices makes it possible to obtain solar control properties through the glazing without affecting the optical properties of the initial (uncoated) glazing. The thin layers of the dielectric stack may be deposited for example by a magnetron process or by a wet coating process, for example by a sol-gel development process.

[0058] As already mentioned, the dielectric layers may be layers of nitride or oxide (metallic, metalloid or mixed), consisting essentially (at least 50%, and in particular at least 80% by weight), or even solely (with the exception of any impurities present), of nitrogen (for nitrides) or oxygen (for oxides), and one or more metals and / or metalloids mentioned in their name, the designation "metal or metalloid oxide or nitride" not excluding, where appropriate, the presence of other chemical elements, each layer being able in particular to be doped, and not necessarily meaning that the oxides or nitrides are stoichiometric, these oxides or nitrides being able in fact to be sub-stoichiometric, super-staichiometric or stoichiometric.

[0059] The dielectric stack covers at least part or an entire face of one of the main faces of a glass sheet, this face being in particular the external face for a monolithic glazing, or one of the faces F2 or F3 for a laminated glazing. Optionally, the glazing may also have a solar control stack on at least two different faces (these stacks may be identical or different) so as to amplify the solar control effect.

[0060] The glazing may also include other coatings, such as one or more layers of liquid crystals (PDLC), conductive strips, etc., depending on the desired functionalities or characteristics.

[0061] As indicated previously, the present invention also relates to a method for manufacturing a motor vehicle roof incorporating glazing according to the invention as defined further above. In this method, the ink is deposited by digital printing of the inkjet type. In this technique allowing efficient and rapid deposition and drying, the liquid ink pulsed through printing nozzles separates into droplets, each microdrop being, if necessary, projected and / or deflected, electrically or magnetically, during its projection towards the printing support. The printed image is thus formed from a large number of small juxtaposed ink spots.

[0062] In a particularly preferred embodiment, the printing is carried out using a high-productivity printing machine (with a printing speed per glass sheet of less than 60 s) of the "single-pass printer" type, more compatible with the automotive market, the selected inks being adapted to this printing method. An example of a single-pass printer is given for example in patent application WO2018050946A1, single-pass printers being able, if necessary, to use a rotation of the print head and vector printing (instead of the "raster" mode that traditional machines have), no use with the inks and coatings selected according to the present invention with a high coverage rate and an opacifying effect for the desired application having, however, been envisaged until now with such printers.Preferably also the printer used is equipped with six sets of print heads to enable printing with a set of six colors.

[0063] To create a chosen design, one can, for example, use, in a preliminary step, a simple good quality photo, or a vector file corresponding to the desired design, and extract the digital data (by carrying out what is called a "RIP") to put them in the machine format, before printing.

[0064] The inks used according to the invention may be initially made by forming a dispersion of the frit (obtained in a known manner from the high-temperature melting of a mixture of vitrifiable raw materials) or selected glass frits in a dispersion medium, grinding the dispersion to reduce the particle size, and filtering the dispersion to remove oversized particles. For pigments, a second dispersion of the pigment(s) may also be formed, this dispersion may be ground to reduce the particle size and filtered and combined with the filtered frit(s) dispersion, or the frit(s) and pigment(s) may be dispersed together and ground into a single dispersion which is then filtered. Commercial inks may also be used if they meet the conditions of the invention and / or be adapted (diluted, ground, etc.) to fulfill the conditions of the invention. In particular, the frit and any pigments may be ground as required until the D90 of the particle size distribution of the glass frit(s) and pigment(s) is less than 2 µm, in particular less than 1 µm, and the rheological properties, and in particular the viscosity, of the ink may be adjusted if necessary.

[0065] Commercially available inks that can be used as inks according to the invention include, in particular, the inks marketed under the reference Spectrum R by the company Ferro.

[0066] Where appropriate, other agents may be added to the inks formed and / or chosen according to the invention, such as a dispersing agent (for example when adding the solvent), a surfactant (for example after grinding), an anti-adhesive agent, etc., before, during or after the grinding and filtering steps.

[0067] The ink compositions are applied to the surface of at least one glass sheet of the automotive roof glazing to form the desired decoration(s), generally on the float glass before heat treatment of the glazing and baking of the inks. If necessary, the glazing is bent in a mold or in a collapse holder to obtain the desired shape, while the ink composition(s) is / are baked.

[0068] The deposition of each layer may be followed, if necessary, by a drying step to evaporate the solvent, and solidify and fix the layer. The ink may, if necessary, be dried at room temperature (in particular by allowing the substrate coated with the ink to dry in the open air), but, due to the high printing speeds and the nature of the support, forced drying is preferably carried out, in particular by heat treatment, convection and / or radiation, in particular at less than 200°C, for example between 150 and 180°C. Where appropriate, when several layers of ink are printed, in particular one on top of the other, intermediate drying is preferably carried out (for example at around 150°C) after each print.

[0069] After deposition and possible drying, the mineral inks undergo a heat treatment or baking which in particular fixes the inks and is generally carried out (in particular for laminated glazing) during the usual bending of the glass, this heat treatment being carried out for example for a few hundred seconds (for example 200 s) and at temperatures of several hundred degrees, for example of the order of 650°C - 700°C.

[0070] In the process for producing a motor vehicle roof incorporating curved monolithic glazing, the glass, preferably tempered, is produced in particular in a pressure bending furnace. The glass is first heated to approximately 650-700°C and then passes through a press and is pressed into the desired shape. As already mentioned, advantageously, the inks selected according to the invention do not stick to the dies of said press.

[0071] In the method for producing a motor vehicle roof incorporating curved laminated glazing, once the coating with the ink layer(s) has been carried out on one and / or the other glass sheet, the printed glass sheet may, if necessary, be pre-baked to develop the non-stick effect of the coating in question. The glass sheets are placed one on top of the other before simultaneously bending the sheets by a hot bending process and baking the inks. A lamination treatment for assembling the glass sheets with an interlayer may also be carried out by assembling the sheets, if necessary already curved, with the interlayer and subjecting the assembly to an increase in temperature and a decrease in pressure, for example by an autoclave process, a vacuum process, a calendering process, etc.

[0072] As already mentioned previously, in one embodiment of the invention, it is possible to deposit on the layer of ink(s) once applied, an anti-adhesive agent or an anti-adhesive layer, for example by spraying, digital printing, curtain, roller or screen printing, in addition to the layer(s) of ink deposited.

[0073] In the case of other combined layers (for example low-emissive, solar control, etc.), they can also be deposited in another step before or after printing the ink layer(s) before possible assembly, possible bending, and baking.

[0074] Where appropriate, the method may also include an operation of cutting the glass sheet(s), for example by water jet or by a mechanical tool, etc., followed by a shaping operation (grinding, beveling, etc.).

[0075] The printed inks preferably comprise one or more inorganic pigment(s) which have an average diameter of less than 500 nm, more preferably an average diameter of between 100 and 300 nm. The average diameter can be measured using a scanning electron microscope (SEM). Said pigments have the advantage of not having been altered during the process, in particular after drying and baking of the inks. The printed inks show satisfactory lamination feasibility and offer good adhesion, without requiring prior treatment of the support and / or the use of an adhesion promoter or a primer, the ink layers being printed directly in contact with the glass. In addition, the ink layers weaken the glass less mechanically than conventional enamels, allowing in particular printing over a large surface.They also offer good resistance to scratches (around 20N - measured with a sclerometer), or to mechanical stresses such as metallic friction, this resistance being compatible with automotive specifications, and good results in the climate change resistance test of the EN1 096-2 standard. The decorations obtained after drying and baking the inks are also particularly resistant to soiling, and the selected inks are also stable to light and have excellent resistance to ultraviolet radiation, due in particular to their mineral nature.

[0076] The glazing of the present invention is suitable for equipping any transport vehicle that may have a glass roof (such as a car, a bus, etc.). The glazed motor vehicle roof may be fixed or opening, sliding and / or tilting and / or lifting, or panoramic or canopy-type. The roof and its control may be manual or electrical. The roof may also comprise one or more additional functional or structural elements such as a frame, one or more connectors, one or more cables, one or more fasteners, etc.

[0077] The characteristics and advantages of the invention are illustrated by the non-limiting examples described below.

[0078] Example 1: In the first example according to the invention, a laminated glazing unit for an automobile roof was produced, formed from two sheets of glass separated by a thermoplastic intermediate layer, this glazing unit being decorated on the F2 side and on the F4 side. Each sheet of glass was a clear and neutral soda-lime float glass 2.1 mm thick marketed by the company Saint-Gobain Glass under the brand Planiclear ®< (hereinafter referred to by the abbreviation PLC) and having, when taken alone, a light transmission TL of 90%, and the thermoplastic intermediate layer was a 0.76 mm thick layer of polyvinyl butyral (hereinafter referred to by the abbreviation PVB) marketed by the company Solutia under the reference RC41.The coating of the outer glass sheet was obtained by first producing a first decoration on face F2 over the entire face by inkjet printing using a single-pass machine equipped with six-color print heads (with drying after deposition for 2 min at 130°C) to obtain a layer of inks 5 µm thick (final), the viscosity of the inks at deposition being less than 50 mPa.s, then by producing on this decoration the deposition of an anti-adhesive layer by screen printing at a wet thickness of 15 µm (giving a final thickness of the layer of 6 µm) and at a viscosity of 15 Pa.s, before pre-baking for 180s at 600°C.

[0079] The coating of the inner glass sheet was obtained by producing a second decoration on face 4 over the entire face by inkjet printing using a single-pass machine (with drying after deposition for 2 min at 130°C) to obtain a layer of inks 5 µm thick (final), the viscosity of the inks upon deposition being less than 50 mPa.s.

[0080] The inks used for the decorations were inks from the range of inks marketed by the Ferro company under the reference Spectrum R, formed from frits and inorganic pigments and having a D90 value of the particle size distribution of less than 2 µm, and the material of the added anti-adhesive layer was an enamel with the reference DV788380, marketed by the Prince Minerals company.

[0081] The coated glass sheets were then bent for approximately 200 s at temperatures of around 680°C.

[0082] It was observed that the two glasses could be separated without difficulty and that no transfer of material was visible on the inner glass.

[0083] The coated sheets were then laminated via the PVB interlayer. The optical density of the resulting coated glazing was greater than 3.

[0084] After lamination, the first decoration was visible from the outside of the car and the second decoration visible from the inside. This configuration also made it possible to include various functional elements (sensors, antennas, etc.) between the two windows while being hidden by the decorations.

[0085] Example 2: In the second example according to the invention, a laminated glazing unit for an automobile roof was produced, formed from two sheets of glass separated by a thermoplastic intermediate layer, this glazing unit being decorated on the F2 side. The outer sheet of glass (intended to be placed on the outside of the vehicle) was a PLC glass 2.1 mm thick, the other (inner) sheet of glass was a soda-lime float glass 2.1 mm thick, tinted and having, when used alone, a light transmission TL of 71%, namely a glass of the reference TSA 3+ (hereinafter designated by the abbreviation TSA) from the company Saint-Gobain Glass, and the thermoplastic intermediate layer was a PVB layer 0.76 mm thick as in example 1.The coating of the outer glass sheet was obtained by producing a decoration on the F2 face over the entire face by inkjet printing using a single-pass machine equipped with six-color print heads (with drying after deposition for 2 min at 130°C) to obtain a layer of inks 5 µm thick (final), the viscosity of the inks at deposition being less than 50 mPa.s, then by producing on this decoration the deposition of an anti-adhesive layer by screen printing at a wet thickness of 15 µm (giving a final thickness of the layer of 6 µm) and at a viscosity of 15 Pa.s, before pre-baking for 180s at 600°C, the outer glass remaining bare.

[0086] The inks used for the decoration and the material of the added release layer were those of example 1.

[0087] The coated glass sheets were then bent as in Example 1 and it was again observed that the two glasses could be separated without difficulty and that no material transfer was visible on the inner glass.

[0088] The coated sheets were then laminated as in Example 1, the optical density of the coated glazing obtained being greater than 3. After lamination, the decoration was visible from the outside of the car, the inner side of the glazing having a homogeneous appearance provided by the overlapping of the anti-adhesive layer and the layer of inks, the reflection of the surface of the glass on the F4 side also being preserved.

[0089] By way of comparison, for the same glazing produced in the same way but this time without coating the decoration with the non-adhesive layer, the glass could not be detached without degradation after bending, a transfer of parts of the decoration taking place from the outer glass to the inner glass (unlike the case of example 2 according to the invention making it possible to obtain curved glazing without degrading the aesthetic appearance of the decoration on face F2).

[0090] Example 3: In the third example according to the invention, a laminated glazing unit for an automobile roof was produced, formed from two sheets of glass separated by a thermoplastic intermediate layer, this glazing unit being decorated on face F3 and having a functional thermal comfort layer on face F2. Each sheet of glass was a 2.1 mm thick PLC glass, and the thermoplastic intermediate layer was a PVB layer as in example 1. The coating of the inner glass sheet was obtained by producing a decoration on face F3 over the entirety of said face by inkjet printing using a single-pass machine equipped with six-color print heads to obtain a layer of inks 5 µm thick (final) (with drying after deposition for 2 min at 130°C), the viscosity of the inks at deposition being less than 50 mPa.s, then by depositing on this decoration a non-stick layer by screen printing at a wet thickness of 15 µm (giving a final layer thickness of 6 µm) and at a viscosity of 15 Pa.s, before pre-baking for 180 s at 600°C.

[0091] The outer glass sheet was further coated with a silver-based infrared reflective layer, this layer being deposited by magnetron on the F2 face.

[0092] The inks used for the decoration were those used in the previous examples, and the material of the added non-stick layer was an enamel reference 1L6030, marketed by the company Johnson Matthey.

[0093] The coated glass sheets were then bent as in Example 1 and it was again observed that the two glasses could be separated without difficulty and that no material transfer was visible on the inner glass.

[0094] The coated sheets were then laminated as in Example 1, the optical density of the coated glazing obtained being greater than 3. After lamination, the decoration was visible from inside the car, the exterior side of the glazing having a homogeneous appearance provided by the overlapping of the anti-adhesive layer and the layer of inks, the reflection of the surface of the glass on face F1 also being preserved, the infrared reflective layer on face F2 also ensuring the thermal comfort of the passengers.

[0095] By way of comparison, for the same glazing produced in the same way but this time without coating the decoration with the non-adhesive layer, the glass could not be detached without degradation after bending, a transfer of parts of the decoration taking place from the inner glass to the outer glass (unlike the case of example 3 according to the invention making it possible to obtain curved glazing without degrading the aesthetic appearance of the decoration on face F3).

[0096] Example 4: In the fourth example according to the invention, a laminated glazing unit for an automobile roof was produced, formed from two sheets of glass separated by a thermoplastic intermediate layer, this glazing unit being decorated on face F2 and having a functional thermal comfort layer on face F4. The outer glass sheet was a 2.1 mm thick PLC glass, the other (inner) glass sheet was a 2.1 mm thick soda-lime float glass, reference VG10 from the company Saint-Gobain Glass, and the thermoplastic intermediate layer was a 0.76 mm thick PVB layer as in example 1.The coating of the outer glass sheet was obtained by producing a decoration on the F2 face over the entire face by inkjet printing using a single-pass machine equipped with six-color print heads to obtain a layer of inks with a thickness of 5 µm (final) (with drying after deposition for 2 min at 130°C), the viscosity of the inks upon deposition being less than 50 mPa.s, then by producing on this decoration the deposition of an anti-adhesive layer by screen printing at a wet thickness of 15 µm (giving a final thickness of the layer of 6 µm) and at a viscosity of 15 Pa.s, before pre-baking for 180 s at 600°C.

[0097] The inner glass sheet was further coated with a low-emissive layer, this layer being formed of ITO and being deposited by magnetron on the F4 face.

[0098] The inks used for the decoration were those used in the previous examples, and the material of the added non-stick layer was an enamel reference 1L6030, marketed by the company Johnson Matthey.

[0099] The coated glass sheets were then bent as in Example 1 and it was again observed that the two glasses could be separated without difficulty and that no material transfer was visible on the inner glass.

[0100] The coated sheets were then laminated as in Example 1, the optical density of the coated glazing obtained being greater than 3. After lamination, the decoration was visible from the outside of the car, the inner side of the glazing having a homogeneous appearance provided by the overlapping of the anti-adhesive layer and the layer of inks, the reflection of the surface of the glass on the F4 side also being preserved, the low-emissive layer on the F4 side also ensuring the thermal comfort of the passengers.

[0101] Example 5: In the fifth example according to the invention, a monolithic glazing unit for an automobile roof was produced, formed from a single sheet of glass decorated on the F2 side. The glass sheet was a 2.1 mm thick PLC glass. The coating of the glass sheet was obtained by producing the decoration on face F2 over the entire face by inkjet printing using a single-pass machine equipped with six-color print heads to obtain a layer of inks 5 µm thick (final) (with drying after deposition for 2 min at 130°C), the viscosity of the inks at deposition being less than 50 mPa.s, then by producing on this decoration the deposition of an anti-adhesive layer by inkjet at a wet thickness of 15 µm (giving a final thickness of the layer of 6 µm) and at a viscosity of 15 Pa.s, before pre-baking for 180s at 600°C.

[0102] The inks used for the decoration were the same inks as in example 1, and the material of the added release layer was a reference ink DJ70474 marketed by the company Prince Minerals.

[0103] The coated glass sheet was then bent by pressing for a few hundred seconds at temperatures of around 680°C without any material transfer taking place on the pressing die. The optical density of the coated glazing obtained was greater than 3. The decoration, having not suffered any degradation during bending, was visible from the outside, the inner side of the glazing having a homogeneous black “carbon effect” appearance provided by the overlapping of the anti-adhesive layer and the ink layer, the reflection of the glass surface on the F1 side also being preserved.

[0104] By way of comparison, for the same glazing produced in the same way but this time without coating the decoration with the non-adhesive layer, the bending soiled the pressing die and the decoration obtained was incomplete (unlike the case of example 5 according to the invention making it possible to obtain a curved glazing without degrading the aesthetic appearance of the decoration on face F3 and without degrading the bending tool).

[0105] In the examples according to the invention carried out previously, the inks used have notably shown: satisfactory lamination feasibility on Solutia RB41, scratch resistance of approximately 20N, compatible with automotive specifications, good results in the climate change resistance test of EN1 096-2 on coated glasses (differing from usual automotive specifications but aiming to test the same characteristics).

[0106] In addition, the resistance to soiling and the ability to be cleaned were evaluated using the protocols detailed in the EN14428 standard simulating the cleaning of a glass plate and gave satisfactory results.

[0107] The glazings according to the invention can in particular be used advantageously to produce a new range of automobile roofs for transport vehicles.

Claims

1. A method for manufacturing a motor vehicle roof incorporating a glazing, in which at least one opacifying layer of ink(s), in particular at least one layer of colored ink(s), is applied by digital printing, in particular by inkjet, over at least 40% of the surface of one of the faces of at least one glass sheet, such that the composition of said ink(s) comprises at least one glass frit, and where applicable one or more inorganic pigment(s), with a D90 value for the particle size distribution of less than 2 µm, and such that said ink(s) have a viscosity of between 1 and 50 mPa.s, said ink(s) further comprising a non-stick agent and / or a non-stick component and / or at least one non-stick agent and / or at least one non-stick layer being further applied to at least one layer of ink(s) and / or to at least one glass sheet.

2. The method according to claim 1, characterized in that the printing is performed using a single-pass printing machine.

3. The method according to one of claims 1 or 2, characterized in that the printer used is equipped with six series of print heads to enable printing with a set of six colors.

4. The method according to one of claims 1 to 3, characterized in that the surface tension of the ink is between 20 and 40 mN / m.

5. A motor vehicle roof able to be obtained by the method according to one of the preceding claims, said vehicle roof incorporating a glazing comprising: - one or more glass sheets, at least one glass sheet being coated over at least 40% of the surface of at least one face with at least one opacifying layer of ink(s), such that the composition of said ink(s) comprises at least one glass frit, and - at least one layer of ink(s) and / or at least one glass sheet being coated with at least one non-stick agent and / or at least one non-stick layer, and / or - at least one layer of ink(s) comprising at least one non-stick agent and / or one non-stick component.

6. The motor vehicle roof according to claim 5, characterized in that the opacifying layer of ink(s) is at least one layer of colored ink(s).

7. The motor vehicle roof according to one of claims 5 or 6, characterized in that the composition of said ink(s) comprises one or more inorganic pigment(s).

8. The motor vehicle roof according to one of claims 5 to 7, characterized in that said glazing is a monolithic glazing formed of a single glass sheet, said sheet being coated with at least one layer of said ink(s) on one face, in particular face F2, or characterized in that said glazing is preferentially a laminated glazing formed of at least two glass sheets and an interlayer, at least one of said glass sheets being coated with at least one layer of said ink(s) on one face, in particular face F2, F3, or F4.

9. The motor vehicle roof according to one of claims 5 to 8, characterized in that said glazing has a light transmission TL of less than 10%, in particular less than or equal to 0.1%, or an optical density of greater than or equal to 1, in particular greater than or equal to 3.

10. The motor vehicle roof according to one of claims 5 to 9, characterized in that two different decorations are printed, for a different effect on the outside and on the inside of the passenger compartment.

11. The motor vehicle roof according to one of claims 5 to 10, characterized in that several layers of inks are overlayed on the same face in order to produce a double image, for example a first layer or print forming a first image, a second layer or print being a white layer, and a third layer or print forming a second image.

12. The motor vehicle roof according to one of claims 5 to 11, characterized in that said glazing is equipped, on the same face and / or on at least two different faces of glass sheet(s) of the glazing, with at least two different coatings or two different layers including at least one layer of said ink(s), the second layer or the second coating being either a second mineral layer formed of digital printing ink(s), or a layer with a different decorative effect from said layer or layers of ink(s), or a layer or a coating or a film or a sheet with an additional functional effect, particularly in terms of thermal comfort, such as a low-emissivity or solar control coating.