WO2022053404A1

WO2022053404A1 - Process for producing a composite pane having a hologram

Info

Publication number: WO2022053404A1
Application number: PCT/EP2021/074376
Authority: WO
Inventors: Andreas GOMER; Raphaela KANNENGIESSER; Adrien CERIPA; Valentin SCHULZ
Original assignee: Saint-Gobain Glass France
Priority date: 2020-09-14
Filing date: 2021-09-03
Publication date: 2022-03-17
Also published as: CN114531858A; EP4210942A1

Abstract

The invention relates to a process for producing a composite pane (100) having a hologram, at least comprising the steps of: a) providing a first pane (1) and a second pane (2), b) spraying a photosensitive material (15) as a hologram element (5) at least in a coating region (7) on the surface (III) of the first pane (1), c) generating at least one hologram by means of selective laser irradiation of the exposed hologram element (5), d) forming a layer stack from the first pane (1), a thermoplastic intermediate layer (3) and a second pane (2), the hologram element (5) being arranged between the two panes (1, 2), e) joining the first pane (1) and the second pane (2) by means of the thermoplastic intermediate layer (3) to form a composite pane (100) in a lamination process.

Description

Process for the manufacture of a laminated pane with a hologram

The invention relates to a method for producing a composite pane, in particular for a holographic head-up display, a composite pane for such a display, and the use of such a composite pane.

Composite glazing is used in many places today, particularly in vehicle construction. The term vehicle includes, among other things, road vehicles, aircraft, ships, agricultural machines or also work equipment.

Composite panes are also used in other areas. These include, for example, building glazing or information displays, e.g. in museums or as advertising displays.

Laminated windows are also often used as a head-up display (HUD) to display information. An image is projected onto the laminated glass panes by means of a projection device in order to display information in the viewer's field of vision. In the vehicle area, the projection device is arranged, for example, on the dashboard so that the projected image is reflected in the direction of the viewer on the closest glass surface of the laminated glass pane inclined towards the viewer (cf. e.g. European Patent EP 0420228 B1 or German Offenlegungsschrift DE 10 2012 211 729 A1).

Holograms that are laminated between the panes of a composite pane can be used for head-up displays. The hologram may contain information recorded thereon. The hologram can be activated by means of light emitted by a projector and the information recorded in the hologram can thus be reproduced for the viewer. Head-up displays comprising holographic optical elements are disclosed, for example, in the publications WO 2012/156124 A1 and US 2019/0056596 A1.

There are different types of holograms. These include, for example, reflection holograms or holograms that are based on the principle of guiding light waves in the hologram, so-called waveguides or waveguide holograms. waveguide Holograms are described for example in US10394032 B2, LIS2015205138A1 or US10061069B2.

A hologram can be created in a photosensitive layer applied to a substrate. For example, photopolymers or gelatin with silver halides or dichromates are known as photosensitive material. DE805202C describes the production of photographic emulsions which can be applied to various supports and, for example, can also be sprayed on.

DE 68912246T2 discloses a method for producing a laminated pane, in which a hologram is introduced between two panes by means of a carrier, with the carrier having to be removed before the final lamination. This is a comparatively complex process that is difficult to automate.

JP 409113840 A describes a pane with a hologram element that is cut back along the edges and embedded in a thermoplastic intermediate layer. In this case, prefabricated photosensitive films are used, which have to be fixed in/on the pane.

EP 0521296 A1 discloses a method for producing a substrate with a photosensitive layer made of photopolymers, the layer made of photopolymers being provided with a water-based polymeric protective layer, such as a polyvinyl alcohol layer. This protective layer is required at least during the exposure step of the photosensitive layer and also serves as a barrier against plasticizers from adjacent layers. However, such water-based polymeric protective layers have proven to be troublesome in laminated products and must therefore first be removed prior to lamination. This causes a considerable effort.

The object of the present invention is therefore to provide an improved method for producing a laminated pane with a hologram, and to provide an improved laminated pane.

The object of the present invention is solved by a method according to independent claim 1 . Preferred embodiments emerge from the dependent claims. A laminated pane according to the invention and its use emerge from further independent claims. The invention relates to a method for producing a laminated pane with a hologram. In step (a), a first pane and a second pane are provided. If necessary, the slices are washed and dried and thus prepared for further processing.

In step (b), a photosensitive layer is sprayed on as a hologram element at least in a coating area on a surface of the first pane. The surface here is a first surface of the pane, so that the photosensitive material is only applied to one surface and not to the opposite, second surface. Coating by spraying has the advantage that a very homogeneous layer can be applied and the layer thickness can be determined in a targeted manner.

The coating area can extend over the entire surface of the first pane, ie the photosensitive material is applied over the entire surface of the first pane. Alternatively, the photosensitive layer can also be applied exclusively in a partial area of the first pane, ie the coating area only extends over part of the first pane. The coating area is the area where the photosensitive material is applied.

At least one hologram is produced in the exposed hologram element in step (c) by selective exposure of the hologram element by means of a laser. Selectively means that the laser irradiation records holograms in the photosensitive layer at the points where holograms are later to be able to be displayed. For example, the holograms can only be located in a partial area or distributed over the entire surface of the pane. Exposed means that the hologram element is not protected from the environment by a protective layer when it is irradiated by a laser. An oil film is also not required, since laser irradiation does not require it. Thus, the recording of the holograms can be started immediately after the spraying process and any subsequent drying process.

Step (c) is performed before the lamination in step (e), so that lamination can be done without any precautions regarding the unexposed photosensitive material.

In step (d), the first disc, a thermoplastic intermediate layer and the second disc are arranged to form a layer stack that the hologram element between the first disc and the second disc is arranged. The thermoplastic intermediate layer serves to connect the first pane and the second pane and thus extends flat over the entire surface of the first pane or the second pane.

In step (e), the first pane and the second pane are laminated via the thermoplastic intermediate layer to form a composite pane. This usually takes place in a lamination process under the influence of pressure and temperature.

Further steps can be integrated into the process and further layers can be integrated into the laminated pane. The order of the steps can be varied.

The method according to the invention thus offers a possibility for the simple production of a laminated pane with at least one hologram. The production of the layer of photosensitive material by spraying is a particularly suitable method for producing homogeneous layers with a constant layer thickness over the entire coating area. Since this is a non-contact application method, traces such as those caused by spreading a solution are avoided. The spraying process can be automated very well and can be carried out continuously. Since no water-based polymeric protective layer is required over the hologram element during irradiation, the process is significantly simplified, since otherwise the protective layer would first have to be removed before lamination.

A reflection hologram or a waveguide hologram that is arranged within a hologram element is referred to as a hologram. The hologram element refers to the holographic medium in which the hologram is contained. The hologram element is obtained by applying a photosensitive material comprising a matrix and photosensitive substances. A hologram can be recorded in this photosensitive material or in this photosensitive layer by exposure to a suitable light source. In the finished laminated pane, the material of the hologram element is no longer sensitive to light, since the photosensitive material is changed to such an extent during the process that it is no longer possible to record a reflection hologram. The term hologram element refers to both the unexposed photosensitive material hologram element and the final hologram recorded hologram element. The hologram element according to the invention comprises at least one hologram, but preferably several individual holograms.

The first panel and the second panel each have an outside surface, i.e., an outer surface, and an interior-side surface, i.e., an inner surface, and a peripheral side edge extending therebetween. Within the meaning of the invention, the outer surface designates that main surface which is intended to face the external environment in the installed position. Within the meaning of the invention, inner surface designates that main surface which is intended to face the interior in the installed position. The outer surface of the first pane and the inner surface of the second pane face each other in the laminated pane according to the invention.

If the laminated pane is intended to separate an interior from the outside environment in a window opening of a vehicle or a building, the inner pane within the meaning of the invention refers to the pane facing the interior (vehicle interior). The outer pane refers to the pane facing the outside environment. The first pane can be the outer pane or the inner pane and the second pane can be the outer pane or the inner pane.

The first pane is preferably the inner pane and the second pane is the outer pane. In this case, in step (b), the photosensitive material is applied as a hologram element to the outer surface of the inner pane. Since the hologram element is applied to the inner pane, the perception of the hologram by a vehicle occupant is not disturbed by an intervening thermoplastic intermediate layer.

In a preferred embodiment, the surface of the first pane is pretreated at least in the coating area in order to improve the adhesion of the photosensitive material. This can be a particularly thorough cleaning, or pre-treatment with an adhesion promoter or primer, or activation using a plasma. The pre-treatment takes place before the application of the photosensitive material.

The coating area is the area in which the photosensitive material is applied, i.e. the area intended for the hologram element.

In a preferred embodiment, at least the first disc is bent in one or more directions of space, with the radius of curvature or the Radius of curvature are independently in the range of 10 cm to 40 m. The first pane and the second pane are particularly preferably curved. The method according to the invention is particularly suitable for the production of curved composite panes, since the coating with the photosensitive material takes place directly on the first pane and, thanks to the spraying process, a particularly uniform layer can be created.

The photosensitive material preferably comprises gelatin with silver halides or gelatin with dichromates. These materials have proven to be suitable for use in laminates and are stable during exposure even without the use of separate protective layers. Silver halides or dichromates are usually used in a gelatine matrix, which is first slightly dried at room temperature (about 20°C to 30°C) before the hologram is recorded by exposure. The exposed layer is then fixed and freed from unreacted metal salts, elemental silver and by-products in one or more washing steps and dried at 50° C. to 120° C. in a final drying process. The use of silver halides and dichromates as photosensitive material is known, for example, from EP0179741A2, DE3909289A1 and DE69020975T2.

The combination of silver halide crystals in a gelatin layer is called a photographic emulsion. There are three types of silver halides, silver chloride, silver bromide and silver iodide. Silver chloride is used for slow speed emulsions. Emulsions containing a combination of silver chloride and silver bromide have high photosensitivity, and emulsions containing a combination of silver bromide and silver iodide have even higher photosensitivity. Silver iodide is generally never used alone, but in combination with silver bromide, with the silver iodide proportion by weight being 5% or less. Photographic materials based on silver halides embedded in a gelatin layer are disclosed in the publications DE 10 2011 006 889 A1, EP 0 611 992 A1, EP 0 677 773 A1 and EP 0 682 287 A1.

The rheological properties of photosensitive materials based on silver halides embedded in a gelatine layer or based on a dichromated gelatine can also be influenced by additives which preferably evaporate in a subsequent drying process. The rheological properties affect the sprayability of the solution. As described above, photosensitive materials often contain gelatin as a hydrophilic colloid binder. EP 0 611 992 A1 discloses that mixtures of different gelatins with different viscosities can be used in order to adjust the rheological properties of the photosensitive material.

The rheological properties of the photosensitive material can also be specifically influenced via the temperature. On the one hand, the entire process can be carried out at a specific temperature. However, it is also possible for only the photosensitive material to be brought to a specific temperature before spraying on and for the nozzle used to be temperature-controlled and/or for the pane to be coated to be cooled down or heated to a specific temperature. The entire process is preferably carried out at temperatures between room temperature and 100° C., in particular at temperatures between 30° C. and 100° C., for example at 70° C.; or at least the photosensitive material to be applied is heated to temperatures between room temperature and 100.degree. C., in particular at temperatures between 30.degree. C. and 100.degree. C., for example 70.degree.

In a preferred embodiment, the thermoplastic intermediate layer or an adhesive layer is arranged directly adjacent to the hologram element in the layer stack. This leads to a particularly stable composite pane, since the thermoplastic intermediate layer or the adhesive layer ensure a secure connection to the hologram element and other layers of the stack of layers.

The thermoplastic intermediate layer preferably contains at least polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU) or copolymers or derivatives thereof or consists of them, preferably polyvinyl butyral (PVB), particularly preferably polyvinyl butyral (PVB) and additives known to those skilled in the art, such as plasticizers. The thermoplastic intermediate layer preferably contains at least one plasticizer. These materials are particularly suitable for composite safety panes.

Plasticizers are chemical compounds that make plastics softer, more flexible, more supple and/or more elastic. They shift the thermoelastic range of plastics to lower temperatures so that the plastics have the desired more elastic properties in the operating temperature range. Preferred plasticizers are carboxylic acid esters, in particular low-volatile carboxylic acid esters, Fats, oils, soft resins and camphor. Other plasticizers are preferably aliphatic diesters of triethylene or tetraethylene glycol. Plasticizers 3G7, 3G8 or 4G7 are particularly preferably used, the first digit designating the number of ethylene glycol units and the last digit designating the number of carbon atoms in the carboxylic acid part of the compound. Thus, 3G8 stands for triethylene glycol bis-(2-ethylhexanoate), ie for a compound of the formula C ₄ H ₉ CH (CH ₂ CH ₃ ) CO (OCH ₂ CH ₂ ) 3O ₂ CCH (CH ₂ CH ₃ ) C ₄ H ₉ .

The thermoplastic intermediate layer preferably contains at least 3% by weight, preferably at least 5% by weight, particularly preferably at least 20% by weight, even more preferably at least 30% by weight and in particular at least 40% by weight of a plasticizer. The plasticizer preferably contains or consists of triethylene glycol bis(2-ethylhexanoate).

The thermoplastic intermediate layer more preferably contains at least 60% by weight, particularly preferably at least 70% by weight, in particular at least 90% by weight and for example at least 97% by weight, of polyvinyl butyral.

The thermoplastic intermediate layer can be formed by a single film or by more than one film.

The thermoplastic intermediate layer can also be a functional thermoplastic intermediate layer, in particular an intermediate layer with acoustically damping properties, an intermediate layer which reflects infrared radiation, an intermediate layer which absorbs infrared radiation, an intermediate layer which absorbs UV radiation, an intermediate layer which is colored at least in sections and/or an intermediate layer which is tinted at least in sections. For example, the thermoplastic intermediate layer can also be a belt filter film.

The thickness of the thermoplastic intermediate layer is between 30 μm and 1500 μm, preferably between 50 μm and 780 μm, preferably between 380 μm and 760 μm.

An adhesive layer is preferably a so-called optically clear adhesive (OCA) or a transparent adhesive. Such adhesives are distinguished by high light transmission, low haze, no double refraction of light, high UV resistance and good aging resistance. This can lead to uncontrolled and therefore undesirable impairments in light transmission or unaesthetic distortions be avoided. The adhesive layer preferably has an absorption in the visible spectral range of less than 5%, in particular less than 2% or even 1% and preferably a turbidity of less than 5%, in particular less than 2% or even 1%.

An adhesive layer preferably has a thickness of from 20 μm to 200 μm, particularly preferably from 50 μm to 150 μm, very particularly preferably from 60 μm to 100 μm. This effectively prevents delamination between the hologram element and the adjoining layer and achieves good optical properties. In addition, adhesive layers with these thicknesses are commercially available as adhesive films. Alternatively, the adhesive can also be used as a liquid adhesive.

The adhesive is preferably a chemically active, in particular chemically curing adhesive or UV-curing, particularly preferably an acrylate adhesive or a silicone-based adhesive.

In a preferred embodiment, the photosensitive material is sprayed on in step (b) as a solution with a viscosity of between 10 mPas and 500 mPas. With this viscosity, the solution can be applied to a pane as a homogeneous layer. Spraying is preferably carried out at a pressure of between 1.0 bar and 2.0 bar.

In a preferred embodiment, the photosensitive material is sprayed on in step (b) using at least one nozzle that has a diameter of between 1.0 mm and 2.0 mm.

During the spraying process, a substantially constant distance is preferably maintained between the nozzle and the surface of the pane to be coated. This leads to a homogeneous thickness of the coating, which is of particular importance for the error-free display and recording of the hologram.

The thickness of the layer can be adjusted via the distance from the nozzle to the pane and the duration of the spraying. The process parameters are preferably chosen such that a coating with a thickness of 5 μm to 500 μm, preferably 10 μm to 200 μm and particularly preferably 15 μm to 150 μm is applied to the first pane. The specified thicknesses relate to the dried hologram element. The hologram element can be applied in a single spraying process as a single layer or in several spraying processes carried out one after the other in several layers. The specified thicknesses relate to the dried hologram element.

The photosensitive material is preferably applied in a uniform layer thickness d in the coating area. The layer thickness d deviates by a maximum of 5 μm to 25 μm. This means that the total layer thickness deviates by a maximum of 5 μm to 25 μm. The specified thicknesses relate to the dried hologram element.

Any prints that may be present, for example opaque cover prints (black print in the edge area of the pane) are preferably applied using the screen printing process.

The lamination is preferably carried out under the action of heat, vacuum and/or pressure. Methods known per se can be used for lamination, for example autoclave methods, vacuum bag methods, vacuum ring methods, calendering methods, vacuum laminators or combinations thereof.

In a preferred embodiment, before step (b) of the method according to the invention, a masking stripe is arranged on a surface of the first pane, so that the masking stripe delimits the coating area. The masking strip completely frames the coating area that is provided for the hologram element and thus specifies the dimensions of the hologram element. The masking strip functions as a delimitation strip as it delimits the area for the hologram element. It also covers or masks the area in which it is arranged and prevents photosensitive material from being applied there as well. In this respect, it also assumes the function of a cover strip.

After the application of the photosensitive material, the masking strip is removed again from the surface of the first pane, so that a peripheral edge of the hologram element made of photosensitive material is exposed. A frame area, in which no photosensitive material is arranged, is thus formed circumferentially around the hologram element. The hologram element therefore does not extend to the edge of the pane and is protected in the finished laminated pane from moisture, chemicals or cleaning agents with which the edge of the pane can come into contact. In this embodiment, the thermoplastic intermediate layer has a larger area than the hologram element. If no additional barrier film is arranged, which surrounds the hologram element, the peripheral edge of the hologram element is sealed by the thermoplastic intermediate layer and thus protected from external influences.

The masking strip can consist of a continuous frame or a composite frame.

The masking strip is preferably applied to the surface of the first pane in liquid form, which can be detached again after a hardening process. This simplifies the continuous application even with curved geometries of the hologram element. Alternatively, the masking strip is preferably composed of solid, foil-like pieces (tape) to form a continuous border around the cutout. This can be flexibly adapted and is particularly advantageous in the case of smaller quantities and simple, preferably rectangular, geometries. A self-adhesive adhesive tape is preferably used, which is removed again after the application of the photosensitive material. Adhesive tape is preferably used here, which can be removed again without leaving any residue. Adhesive tape refers to a plastic foil or paper layer that is coated with an adhesive compound on one side. When using a masking strip, which is applied to the pane in solid or film-like form, the application of a suitably tailored border is alternatively preferred. This is particularly interesting for larger quantities, for which it is worthwhile to produce a border beforehand.

Before removing the masking strip, the contour of the coating area is preferably traversed along the masking strip on the side facing the hologram element with a cutting tool such as a knife or laser, so that a clean edge of the hologram element is produced.

In a preferred embodiment of the method, in an additional step after the removal of the masking strip, a blocking film in the form of a peripheral frame is arranged directly adjacent to the peripheral edge of the hologram element. The surrounding frame completely frames the hologram element without interruption. The barrier foil preferably has a thickness which corresponds approximately to the thickness of the hologram element. In this way, air inclusions in the area of the peripheral edge of the hologram element can be avoided during lamination with the thermoplastic intermediate layer. In addition, in the later composite pane a local thickness difference between the area with the hologram element and the surrounding area can be at least partially compensated for by the blocking film. According to the invention, the blocking film does not overlap the hologram element, but rather is only attached in its immediate vicinity adjacent to the peripheral edge of the hologram element, as a result of which this compensation for differences in thickness becomes possible. The barrier film has a cutout whose dimensions correspond to the dimensions of the coating area defined by the masking strip.

The barrier film can be assembled from individual sections of a barrier film to form a peripheral frame or used as a continuous frame-shaped film. In this sense, continuous means that the corresponding blocking film is uninterrupted all the way around the hologram element, ie has no interruptions. The frame results from the cut-out in the area of the coating area. A particularly good seal can be achieved by means of an uninterrupted, continuous shape

The barrier film is preferably a polymer layer and preferably contains or consists of polyvinyl butyral (PVB), polyethylene terephthalate (PET), polyamide (PA), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl chloride (PVC), cellulose triacetate (TAC). essentially from it.

In a preferred embodiment, the thickness of the barrier foil and the thickness of the hologram element are essentially the same. In this way, local differences in height are completely compensated for by the barrier film and there are no tensions caused by differences in height.

Adhesion-improving layers and, in particular, adhesion promoters can be present between the individual layers and foils of the layer stack. In particular, the barrier film is preferably fixed to the first pane by means of an adhesion promoter in order to prevent it from slipping during the process.

The invention further relates to a laminated pane with a hologram, which was produced in a method according to the invention. The statements already made in the description of the method according to the invention with regard to the method resulting composite pane, of course also apply to the pane itself and vice versa.

The laminated pane according to the invention contains a hologram. The laminated pane according to the invention is produced in a method according to the invention. The laminated pane comprises at least one stacked sequence of a first pane, a thermoplastic intermediate layer and a second pane. A hologram element is positioned between the first disc and the thermoplastic interlayer. A hologram element is arranged directly on a surface of the first pane. The hologram element is in direct contact with the surface and is produced by spraying a photosensitive material onto the first pane in a homogeneous layer thickness. The homogeneous layer thickness is an important prerequisite for a hologram that is easy to read. One or more holograms are recorded in the hologram element using a laser. The thermoplastic intermediate layer serves to bond the first and second panes and is therefore identical in area to the first pane and the second pane.

A windshield has an upper edge and a lower edge and two side edges running between the upper edge and the lower edge. The top edge designates that edge which is intended to point upwards in the installation position. The lower edge designates that edge which is intended to point downwards in the installation position. The upper edge is often referred to as the roof edge and the lower edge as the engine edge.

Windshields have a central field of vision, with high demands being placed on the optical quality. The central field of view must have high light transmission (typically greater than 70%). Said central field of view is in particular that field of view which is referred to as field of view B, field of view B or zone B by those skilled in the art. Field of view B and its technical requirements are specified in United Nations Economic Commission for Europe (UN/ECE) Regulation No. 43 (ECE-R43, "Uniform Conditions for the Approval of Safety Glazing Materials and Their Installation in Vehicles"). There, the field of view B is defined in Appendix 18.

The hologram element is advantageously located within the central field of view (field of view B) in a windshield. The hologram element can, but does not have to cover the entire area, and can also extend beyond it. The position of the hologram / holograms in the hologram element is variable and is determined depending on the application. The hologram(s) can be distributed over the entire surface of the hologram element or only arranged in a small sub-area. The hologram element preferably extends over at least 30%, particularly preferably over at least 50%, further particularly preferably over at least 80% of the surface of the first pane, particularly preferably over 100% of the surface of the first pane. In this way, visible transitions between the hologram element and a section without a hologram element in the visible area of the pane can be avoided. If the hologram element does not extend over the entire surface of the pane, the hologram element is preferably arranged in such a way that the peripheral edge of the hologram element is arranged in the area of an opaque cover print. This has the advantage that the opaque masking print covers the transition from the hologram element to the barrier film or the surrounding layer.

A cover print is usually located in the edge area of the pane and hides the view of attachments or bonding. Windshields typically have an all-round peripheral masking print made of an opaque enamel, which serves in particular to protect the adhesive used to install the windshield from UV radiation and to conceal it from view. Both the outer pane and the inner pane preferably have a masking print, so that the view through the edge area is prevented from both sides.

The hologram element can also have recesses or holes, for example in the area of so-called sensor windows or camera windows. These areas are intended to be equipped with sensors or cameras whose function could be affected by a hologram element in the beam path.

The hologram element (or all of the hologram elements) is preferably arranged over the entire width and the entire height of the laminated pane, particularly preferably minus a peripheral edge area with a width of, for example, 5 mm to 50 mm. The hologram element is thus encapsulated within the thermoplastic interlayer and protected from contact with the surrounding atmosphere and corrosion. The width of the surrounding edge area can be constant or can vary along the frame. The first and second panes are preferably made of glass, particularly preferably of soda-lime glass, as is customary for window panes. However, the panes can also be made from other types of glass, for example quartz glass, borosilicate glass or alumino-silicate glass, or from rigid, clear plastics, for example polycarbonate or polymethyl methacrylate. The panes can be clear, tinted or tinted. Windshields must have sufficient light transmission in the central viewing area, preferably at least 70% in the main viewing area A in accordance with ECE-R43. The first and the second pane are preferably curved, ie they have a curvature.

The first pane and/or the second pane can have further suitable coatings known per se, for example anti-reflection coatings, non-stick coatings, anti-scratch coatings, photocatalytic coatings or sun protection coatings or low-E coatings.

The thickness of the first and the second pane can vary widely and can thus be adapted to the requirements in the individual case. The first and second panes preferably have thicknesses of 0.5 mm to 5 mm, particularly preferably 1 mm to 3 mm.

The laminated pane can be, for example, the windshield or the roof pane of a vehicle or other vehicle glazing, for example a partition pane in a vehicle, preferably in a rail vehicle or a bus. Alternatively, the laminated pane can be architectural glazing, for example in an exterior facade of a building, or a separating pane inside a building.

The statements already made in the description of the method according to the invention with regard to the laminated pane resulting from the method naturally also apply to the pane itself and vice versa.

The invention also includes a projection arrangement for displaying information for an observer, at least including a laminated pane according to the invention and a projector which is directed onto the hologram element from the inside. The composite pane according to the invention is designed as described above. The projector emits light at wavelengths to which the hologram in the hologram element is responsive. Laser projectors are preferred because very discrete wavelengths can be achieved with them.

The features of the previously described embodiments of the composite pane also relate to the projection arrangement,

The invention also includes the use of a laminated pane according to the invention with a hologram as interior glazing or exterior glazing in a vehicle or a building.

The invention also includes the use of a composite pane according to the invention as a windshield of a vehicle.

The invention is explained in more detail with reference to a drawing and exemplary embodiments. The drawing is a schematic representation and not to scale. The drawing does not limit the invention in any way. Show it:

FIG. 1 shows a cross section of a curved pane with a coating applied thereto with an inhomogeneous thickness,

FIG. 2 shows a cross section of an embodiment of a curved laminated pane produced using the method according to the invention,

FIG. 3 shows a cross section of an embodiment of a laminated pane produced using the method according to the invention,

FIG. 4 shows a cross section of an embodiment of a laminated pane produced using the method according to the invention,

FIG. 5 shows a plan view of an embodiment of a composite pane according to the invention as a windshield,

Figure 6 is a schematic representation of a method according to the invention and

Figure 7 shows a cross section through an embodiment of a projection arrangement 101 according to the invention.

FIG. 1 shows a cross section of a curved pane 1 with a coating of a photosensitive material 15 applied thereto with an inhomogeneous thickness Different angles of incidence ßi and ß2 of the radiation for recording or for activating the hologram in different areas of the disc. Therefore, with an inhomogeneous layer thickness, the recording and activation of the hologram is poor. In addition, an inhomogeneous layer thickness of the photosensitive material can cause optical distortions.

FIG. 2 shows a cross section of an embodiment of a laminated pane 100 according to the invention with at least one hologram. The laminated pane is curved, as is usual for vehicle panes, particularly windshields. The curved laminated pane 100 comprises an outer pane 2 and an inner pane 1 which are connected to one another via a thermoplastic intermediate layer 3 . The outer pane 2 has an outer surface I and an inner surface II, and the inner pane 1 has an outer surface III and an inner surface IV. In the embodiment shown, a photosensitive material 15 is applied as a hologram element 5 over the entire surface of the outer surface III of the inner pane 1 . This is procedurally particularly simple. The outer surface III of the inner pane 1 is coated with a spray device, which allows a uniform coating up to the edge. The hologram element 5 has five holograms, for example. The outer pane 2 consists, for example, of soda-lime glass and is 2.1 mm thick. The inner pane 1 consists, for example, of soda-lime glass and is 1.6 mm thick. The laminated pane 100 can be a windshield, for example. The thermoplastic intermediate layer 3 comprises a thermoplastic film with a thickness of 0.76 mm and contains, for example, 78% by weight of polyvinyl butyral (PVB) and 20% by weight of triethylene glycol bis(2-ethylhexanoate) as a plasticizer. The hologram element 5 contains dichromated gelatin and has a thickness of 10 μm to 45 μm, for example 20 μm.

FIG. 3 shows an embodiment of a laminated pane 100 according to the invention. The laminated pane 100 comprises a first pane 1, a second pane 2, a thermoplastic intermediate layer 3 and a hologram element 5. FIG. 5 shows a plan view of a laminated pane 100. FIG. 3 shows a possible cross section through a laminated pane according to FIG. 5 along section line BB'. The composite pane 100 may be a windshield, for example, and is curved. The first pane 1 is the inner pane and the second pane 2 is the outer pane. The outer pane consists of soda-lime glass, for example, and is 2.1 mm thick. The inner pane 1 consists, for example, of soda-lime glass and is 1.6 mm thick. By doing A black print 18 is shown in cross-section, which is arranged on the inside II of the outer pane 2 and which thus conceals the view of the peripheral edge 8 of the hologram element 5 .

The first pane 1 and the second pane 2 are connected to one another via the thermoplastic intermediate layer 3 . A hologram element 5 is arranged between the thermoplastic intermediate layer 3 and the first pane 1 and is also connected to the second pane 2 via the thermoplastic intermediate layer 3 . The hologram element 5 is arranged on the outer surface III of the first pane 1 . The hologram element 5 is sprayed directly onto the outer surface III, so that the hologram element 5 can be perceived without interference by the observer arranged on the side of the first pane. The thermoplastic intermediate layer 3 protrudes beyond the hologram element 5 along the entire peripheral edge 8 of the hologram element. Since the thermoplastic intermediate layer 3 projects beyond the hologram element 5 on all sides, the hologram element 5 does not reach the edge of the pane. Since the thermoplastic intermediate layer 3 fills the area up to the edge of the pane, the hologram element 5 is sealed and protected against moisture or corrosive substances.

The thermoplastic intermediate layer 3 comprises a thermoplastic film with a thickness of 0.76 mm and contains, for example, 78% by weight of polyvinyl butyral (PVB) and 20% by weight of triethylene glycol bis(2-ethylhexanoate) as a plasticizer. The hologram element 5 contains silver halides and has a thickness of 20 μm to 45 μm, for example 25 μm.

Figure 4 shows a further embodiment of a composite pane 100 according to the invention. The composite pane 100 in Figure 4 differs from the composite pane shown in Figure 3 by the hologram element 5 and an additional barrier film 6. The hologram element 5 has a peripheral edge 8. Along the peripheral edge 8 A blocking film 6 is arranged on the hologram element, which encloses the peripheral edge 8 . Since the peripheral edge 8 of the hologram element 5 is completely enclosed by the barrier film 6, the hologram element 5 is effectively protected from moisture or cleaning agents or other substances that come into contact with the edge of the laminated pane. The hologram element 5 contains silver chloride in a gelatin matrix and has a thickness of about 100 μm. Since the hologram element has a thickness of more than 50 µm, the probability of air pockets being generated along the peripheral edge 8 in the final laminate increases. To this prevent, a blocking film 6 is arranged in the form of a peripheral frame 12 in the same plane as the hologram element 5 on the first pane 1. A thickness difference between the area with the hologram element 5 and the surrounding area is thus avoided, which leads to less stress in the composite pane. The barrier film 6 consists, for example, of two frames 12 made of PVB with a plasticizer content of at most 0.5% by weight laid flat one on top of the other. The barrier film 6 has a thickness of 100 μm and consists of two film frames placed one on top of the other, each with a thickness of 50 μm. The barrier film 6 made of PVB has excellent adhesion to the first pane 1 and to the thermoplastic intermediate layer 3, which is also made of PVB. Therefore, the composite pane is extremely stable and resistant to aging.

The blocking film 6 has a cutout 17 which is completely filled by the hologram element 5, ie the blocking film is in direct contact with the hologram element

5 along the peripheral edge 8. The cutout 17 corresponds to the coating area 7 in which the photosensitive material is sprayed on. The barrier film

6 does not show any overlap with the surface of the hologram element 5, but allows a targeted, selective edge sealing due to the direct contacting of the side edges. In this sense, the surface of the hologram element 5 that runs essentially parallel to the panes 1, 2 is referred to as the surface of the hologram element, while the edges show a course that is essentially orthogonal to the panes 1, 2.

FIG. 5 shows a plan view of a composite pane 100. The composite pane is designed as a windshield. The windshield comprises a trapezoidal composite pane 100 with a first pane 1 as the inner pane and a second pane 2 as the outer pane, which are connected to one another via a thermoplastic intermediate layer 3 . The windshield has an upper edge D facing the roof in the installed position and a lower edge M facing the engine compartment in the installed position. The cross-section of composite pane 100 is shown in detail in various embodiments in FIGS. The edge area of the laminated pane is covered by an all-round black print 18 (all-round peripheral covering print), which is applied at least to the inside II of the outer pane. The black print 18 is formed by printing an opaque enamel on the interior-side surface II (facing the interior of the vehicle in the installed position) of the second pane 2 . A black print 18 can optionally also be applied to the inside IV of the first pane 1 . The peripheral edge 8 of the hologram element 5 is in the area of the black print 18, so that this is not recognizable when looking at the laminated pane from the outside. The distance between the hologram element 5 and the peripheral edge of the pane is therefore smaller than the width of the black print 18.

FIG. 6 shows a schematic representation of a method according to the invention for producing a laminated pane 100 as shown, for example, in FIG. 2 in the form of a flowchart.

As a first step P1, the method comprises the provision of a curved outer pane 2 with an outer surface I and an inner surface II, a curved inner pane 1 with an outer surface III and an inner surface IV and a thermoplastic intermediate layer 3.

In a second step P2, the method includes spraying a photosensitive material, for example a solution of gelatine with silver chloride, on the outer surface III of the inner pane 1. The layer is applied with a homogeneous layer thickness, which is achieved by a constant distance between the spray nozzle and the pane and a constant spray duration is ensured. In this way, an even coating can be ensured despite the curved geometry of the pane. The freshly applied material dries slightly at an ambient temperature of around 25°C-30°C for around 5 to 10 minutes and is then processed further in the third step P3.

In a third step P3, at least one hologram is produced by selective laser irradiation of the exposed hologram element. The hologram is recorded on the exposed hologram element, i.e. no further layer of material is applied to the hologram element after the spraying process. This leads to a simplification of the method since no additional intermediate steps have to be carried out. In addition, subsequent fixing steps and washing steps can be performed directly on the exposed layer, which makes washing out much more effective than if one or more further layers are arranged on top.

In a fourth step P4, the coated hologram-recorded disc is passed through a fixer bath, and then washed in a washing solution so that unexposed silver chloride is removed and elemental silver is also dissolved out to obtain a transparent hologram-recorded disc receives. Finally, the pane is dried at a slightly elevated temperature of 50°C to 120°C.

In a fifth step P5, a layer stack is formed from the first pane with the hologram element thereon, a thermoplastic intermediate layer and a second pane, which are then connected in a lamination process to form a composite pane.

FIG. 7 shows a cross section through an embodiment of a projection arrangement 101. The projection arrangement 101 comprises a compound pane 100 according to an embodiment shown in FIG. 4 and a projector 19. The projector 19 is arranged in an interior space. The beam path for light emanating from a projector is provided with reference number 21 in the drawing. The light emanating from the projector 19 hits the hologram element 5 and activates the hologram. The light emitted by the projector 19 is reflected by the hologram element 5, so that the holograms are perceived by a viewer 20 as virtual or real images on the side of the laminated pane 100 facing away from him when his eyes are inside the so-called eyebox E.

Reference list:

1 first disc

2 second disc

3 thermoplastic interlayer

5 hologram element

6 barrier film

7 coating area

8 peripheral edge of the hologram element

12 surrounding frame

15 photosensitive material

17 Cutout in barrier film

18 black print

19 projector

20 drivers, observers

21 Beam path for light emanating from a projector

I outer surface of the second disc 2

II inner surface of the second disc 2

III Outer surface of the first disc 1

IV inner surface of the first disc 1

30 air that is trapped

100 Composite Disc

101 projection arrangement

BB' cut lines

S field of view B

M motor edge

D roof edge

E eye box

Claims

23

Method for producing a composite pane (100) with a hologram, at least comprising the steps: a) providing a first pane (1) and a second pane (2), b) spraying on a photosensitive material (15) as a hologram element (5). in a coating area (7) on a surface (III) of the first pane (1), c) producing at least one hologram by selective laser irradiation of the exposed hologram element (5), d) forming a layer stack from the first pane (1), a thermoplastic Intermediate layer (3) and a second pane (2), the hologram element (5) being arranged between the two panes (1, 2), e) connecting the first pane (1) and the second pane (2) via the thermoplastic intermediate layer (3) to a composite pane (100) in a lamination process. Method according to Claim 1, in which the first pane (1) is coated with an adhesion promoter at least in the coating region (7) for the hologram element (5) or is pretreated by plasma activation. Method according to claim 1 or 2, wherein at least the first pane (1) is curved in one or more directions of space and preferably the radius of curvature or the radii of curvature are independently in the range of 10 cm to 40 m. A method of making a hologram laminated sheet (100) according to any one of claims 1 to 3, wherein the photosensitive material (15) comprises gelatin and silver halides or gelatin and dichromates. Method for producing a laminated pane (100) with a hologram according to one of Claims 1 to 4, the thermoplastic intermediate layer (3) or an adhesive layer being arranged directly adjacent to the hologram element (5) in the layer stack. 6. A method for producing a laminated pane (100) with a hologram according to any one of claims 1 to 5, wherein the photosensitive material (15) in step (b) is sprayed on as a solution having a viscosity of 10 mPas to 500 mPas.

7. The method for producing a composite pane (100) with a hologram according to any one of claims 1 to 6, wherein the spraying in step (b) is carried out at a pressure of between 1.0 and 2.0 bar.

8. The method for producing a laminated pane (100) with a hologram according to any one of claims 1 to 7, wherein the photosensitive material (15) is applied in a uniform layer thickness d in the coating area (7), the layer thickness d increasing by at most 5 μm to 25 μm pm differs.

9. A method for producing a composite pane (100) with a hologram according to any one of claims 1 to 8, wherein the first pane (1) is the inner pane of the composite pane and in step (b) the photosensitive material (2) as a hologram element (5) is applied to the outer surface (III) of the inner pane.

10. A method for producing a composite pane (100) with a hologram according to any one of claims 1 to 9, wherein prior to step (b) a masking stripe is arranged on the surface of the first pane (1) so that the masking stripe delimits the coating area (7). and wherein the masking strip is removed again after step (b) and before step (d).

11. Composite pane (100) produced by a method according to any one of claims 1 to 10.

12. Use of a composite pane (100) produced in a method according to one of claims 1 to 10 as interior glazing or exterior glazing in a vehicle or a building, in particular as a vehicle pane in means of transport for traffic on land, in the air or on water, in particular in automobiles and particularly as a windshield serving as a projection screen.