METHOD FOR PRODUCING A COMPOSITE PANE WITH A FUNCTIONAL ELEMENT HAVING ELECTRICALLY CONTROLLABLE OPTICAL PROPERTIES

Abstract

A method for producing a composite pane with a functional element having electrically controllable optical properties, includes providing a first pre-composite including a first thermoplastic laminating film and a first barrier film as well as a second pre-composite including a second thermoplastic laminating film and a second barrier layer trimming and the pre-composites substantially to the dimensions of the composite pane, forming a circumferential back cut in the barrier films, arranging the first pane, the first pre-composite, a functional element, the second pre-composite, and a second pane one over another in this order, the barrier films being arranged sheet-wise directly adjacent the functional element, surrounding the circumferential edge of the functional element, and touching one another sheet-wise at least in sections in an overhang u protruding beyond the functional element, and bonding the layer stack.

Claims

1. A method for producing a composite pane with a functional element having electrically controllable optical properties, the method comprising: a) providing a first pre-composite comprising a first thermoplastic laminating film and a first barrier film as well as a second pre-composite comprising a second thermoplastic laminating film and a second barrier layer and trimming the first and second pre-composites substantially to dimensions of the composite pane to be produced, b) forming a circumferential back cut in the first and second barrier films, c) arranging a first pane, the first pre-composite, a functional element, the second pre-composite, and a second pane one over another in this order, wherein the first and second barrier films are arranged sheet-wise directly adjacent the functional element with, at least in sections, a common overhang that is beyond the circumferential edge of the functional element and surrounds the circumferential edge of the functional element, and d) bonding the layer stack comprising, in this order, the first pane, the first thermoplastic laminating film, the first barrier film, the functional element, the second barrier film, the second thermoplastic laminating film, and the second pane by autoclaving to form the composite pane.

2. The method according to claim 1, wherein before step a), the first barrier film is joined to the first thermoplastic laminating film by heating to form a first pre-composite and/or the second barrier film is joined to the second thermoplastic laminating film by heating to form a second pre-composite.

3. The method according to claim 1, wherein in step b), cutouts are made in the barrier films of the pre-composites.

4. The method according to claim 1, wherein in step c), a thermoplastic frame film is arranged between the first pane and the first thermoplastic laminating film and/or between the second pane and the second thermoplastic laminating film, which thermoplastic frame film surrounds the region of the first thermoplastic laminating film and/or the second thermoplastic laminating film into which the functional element is introduced.

5. The method according to claim 1, wherein the first thermoplastic laminating film and/or the second thermoplastic laminating film contain in each case at least one plasticizer.

6. The method according to claim 5, wherein the first and the second thermoplastic laminating film contain at least 3 wt. % of a plasticizer, and the plasticizer contains or is made of aliphatic diesters of tri- or tetraethylene glycol.

7. The method according to claim 1, wherein the thermoplastic laminating films contain at least 60 wt. % of polyvinyl butyral (PVB).

8. The method according to claim 1, wherein the first and the second barrier film are implemented such that the first and the second barrier film prevent the diffusion of plasticizer through the barrier film.

9. The method according to claim 8, wherein the first and the second barrier film are plasticizer-free and contain or are made of polyethylene terephthalate (PET) or polyvinyl fluoride (PVF).

10. The method according to claim 1, wherein the material composition of the first and second barrier films differs in terms of its main constituent by weight from the main constituent by weight of the thermoplastic laminating films.

11. The method according to claim 10, wherein the first and second barrier films contain polyethylene terephthalate (PET) as the main constituent by weight and the thermoplastic laminating films contain polyvinyl butyral (PVB) as the main constituent by weight.

12. A composite pane containing a functional element having electrically controllable optical properties produced in a method according to claim 1, comprising in this order a first pane, a first pre-composite comprising a first thermoplastic laminating film with at least one plasticizer and a first barrier film, wherein the first barrier film is in direct contact with the circumferential edge of the functional element, a functional element, a second pre-composite comprising a second thermoplastic laminating film with at least one plasticizer and a second barrier layer, wherein the second barrier film is in direct contact with the circumferential edge of the functional element, a second pane, wherein the first and second barrier films are arranged sheet-wise directly adjacent the functional element, surround the circumferential edge of the functional element, and touch one another sheet-wise at least in sections in an overhang protruding beyond the functional element.

13. The composite pane according to claim 12, wherein the overhang of the first and the second barrier film protruding beyond the functional element is at least 1 mm, and the overhang of the first and the second barrier film protruding beyond the functional element is at most 50 mm.

14. The composite pane according to claim 12, wherein the functional element is a polymer dispersed liquid crystal film.

15. The composite pane according to claim 12, wherein in the region of the functional element, cutouts are made in the barrier films of the pre-composite, and the first barrier film and/or the second barrier film are implemented in each case in the form of a continuous circumferential frame.

16. The method according to claim 6, wherein the first and the second thermoplastic laminating film contain at least 30 wt.-% of a plasticizer.

17. The method according to claim 6, wherein the plasticizer is triethylene glycol-bis-(2-ethyl hexanoate).

18. The method according to claim 7, wherein the thermoplastic laminating films contain at least 90 wt.-% of polyvinyl butyral (PVB).

19. The composite pane according to claim 13, wherein the overhang of the first and second barrier film protruding beyond the functional element is at least 5 mm.

20. The composite pane according to claim 13, wherein the overhang of the first and the second barrier film protruding beyond the functional element is at most 20 mm.

Description

[0092] The invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings in no way restrict the invention. They depict:

[0093] FIG. 1a a cross-section of a pre-composite comprising barrier film and thermoplastic laminating film during cutting of the film to size,

[0094] FIG. 1b a layer stack of an embodiment of the composite pane according to the invention prior to lamination of the pane,

[0095] FIG. 1c a layer stack of another embodiment of the composite pane according to the invention with a thermoplastic frame film prior to lamination of the pane,

[0096] FIG. 2a a plan view of an embodiment of the composite pane according to the invention,

[0097] FIG. 2b a cross-section through the composite pane of FIG. 2a along the section line A-A,

[0098] FIG. 2c an enlarged representation of the region Z of FIG. 2b,

[0099] FIG. 3 a cross-section through an embodiment of the composite pane according to the invention with a thermoplastic frame film,

[0100] FIG. 4 a cross-section through another embodiment of the composite pane according to the invention with a thermoplastic frame film,

[0101] FIG. 5a a plan view of another embodiment of a composite pane according to the invention as a roof panel with a functional element,

[0102] FIG. 5b a cross-section through the composite pane of FIG. 5a along the section line B-B,

[0103] FIG. 6 a plan view of another embodiment of a composite pane according to the invention as a windshield with a sun visor.

[0104] FIG. 1a depicts a pre-composite 3 or 4 according to the invention comprising a thermoplastic laminating film 3a or 4a and a barrier film 3b or 4b and the processing steps for cutting the barrier film to size, represented as states A to C. This can, analogously, be a composite 3 of the first thermoplastic laminating film 3a with the first barrier film 3b, or a composite 4 of the second thermoplastic laminating film 4a with the second barrier film 4b. The pre-composites 3 or 4 per state A) in FIG. 1a were produced by routing a thermoplastic laminating film 3a or 4a together with a barrier film 3b or 4b through a heated pair of rollers with a temperature of 45 C. and a speed of 4 m/min. The rollers press the films together under heating, bonding them to form a pre-composite. The thermoplastic laminating films 3a and 4a are made of 78 wt.-% polyvinyl butyral (PVB) and 20 wt.-% triethylene glycol bis(2-ethyl hexanoate) as plasticizer and have in each case a thickness of 0.38 mm, while the barrier films 3b and 4b are made substantially of polyethylene terephthalate (PET) and are in each case 50 m thick. Here, the barrier film 3b and 4b are made, for example, substantially of PET, i.e., at a rate of at least 97 wt.-%. The barrier films 3b and 4b contain less than 0.5 wt.-% plasticizer and are preferably plasticizer-free. The barrier films 3b, 4b are suitable to decisively reduce or prevent the diffusion of plasticizer out of thermoplastic laminating films 3a, 4a. The pre-composites 3 and 4 can be constructed with the same or different materials and film thicknesses. In such a pre-composite 3 or 4, cuts 18 are made in the barrier film 3b or 4b of the pre-composite 3, 4 using a cutting tool 17. The cutting depth is selected such that the thermoplastic laminating film remains substantially undamaged. The cuts 18 made in the barrier film 3b, 4b produce a back cut 7 in the edge region of the barrier films 3b, 4b, as a result of which the barrier films 3b, 4b are set back relative to the circumferential edge of the subsequent composite pane. Furthermore, a cutout 6 is produced within the surface of the barrier films 3b, 4b. The cuts 18 necessary for the back cut 7 in the edge region as well as the cutout 6 within the surface of the barrier films 3b, 4b are depicted in state B) of FIG. 1a and run circumferentially. Suitable cutting tools 17 are known to the person skilled in the art. A plotter equipped with a cutting blade has, for example, proved to be quite suitable. However, other methods can also be used, such as laser cutting. The barrier films 3b, 4b are removed in the region of the cut back 7 and of the cutout 6. This is possible by lifting the barrier film 3b, 4b to be detached at the edge of a cut 18. Starting from such a raised corner, the regions of the barrier film 3b, 4b to be removed are peeled off. This is possible with moderate expenditure of force and without damaging the films. This creates a pre-composite 3, 4 comprising a continuous thermoplastic laminating film 3a, 4a and a frame-shaped barrier film 3b, 4b, that is present only at the locations on the pre-composite where it is necessary for the sealing of the functional element (see C) in FIG. 1a). A single barrier film 3b, 4b trimmed to a frame shape has no dimensional stability at all such that it cannot be handled by machine and can hardly be handled manually. Through the use according to the invention of a bilayer (pre-composites 3, 4), the barrier films 3b, 4b can be cut in any geometries without any restrictions. The stability and handleability of the assembly is, consequently, always ensured by the thermoplastic laminating film 3a, 4a.

[0105] Accordingly, the use of bilayers is decisive for the ability to automate the process as well as for the variable shaping of the functional element.

[0106] FIG. 1b depicts a layer stack for producing the composite pane according to the invention using the pre-composite per FIG. 1a. The plus signs situated between the plies of the layer stack indicate the layer sequence in which the components are arranged on one another. A bilayer (pre-composite 3 per FIG. 1a) comprising a first thermoplastic laminating film 3a and a first barrier film 3b present on subregions of the laminating film 3a is placed on a first pane 1 made of clear soda lime glass with a thickness of 2.1 mm. The thermoplastic laminating film 3a is placed adjacent the first pane 1. The first pane 1 per FIG. 1b has a thickness of 2.1 mm and represents the outer pane of the windshield of a motor vehicle. A functional element 5 is placed on the first barrier film 3a, with the barrier film 3a and the functional element 5 coordinated with one another in their dimensioning such that the circumferential edge of the functional element 5 rests on the surface of the barrier film 3a. The functional element is implemented as a PDLC element with a thickness of 100 m. Another bilayer (pre-composite 4 per FIG. 1a) which points with a second barrier layer 4b in the direction of the functional element 5, is applied on the functional element 5. A second pane 2 is placed above the second thermoplastic laminating film 4a, completing the layer stack. The second pane 2 has a thickness of 1.6 mm and is also made, for example, of clear soda lime glass. In this case, the second pane 2 represents the inner pane of a windshield and is bent congruently together with the first pane. The barrier films 3b, 4b are trimmed per FIG. 1 a such that they are substantially congruent with one another per FIG. 1b and, together, cover the circumferential edge of the functional element 5. Any additional films, for example, functional films or colored films, can be arranged between the first thermoplastic laminating film 3a and the first pane 1 or between the second thermoplastic laminating film 4a and the second pane 2. The pre-composites 3, 4 remain in the vicinity of the functional element 5 with direct contact between the functional element 5 and the barrier films 3b, 4b, even if the layer stack is extended. Such a layer stack can be assembled by machine. The use of pre-composites thus represents a significant simplification in terms of the production process of the composite pane.

[0107] FIG. 1c depicts a layer stack for producing the composite pane according to the invention using the pre-composite per FIG. 1a. The structure of the layer stack corresponds substantially to that described in FIG. 1b. In contrast thereto, the functional element 5 has a thickness of 400 m. In order to compensate for the difference in thickness between the region of the composite pane with a functional element 5 and the region of the composite pane without a functional element 5, a frame-shaped thermoplastic laminating film 9 with a thickness of 0.38 mm is inserted into the layer stack. This can, for example, be arranged adjacent the first pane 1 or adjacent the second pane 2. The laminating film 9 corresponds in its composition to the composition of the thermoplastic laminating films 3a and 4a already described (FIG. 1a).

[0108] FIG. 2a depicts an embodiment of a composite pane 100 according to the invention comprising a first pane 1, a second pane 2, a first thermoplastic laminating film 3a, a second thermoplastic laminating film 4a, a first barrier layer 3b, a second barrier layer 4b, and a functional element 5. FIG. 2b depicts a cross-section of the composite pane per FIG. 2a along the section line A-A. An enlargement of the region Z of FIG. 2b is presented in FIG. 2c. The composite pane 100 can, for example, be arranged as architectural glazing in the frame of a window with additional panes to form an insulating glazing unit. The first and the second pane 1, 2 are made of clear soda lime glass with a thickness of 2.0 mm in each case. The first pane 1 and the second pane 2 are joined to one another via the first thermoplastic laminating film 3a and the second thermoplastic laminating film 4a. A functional element 5, which is also bonded to the panes 1, 2 via the thermoplastic laminating films 3a, 4a, is inserted between the first thermoplastic laminating film 3a and the second thermoplastic laminating film 4a. A first barrier film 3b and a second barrier film 4b, which surround the circumferential edge 8, are arranged along the circumferential edge 8. For this purpose, the first barrier film 3b and the second barrier film 4b are positioned directly against opposite surfaces of the functional element 5. The barrier films 3b, 4b are positioned substantially congruent to one another and have an overlap x (see FIG. 2a, 2b) of 10 mm with the functional element. Moreover, the barrier films 3b, 4b have an overhang u (see FIG. 2a, 2b) of 10 mm beyond the circumferential edge 8 of the functional element 5. Here, the barrier films 3b, 4b have, for example, an overhang u on all sides and an overlap x protruding on all sides beyond the functional element 5. Here, on all sides means that the overhang u and the overlap x are present on every side edge of the circumferential edge 8. In the region of the overhang u, the surfaces of the first barrier film 3b and the second barrier film 4b touch each other directly. Thus, the circumferential edge 8 of the functional element 5 is completely enclosed by the barrier films 3b, 4b. The barrier films 3b, 4b are formed as circumferentially continuous frame-shaped films. Due to the use of the barrier films 3b, 4b as pre-composites 3, 4 with the thermoplastic laminating films 3a, 4a, such complex geometries of the barrier films are possible and can be readily handled. The overhang u and the overlap x further improve the sealing of the circumferential edge 8 such that, in aging tests, the composite pane 100 with a functional element 5 showed either no brightening or hardly any visually perceptible brightening in the edge region of the functional element 5. According to the invention, diffusion of the plasticizer out of the thermoplastic laminating films 3a, 4a into the functional element 5 and degradation of the functional element 5 associated therewith are avoided.

[0109] The optical properties of the functional element 5 can be controlled by applying an electrical voltage. For the sake of simplicity, the electrical supply lines are not shown.

[0110] The controllable functional element 5 is, for example, a PDLC multilayer film, consisting of an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The active layer 11 contains a polymer matrix with liquid crystals dispersed therein, which align themselves as a function of the electrical voltage applied on the surface electrodes, by which means the optical properties can be controlled. The carrier films 14, 15 are made of PET and have a thickness of, for example, 50 m. The carrier films 14, 15 are provided with a coating of ITO facing the active layer 11 and having a thickness of approx. 100 nm, forming the surface electrodes 12, 13. The surface electrodes 12, 13 can be connected to a voltage source via bus bars (not shown) (implemented, for example, by a silver-containing screen print) and connecting cables (not shown).

[0111] The thermoplastic laminating films 3a, 4a comprise in each case a thermoplastic film with a thickness of 0.38 mm and are made, for example, of 78 wt.-% polyvinyl butyral (PVB) and 20 wt.-% triethylene glycol bis(2-ethyl hexanoate) as a plasticizer.

[0112] The barrier films 3b, 4b are made, here, for example, substantially of PET, i.e., at a rate of at least 97 wt.-%. The barrier films 3b, 4b contain less than 0.5 wt.-% plasticizer and are suitable for preventing the diffusion of plasticizer out of the thermoplastic laminating layers 3a, 4a via the circumferential edge 8 into the functional layer 5.

[0113] The barrier films 3b, 4b are in direct contact with the functional element 5, in the present case, in sheet-wise contact with the surfaces of the carrier films 14, 15, as well as, additionally, direct contact with the open cross-section of the functional element 5 along the circumferential edge 8. In the region of the overhang x, the barrier films 3b, 4b are in direct sheet-wise contact with one another. Here, the term in direct contact means that no other components or chemical compounds at all, for example, adhesives, are arranged between the barrier films 3b, 4b and between the barrier films and the functional element 5. According to the prior art, slippage of the barrier films during assembly is prevented by an adhesive connection.

[0114] According to the invention, an adhesive connection is unnecessary and undesirable. Slippage of the adhesive films is achieved through the use of pre-composites 3, 4, comprising in each case a barrier film 3b, 4b and a thermoplastic laminating film 3a, 4a. The embodiment of the invention described in FIGS. 2a, 2b, and 2c includes pre-composites 3, 4 produced per FIG. 1a. The use of pre-composites ensures not only a shifting of the barrier film in the layer stack but also facilitates the assembly of the layer stack. At the same time, inclusions of air bubbles and resultant optical defects or adverse effects are avoided since the barrier films 3b, 4b rest evenly on the functional element 5. The barrier films 3b, 4b according to the invention in the region of the circumferential edge of the functional element 5 are firmly pressed and fixed against one another by the inner pressure in the finished laminated composite pane 100, as a result of which hermetic sealing occurs even without use of adhesives. This was unexpected and surprising for the person skilled in the art.

[0115] FIG. 3 depicts a further development of the composite pane 100 according to the invention of FIGS. 2a, 2b, and 2c. The composite pane 100 of FIG. 3 corresponds substantially to the composite pane 100 of FIGS. 2a, 2b, and 2c such that, in the following, only the differences are discussed.

[0116] In this embodiment, a thermoplastic frame film 9 is arranged in sections between the second thermoplastic laminating film 4a and the second pane 2. The thermoplastic frame film 9 is made, for example, of the same material as the thermoplastic laminating films 3a, 4a. The thermoplastic frame film 9 has a cutout, into which the functional element 5 with the barrier films 3b, 4b and the thermoplastic laminating films 3a, 4a is inserted precisely, i.e., flush on all sides. The thermoplastic frame film 9 thus forms a sort of passe-partout for the functional element 5 and the film sections of the laminating film and barrier films surrounding it. By means of the thermoplastic frame film 9, the differences in thickness caused by the material thickness of the functional element 5 can be compensated. The thicknesses of the functional element 5 and of the thermoplastic frame film correspond to the values described in FIG. 1c.

[0117] FIG. 4 depicts another embodiment of the composite pane 100 according to the invention per FIG. 3. The composite pane 100 of FIG. 4 corresponds substantially to the composite pane 100 of FIG. 3, wherein the barrier films 3b, 4b have no cutouts 6. As a result, the entire functional elements 5 are enclosed by the barrier films 3b, 4b.

[0118] FIG. 5a depicts a plan view of an embodiment according to the invention of a composite pane 100 as a roof panel of a motor vehicle. FIG. 5b depicts a cross-section of the roof panel per FIG. 5a along the section line BB. The roof panel comprises a first pane 1, a second pane 2, a first thermoplastic laminating film 3a, a second thermoplastic laminating film 4a, a first barrier layer 3b, a second barrier layer 4b, and a functional element 5. The first and the second pane 1, 2 are bent congruently with one another. The first pane 1 is the outer pane of the glazing, in other words, it is oriented toward the vehicle's surroundings, whereas the second pane 2 is the inner pane of the composite pane and points toward the vehicle interior. The first pane 1 is made of clear soda lime glass with a thickness of 2.1 mm. The second pane 2 is made of soda lime glass with a thickness of 1.6 mm and is tinted gray. The tinted inner glass contributes to the attractive appearance of the pane, even for the vehicle occupant when looking through the roof panel. The first pane 1 and the second pane 2 are joined to one another via the first thermoplastic laminating film 3a, the second thermoplastic laminating film 4a, and an additional thermoplastic laminating film 19. A functional element 5 that is also bonded to the panes 1, 2 via the thermoplastic laminating films 3a, 4a is inserted between the first thermoplastic laminating film 3a and the second thermoplastic laminating film 4a. A first barrier film 3b and a second barrier film 4b that enclose the circumferential edge 8 are arranged along the circumferential edge 8 of the functional element. For this purpose, the first barrier film 3b and the second barrier film 4b lie directly against opposite surfaces of the functional element 5. The barrier films 3b, 4b are positioned substantially congruent with one another. The functional element 5 and the barrier films 3b, 4b overlap by x=15 mm in order to obtain good sealing of the edge 8. The overhang u of the barrier films 3b, 4b beyond the circumferential edge 8 of the functional element 5 is 10 mm. Here, the barrier films 3b, 4b have an overhang u on all sides and an overlap x on all sides protruding beyond the functional element 5. Here, on all sides means that the overhang u and the overlap x are present on each side edge of the circumferential edge 8. In the region of the overhang u, the surfaces of the first barrier film 3b and the second barrier film 4b touch each other directly. Thus, the circumferential edge 8 of the functional element 5 is completely enclosed by the barrier films 3b, 4b. The overhang u and the overlap x further improve the sealing of the circumferential edge 8 such that, in aging tests, the composite pane 100 with a functional element 5 shows either no brightening or hardly any visually perceptible brightening in the edge region of the functional element 5. According to the invention, diffusion of the plasticizer out of the thermoplastic laminating films 3a, 4a into the functional element 5 and degradation of the functional element 5 associated therewith are avoided. The first thermoplastic laminating film 3a and the second thermoplastic laminating film 4a are tinted gray to make the appearance of the pane attractive. The additional thermoplastic laminating film 19 is colorless and is attached adjacent the outer pane (first pane 1). The additional thermoplastic laminating film 19 is used to incorporate an additional carrier film 20 having an infrared reflecting coating 21 into the layer stack. The additional carrier film 20 is a PET film with a thickness of 50 m that is attached between the additional thermoplastic laminating film 19 and the first thermoplastic laminating film 3a. The infrared reflecting coating 21 is oriented in the direction of the first pane 1 (outer pane) and is used to reduce heating of the passenger compartment by solar radiation.

[0119] The optical properties of the functional element 5 can be controlled by applying an electrical voltage. For the sake of simplicity, the he electrical supply lines are not shown. The controllable functional element 5 is, for example, a PDLC multilayer film, comprising an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The further structure of the functional element corresponds to that described in FIG. 2a-2c.

[0120] The thermoplastic laminating films 3a, 4a and the barrier films 3b, 4b correspond in their chemical composition and their layer thickness to the dimensions described in FIG. 2a-2c.

[0121] The edge region of the roof panel is concealed by a circumferential black print 10 (circumferential peripheral masking print) that is applied at least on the inner side of the outer pane. The black print is formed by printing an opaque enamel onto the interior-side surface (facing the interior of the vehicle in the installed position) of the pane 1. Optionally, a black print 10 can also be applied on the inner side of the second pane. The circumferential edge 8 of the functional element 5 lies in the region of the black print 10 such that it is not perceptible when viewing the roof panel from the outside. The distance of the functional element 5 from the circumferential edge of the roof panel is thus smaller than the width of the black print 10. The electrical connections (not shown) are also reasonably mounted in the region of the black print 10 and thus hidden.

[0122] The barrier films 3b, 4b are in direct contact with the functional element 5, in the present case, in sheet-wise contact with the surfaces of the carrier films 14, 15, and, additionally, in direct contact with the open cross-section of the functional element 5 along the circumferential edge 8. In the region of the overhang x, the barrier films 3b, 4b are in direct sheet-wise contact with each other. Also, according to the exemplary embodiment of FIGS. 5a and 5b, no adhesive or other adhesion-promoting substances at all are used; instead, the barrier films 3b, 4b are used as pre-composites 3, 4 per FIGS. 1a and 1b with the thermoplastic laminating films 3a, 4a.

[0123] The barrier films 3b, 4b according to the invention in the region of the circumferential edge of the functional element 5 are firmly pressed and fixed against one another there by the inner pressure in the finished laminated composite pane 100, as a result of which hermetic sealing occurs even without use of adhesives. This was unexpected and surprising for the person skilled in the art.

[0124] FIG. 6 depicts a plan view of another embodiment of a composite pane according to the invention 100 as a windshield with an electrically controllable sun visor. The PDLC functional element 5 is divided by horizontal isolation lines 16 into six strip-like segments. The isolation lines 16 have, for example, a width of 40 m to 120 m and are spaced 3.5 cm apart. They were introduced into the prefabricated multilayer film by laser. The isolation lines 16 separate, in particular, the electrodes 12, 13 into strips isolated from one another, which have, in each case, a separate electrical connection. The segments can thus be switched independently of one another. The thinner the isolation lines 16, the less conspicuous they are. Even thinner isolation lines 16 can be realized by etching.

[0125] The height of the darkened functional element 5 can be adjusted by the segmentation. Thus, depending on the position of the sun, the driver can darken the entire sun visor or even only part of it. The figure indicates that the upper half of the sun visor is darkened and the lower half is transparent.

[0126] In a particularly convenient embodiment, the functional element 5 is controlled by a capacitive switch area arranged in the region of the functional element, wherein the driver determines the degree of darkening by the location at which he touches the pane.

[0127] The windshield per FIG. 6 comprises a trapezoidal composite pane 100 with a first pane 1 as an outer pane and a second pane 2 as an inner pane that are joined to one another via two thermoplastic laminating films 3a, 4a. The first pane 1 has a thickness of 2.1 mm and is made of a green-colored soda lime glass. The second pane 2 has a thickness of 1.6 mm and is made of a clear soda lime glass. 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 the composite pane 100 is not depicted here in detail since it substantially corresponds to the structure per FIG. 3. Optionally, one or a plurality of thermoplastic laminating films can be inserted outside the region in which the functional element 5 is inserted into the composite pane 100.

[0128] The sun visor is formed by a commercially available PDLC multilayer film as the functional element 5 that is embedded in the thermoplastic laminating films. The height of the sun visor is, for example, 21 cm. The first thermoplastic laminating film 3a is bonded to the first pane 1; the second thermoplastic laminating film 4a is bonded to the second pane 2. A thermoplastic frame film 9 situated between the first thermoplastic laminating film 3a and the first pane 1 has a cutout, into which the cut-to-size PDLC multilayer film is inserted precisely, i.e., flush on all sides. The thermoplastic frame film 9 thus forms, so to speak, a sort of passe-partout for the functional element 5, which is thus encapsulated all around in a thermoplastic material and is protected thereby. In the region of the circumferential edge 8 of the functional element 5, a first barrier film 3b and a second barrier film 4b, which surround the edge 8 and seal the functional element 5. The first barrier film 3b is used as a pre-composite 3 with the first thermoplastic laminating film 3a, while the second barrier film 4b is used as a pre-composite 4 with the second thermoplastic laminating film 4a.

[0129] The first thermoplastic laminating film 3a has a tinted region that is arranged between the functional element 5 and the first pane 1 (outer pane). The light transmittance of the windshield is thus additionally reduced in the region of the functional element 5, and the milky appearance of the PDLC functional element 5 in the diffuse state is mitigated. The aesthetics of the windshield are thus significantly more attractive. The first thermoplastic laminating film 3a has, in the tinted region, for example, average light transmittance of 30%, with which good results are achieved. The region can be homogeneously tinted. However, it is often visually more appealing if the tinting decreases in the direction of the lower edge of the functional element 5 such that the tinted and the non-tinted regions merge smoothly.

[0130] The lower edge of the tinted region and the lower edge of the PDLC functional element 5 can be arranged flush with one another and with the barrier films 3b, 4b situated on this edge. This is, however, not necessarily the case. It is also possible for the tinted region to protrude beyond the functional element 5 or, vice versa, for the the functional element 5 to protrude beyond the tinted region. In the latter case, it would not be the entire functional element 5 that would be bonded to the first pane 1 via the tinted region.

[0131] The controllable functional element 5 is a multilayer film, analogous to the structure depicted in FIG. 2c, consisting of an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The active layer 11 contains a polymer matrix with liquid crystals dispersed therein, which align themselves as a function of the electrical voltage applied to the surface electrodes, as a result of which the optical properties can be controlled. The carrier films 14, 15 are made of PET and have a thickness of, for example, 0.125 mm. The carrier films 14, 15 are provided with a coating of ITO facing the active layer 11 and having a thickness of approx. 100 nm, forming the electrodes 12, 13. The electrodes 12, 13 can be connected to the vehicle's electrical system, via bus bars (not shown) (formed, for example, by a silver-containing screen print) and via connecting cables (not shown).

[0132] A so-called high flow PVB, which has stronger flow behavior compared to standard PVB films, can preferably be used for the thermoplastic laminating films 3a, 4a, 9 per FIGS. 1 to 6. The layers thus flow around the barrier films 3b, 4b and the functional element 5 more strongly, creating a more homogeneous visual impression, and the transition from the functional element 5 to the laminating films is less conspicuous. The high flow PVB can be used for all or even for only one or more of the thermoplastic laminating films 3a, 4a, 9.

LIST OF REFERENCE CHARACTERS

[0133] 1 first pane [0134] 2 second pane [0135] 3 pre-composite comprising first thermoplastic laminating film 3a and first barrier film 3b [0136] 3a first thermoplastic laminating film [0137] 3b first barrier film [0138] 4 pre-composite comprising second thermoplastic laminating film 4a and second barrier film 4b [0139] 4a second thermoplastic laminating film [0140] 4b second barrier film [0141] 5 functional element having electrically controllable optical properties [0142] 6 cutout (of the barrier films) [0143] 7 back cut (in the edge region of the barrier films) [0144] 8 circumferential edge of the functional element 5 [0145] 9 thermoplastic frame film [0146] 10 black print [0147] 11 active layer of the functional element 5 [0148] 12 first surface electrode of the functional element 5 [0149] 13 second surface electrode of the functional element 5 [0150] 14 first carrier film [0151] 15 second carrier film [0152] 16 isolation lines [0153] 17 cutting tool [0154] 18 cuts [0155] 19 additional thermoplastic laminating film [0156] 20 additional carrier film [0157] 21 infrared reflecting coating [0158] 100 composite pane [0159] u overhang [0160] x overlap [0161] AA, BB section lines [0162] Z enlarged region [0163] C field of vision [0164] M engine edge [0165] D roof edge