Composite pane comprising a functional element having electrically controllable optical properties

Abstract

A composite pane includes a functional element having electrically controllable optical properties, including a stack sequence formed of an outer pane, a first intermediate layer, a second intermediate layer, and an inner pane, wherein the intermediate layers contain at least one thermoplastic polymer film with at least one plasticizer, and a functional element having electrically controllable optical properties is arranged between the first intermediate layer and the second intermediate layer at least in sections, wherein between the first intermediate layer and the functional element as well as between the functional element and the second intermediate layer, at least one barrier film is arranged, which has, at least in sections, an overhang u beyond the functional element.

Claims

1. Composite pane comprising a functional element having electrically controllable optical properties, comprising: a stack sequence formed of an outer pane, a first intermediate layer, a second intermediate layer, and an inner pane, wherein the first and second intermediate layers contain at least one thermoplastic polymer film with at least one plasticizer, and a functional element having electrically controllable optical properties is arranged between the first intermediate layer and the second intermediate layer at least in sections, wherein between the first intermediate layer and the functional element as well as between the functional element and the second intermediate layer at least one barrier film is arranged and has, at least in sections, an overhang u beyond the functional element and overhanging sections of the barrier film are arranged immediately adjacent one another and contact one another, and wherein the at least one barrier film covers the functional element completely.

2. The composite pane according to claim 1, wherein at least one barrier film is in each case arranged between the first intermediate layer and the functional element and between the second intermediate layer and the functional element, which barrier film has an all-around overhang u beyond the functional element.

3. The composite pane according to claim 1, wherein the at least one barrier film is arranged between the first intermediate layer and the functional element and between the second intermediate layer and the functional element, which barrier film is folded at least in sections around a side edge of the functional element.

4. The composite pane according to claim 3, wherein the at least one barrier film is folded around each side edge and the barrier films cover the functional element at least in sections.

5. The composite pane according to claim 3, wherein the at least one barrier film has an overhang u beyond the functional element on other side edges of the functional element.

6. The composite pane according to claim 1, wherein at least one of the first and second intermediate layers contains at least 3 wt.-% of a plasticizer and the plasticizer contains or consists of aliphatic diesters of tri- or tetraethylene glycol.

7. The composite pane according to claim 1, wherein at least one of the first and second intermediate layers contains at least 60 wt.-% polyvinyl butyral (PVB).

8. The composite pane according to claim 1, wherein the functional element is a polymer-dispersed liquid crystal (PDLC) film.

9. The composite pane according to claim 1, wherein the barrier film is implemented such that the barrier film prevents the diffusion of plasticizer through the barrier film.

10. The composite pane according to claim 1, wherein the barrier film is low in plasticizer or free of plasticizer and contains or consists of polyethylene terephthalate or polyvinyl fluoride.

11. The composite pane according to claim 1, wherein the overhang u of the barrier film beyond the functional element is at least 0.5 mm.

12. The composite pane according to claim 1, wherein the overhang u of the barrier film beyond the functional element is less than 50 mm.

13. The composite pane according to claim 1, wherein the at least one barrier film includes first and second barrier films are joined to one another at least in sections in the region of the overhang u.

14. The composite pane according to claim 1, wherein the at least one barrier film includes first and second barrier films having the functional element and are joined to one another over their entire surface in the region of the overhang u.

15. The composite pane according to claim 1, wherein the functional element and the barrier film are circumferentially surrounded by a third intermediate layer.

16. Method for producing a composite pane according to claim 1, comprising a) arranging one outer pane, one first intermediate layer, one functional element having electrically controllable optical properties, one second intermediate layer, and one inner pane one atop another in this order, wherein at least one barrier film is arranged between the functional element and the first and second intermediate layers, the at least one barrier film covering the functional element completely, and b) joining the outer pane and the inner pane by lamination, wherein an intermediate layer with an embedded functional element is formed from the first intermediate layer and the second intermediate layer.

17. The method according to claim 16, wherein before step a), a first barrier film and the first intermediate layer and/or a second barrier film and the second intermediate layer are glued to one another.

18. The method according to claim 16, wherein in step a), a third intermediate layer that surrounds the functional element is arranged between the first intermediate layer and the second intermediate layer.

19. A method comprising utilizing a composite pane according to claim 1 as a windshield or roof panel of a vehicle and the electrically controllable functional element as a sun visor.

20. A method comprising utilizing a composite pane having an electrically controllable functional element according to claim 1 as interior glazing or exterior glazing in a vehicle or a building and the electrically controllable functional element as a sun screen or as a privacy screen.

Description

(1) The invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and not true to scale. The drawings in no way restrict the invention. They depict:

(2) FIG. 1A a plan view of a first embodiment of a composite pane according to the invention,

(3) FIG. 1B a cross-section through the composite pane of FIG. 1A along the section line X-X,

(4) FIG. 1C an enlarged view of the region Z of FIG. 1B,

(5) FIG. 2 a cross-section through a development of a composite pane according to the invention,

(6) FIG. 3A a plan view of another embodiment of a composite pane according to the invention,

(7) FIG. 3B a cross-section through the composite pane of FIG. 3A along the section line X-X,

(8) FIG. 3C an enlarged view of the region Z of FIG. 3B,

(9) FIG. 3D an enlarged view of the region Z of an alternative embodiment according to the invention of FIG. 3B,

(10) FIG. 4 a cross-section through a development of a composite pane according to the invention,

(11) FIG. 5A a plan view of another embodiment of a composite pane according to the invention as a windshield with a sun visor,

(12) FIG. 5B a cross-section through the composite pane of FIG. 5A along the section line X-X,

(13) FIG. 5C an enlarged view of the region Z of FIG. 5B,

(14) FIG. 6 a plan view of another embodiment of a composite pane according to the invention as a windshield with a sun visor,

(15) FIG. 7 an exemplary embodiment of the method according to the invention with reference to a flowchart, and

(16) FIG. 8 as a comparative example, a cross-section through a prior art composite pane.

(17) FIG. 1A, FIG. 1B, and FIG. 10 depict in each case a detail of a composite pane 100 according to the invention. The composite pane 100 comprises an outer pane 1 and an inner pane 2 that are joined to one another via a first intermediate layer 3a and a second intermediate layer 3b. The outer pane 1 has a thickness of 2.1 mm and is made, for example, of a clear soda lime glass. The inner pane 2 has a thickness of 1.6 mm and is also made, for example, of a clear soda lime glass. The composite pane 100 has a first edge referenced with D that is called the upper edge in the following. The composite pane 100 has a second edge referenced with M that is arranged opposite the upper edge D and is called the lower edge in the following. The composite pane 100 can be arranged, for example, as architectural glazing in the frame of a window with other panes to form an insulating glazing unit.

(18) A functional element 5 that is controllable in its optical properties via an electrical voltage is arranged between the first intermediate layer 3a and the second intermediate layer 3b. For the sake of simplicity, the electrical leads are not shown.

(19) 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 that are oriented 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, 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 which form the surface electrodes 12, 13. The surface electrodes 12, 13 can be connected to the vehicle's electrical system via busbars (not shown) (formed, for example, by a silver-containing screen print) and connection cables (not shown).

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

(21) A barrier film 4a is arranged between the first intermediate layer 3a and the functional element 5. Furthermore, another barrier film 4b is arranged between the functional element 5 and the second intermediate layer 3b. The barrier films 4a, 4b have here, for example, an all-around overhang u of, for example, 5 mm beyond the functional element 5. Here, all-around means that there is an overhang u over each side edge 5.1, 5.2, 5.3, 5.4 of the functional element 5. In the region of the overhang, sections of the barrier film 4a make contact with directly opposing sections of the barrier film 4b. By means of the all-around overlap, the functional element 5 is completely surrounded and sealed by barrier film 4a, 4b.

(22) The barrier film 4a, 4b is made here, for example, substantially of PET, in other words up to at least 97 wt.-%. The barrier film 4a, 4b contains less than 0.5 wt.-% plasticizer and is suitable for reducing or preventing the diffusion of plasticizer out of the intermediate layers 3a, 3b over the side edges 5.1, 5.2, 5.3, 5.4 into the functional layer 5.

(23) In aging tests, such composite panes 100 present a significantly reduced brightening in the edge region of the functional element 5, since diffusion of the plasticizer out of the intermediate layers 3a, 3b into the functional element 5 and a resulting degradation of the functional element 5 is avoided.

(24) In an advantageous development of the composite pane 100 according to the invention, an adhesive means, for example, an acrylate-based adhesive, that adherently glues the barrier films 4a, 4b to the adjacent carrier films 14, 15 or to the opposing barrier film 4a, 4b is arranged between the barrier film 4a and the functional element 5, between the barrier film 4b and the functional element 5 and the sections of the barrier films 4a, 4b making contact with one another. The adhesive connection prevents slippage of the barrier film 4a, 4b during assembly. At the same time, inclusions of air bubbles and resultant visual distractions or impairments are avoided since the barrier film 4a, 4b rests uniformly on the functional element 5.

(25) FIG. 2 depicts a development of the composite pane 100 according to the invention of FIG. 1A-C. The composite pane 100 of FIG. 2 corresponds substantially to the composite pane 100 of FIG. 1A-C such that, in the following, only the differences will be discussed.

(26) In this embodiment, another, third intermediate layer 3c is arranged in sections between the first intermediate layer 3a and the second intermediate layer 3b. The third intermediate layer 3c is made, for example, from the same material as the first and the second intermediate layer 3a, 3b. The third intermediate layer has a cutout, into which the functional element 5 with the barrier films 4a, 4b is inserted with a precise fit, in other words, flush on all sides. The third intermediate layer 3c thus forms a sort of universal frame for the functional element 5. By means of the third intermediate layer 3c, the differences in thickness that result from the material thicknesses of the functional element 5 and the barrier film 4a, 4b can be compensated.

(27) FIG. 3A, FIG. 3B, and FIG. 3C depict in each case a detail of an alternative composite pane 100 according to the invention. The composite pane 100 of FIG. 3A-C corresponds substantially to the composite pane 100 of FIG. 1A-C such that, in the following, only the differences will be discussed.

(28) In contrast to FIG. 1A-C, in the composite pane 100 of FIG. 3A-C, the barrier film 4 is one piece and is folded around a side edge 5.1 of the functional element 5 (here, the side edge 5.1 of the functional element 5 directly adjacent the edge M of the composite pane 100). Here, folded means that the barrier film 4 is turned 180 and arranged parallel to itself. The functional element 5 is arranged in the intermediate space thus formed. On all other side edges 5.2, 5.3, 5.4 of the functional element 5, the barrier film 4 has an overhang u of, for example, 10 mm.

(29) In an advantageous development of the composite pane 100 according to the invention, an adhesive means, for example, an acrylate-based adhesive, that adherently glues the barrier films 4 to the adjacent carrier films 14, 15 or to the opposing barrier film 4 is arranged between the barrier film 4 and the functional element 5 and the sections of the barrier films 4 making contact with one another. The adhesive connection prevents slippage of the barrier film 4 during assembly. At the same time, inclusions of air bubbles and resultant visual distractions or impairments are avoided since the barrier film 4 rests uniformly on the functional element 5.

(30) As an alternative to the adhesive means, the two layers or sections of the barrier film 4 can be glued to one another or fused with one another, for example, by local heating with a hot object, such as a soldering iron or the like, only in the region of the overhang. Here, it is advantageous for the gluing or fusing to be done only in sections, for example, at the connection sites 7 such that air enclosed between the barrier film 4 and the functional element 5 can escape during lamination and no air bubbles impair the optical properties of the composite pane 100 in the region of the functional element 5.

(31) FIG. 3D depicts an enlarged view of the region Z of an alternative embodiment of the invention of FIG. 3B. In this exemplary embodiment, similarly as in FIG. 3C, the barrier film 4 is one piece and folded around a side edge 5.1 of the functional element 5 (here, the side edge 5.1 of the functional element 5 directly adjacent the edge M of the composite pane 100). The fold is, however, not closely positioned and guided directly along the side edge 5.1, but, instead, forms an overhanging region, in which the upper layer of the barrier film 4 and the lower layer of the barrier film 4 make contact with one another. The overhang u.sub.1 here is, for example, 5.5 mm. On all other side edges 5.2, 5.3, 5.4 of the functional element 5, the barrier film 4 has an overhang u of, for example, 10 mm.

(32) FIG. 4 depicts a development of the composite pane 100 according to the invention of FIG. 3A-C. The composite pane 100 of FIG. 4 corresponds substantially to the composite pane 100 of FIG. 3A-C such that, in the following, only the differences will be discussed.

(33) Analogously to FIG. 2, in this embodiment, another, third intermediate layer 3c is arranged in sections between the first intermediate layer 3a and the second intermediate layer 3b. The third intermediate layer 3c is made, for example, of the same material as the first and the second intermediate layer 3a, 3b. The third intermediate layer has a cutout, into which the functional element 5 with the folded-around barrier film 4 is inserted with a precise fit, in other words, flush on all sides. The third intermediate layer 3c thus forms a sort of universal frame for the functional element 5. By means of the third intermediate layer 3c, the differences in thickness that result from the material thicknesses of the functional element 5 and the barrier film 4 can be compensated.

(34) FIG. 5A, FIG. 5B, and FIG. 5C depict in each case a detail of an alternative composite pane 100 according to the invention as a windshield with an electrically controllable sun visor. The composite pane 100 of FIG. 5A-C corresponds substantially to the composite composite 100 of FIG. 1A-C such that, in the following, only the differences will be discussed.

(35) The windshield comprises a trapezoidal composite pane 100 with an outer pane 1 and an inner pane 2 that are joined to one another via two intermediate layers 3a, 3b. The outer pane 1 has a thickness of 2.1 mm and is made of a green colored soda lime glass. The inner pane 2 has a thickness of 1.6 mm and and is made of a clear soda lime glass. The windshield has an upper edge D facing the roof in the installation position and a lower edge M facing the engine compartment in the installation position.

(36) The windshield is equipped with an electrically controllable functional element 5 as a sun visor that is arranged in a region above the central field of vision B (as defined in ECE-R43). The sun visor is formed by a commercially available PDLC multilayer film as a functional element 5 that is embedded in the intermediate layers 3a, 3b. The height of the sun visor is, for example, 21 cm. The first intermediate layer 3a is joined to the outer pane 1; the second intermediate layer 3b is joined to the inner pane 2. A third intermediate layer 3c positioned therebetween has a cutout, into which the PDLC multilayer cut to size is inserted with precise fit, in other words, flush on all sides. The third intermediate layer 3c thus forms, so to speak, a sort of universal frame for the functional element 5, which is thus encapsulated all around in a thermoplastic material and is protected thereby.

(37) The first intermediate layer 3a has a tinted region 6 that is arranged between the functional element 5 and the outer pane 1. 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 is mitigated in the diffusive state. The aesthetics of the windshield are thus designed significantly more appealing. The first intermediate layer 3a has in the region 6, for example, an average light transmittance of 30%, with which good results are obtained.

(38) The region 6 can be homogeneously tinted. However, it is often more visually appealing for the tinting to decrease in the direction of the lower edge of the functional element 5 such that the tinted and non-tinted region translation smoothly into one another.

(39) In the case depicted, the lower edges of the tinted region 6 and the lower edge of the PDLC functional element 5 (here, its side edge 5.1) are arranged flush with the barrier film 4. However, this is not necessarily the case. It is also possible for the tinted region 6 to protrude beyond the functional element 5 or, conversely, for the functional element to protrude beyond the tinted region 6. In the latter case, the entire functional element 5 would not be connected to the outer pane 1 via the tinted region 6.

(40) The controllable functional element 5 is a multilayer film consisting of an active layer 11 between two surface electrodes 12, 13 and two carrier films 14, 15. The active layer 11 includes a polymer matrix with liquid crystals dispersed therein, which orient 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, 0.125 mm. The carrier films 14, 15 are provided with a coating of ITO facing the active layer 11 with a thickness of approx. 100 nm, which form the electrodes 12, 13. The electrodes 12, 13 can be connected to the vehicle's onboard electrical system via busbars (not shown) (formed, for example, by a silver-containing screen print) and connection cables (not shown).

(41) The windshield has, as is customary, a circumferentially peripheral masking print 9 that is formed by an opaque enamel on the interior-side surfaces (facing the interior of the vehicle in the installation position) of the outer pane 1 and of the inner pane 2. The distance of the functional element 5 from the upper edge D and the side edges of the windshield is less than the width of the masking print 9 such that the side edges of the functional element 5with the exception of the side edge pointed toward the central field of vision Bare covered by the masking print 9. The electrical connections (not shown) are also expediently applied in the region of the masking print 9 and thus concealed.

(42) Analogously to FIG. 3A-C, the barrier film 4 is formed in one piece and folded around one of the edges of the functional element 5 (here, the side edge 5.1, the edge of the functional element 5 directly adjacent the edge M of the composite pane 100). Here, folded means that the barrier film 4 is turned 180 and arranged parallel to itself. The functional element 5 is arranged in the intermediate space thus formed. On all other side edges 5.2, 5.3, 5.4 of the functional element 5, the barrier film 4 has an overhang u of, for example, 10 mm. Alternative windshields have only a small overhang in the region of the fold over of the barrier film 4 on the functional element 5 and are arranged flush with the functional element 5 on the other side edges 5.2, 5.3, 5.4. The brightening and changing of the optical properties due to aging occurring there can be covered, for example, by a masking print. The only optically visible lower side edge 5.1 of the functional element 5, on which the barrier film 4 is folded back, is however particularly protected against aging.

(43) A so-called high flow PVB, which has better flow behavior compared to standard PVB films, can preferably be used for the intermediate layers 3a, 3b, 3c. The layers flow around the barrier film 4 and the functional element 5 better, creating a more homogeneous visual impression, and the transition from the functional element 5 to the intermediate layer 3c is less conspicuous. The high flow PVB can be used for all or even for one or more of the intermediate layers 3a, 3b, 3c.

(44) FIG. 6 depicts a plan view of another embodiment of a composite pane 100 according to the invention as a windshield with an electrically controllable sun visor. The windshield and the functional element 5 as a controllable sun visor correspond substantially to the embodiment of FIG. 5. The PDLC functional element 5 is, however, divided into six strip-like segments by horizontal isolation lines 16. The isolation lines 16 have, for example, a width of 40 m to 50 m and a mutual distance of 3.5 cm. They were introduced into the prefabricated multilayer film using a 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. Thus, the segments are switchable independently of one another. The thinner the isolation lines 16, the less conspicuous they are. Even thinner isolation lines 16 can be realized using etching methods.

(45) As a result of the segmentation, the height of the darkened functional element 5 can be adjusted. Thus, depending on the position of the sun, the driver can darkened the entire sun visor or even only a part thereof. The figure indicates that the upper half of the sun visor is darkened and the lower half is transparent.

(46) In a particularly convenient embodiment, the functional element 5 is controlled by a capacitive switching surface arranged in the region of the functional element, wherein the driver specifies the degree of darkening by the location on which he touches the pane. Alternatively, the functional element 5 can also be controlled by contactless methods, for example, by detecting gestures or as a function of the state of the pupil or eyelid determined by a camera and suitable evaluation electronics.

(47) FIG. 7 depicts an exemplary embodiment of the production method according to the invention with reference to a flowchart.

(48) FIG. 8 depicts a prior art composite pane 100 prior art, as disclosed in FIG. 4 of WO 2014/086554 A1 and the associated description. A polyimide film is disclosed as barrier film 4 (called edge seal), which runs circumferentially around the side edges 5.1, 5.2, 5.3, 5.4 of the functional element 5. The polyimide film extends, starting from the side edges of the functional element, a few millimeters beyond the surface of the carrier films facing away from the active layer.

(49) In the prior art, the polyimide film overlaps the functional element 5. However, there is no region in which the polyimide film has an overhang u beyond the functional element 5 and overhanging sections of the polyimide film are arranged directly adjacent one another and make contact with one another.

(50) In the region in which there is an overhang in a composite pane according to the invention, i.e., in which the barrier films 4a, 4b according to the invention or two ends of the barrier film 4 folded around an opposite side edge contact one another, in the prior art of FIG. 8, only the polyimide film is guided tightly around the side edge. In other words, in the prior art there is no overhang according to the invention.

(51) Since the prior art polyimide film is folded circumferentially around the entire side edge region 5.1, 5.2, 5.3, 5.4, cavities, channels, or kinks inevitably develop in the polyimide film, in particular at the corners of the functional element 5. There, the assembly has only degraded diffusion barrier properties. With the prior art assembly, this results in undesirable aging phenomena and degradation of the optical properties of the functional element, in particular in the region of the corners of the functional element.

(52) With barrier films 4, 4a, 4b according to the invention, the barrier films 4, 4a, 4b contact one another areally and in particular over their entire surface in the region of the overhang u, i.e., in the region in which they protrude laterally beyond the functional element 5. The barrier film sections according to the invention are firmly pressed against one another there by the internal pressure in the finished laminated composite pane 100 and fixed, as a result of which hermetic sealing occurs.

(53) This was unexpected and surprising for the person skilled in the art.

LIST OF REFERENCE CHARACTERS

(54) 1 outer pane

(55) 2 inner pane

(56) 3a first intermediate layer

(57) 3b second intermediate layer

(58) 4, 4a, 4b barrier film

(59) 4 prior art barrier film

(60) 5 functional element having electrically controllable optical properties

(61) 5.1,5.2,5.3,5.4 side edge of the functional element 5

(62) 6 tinted region of the first intermediate layer 3a

(63) 7 connection points

(64) 9 masking print

(65) 11 active layer of the functional element 5

(66) 12 surface electrode of the functional element 5

(67) 13 surface electrode of the functional element 5

(68) 14 carrier film

(69) 15 carrier film

(70) 16 isolation lines

(71) 100 composite pane

(72) 100 prior art composite pane

(73) B central field of vision of the windshield

(74) D upper edge of the windshield, roof edge

(75) M lower edge of the windshield, engine edge

(76) u, u.sub.1 overhang

(77) X-X section line

(78) Z enlarged region