Composite panel with electrically switchable optical properties

Abstract

A composite panel with electrically switchable optical properties, having: an outer panel and an inner panel which are connected to one another over the entire length thereof via an interlayer; within the interlayer, a switchable functional element with at least one active layer; and an infrared protective coating arranged between the outer panel and the active layer over the entire length thereof, wherein the infrared protective coating contains at least three functional layers with reflecting properties for the infrared range.

Claims

1. A composite pane with electrically switchable optical properties, comprising: an outer pane and an inner pane, which are laminarily bonded to one another via an intermediate layer; and inside the intermediate layer, a prelaminated functional element including, a) a switchable functional element that contains, a1) at least one active layer, a2) an infrared protective coating that contains at least three functional layers with reflecting properties for the infrared range, the infrared protective coating being an outer plate electrode, and a3) and inner plate electrode, b) a first carrier film, and c) a second carrier film, wherein the infrared protective coating is laminarily arranged between the outer pane and the active layer, wherein the switchable functional element is laminarily arranged between the first carrier film and the second carrier film, wherein the first carrier film is bonded to the outer pane at least via one first thermoplastic adhesive film and the second carrier film is bonded to the inner pane via at least one second thermoplastic adhesive film, wherein the infrared protective coating is laminarily arranged on the surface of the first carrier film facing the at least one active layer, wherein the at least one active layer is laminarily arranged between the outer plate electrode and the inner plate electrode, wherein the prelaminated functional element is a previously prepared prelaminated functional element with integrated infrared protective coating, and wherein the composite pane has an edge region that is not provided with the infrared protective coating.

2. The composite pane according to claim 1, wherein the switchable functional element is a suspended particle device (SPD) functional element.

3. The composite pane according to claim 1, wherein the functional layers contain at least one metal.

4. The composite pane according to claim 1, wherein each functional layer has a thickness from 5 nm to 50 nm.

5. The composite pane according to claim 1, wherein each functional layer is arranged between two dielectric layers, which contain at least one oxide or one nitride.

6. The composite pane according to claim 1, wherein the outer pane and/or the inner pane contain non-prestressed, partially prestressed, or prestressed glass.

7. The composite pane according to claim 1, wherein the averaged transmittance of the infrared protective coating in the spectral range from 800 nm to 900 nm is less than or equal to 15%.

8. A method for producing the composite pane according to claim 1, the method comprising: a) providing the previously prepared prelaminated functional element, b) arranging the intermediate layer with the previously prepared prelaminated functional element laminarily between the outer pane and the inner pane, and c) bonding the outer pane to the inner pane via the intermediate layer, wherein the providing of the previously prepared prelaminated functional element includes applying the infrared protective coating on a surface of the first carrier film during preparing the previously prepared prelaminated functional element.

9. The method according to claim 8, wherein preparing the previously prepared prelaminated functional element further includes heating the infrared protective coating after the applying of the infrared protective coating to a temperature of at least 200 C.

10. The composite pane according to claim 3, wherein the functional layers contain silver.

11. The composite pane according to claim 4, wherein each functional layer has a thickness from 8 nm to 25 nm.

12. The composite pane according to claim 5, wherein each functional layer is arranged between two dielectric layers, which contain silicon nitride.

13. The composite pane according to claim 6, wherein the outer pane and/or the inner pane contain flat glass, float glass, quartz glass, borosilicate glass, soda lime glass, polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, polystyrene, polyamide, polyester or polyvinyl chloride.

14. The composite pane according to claim 6, wherein the outer pane and/or the inner pane have a thickness from 0.5 mm to 15 mm.

15. The composite pane according to claim 6, wherein the outer pane and/or the inner pane have a thickness from 1 mm to 5 mm.

16. The composite pane according to claim 7, wherein the averaged transmittance of the infrared protective coating in the spectral range from 800 nm to 900 nm is less than or equal to 10%.

Description

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

(2) FIG. 1 a cross-section through a first embodiment of the composite pane according to the invention with electrically switchable optical properties,

(3) FIG. 2 an enlarged view of the detail Z of FIG. 1,

(4) FIG. 3 a cross-section through another embodiment of the composite pane according to the invention,

(5) FIG. 4 a cross-section through another embodiment of the composite pane according to the invention,

(6) FIG. 5 the transmittance of an infrared corrective coating according to the invention and according to the prior art using a diagram,

(7) FIG. 6 an exemplary embodiment of the method according to the invention using a flowchart,

(8) FIG. 7 another exemplary embodiment of the method according to the invention using a flowchart, and

(9) FIG. 8 another exemplary embodiment of the method according to the invention using a flowchart.

(10) FIG. 1 and FIG. 2 each depict a detail of an embodiment of the composite pane according to the invention with electrically switchable optical properties. The composite pane includes an outer pane 1, which is bonded to an inner pane 2 via an intermediate layer 11. The composite pane is provided as a rear window of a motor vehicle and is arranged in the installed position such that the outer pane 1 faces the external environment and the inner pane 2 faces the motor vehicle interior. The outer pane 1 and the inner pane 2 are made of soda lime glass and have thicknesses of 1.6 mm.

(11) A switchable functional element 4 is embedded in the intermediate layer 11. The functional element 4 is an SPD functional element with an active layer 5 between an outer plate electrode 6 and an inner plate electrode 7. The plate electrodes 6, 7 are connected to an external power supply via bus bars (not shown) and connection cables (not shown). The plate electrodes 6, 7 are made of indium tin oxide (ITO) and have a thickness of less than 1 m. The active layer 5 contains polarized particles suspended in a resin. As a function of the voltage applied on the plate electrodes 6, 7, the suspended particles orient themselves along a common spatial direction. Through the orientation of the particles, the absorption of visible light is reduced. Consequently, the transmittance of visible light through the composite pane can be conveniently controlled electrically.

(12) The functional element 4 was provided at the time of the production of the composite pane as a pre-laminated functional element 8. The pre-laminated functional element 8 comprises the functional element 4 between a first carrier film 9 and a second carrier film 10. The carrier films 9, 10 are made of polyethylene terephthalate (PET) and have a thickness of 0.125 mm.

(13) The pre-laminated functional element 8 is bonded to the outer pane 1 via a first thermoplastic adhesive film 12 and to the inner pane 2 via a second thermoplastic adhesive film 13. The thermoplastic adhesive films 12, 13 are made of ethylene vinyl acetate (EVA) and have in each case a thickness of 0.38 mm. The intermediate layer 11 thus comprises the first thermoplastic adhesive film 12, the pre-laminated functional element 8 (with the first carrier film 9, the outer plate electrode 6, the active layer 5, the inner plate electrode 9, and the second carrier film 10), and the second thermoplastic adhesive film 13.

(14) To prevent damage of the active layer 5 of the functional element 4 from infrared radiation, an infrared protective coating 3 is applied on the inside surface of the outer pane 1. The infrared radiation component of sunlight penetrating into the composite pane via the outer pane 1 is reflected by the infrared protective coating 3, before it can strike the active layer 5.

(15) The infrared protective coating 3 comprises four dielectric layers 15 and three functional layers 14, which are applied alternatingly on the outer pane such that each functional layer 14 is arranged between two dielectric layers 15 and adjacent functional layers 14 are separated from one another in each case by a dielectric layer 15. The functional layers 14 are made of silver (with possible production-related impurities) and have, for example, a layer thickness of roughly 15 nm. The dielectric layers 15 contain, in the simplest embodiment, in each case a single layer of a dielectric material, for example, silicon nitride. Those single layers of a dielectric material that are arranged between two functional layers 14 have, for example, in each case a layer thickness of roughly 50 nm. The top and the bottom single layer of a dielectric material have, for example, in each case a layer thickness of 25 nm. However, the dielectric layers 15 can also contain in each case two or more single layers of different materials.

(16) The infrared protective coating 3 according to the invention with the three functional layers 14 has high transmittance in the visible spectral range. In the infrared range, the infrared protective coating 3 has high reflectance and low transmittance. In particular, in the near infrared range, the reflectance is significantly improved compared to a known infrared protective coating with only one or two functional layers. Thus, the functional element 4 is significantly more effectively protected against aging.

(17) After application on the outer pane 1, the infrared protective coating 3 was subjected to a temperature treatment. The outer pane 1 with the infrared protective coating 3 was heated, for example, to at least 300 C. In particular, the crystallinity of the functional layers 14 is improved by the temperature treatment. Thus, the transmittance of visible light and the reflecting properties relative to infrared radiation are significantly improved.

(18) FIG. 3 depicts a cross-section through another embodiment of the composite pane according to the invention with electrically switchable optical properties. The outer pane 1, the inner pane 2, the thermoplastic adhesive films 12, 13, the carrier films 9, 10, and the functional element 4 are configured as in FIG. 1. The infrared protective coating 3 is applied on the surface of the first carrier film 9 facing away from the functional element 4 and thus arranged in the composite pane between the first thermoplastic adhesive film 12 and the first carrier film 9. With a thus positioned infrared protective coating 3, the aging of the active layer 5 can also be effectively prevented.

(19) Alternatively, the infrared protective coating 3 can also be applied on the first thermoplastic adhesive film 12. It is, alternatively, also possible to apply the infrared protective coating 3 on another film which is inserted between the first thermoplastic adhesive film 12 and the carrier film 9 during production of the composite pane.

(20) FIG. 4 depicts a cross-section through another embodiment of the composite pane according to the invention with electrically switchable optical properties. The infrared protective coating 3 is applied on the surface of the first carrier film 9 facing the active layer 5. The infrared protective coating 3, which is itself electrically conductive, serves simultaneously as the outer plate electrode 6. This simplifies the production of the composite pane. For this, the infrared protective coating 3 is connected to the external power supply via a bus bar and a connecting cable (not shown). In addition, the infrared protective coating 3 is advantageously protected against corrosion and other damage in the interior of the pre-laminated functional element 8. Consequently, the pre-laminated functional element 8 with the integrated infrared protective coating 3 can be prepared in relatively large quantities before the production of the composite pane.

(21) Alternatively, of course, another layer made, for example, of indium tin oxide can be applied on the infrared protective coating 3 as the outer plate electrode 6.

(22) FIG. 5 depicts a diagram of the transmittance through a composite pane with an infrared protective coating 3 according to the invention. The infrared protective coating 3 was applied on the inner surface of the outer pane 1 and comprised three functional layers 14 made of silver. The infrared protective coating 3 was tempered. The diagram further depicts the transmittance through a composite pane with an infrared protective coating according to the prior art, which contained only two functional layers made of silver and which was applied on another thermoplastic film made of PET inserted in the intermediate layer. For better comparison of the transmittance is of the infrared protective coatings, the composite panes have no functional element 4. It is clearly discernible that the infrared protective coating 3 according to the invention has lower transmittance in the infrared radiation range, in particular even in the near infrared range. Consequently, a functional element 4 is better protected against aging due to infrared radiation by an infrared protective coating 3 according to the invention.

(23) FIG. 6 depicts an exemplary embodiment of the method according to the invention for producing a composite pane with electrically switchable optical properties. The exemplary embodiment results in a composite pane according to the invention in accordance with FIG. 1. First, an infrared protective coating 3 is applied on the inner surface of the outer pane 1. Then, the coated outer pane 1 is subjected to a temperature treatment at 300 C. The switchable functional element 4 contains an active layer 5 between an outer plate electrode 6 and an inner plate electrode 7. The switchable functional element 4 is provided as a pre-laminated functional element 8 between a first carrier film 9 and a second carrier film 10. An inner pane 2, a second thermoplastic adhesive film 13, the pre-laminated functional element 8, a first thermoplastic adhesive film 12, and the outer pane 1 are arranged laminarily one over another in the order indicated and then laminated under the action of temperature, pressure, and/or vacuum to form the composite pane.

(24) FIG. 7 depicts an exemplary embodiment of the method according to the invention for producing a composite pane with electrically switchable optical properties. The exemplary embodiment results in a composite pane according to the invention in accordance with FIG. 3. The switchable functional element 4 contains an active layer 5 between an outer plate electrode 6 and an inner plate electrode 7. The switchable functional element 4 is provided as pre-laminated functional element 8 between a first carrier film 9 and a second carrier film 10. An infrared protective coating 3 is applied on the surface of the first carrier film 9 facing away from the functional element 4. An inner pane 2, a second thermoplastic adhesive film 13, the pre-laminated functional element 8, a first thermoplastic adhesive film 12, and an outer pane 1 are arranged laminarily one over another in the order indicated and then laminated under the action of temperature, pressure, and/or vacuum to form the composite pane.

(25) FIG. 8 depicts an exemplary embodiment of the method according to the invention for producing a composite pane with electrically switchable optical properties. The exemplary embodiment results in a composite pane according to the invention in accordance with FIG. 4. First, an infrared protective coating 3 is applied on the surface of a first carrier film 9. The first carrier film 9, an active layer 5, an inner plate electrode 7, and a second carrier film 10 are arranged laminarily one over another in the order indicated such that the infrared protective coating 3 faces the active layer 5. The infrared protective coating 3 serves as the outer plate electrode 6 and is appropriately contacted electrically for that purpose. The first carrier film 9 with the infrared protective coating 3, the active layer 5, the inner plate electrode 7, and the second carrier film 10 are bonded under the action of temperature, pressure, and/or vacuum to form a pre-laminated functional element 8. Next, an inner pane 2, a second thermoplastic adhesive film 13, the pre-laminated functional element 8, a second thermoplastic adhesive film 12, and an outer pane 1 are arranged laminarily one over another in the order indicated and then laminated under the action of temperature, pressure, and/or vacuum to form the composite pane.

EXAMPLE

(26) A composite pane according to the invention with electrically switchable optical properties in accordance with FIG. 1 was produced. The infrared protective coating 3 was subjected, after application on the inner surface of the outer pane 1, to a temperature treatment. For this, the coated outer pane 1 was heated for 7 minutes to a temperature of 640 C. Then, the outer pane 1 with the infrared protective coating 3, the pre-laminated functional element 8, and the inner pane 2 were laminated via the first thermoplastic adhesive film 12 and the second thermoplastic adhesive film 13 at a temperature of roughly 120 C. and a pressure of roughly 2 bar to form the composite pane.

(27) The composite pane was subjected to a standardized WeatherOmeter (WOM) Test. The composite pane was irradiated for 800 hours with a xenon arc lamp, whose radiation simulates the solar spectrum. The outer pane 1 was arranged facing the light source. After the irradiation, the value E, which is presented in Table 1, was determined. The value E indicates the changes in brightness and color of the composite pane due to the WOM Test. It is calculated using the following formula:

(28) $E=\sqrt{{\left(\frac{L^{*}}{2}\right)}^2+a^{{*}^2}+b^{{*}^2}}$

(29) L* is the brightness value, a* and b* are the color coordinates in the L*a*b* Color Space. refers to the difference of the respective variable before and after the WOM Test.

COMPARATIVE EXAMPLE 1

(30) The Comparative Example 1 was performed exactly the same as the Example. The difference resided in the infrared protective coating 3. The infrared protective coating 3 comprised, according to the prior art, only two functional layers made of silver. The infrared protective coating 3 was also not applied on the outer pane 1, but, instead, on another thermoplastic film made of PET, which was inserted between the first thermoplastic adhesive layer 12 and the pre-laminated functional element 8 in the composite (Southwall XIR-75 PET). The composite pane was subjected to the same WOM Test. The value E determined thereafter is presented in Table 1.

COMPARATIVE EXAMPLE 2

(31) The Comparative Example 2 was performed exactly the same as the Example. However, in contrast to the Example, the composite pane had no infrared protective coating 3. The composite pane was subjected to the same WOM Test. The value E determined thereafter is presented in Table 1.

(32) TABLE-US-00001 TABLE 1 Comparative Comparative Example Example 1 Example 2 E 2.4 4.1 4.8

(33) It can be discerned from Table 1 that the infrared protective coating 3 according to the invention results in substantially reduced aging of the functional element 4. The protection of the functional element 4 is substantially improved compared to a composite pane with an infrared protective coating according to the prior art. This result was unexpected and surprising for the person skilled in the art.

LIST OF REFERENCE CHARACTERS

(34) (1) outer pane (2) inner pane (3) infrared protective coating (4) switchable functional element (5) active layer of the functional element 4 (6) outer plate electrode of the functional element 4 (7) inner plate electrode of the functional element 4 (8) pre-laminated functional element (9) first carrier film of the pre-laminated functional element 8 (10) second carrier film of the pre-laminated functional element 8 (11) intermediate layer (12) first thermoplastic adhesive film (13) second thermoplastic adhesive film (14) functional layer with reflecting properties in the infrared range (15) dielectric layer Z detail of the composite pane