DE102011105718B4 - Semitransparent layer system with high IR reflection, process for its production and architectural glass element - Google Patents

Abstract

Partially transparent IR-reflecting layer system (1), which is arranged on a transparent substrate (2) and has a base layer arrangement with at least one dielectric base layer (6), a functional layer arrangement with at least one IR reflection layer (10) and a layer from the substrate (2) upwards Cover layer arrangement comprising at least one dielectric cover layer (14), characterized in that between the substrate (2) and the base layer arrangement is a very highly refractive layer, partially absorbing in the wavelength range of solar global radiation, hereinafter referred to as partial absorption layer (4), with a refractive index of 2 , 6 and larger is arranged.

Description

The invention relates to a partially transparent layer system with high IR reflection, which is arranged on a transparent substrate. It also relates to a method for producing such a layer system and to an architectural glass element comprising such an IR-reflecting layer system.

Transparent IR-reflecting layer systems, which include the partially transparent layer systems and which are referred to below as IR-reflecting layer systems, are known as so-called low-E layer systems in thermal insulation glazings. They are to prevent the heat radiation, d. H. have a low energy emission. According to Kirchhoffschem radiation law this is synonymous with low absorption and high reflection in the wavelength range of infrared radiation (IR) of >> 3 microns. According to various applications, either a high transmission or a specifically adjustable transmission in the range of global solar radiation (solar energy transmission) is desired, which covers the wavelength ranges of the near infrared (NIR) and visible light (VIS) of 300 nm to <3 μm (Solar Area). The ratio of transmission, limited to the visible light range, relative to the energy transmission characterizes the filter effect for visible light and is referred to as selectivity. In building glazings in climatic regions with predominant energy loss a high solar energy transmission of the glazing is preferred, resulting in a solar energy gain, while in climatic regions where the energy input through the glazing predominates, a low energy transmission and thus high selectivity of the glazing used is beneficial.

In the first case of required in thermal insulation glazing versions of the LowE layer system, a steep edge in the transition from NIR to IR of the light is desired, which represents a large drop in transmission and a sharp increase in reflection, regularly the reflection transmission edge with increasing number of functional IR reflection layers becomes steeper. In the second case, which is also referred to as sun protection glazing (LowE-Sun), the transmission is reduced in the entire solar range and / or it is specifically a hue of the layer system adjustable. Furthermore, the above-described edge of the transmission drop is preferably shifted in the direction of the transition from the visible (VIS) to the near infrared (NIR) spectral range, which is about 800 nm.

Generally, an IR-reflective layer system, viewed from the substrate upwards, first comprises a base layer arrangement, which in particular has the adhesion of the system to the glass, the chemical and / or mechanical resistance and / or the adjustment of optical properties of the system, e.g. B. the anti-reflection is used.

The base layer arrangement is followed by a functional layer arrangement, which comprises the IR reflection layer and, optionally, further layers which support this function and enable it to influence its optical, chemical, mechanical and electrical properties. Regularly, the IR reflection layers consist of a noble metal, usually silver, or a noble metal alloy. Other materials are also used, most often layers comprising metallic or dielectric nickel or chromium or alloys of both. These materials in turn require adaptation of the remaining layers belonging to the layer system. The optional complementary layers of the functional layer arrangement include, in particular, blocking layers which prevent or at least significantly reduce diffusion and migration processes in the functional layer and are arranged above and / or below an IR reflection layer, as well as absorbing layers, by means of which the light transmission of the layer system can be adjusted let shape.

An IR-reflecting layer system is terminated at the top by a cover layer arrangement which comprises at least one mechanically and / or chemically stabilizing protective layer. This can affect itself or through complementary layers and the optical effect of the layer system, for. As an antireflection taking advantage of interference effects, so that optionally also in conjunction with an anti-reflective high-refractive base layer, the transmission can be increased. The cover layer assembly usually consists of one or more layers of a dielectric oxide or nitride of a metal or a semiconductor, with more than one layer of varying refractive index. The latter is known as a high-low layer arrangement. High refractive index materials are generally used in layer systems whose refractive index is in the range from 1.8 to 2.6, preferably around 2.0. For comparison, the substrate, usually float glass, which has a low refractive index of about 1.52 on the other hand. These high refractive dielectric materials are considered as non-absorbent materials, qualifying them for the described optical function.

The term "layer arrangement" as described generally comprises more than one layer, but also includes that a Layer arrangement consists only of a single layer, which realizes the respective function. The assignment of individual layers to the basic, functional, covering or further layer arrangement is not always unambiguous, since each layer has an influence on both the adjacent layers and on the entire system. Generally, a layer is assigned based on its function.

Thus, a base layer arrangement is generally attributed to those layers which primarily represent a mediator between the substrate and the further layer sequence. Other layers of the base layer arrangement can also influence the properties of the layer system as a whole, such. B. anti-reflection layers or protective layers.

In addition to the IR reflection layer, the functional layer arrangement also includes those layers which directly influence their properties, such as blocking layers for suppressing diffusion processes of adjacent layers into the IR reflection layer or such as intermediary layers which serve to adhere or adjust electrical and optical settings of the adjacent layer.

Layers of the cover layer arrangement close off the layer system and, like the base layer arrangement, can functionally affect the entire system.

Such a so-called single-low E can be supplemented by insertion of a (double-low-E) or several further functional layer arrangement, which are constructed by coupling or middle layer arrangements on the first functional layer arrangement. The above considerations should also be used for the assignment of a layer to the middle layer arrangement. The particular sequence of monolayers and layer arrangements can be modified either within a layer arrangement or in the sequence of layer arrangements so that specific requirements arising from the application or the manufacturing process can be met.

Thus, in the course of the production of the layer system, different temperature loads occur in already applied layer sequences, which are caused by an energy input associated with the deposition or different treatment steps of deposited layers.

In addition, IR-reflecting layer systems for curing and / or forming the substrate are often subjected to annealing processes. In this case, they have such a layer sequence with such layer properties, which make it possible to heat-treat a substrate carrying the layer system and to keep occurring changes in the optical, mechanical and chemical properties of the layer system within defined limits. Depending on the application of a coated substrate, its layer system is exposed to different climatic conditions in the annealing process in different time regimes.

As a result of such temperature loads, there are various processes which change the reflectivity of the IR reflection layer and the transmission of the layer system, in particular for the diffusion of components of the anti-reflection layer into the IR reflection layer and vice versa, and consequently to oxidation processes in the IR reflection layer.

To avoid such diffusion and oxidation processes, a blocker layer is inserted on one or both sides of the IR reflection layer, which serves as a buffer for the diffusing components. These blocking layers are structured and arranged in accordance with the temperature load that occurs and protect the sensitive, often very thin IR reflection layer or the IR reflection layers from the influence of adjacent layers. By inserting one or more blocking layers, in particular color shifts of the layer system as well as the increase of the surface resistance of the layer system as a result of the annealing process are reduced. In particular, NiCr or NiCrOx layers which include the IR-reflecting silver layers or protect them at least on one side are known as blocking layers of temperature-capable layer systems.

In addition, it was found that the reflection and transmission properties of the layer system are also influenced by diffusion processes that emanate from the glass. In order to influence this, was in the US 2004/0086723 A1 inserted below the functional layer arrangement, a barrier layer, which is intended to reduce the diffusion of sodium ions of the glass in the layer system. Also, with such a barrier layer quality problems can be reduced, which are due to undefined starting conditions in the raw glass, ie fluctuating chemical composition of the glass, in particular in terms of its sodium content. In addition, other glass influences, such as corrosion or imprints of the handling of the glass serving nipple, which are often not detectable by visual inspections and can not be eliminated by conventional cleaning, cause undesirable changes in the properties of the layer system. Particularly disadvantageous in such glass influences that their effects on the properties of Layer system will be visible only after the annealing process.

IR-reflecting layer systems find particular application in architecture, where large wall portions are formed by glass and the low emissivity and high IR reflection is important to reduce either heat ingress or heat leakage. Increasingly, in addition to the functionality of the coated glasses, their aesthetic effect also comes to the fore. In the DE 699 34 637 T2 For example, a transparent IR-reflecting layer system having the above-described basic-function and cover-layer arrangement is described, which has an improved appearance due to the ratio of the refractive indices of the transparent dielectric layers of the cover layer arrangement, especially with a more neutral coloration upon reflection.

More recently, LowE-Sun systems in certain colors have been in demand as a replacement for the usually very color-intensive non-selective coating systems of the Solar Control family. Currently, these layers do not meet the energy requirements for LowE systems, in particular for golden reflection colors, because they have too low a selectivity and too high an emissivity.

Attempts to produce a gold-leaf glass LowE-Sun layer system by modifying the layer parameters of typical IR reflective layer systems with the current neutral, but mostly blue to blue-glass side reflection, did not produce aesthetically acceptable results because the reflection color associated with the golden glass side reflection the coated side of the glass is unacceptable.

The invention is therefore based on the object to provide a partially transparent IR-reflective layer system with a specifically adjustable, in particular a golden hue and a method for its production.

The object is achieved by an IR-reflecting layer system which, viewed from the substrate, the known structure of the IR-reflecting layer system, a base layer arrangement at least with a dielectric base layer, a functional layer arrangement at least with an IR reflective layer and a cover layer arrangement at least with a dielectric Covering layer, supplemented by at least one very high-refractive, partially absorbing layer. In doing so, it leads equally to the desired success if this layer or layers are deposited above or below an IR-reflecting layer system known from the prior art or at both positions.

The deposition of the layer system according to the invention takes place by means of magnetron sputtering, which enables the production of dense monolayers even with only very small layer thicknesses whose properties can be set very well and reproducibly by means of the type of sputtering and the sputtering parameters.

Such, the known IR-reflective layer systems expanding layer system meets the requirements for selectivity and emissivity and is also selectively adjustable in its color. For example, various gold tones are adjustable, ranging from copper / bronze to light bronze to gold and silver. Very colored layer systems with a metallic luster can also be achieved, such as pinks or blues, which can be shifted to silvery ones.

In particular, with such an IR-reflecting layer system according to the invention, a transmission in the visible range of T _vis ≦ 50%, preferably of T _vis ≦ 20%, and an emissivity of ε ≦ 10%, preferably of ε <6%, can be achieved.

For the remaining layer system, the known layer sequences for low-layer systems can be used. In this way, the layer system according to the invention can be adapted to the further requirements, in particular a temperability, by configuring the basic, functional and cover layer arrangement for these requirements. For the temperability, such layer systems can have blocking, barrier and / or migration layers as described above. Also supplements by z. B. adhesion-promoting or chemical intermediary layers and the materials used in the layer system can be selected according to the further requirements of the IR-reflecting layer system.

In addition, the transmission can be varied by means of the supplemented layer or layers due to its partially absorbing property. Semi-absorbent materials are usually referred to as those which, in contrast to the dielectric layers, exhibit changes in the transmission in the range of several percentage points as the thickness of the layer increases with the layer thicknesses of a few to a few hundred nanometers customary for solar applications. Merely for conceptual distinction, the partially absorbing layer, which has a very high refractive index, will be referred to below as a partial absorption layer

The setting of a desired transmission can, in accordance with an embodiment of the layer system, be carried out in conjunction with a further partially absorbing layer of the IR-reflecting layer system in a very wide range. Such transmission variations for LowE-Sun layer systems are known for example by means of chromium nitride layers, which are usually used as a blocking layer in the functional layer arrangement. However, other known modifications of the IR-reflecting layer system for influencing the transmission can also be combined with an additional, partially absorbing layer according to the invention.

According to the invention, one or the two complementary partially absorbing layers are deposited from such a material, which has a very high refractive index. The range of the very high refractive property of a single layer is, as usual, to be considered in relation to the materials used in the layer system as well as the substrate and by no means absolute, since an optical effect is measured by the sequence of the optical density of adjacent layers. If the substrate is glass, in the context of solar applications, its refractive index in the range of about 1.5 and a few tenths above and below will be considered to be low refractive index while the refractive index of silicon nitride or metal oxides is 2.0 and a few tenths above it, which is why it is considered highly destructive. In contrast to a refractive index of 1.5 and lower, however, a refractive index of 1.8 or 1.9 can also be regarded as highly refractive. These limits are, as stated, oriented to the materials mentioned. At higher refractive indices, close to the high refractive index region are the very high refractive index materials. If the refractive indices of the materials used shift, then the limits also shift.

Thus, refractive indices of the layer systems described herein as preferred, applied to glass by 1.5 as low refractive, are in the range of 1.8 to 2.6, preferably around 2.0, as high refractive and in the range of 2.6 and to look taller than very high breaking.

Such refractive indices are obtained according to an embodiment of the layer system with partial absorption layers of a semiconducting or a semi-metallic material. In this case, pure semiconductors or semimetals as well as compounds thereof come into consideration. As suitable z. For example, the following materials have been found: silicon having a refractive index of 4.1 to 4.8 at the centroid wavelength of 550 nm, germanium having a refractive index of 4.5 to 5.0, or silicon carbide having a refractive index of about 2.7 , wherein the respective refractive indices may vary within limits depending on the material structure or deposition process. These materials may also have admixtures that do not change the semiconducting or metallic character and z. B. purely technological reasons, such. As silicon with aluminum or borane parts. These are usually up to approx. 10% for taring.

In particular, the possibility that the IR-reflective layer system according to the invention already with a partial absorption layer has the desired properties and that they are particularly achievable with silicon-containing materials, allows the production of the layer system according to the invention also on existing sputtering systems in which z. B. one of several base and / or outer layers is replaced by a partial absorption layer. Depending on the system configuration, only a simple retrofitting may be necessary.

It is also advantageous that the lower partial absorption layer, which lies between the substrate and the base layer arrangement, can be deposited directly on the substrate. Because for most materials of this layer, a good adhesion to the substrate without adhesion-promoting intermediate layer is possible. Alternatively, such an adhesive layer is also possible under the partial absorption layer, without appreciably influencing the above-described properties of the IR-reflecting layer system according to the invention.

Surprisingly, it has been found that regardless of the use of only one or two partial absorption layers, the color phenomena of the IR-reflecting layer system can be set the same for viewing from both sides of the substrate. This is of interest in that in the known color systems of IR-reflecting layer systems, which are achieved via interference of the cover layer arrangement, the glass side resulting color appearance is strongly linked to the layer color appearance, which can lead to unacceptable side coloration in certain and intense glass-side reflection colors , The color appearance is the color that the viewer clearly identifies under solar radiation. This includes minor deviations in the respective wavelength range.

The two-sided color adjustment is carried out according to a further process-side embodiment of the invention by means of the deposited thickness of a partial absorption layer and / or the optical thickness of a thereto adjacent layer. The thickness setting only one or both Layers are carried out according to the desired color and transmission and the other materials used in the IR-reflecting layer system. This can be done by coating experiments or simulations of the layer system.

Such an IR-reflective layer system can be used as architectural glass element, for. B. as a window and door element or as a facade element of glass facades. These are usually designed for energy reasons with multiple glazing, so that different positions are possible for the IR-reflective layer system depending on the purpose. The possible positions of layers and layer systems within multiple glazings are counted from outside to inside based on the available surfaces such that the outermost surface is position I, the first inward position II, etc. During position II the heat input by solar radiation reduced inwardly and often also has a reduced transmission (LowE-Sun systems), reduces an IR-reflective layer system to position III, d. H. on the first inner glass pane, heat losses to the outside (thermal insulation systems). In the latter case, however, usually a high transmission of the IR-reflecting layer system is desired.

Because of these properties, the IR-reflecting layer system with adjustable transmission and adjustable color shade according to the invention is particularly suitable for LowE-Sun layer systems and, at the same time, for energy as well as for design reasons.

The invention will be explained in more detail with reference to an exemplary embodiments. In the accompanying drawing shows in

1 the structure of an IR-reflecting layer system according to the invention,

2A to 2C the transmission and glass and layer reflection of an embodiment of the IR-reflective layer system and

3 the basic structure of a architectural glass element with an IR-reflective layer system.

The IR-reflective layer system 1 according to 1 is by sputtering on a substrate 2 deposited and has the following structure of the substrate 2 considered upward on:
Right on the substrate 2 made of float glass is a very high-breaking, partially absorbing layer, the partial absorption layer 4 arranged. The partial absorption layer 4 consists of silicon with an aluminum content of less than 10% and has a refractive index of about 4.7. Its thickness is about 20 nm. Alternatively, small amounts or other admixtures or pure silicon can be used. The thickness of the partial absorption layer 4 for the embodiment according to 1 is preferably in the range of 20 to 45 nm, depending on the desired hue and the desired transmission.

Over the partial absorption layer 4 the base layer arrangement is deposited. It consists of a dielectric base layer 6 and an overlying adhesion promoting interlayer 8th , The base layer 6 consists of titanium oxide (TiO ₂ ), which has a refractive index of about 2.5 and is therefore highly refractive. The base layer 6 has an optical thickness (product of refractive index and layer thickness) of about 50 nm, these also depending on the desired hue of the IR-reflecting layer system 1 can be varied while being in the range of 20 to 125 nm. This results in a layer thickness in the range of 6 to 65 nm due to the refractive index of TiO _2. Alternative materials are for the base layer 6 also other high-refractive dielectric materials usable, such. As tin oxide (SnO ₂ ) or zinc stannate (ZnSnO), the layer thickness may be in the range of 9 to 80 nm.

The adhesion-promoting intermediate layer 8th consists in the embodiment of zinc oxide (ZnO), which may alternatively have aluminum additions. The thickness of the intermediate layer 8th is in the range of 5 to 8 nm, in the embodiment at the lower limit of this range. It serves, in particular, for the adhesion of the IR reflection layer deposited over it 10 and could also be attributed to the functional layer arrangement, since this assignment is merely an aid, without influencing the properties of the IR-reflecting layer system 1 ,

The IR reflection layer 10 consists in the embodiment of silver (Ag), but may also be one of the known alternative IR reflection materials. It has a layer thickness in the range of 10 to 12 nm.

Above the IR reflection layer 10 is a blocker layer 12 deposited from a nickel chromium oxide (NiCrO _x ) with a thickness of about 2 nm. This layer can also be deposited with other thicknesses and / or materials. Variants of this layer can be deposited from nickel chrome (NiCr), this also as a partially reactive layer (NiCrN _x ) or from chromium nitride (CrN). The latter is associated, for example, with a nitridic topcoat 14 , z. As silicon nitride (Si ₃ N ₄ ), suitable as a further partially absorbing layer. For this purpose, the layer thickness of the blocking layer lies 12 preferably in the range of 0.8 to 3 nm, depending on the desired transmission. The use of nitridic or oxidic nickel, chromium or a combination of both also depends on the overlying topcoat 14 ,

This may also be formed nitridic or oxidic and alternatively to the silicon nitride of tin oxide (SnO ₂ ) or zinc stannate (ZnSnO) exist. Their layer thicknesses are in the range of 8 to 12 nm. In the exemplary embodiment, the cover layer of silicon nitride is deposited with a layer thickness of about 12 nm.

This IR-reflective layer system 1 according to 1 has a golden hue combined with metallic luster, both from the glass side and from the layer side.

The spectral transmission T as well as the glass-side reflection Rg and the layer-side reflection Rf of this exemplary embodiment, in each case in percent, are in 2 B shown. The energy transmittance of this IR-reflecting layer system is about 10%, the energy reflectance is about 51% on the layer side and about 41% on the glass side. The emissivity is approx. 0.06.

The diagrams of 2A represent the spectral transmission and reflection of a bronze and the 2C a copper-colored IR-reflecting layer system 1 Their values of energy transmittance, energy reflectance and emissivity are within the comparable scope as in the embodiment according to 2 B ,

• (1) sehr hoch brechende, teilabsorbierende Schicht 4,
• (2) dielektrische Grundschicht 6,
• (3) haftvermittelnde Zwischenschicht 8,
• (4) IR-Reflexionsschicht 10,
• (5) Blockerschicht 12 und
• (6) dielektrische Deckschicht.

In 3 is an architectural glass element with double glazing, with an outer glass pane 30 which faces the solar light and one at a distance a from the outer glass inner pane 31 , The light is in 3 schematically represented by three arrows. On the side facing away from the light has the outer glass pane 30 an example of an IR-reflective layer system 1 as described above 1 on. Consequently, the outer glass pane 31 the substrate 2 according to the above description, so that the following layer structure (not shown in detail) from the outside to the inside of the IR-reflecting layer system 1 is present:

• (1) very high refractive, partially absorbing layer 4 .
• (2) dielectric base layer 6 .
• (3) adhesion-promoting intermediate layer 8th .
• (4) IR reflection layer 10 .
• (5) blocker layer 12 and
• (6) Dielectric capping layer.

Such an arrangement of the IR-reflecting layer system 1 within the multiple glazing in position II reduces the heat absorption from the outside and thus the entire energy transmission.

LIST OF REFERENCE NUMBERS

1

IR-reflective layer system

2

substratum

4

Part absorption layer

6

base layer

8th

interlayer

10

IR-reflective layer

12

blocker layer

14

topcoat

30

outer glass pane

31

inner glass pane

a

distance

Rf

layer-side reflection

rg

glass side reflection.

T

transmission

Claims (13)

Semitransparent IR-reflecting layer system ( 1 ), which is placed on a transparent substrate ( 2 ) and from the substrate ( 2 ) a base layer arrangement at least with a dielectric base layer ( 6 ), a functional layer arrangement with at least one IR reflection layer ( 10 ) and a cover layer arrangement at least with a dielectric cover layer ( 14 ), characterized in that between the substrate ( 2 ) and the base layer arrangement has a very high-refractive-index layer which absorbs part of the wavelength of the solar global radiation, subsequently as a partial absorption layer (US Pat. 4 ), having a refractive index of 2.6 and greater. Semitransparent IR-reflecting layer system ( 1 ) according to claim 1, characterized in that the partial absorption layer ( 4 ) consists of a semiconducting material or a semi-metal. Semitransparent IR-reflecting layer system ( 1 ) according to one of the preceding claims, characterized in that the partial absorption layer ( 4 ) preferably has a refractive index in the range of 4.0 to 5.0. Semitransparent IR-reflecting layer system ( 1 ) according to one of the preceding claims, characterized in that a partial absorption layer ( 4 ) directly on the substrate ( 2 ) is arranged. Semitransparent IR-reflecting layer system ( 1 ) according to one of the preceding claims, characterized in that the IR reflective layer system has the same color appearance on both sides. Semitransparent IR-reflecting layer system ( 1 ) according to one of the preceding claims, characterized in that the IR-reflecting layer system ( 1 ) comprises a further partially absorbing layer for adjusting the transmission of the IR-reflecting layer system. Architectural glass element with a substrate ( 2 ) of glass or several of them, wherein on a substrate ( 2 ) an IR-reflecting layer system ( 1 ), characterized in that an IR-reflecting layer system ( 1 ) according to one of claims 1 to 6 on the inside, ie the side facing away from the light incident on the architectural glass element, that substrate ( 2 ) which is the outermost of the architectural glass element. Process for the preparation of a partially transparent IR-reflecting layer system ( 1 ), wherein the following layer arrangements and layers are deposited by means of sputtering: deposition of a base layer arrangement with at least one dielectric base layer 6 ) above the substrate ( 2 ), - depositing a one or more layers comprising functional layer arrangement at least with an IR reflective layer ( 10 ) over the base layer arrangement, - deposition of a cover layer arrangement at least with a dielectric cover layer ( 14 ) over the functional layer arrangement and - deposition of at least one in the wavelength range of the solar global radiation partially absorbing, very high refractive layer, subsequently as a partial absorption layer ( 4 ) under the base layer arrangement. A method for producing a partially transparent IR-reflecting layer system according to claim 8, wherein the color appearance of the IR-reflecting layer system ( 1 ) by means of the thickness of a partial absorption layer ( 4 ) and / or the optical thickness of a layer adjacent thereto. Process for the preparation of a partially transparent IR-reflecting layer system ( 1 ) according to one of claims 8 or 9, wherein the partial absorption layer ( 4 ) is deposited as a layer of a semiconductor material or a semimetal. Process for the preparation of a partially transparent IR-reflecting layer system ( 1 ) according to one of claims 8 to 10, wherein the partial absorption layer ( 4 ) having a refractive index greater than 3.0, preferably in the range of 4.0 to 5.0. Process for the preparation of a partially transparent IR-reflecting layer system ( 1 ) according to any one of claims 8 to 11, wherein a partial absorption layer ( 4 ) directly on the substrate ( 2 ) is deposited. Process for the preparation of a partially transparent IR-reflecting layer system ( 1 ) according to one of claims 8 to 12, wherein a further partially absorbing layer for adjusting the transmission of the IR-reflecting layer system ( 1 ) is deposited.

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