DE102023100216B3 - Laminated pane with solar protection coating and heat-reflecting coating and its use - Google Patents

Abstract

The invention relates to a laminated pane which has a transmission index A of 0.5 to 10, the transmission index A being determined according to the following formula:A=TLlaminated glass pane/(TLLow−E−coated pane*TE),where TL is the corresponding light transmittance and TE is the energy transmittance measured according to ISO 9050.The invention also relates to the use of such a laminated pane.

Description

The invention relates to a composite pane with a sun protection coating and a heat-ray reflecting coating and to the use thereof.

A generic composite pane is, for example, made of DE 19927683 C1 known. The DE 19927683 C1 discloses a laminated glass pane made of at least two glass panes and a transparent composite layer connecting them and with a sun protection layer that essentially reflects rays outside the visible spectrum of solar radiation, in particular infrared rays. The laminated glass pane is provided on its surface facing an interior with a further transparent coating (low-E layer) that is spatially separated from the sun protection layer and essentially reflects heat rays.

Glazing, such as that used in sunroofs and sliding roofs, requires a light transmission of between 0.5 and 12% and specific sun protection, characterized by the TTS value, which is a measure of the total transmitted heat radiation from the sun through the pane and is determined, for example, in accordance with ISO 13837. With a higher light transmission, too much heat radiation is transmitted and, on the other hand, people behind the glazing may be visually disturbed by too much light. With a lower light transmission, the glazing is too dark overall, so that people behind the glazing can no longer see through it or can only see through it to a limited extent.

The aim is therefore to achieve the lowest possible TTS value in combination with a light transmission of 0.5 to 12% to ensure the best possible compromise between visibility to the outside through the roof and good thermal properties. Therefore, low radiance and IR-reflective, i.e. solar radiation controlling, functions must be combined in laminated sunroofs and sliding roofs.

IR-reflecting functions, i.e. functions that control solar radiation, are typically achieved by silver-based coatings on the inside of the outer pane or a polyethylene terephthalate film between two polyvinyl butyral films. Silver-based coatings have the intrinsic disadvantage that the reflection in the visible range of light is relatively high, at least 10%. This reflection has an influence on the reflection perceived by the glazing on the interior side. Light reflections of less than 6%, or better of less than 4%, are not perceived as disturbing by the vehicle occupants. Even the use of dark-tinted polyvinyl butyral films between the sun-controlling coating and the inner pane cannot completely compensate for this influence and, depending on the light transmission, the light reflection from the inside of the inner pane can increase. This increase in light reflection is typically perceived as a disadvantage by vehicle occupants, especially those in the rear seats, because visibility through the sunroof or sliding roof deteriorates and optical inconveniences occur, e.g. due to strong reflection of the dashboard in the sunroof or sliding roof.

This therefore also applies to laminated glass panes in sunroofs and sliding roofs, such as those used in DE 19927683 C1 are disclosed.

The WO 2013/127563 A1 discloses another composite pane with a sun protection layer between the glass panes and a low-E coating on the interior surface. The low-E coating is based on niobium, tantalum, molybdenum or zirconium.

The WO 2019/110172 reveals a generic composite pane.

WO 2022/ 063 505 A1 relates to a composite pane with electrically switchable optical properties and a method for producing a composite pane.
One object of the invention is to reliably achieve a constant light reflection of less than 6%, preferably less than 4%, perceived on the inside of the inner pane over the required range of the preferred light transmission through the composite pane of 0.5 to 12%. A further object is to reliably achieve the lowest possible TTS value.

wobei TL (allgemein, gilt für Verbundglasscheibe wie Low-E-beschichtete Scheibe) der entsprechende Lichttransmissionsgrad, und TE die Energietransmission jeweils gemessen nach ISO 9050 ist.According to the invention, this object is achieved by a composite pane according to claim 1. The composite pane according to the invention has an outer pane with an outside surface and a interior-side surface, an inner pane with an exterior surface and an interior-side surface and a thermoplastic intermediate layer. The thermoplastic intermediate layer connects the interior-side surface of the outer pane with the exterior surface of the inner pane. The composite pane has at least one sun protection coating between the outer pane and the inner pane, which essentially reflects or absorbs rays outside the visible spectrum of solar radiation, in particular infrared rays. The laminated glass pane has a heat-ray reflecting coating on the interior-side surface of the inner pane. Light reflection of the composite pane on the interior-side surface of the inner pane at an angle of 8° is less than 6%. The intermediate layer is formed from at least one polymer film, which preferably contains polyvinyl butyral, ethylene vinyl acetate, polyurethane and/or mixtures thereof and/or copolymers thereof, preferably polyvinyl butyral. The at least one polymer film has a light transmittance of 2% to 80%, preferably from 5 to 50%, particularly preferably from 8 to 36%. The composite pane has a transmission index A of 0.5 to 10, whereby the transmission index A (A value) is determined according to the following formula: $$\text{A}={\text{TLS}}_{\text{Laminated glass pane}}/\left({\text{TLS}}_{\text{Low}-\text{E}-\text{coated disc}}*\text{TE}\right),$$

where TL (general, applies to laminated glass panes such as Low-E coated panes) is the corresponding light transmittance and TE is the energy transmittance, each measured according to ISO 9050.

TL _{laminated glass pane} refers to the light transmission through the entire laminated pane. TL _{Low-E coated pane} refers to the light transmission through the inner pane including the heat-ray reflecting coating. The TL values can be suitably adjusted by choosing the tint of the components of the laminated pane, i.e. the inner pane, the outer pane and the intermediate layer. The TE value refers to the energy transmission (also known as direct solar transmittance or direct solar transmission). The TE value is also determined by choosing the tint of the components of the laminated pane and also by the properties of the sun protection coating and the heat-ray reflecting coating. The corresponding values can be suitably selected by the person skilled in the art in order to achieve a transmission index A according to the invention.

The TL values are numbers, in particular decimals, in the range from 0 to 1 or from 0% to 100%.

Der TE-Wert ist eine Zahl, insbesondere Dezimalzahl, im Bereich von 0 bis 1 bzw. von 0% bis 100%.
Dabei sind gemäß ISO 9050:

ρe

die direkte solare Reflexion (englisch: direct solar reflectance)

αe

die direkt solare Absorption (englisch: solar direct absorptance)

The TE value is a number, especially a decimal number, in the range from 0 to 1. The TE value can also be described as τ _e . According to ISO 9050, the following equation applies: $${\mathrm{\tau }}_{\text{e}}+{\mathrm{\rho }}_{\text{e}}+{\mathrm{\alpha }}_{\text{e}}=1$$

The TE value is a number, especially a decimal number, in the range from 0 to 1 or from 0% to 100%.
According to ISO 9050:

ρe

direct solar reflection

αe

direct solar absorption (solar direct absorptance)

• TLVerbundglasscheibe = 0,0155
• TLLow-E-beschichtete Scheibe = 0,899
• TE=0,0094.
• Dadurch ergibt sich ein Transmissionsindex A=1,83.

The following values form an example according to the invention:

• TL laminated glass pane = 0.0155
• TLLow-E coated disc = 0.899
• TE=0.0094.
• This results in a transmission index A=1.83.

Instead of ISO 9050, other standards can be chosen, whereby the transmission index A changes only slightly, if at all.

Surprisingly, it has been shown that such a composite pane has a low light transmission of 0.5% to 12%, for example 1.5%, preferably 2 to 10%, and at the same time a low total transmitted thermal radiation (TTS) of in particular less than 50%, preferably less than 35%, particularly preferably less than 25% (measured according to ISO 13837), the light reflection of the composite glass pane being less than 6%, in particular less than 4%. In particular, the inventors It has been recognized that with a transmission index A according to the invention of far greater than 0.08, in particular up to 10, particularly suitable laminated glass panes can be produced which reliably and reliably solve the above-mentioned tasks.

The light reflection refers to the reflection at angles of 8°.

This means that only a small part of the incoming solar radiation reaches the space behind the pane, which on the one hand ensures advantageous sun protection and on the other hand largely prevents the space behind the composite pane from heating up, while at the same time the reflection on the inside of the inner pane can be reduced to a minimum.

The values for light transmission (TL) and reflection (RL) refer (as is usual for automotive glazing) to the type of light (also used in the literature with the capital letter A), i.e. the visible part of sunlight at a wavelength of 380 nm to 780 nm. Rays, which are essentially rays of the visible spectrum of solar radiation, in particular infrared rays, are rays with a wavelength greater than about 800 nm.

The transmission index A is 0.5 to 10, in particular 2 to 8, preferably 4 to 8, particularly preferably 6 to 8 and very particularly preferably 7 to 8.

The composite pane is intended to separate an interior, in particular the interior of a vehicle, from the outside environment in a window opening. The composite pane is a laminate and comprises a first and a second glass pane, which are referred to as the outer pane and the inner pane in the sense of the invention and are connected to one another via a thermoplastic intermediate layer. In the context of the present disclosure, the inner pane refers to the pane that faces the interior in the installed position. The outer pane refers to the pane that faces the outside environment in the installed position. In the context of the present disclosure, the interior-side surface (or inner side or inner surface) is understood to mean the surface of the panes that faces the interior in the installed position. In the context of the invention, the outside-side surface (or outer side or outer surface) is understood to mean the surface of the panes that faces the outside environment in the installed position.

The surfaces of the glass panes are typically referred to as follows:

The outside of the outer pane is called side 1 or I. The inside of the outer pane is called side 2 or II. The outside of the inner pane is called side 3 or III. The inside of the inner pane is called side 4 or IV.

The interior surface of the outer pane and the exterior surface of the inner pane face each other and are connected to each other by means of the thermoplastic intermediate layer.

The thermoplastic intermediate layer is formed by one or more thermoplastic films. The thermoplastic films preferably contain polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), polyurethane (PU) and/or mixtures thereof and/or copolymers thereof, particularly preferably polyvinyl butyral. The films are preferably formed on the basis of the materials mentioned, but can contain further components, for example plasticizers, colorants, IR or UV absorbers, preferably in a proportion of less than 50%.

It is preferred that the at least one thermoplastic polymer film, in particular the at least one PVB film, is a tinted thermoplastic polymer film, in particular a tinted PVB film, with a light transmission level of 2 to 80%, preferably 5 to 50%, 5 to 26% and particularly preferably 8 to 36%. The use of a tinted thermoplastic polymer film has the advantage that the light transmission, based on the entire laminated glass pane, can be advantageously adjusted by choosing the thermoplastic polymer film. In addition, by combining thermoplastic polymer films with certain light transmission levels and certain low-E layers, the reflection on side 4 of the laminated glass pane can be adjusted to the preferred range of less than 6%.

The individual polymer films, in particular the PVB films, preferably have a thickness of about 0.2 mm to 1 mm, for example 0.38 mm or 0.76 mm. Other properties of the laminated glass pane can be influenced by the thickness of the films. For example, thicker PVB films result in improved sound absorption, especially if they contain an acoustically effective core, increased burglary resistance of the laminated glass pane and also increased protection against ultraviolet radiation (UV protection).

According to the invention, the sun protection coating (or sun protection layer) is arranged between the outer pane and the inner pane. In a preferred embodiment, the sun protection coating is applied to the interior surface of the outer pane. In a further preferred embodiment, the sun protection coating is embedded in the thermoplastic intermediate layer. For this purpose, the sun protection coating is applied to a carrier film which is arranged between two thermoplastic films. The carrier film preferably contains polyethylene terephthalate (PET) and has a thickness of 20 µm to 100 µm, for example about 50 µm. In a further embodiment, the sun protection coating is applied to the outside surface of the inner pane.

The sun protection coating has the task of filtering out parts of the sun's radiation, particularly in the infrared range. The sun protection coating preferably comprises at least one thin transparent metallic layer, which is embedded between at least one dielectric layer. Silver has become the preferred metal for the metallic layer, as it has a relatively neutral color effect and also selectively reflects infrared radiation outside the visible range of solar radiation. The dielectric layers have the task of improving the optical properties of the coated pane via their refractive indices and protecting the metallic functional layer from oxidation. Such sun protection layers, which can be produced using the reactive sputtering process, for example, are used on a large scale in glazing for buildings, but also in motor vehicles. In most cases, layer systems with two silver functional layers, but also three or four silver functional layers are used, as their efficiency, i.e. the reflection of infrared radiation outside the visible range in relation to the transmission of visible radiation, is greater.

Suitable sun protection coatings are available, for example, from WO 2013/104439 A1 and the DE 19927683 C1 known.

The dielectric layers are preferably formed on the basis of dielectric oxides or nitrides, such as ZnO, SnZnO, AlN, SiO ₂ , TiO ₂ or Si ₃ N ₄ .

As an alternative to inorganic, particularly silver-based coatings, the sun protection coating can also be based on a non-metallic, organic basis. In this case, the sun protection coating is preferably a stack of several, typically several hundred, organic layers with different or alternating refractive indices. The stack is a birefringent dielectric interference stack that reflects IR radiation due to interference effects. Such organic coatings have the advantage of greater color neutrality and higher light transmission compared to metallic coatings. In addition, they do not interfere with the transmission of electromagnetic signals. Such sun protection coatings on PET carrier films are provided, for example, by 3M under the brand name “Ultra-Clear Solar Film”.

According to the invention, a coating that reflects heat rays is applied to the inside of the inner pane (side 4). Such coatings are known, for example, from WO 2013/131667 A1 The heat-ray reflecting coating can also be referred to as a low-emissivity coating, emissivity-reducing coating, low-E coating or low-E layer. Its job is to reflect heat radiation, in particular IR radiation, which has a longer wavelength than the IR portion of solar radiation. At low outside temperatures, the low-E coating reflects heat back into the interior and reduces the cooling of the interior. At high outside temperatures, the low-E coating reflects the thermal radiation of the heated composite pane outwards and reduces the heating of the interior. On the inside of the inner pane, the coating according to the invention is particularly effective in reducing the emission of heat radiation from the pane into the interior in summer and the radiation of heat into the outside environment in winter.

The heat-ray-reflecting coating preferably comprises a functional layer which contains a transparent conductive oxide (TCO), preferably indium tin oxide, tin oxide doped with antimony or fluorine and/or zinc oxide doped with gallium and/or aluminum (ZnO:Ga or ZnO:Al), with indium tin oxide being preferred. The functional layer can also contain other electrically conductive oxides, for example fluorine-doped tin oxide (SnO ₂ :F), antimony-doped tin oxide (SnO ₂ :Sb), indium-zinc mixed oxide (IZO), gallium-doped or aluminum-doped zinc oxide, niobium-doped titanium oxide, cadmium stannate and/or zinc stannate. This achieves particularly good results in terms of the emissivity and flexibility of the coating according to the invention. The refractive index of the material of the functional layer is preferably 1.7 to 2.5.

The indium tin oxide is preferably deposited by means of magnetic field-assisted cathode sputtering with a target made of indium tin oxide. The target preferably contains from 75% by weight to 95% by weight of indium oxide and from 5% by weight to 25% by weight of tin oxide as well as impurities resulting from the production process. The tin-doped indium oxide is preferably deposited under a protective gas atmosphere, for example argon. A small proportion of oxygen can also be added to the protective gas, for example to improve the homogeneity of the functional layer. Alternatively, the target can preferably contain at least from 75% by weight to 95% by weight of indium and from 5% by weight to 25% by weight of tin. The indium tin oxide is then preferably deposited with the addition of oxygen as a reaction gas during the cathode sputtering.

The heat-ray reflecting coating also typically comprises dielectric layers, in particular formed from dielectric oxides or nitrides, such as ZnO, SnZnO, AlN, TiO ₂ , SiO ₂ or Si ₃ N ₄ . The layer of reflective, conductive oxide is anti-reflective by using additional dielectric layers above and below to ensure sufficiently low reflection from the inside.

The emissivity of the pane according to the invention can be influenced by the thickness of the functional layer of the heat-ray-reflecting coating. The thickness of the functional layer is preferably 40 nm to 200 nm, particularly preferably 60 nm to 150 nm and very particularly preferably 65 nm to 85 nm, for example about 75 nm. In this thickness range, particularly advantageous values for the emissivity and a particularly advantageous ability of the heat-ray-reflecting coating to withstand mechanical transformation such as bending or tempering without damage are achieved.

The interior-side emissivity of the disclosed composite pane is preferably less than or equal to 50%, particularly preferably from 10% to 50%, very particularly preferably from 15% to 25%. Interior-side emissivity refers to the measure that indicates how much heat radiation the pane emits in the installed position into an interior, for example a building or a vehicle, compared to an ideal heat radiator (a black body). In the sense of the invention, emissivity is understood to mean the normal emissivity at 283 K according to the EN 12898 standard.

The composite pane is further preferably characterized in that the inner pane together with the heat-ray reflecting coating (low-E layer) applied thereto has a light transmittance of 25% to 95%.

The outer pane and the inner pane are preferably formed independently of one another from glass or plastic, preferably soda-lime glass, alkali aluminosilicate glass, polycarbonate or polymethacrylate. In a particularly preferred embodiment, the outer pane and the inner pane are made of glass.

Suitable glass panes typically have light transmission values between 5% and 50% based on a 4mm pane and can have a green or grey tint. Examples of glass panes can be found under the trade names VG10, VG20, VG40 or TSANx, TSA3+, TSA4+, whereby the VG glasses are grey-tinted glasses and the TSA glasses are green-tinted glasses.

The outer and/or the inner pane preferably has, independently of one another, a thickness of 0.1 to 4 mm, preferably of 1 to 4 mm, particularly preferably of 1.6 mm to about 2.1 mm.

The composite pane preferably has a light transmittance of 0.5% to 12%, preferably 2% to 10% (measured according to ISO 9050).

The inner pane with the heat-ray-reflecting coating (low-E layer) applied to it preferably has a light reflection (RL) below 8° of less than 6%, particularly preferably less than 4.0% (measured according to ISO 9050). This refers to the light reflection of the coated inner pane as part of the composite pane - in other words, the interior-side light reflection of the composite pane, i.e. the light reflection on the surface of the inner pane facing away from the outer pane.

• - im Bereich von 2 bis 8 bei einem Lichttransmissionsgrad (TL) der Zwischenschicht von 5 bis 20 %,
• - im Bereich von bis 4 bis 8 bei einem Lichttransmissionsgrad Zwischenschicht von 20 bis 25 %,
• - im Bereich von 5 bis 8 bei einem Lichttransmissionsgrad der Zwischenschicht von 25 bis 30 % und
• - in einem Bereich von 7 bis 8 bei einem Lichttransmissionsgrad der Zwischenschicht von insbesondere größer als 30 %, bevorzugt von 30 % bis 50 %.

The transmission index A is ideally adjusted depending on the light transmission of the intermediate layer in order to achieve optimum properties. The transmission index A is preferably

• - in the range of 2 to 8 with a light transmission factor (TL) of the intermediate layer of 5 to 20 %,
• - in the range of 4 to 8 with a light transmission level of the intermediate layer of 20 to 25 %,
• - in the range of 5 to 8 with a light transmission of the intermediate layer of 25 to 30 % and
• - in a range from 7 to 8 with a light transmittance of the intermediate layer of in particular greater than 30%, preferably from 30% to 50%.

Preferably, the above-mentioned ranges for the light transmittance of the intermediate layer are final, i.e. the intermediate layer has a light transmittance of 5 to 50%, wherein the transmission index A shows the above-described dependence on the light transmittance of the intermediate layer.

In a particularly advantageous embodiment, the composite pane has a transmission index A of 7 to 8, with the light transmission level of the intermediate layer being between 8% and 36%. This achieves particularly good results.

In an advantageous development of the invention, a functional element with electrically controllable optical properties is embedded in the thermoplastic intermediate layer. This allows the view through the composite pane to be electrically controlled, in particular between a clear, transparent state and a state of reduced transmission. The values given for the light transmission of the composite pane or the intermediate layer always refer to the composite pane with the functional element in the clear, transparent state.

Such functional elements are typically used in combination with sun protection coatings to protect the functional elements from harmful IR radiation. The disclosed composite pane with reduced interior reflection reveals its advantages particularly in combination with an electrically controllable functional element: the undesirable interior reflection would be perceived as disturbing, especially when switched to see-through mode, since it is precisely in this state that an unobstructed view to the outside is desired.

The functional element is arranged between at least two layers of thermoplastic material of the intermediate layer, in particular between two polymer films, whereby it is connected to the outer pane by the first layer and to the inner pane by the second layer. The side edge of the functional element is preferably completely surrounded by the intermediate layer, so that the functional element does not extend to the side edge of the composite pane and thus has no contact with the surrounding atmosphere. In order to compensate for the thickness of the functional element in the edge region, the functional element can be inserted in a recess in a third layer of thermoplastic material.

The functional element comprises at least one active layer arranged between a first carrier film and a second carrier film. The active layer has variable optical properties that can be controlled by an electrical voltage applied to the active layer. In the sense of the invention, electrically controllable optical properties are understood to mean properties that can be continuously controlled, but equally also those that can be switched between two or more discrete states. The said optical properties relate in particular to the light transmission and/or the scattering behavior. The functional element also comprises surface electrodes for applying the voltage to the active layer, which are preferably arranged between the carrier films and the active layer.

In a preferred embodiment, the functional element is a PDLC functional element (polymer dispersed liquid crystal). The active layer of a PDLC functional element contains liquid crystals, which are embedded in a polymer matrix. If no voltage is applied to the surface electrodes, the liquid crystals are aligned in a disordered manner, which leads to a strong scattering of the light passing through the active layer. If a voltage is applied to the surface electrodes, the liquid crystals align in a common direction and the transmission of light through the active layer is increased.

In a further preferred embodiment, the functional element is an SPD functional element (suspended particle device). The active layer contains suspended particles, whereby the absorption of light by the active layer can be changed by applying a voltage to the surface electrodes. In principle, however, it is also possible to use other types of controllable functional elements, for example electrochromic functional elements. The controllable functional elements mentioned and their mode of operation are known to the person skilled in the art, so that a detailed description can be omitted at this point.

The surface electrodes are preferably designed as transparent, electrically conductive layers. The surface electrodes preferably contain at least one metal, a metal alloy or a transparent conductive oxide (TCO). The surface electrodes can contain, for example, silver, gold, copper, nickel, chromium, tungsten, indium tin oxide (ITO), gallium-doped or aluminum-doped zinc oxide and/or fluorine-doped or antimony-doped tin oxide. The surface electrodes preferably have a thickness of 10 nm to 2 µm, particularly preferably 20 nm to 1 µm, very particularly preferably 30 nm to 500 nm.

The functional element is in particular present as a multilayer film with two outer carrier films. In such a multilayer film, the surface electrodes and the active layer are typically arranged between the two carrier films. By outer carrier film is meant here that the carrier films form the two surfaces of the multilayer film. The functional element can thus be provided as a laminated film that can be advantageously processed. The functional element is advantageously protected from damage, in particular corrosion, by the carrier films. The multilayer film contains at least one carrier film, a surface electrode, an active layer, a further surface electrode and a further carrier film in the order given. Typically, the carrier films each have an electrically conductive coating that faces the active layer and functions as a surface electrode. The carrier films typically contain PET and have a thickness of 0.1 mm to 1 mm, in particular 0.1 mm to 0.2 mm.

The present invention also relates to the use of the composite pane according to the invention in a vehicle, preferably as a roof pane of a vehicle, particularly preferably as a roof pane of a motor vehicle, in particular a passenger car.

The present invention further relates to a vehicle, preferably a motor vehicle, comprising the laminated glass pane according to the invention.

In the following, the invention is explained in more detail with reference to the figures and embodiments.

• 1 einen Querschnitt durch eine Ausgestaltung der erfindungsgemäßen Verbundscheibe,
• 2 ein Diagramm des Reflexionsgrads einer Ausgestaltung der erfindungsgemäßen Verbundscheibe in Abhängigkeit von der Lichttransmission der Zwischenschicht.

Show it:

• 1 a cross section through an embodiment of the composite pane according to the invention,
• 2 a diagram of the reflectance of an embodiment of the composite pane according to the invention as a function of the light transmission of the intermediate layer.

1 shows a cross section through an embodiment of the composite pane according to the invention. The composite pane comprises an outer pane 1 and an inner pane 2, which are connected to one another via a thermoplastic intermediate layer 3. In the example, the composite pane has a size of approximately 1 m ² and is intended as a roof pane of a passenger car, with the outer pane 1 being intended to face the outside environment and the inner pane 2 being intended to face the vehicle interior. The outer pane 1 has an outside surface I and an inside surface II. The inner pane 2 has an outside surface III and an inside surface IV. The outside surfaces I and III face the outside environment in the installed position (for example in a vehicle roof), and the inside surfaces II and IV face the vehicle interior in the installed position. The inside surface II of the outer pane 1 and the outside surface III of the inner pane 2 face one another. The outer pane 1 and the inner pane 2 contains soda-lime glass and each has a thickness of 2.1 mm. The thermoplastic intermediate layer 3 contains or consists of polyvinyl butyral (PVB) and has a thickness of 0.76 mm.

A sun protection coating 4 is arranged on the interior-side surface II of the outer pane 1. The sun protection coating 4 extends over the entire surface II minus a surrounding frame-shaped coating-free area with a width of 8 mm. The coating-free area is hermetically sealed by gluing to the thermoplastic intermediate layer 3. The sun protection coating 4 is thereby advantageously protected against damage and corrosion. The sun protection coating 4 comprises, for example, at least two functional layers which contain at least silver or consist of silver and have a layer thickness between 10 nm and 20 nm, each functional layer being arranged between two dielectric layers of silicon nitride with a thickness of 40 nm to 70 nm.

A heat-ray reflecting coating 5 is arranged on the interior-side surface IV of the inner pane 2. The coating 5 comprises a functional ITO layer with a thickness of 60 nm to 150 nm. The coating 5 also comprises further dielectric layers above and below the functional layer, in particular made of Al-doped SiO ₂ and Si ₃ N ₄ .

The sun protection coating 4 leads to a reduced heating of the vehicle interior and the inner pane 2 due to the reflection of infrared radiation. The heat-ray reflecting coating 5 reduces, on the one hand, the emission of heat radiation through the composite pane into the vehicle interior, particularly at high outside temperatures. On the other hand, the heat-ray reflecting coating 5 reduces the emission of heat radiation from the vehicle interior at low outside temperatures.

2 shows the light reflection of the reflective coating (low-E layer) of certain laminated glass panes with different values for the transmission index A depending on the light transmittance of the intermediate layer 3 made of PVB. The diagram is discussed in connection with the example.

The invention is explained in more detail below using non-limiting embodiments with reference to the attached figure.

Example:

Table 1 TL% IRR Glass TL % PVB TL % Low-E Glass TL % Product RL % Page 4 TE A a 76 36 27.2 9.9 3.3 0.0455 8.0 76 17 26.9 4 6.3* 0.0185 8.0 76 8th 27 2.2 3.1 0.0102 8.0 b 76 28 39.5 11 3.5 0.0557 5.0 76 8th 39.5 3.2 3.3 0.0162 5.0 c 76 23 54.5 12 3.8 0.0550 4.0 76 8th 54.5 4.4 3.5 0.0202 4.0 d 76 13 76.9 10 3.9 0.0433 3.0 76 8th 76.9 6.3 3.8 0.0273 3.0 e 76 8th 91.3 7.4 3.9 0.0405 2.0 76 8th 91.3 7.4 3.9 0.0405 2.0 e 76 5 87.6 3.2 6.3* 0.0192 1.9 76 17 87.6 11.8 6.3* 0.0617 2.2 G 76 5 37.6 1.4 6.3* 0.0078 4.8 76 17 37.6 5.1 6.3* 0.0255 5.3

A:

Transmissionsindex, wie vorstehend definiert

They mean: IRR glass: Outer pane 1 with solar protection coating 4 PLC 2.1 mm glass pane with solar protection coating 4, comprising three functional silver layers PVB: Intermediate layer 3 Tinted PVB film with different TL Low-E glass: Inner pane 2 with heat-ray reflecting coating 5 Glass panes with different light transmission, each with heat-ray reflecting coating 5, comprising a functional ITO layer a) VG10 glass, 2.1 mm b) VG20 glass, 2.1 mm c) VG40 glass, 2.1 mm d) TSA4+ glass, 2.1 mm e) PLC glass, 2.1 mm
Product: Complete composite pane
RL Page 4: Reflection as defined above

A:

Transmission index as defined above

Examples not according to the invention are marked with * in the column “RL page 4” of Table 1.

It is shown that the advantageous reflection of less than 6%, preferably less than 4%, can be achieved with the combinations listed in Table 1. It is also shown that with high transmission indices A of 5 to 8, a high variability in the transmission levels of the PVB films used is possible without the RL on page 4 being significantly impaired. The smaller the transmission index, the lower the variability in the transmission levels of the PVB films used without the RL on page 4 leaving the preferred range.

This is also from 2 visible.

A laminated pane with dark VG10 2.1 mm glass has a transmission index A of 8 (diamond-shaped symbol in 1 ). A laminated pane with brighter PLC 2.1 mm glass has a transmission index A of 2 (cross-shaped symbol consisting of three lines in 1 ).

2 shows that with increasing light transmittance of the intermediate layer 3, the light reflection of the reflective coating (low-E layer) of all laminated glass panes with different values for the transmission index A increases. For laminated glass panes with a higher transmission index A, e.g. 8, the increase in light reflection of the reflective coating (low-E layer) with increasing light transmittance of the intermediate layer 3 increases more slowly than for those with a low transmission index A, e.g. 2.

List of reference symbols:

1

Outer pane

2

Inner pane

3

thermoplastic intermediate layer

4

Sun protection coating

5

Heat ray reflective coating / Low-E coating

I

outside surface (outer surface) of (1)

II

interior surface (inner surface) of (1)

III

outside surface (outer surface) of (2)

IV

interior surface (inner surface) of (2)

Claims (12)

Composite pane, comprising an outer pane (1) with an outer surface (I) and an interior surface (II), an inner pane (2) with an outer surface (III) and an interior surface (IV), and a thermoplastic intermediate layer (3) which connects the interior surface (II) of the outer pane (1) to the outer surface (III) of the inner pane (2), wherein the composite pane has at least one sun protection coating (4) between the outer pane (1) and the inner pane (2), which essentially reflects or absorbs rays outside the visible spectrum of solar radiation, in particular infrared rays, and wherein the composite pane has a heat-ray reflecting coating (5), low-E coating, on the interior surface (IV) of the inner pane (2), the heat-ray reflecting coating (5) contains a transparent conductive oxide, the composite pane has a light transmittance TL _{laminated glass pane} of 0.5% to 12%, the light reflection of the composite pane on the interior surface (IV) of the inner pane (2) at an angle of 8° is less than 6%, the intermediate layer (3) is formed from at least one polymer film, which preferably contains polyvinyl butyral, ethylene vinyl acetate, polyurethane and/or mixtures thereof and/or copolymers thereof, preferably polyvinyl butyral, wherein the at least one polymer film has a light transmittance of 2% to 80%, preferably from 5 to 50%, particularly preferably from 8 to 36%, and the composite pane has a transmission index A of 0.5 to 10, wherein the transmission index A is determined according to the following formula: $$\text{A}={\text{TLS}}_{\text{Laminated glass pane}}/\left({\text{TLS}}_{\text{Low}-\text{E}-\text{coated disc}}*\text{TE}\right),$$

where TL is the corresponding light transmittance and TE is the energy transmittance measured according to ISO 9050. Composite pane according to Claim 1 , wherein the sun protection coating (4) comprises a layer system with at least one metal layer embedded between dielectric oxide or nitride layers, in particular at least one metallic silver layer. Composite pane according to one of the Claims 1 until 2 , wherein the sun protection coating (4) is applied directly to the interior surface (II) of the outer pane (1). Composite pane according to one of the Claims 1 until 2 , wherein the sun protection coating (4) is arranged on a carrier film embedded in the intermediate layer (3). Composite pane according to one of the Claims 1 until 4 , wherein the heat-ray reflecting coating (5) contains indium tin oxide, antimony- or fluorine-doped tin oxide and/or aluminum-doped zinc oxide (ZnO:Al) and/or gallium-doped zinc oxide (ZnO:Ga), wherein indium tin oxide is preferred. Composite pane according to one of the Claims 1 until 5 , wherein the inner pane (2) together with the heat-ray reflecting coating (5) applied thereto has a light transmittance TL _{Low-E coated pane} of 25% to 95%. Composite pane according to one of the Claims 1 until 6 which has a light transmission factor TL _{laminated glass pane} of 2% to 10%. Composite pane according to one of the Claims 1 until 7 , wherein the inner pane (2) with the heat-ray reflecting coating (5) applied thereto has a light reflection at an angle of 8° of less than 6%, preferably less than 4.0%. Composite pane according to one of the Claims 1 until 8th , wherein the transmission index A - is in the range from 0.5 to 10 when the light transmittance of the intermediate layer (3) is from 5 to 30%, - is in a range from 7 to 10 when the light transmittance of the intermediate layer (3) is greater than 30%, preferably from 30% to 50%. Composite pane according to one of the Claims 1 until 9 , wherein the outer pane (1) and/or the inner pane (2) have a thickness of 0.5 mm to 4 mm, preferably 1.6 mm to 2.1 mm. Composite pane according to one of the Claims 1 until 10 , wherein a functional element with electrically controllable optical properties, in particular a PDLC element, an LC or an SPD element, is embedded in the intermediate layer (3). Use of the composite pane according to one of the Claims 1 until 11 as a roof window of a vehicle.