Composite pane having sun protection coating and thermal-radiation-reflecting coating

Abstract

A composite pane, includes an outer pane having an outer-side surface and an interior-side surface, an inner pane having an outer-side surface and an interior-side surface, and a thermoplastic intermediate layer, which joins the interior-side surface of the outer pane to the outer-side surface of the inner pane. The composite pane has, between the outer and inner panes, a sun protection coating, which substantially reflects or absorbs rays outside the visible spectrum of solar radiation. The composite pane has, on the interior-side surface of the inner pane, a thermal-radiation-reflecting coating (low-E coating). The composite pane has a transmittance index A of 0.02 to 0.08, wherein the transmittance index A is determined according to the following formula A=TL.sub.composite glass pane/(TL.sub.low-E-coated pane*TE). TL is the light transmittance and TE is the energy transmittance measured according to ISO 9050.

Claims

1. A composite pane, comprising an outer pane having an outer-side surface and an interior-side surface, an inner pane having an outer-side surface and an interior-side surface, and a thermoplastic intermediate layer, which joins the interior-side surface of the outer pane to the outer-side surface of the inner pane, wherein the composite pane has, between the outer pane and the inner pane, at least one sun protection coating, which substantially reflects or absorbs rays outside the visible spectrum of solar radiation, and wherein the composite pane has, on the interior-side surface of the inner pane, a thermal-radiation-reflecting coating (low-E coating), wherein the thermal-radiation-reflecting coating contains a transparent conductive oxide, the composite pane has light transmittance TL.sub.composite glass pane of 1% to 12%, and the composite pane has a transmittance index A of 0.02 to 0.08, wherein the transmittance index A is determined according to the following formula (I)
A=TL.sub.composite glass pane/(TL.sub.low-E-coated pane*TE)  (I), where TL is the light transmittance and TE is the energy transmittance measured according to ISO 9050.

2. The composite pane according to claim 1, wherein light reflectance at the interior-side surface of the inner pane at an angle of 8° is less than 6%.

3. The composite pane according to claim 1, wherein the sun protection coating comprises a layer system with at least one metal layer embedded between dielectric oxide or nitride layers.

4. The composite pane according to claim 1, wherein the sun protection coating is applied directly to the interior-side surface of the outer pane.

5. The composite pane according to claim 1, wherein the sun protection coating is arranged on a carrier film embedded in the intermediate layer.

6. The composite pane according to claim 1, wherein the intermediate layer is formed from at least one polymer film.

7. The composite pane according to claim 6, wherein the at least one polymer film has light transmittance of 2% to 80%.

8. The composite pane according to claim 1, wherein the thermal-radiation-reflecting coating contains indium tin oxide, antimony-doped or fluorine-doped tin oxide and/or aluminum-doped zinc oxide (ZnO:A1) and/or gallium-doped zinc oxide (ZnO:Ga).

9. The composite pane according to claim 1, wherein the inner pane together with the thermal-radiation-reflecting coating applied thereto has light transmittance TL.sub.low-E-coated pane of 25% to 95%.

10. The composite pane according to claim 1, which has light transmittance TL.sub.composite glass pane of 2% to 10%.

11. The composite pane according to claim 1, wherein the inner pane with the thermal-radiation-reflecting coating applied thereto has light reflectance at an angle of 8° of less than 6%.

12. The composite pane according to claim 1, wherein the transmittance index A with light transmittance of the intermediate layer of 5 to 20%, with light transmittance of the intermediate layer of 20 to 25%, with light transmittance of the intermediate layer of 25 to 30%, and with light transmittance of the intermediate layer of more than 30% is in a range from 0.07 to 0.08.

13. The composite pane according to claim 1, wherein the outer pane and/or the inner pane have a thickness of 0.5 mm to 4 mm.

14. The composite pane according to claim 1, wherein a functional element with electrically controllable optical properties is embedded in the intermediate layer.

15. A method comprising utilizing composite pane according to claim 1 as a roof panel of a vehicle.

16. The composite pane according to claim 1, wherein the at least one sun protection coating substantially reflects or absorbs infrared rays.

17. The composite pane according to claim 3, wherein the at least one metal layer embedded between dielectric oxide or nitride layers is at least one metallic silver layer.

18. The composite pane according to claim 6, wherein the at least one polymer film contains polyvinyl butyral, ethylene vinyl acetate, polyurethane, and/or mixtures thereof and/or copolymers thereof.

19. The composite pane according to claim 7, wherein the at least one polymer film has light transmittance of 8% to 36%.

20. The composite pane according to claim 14, wherein the functional element with electrically controllable optical properties is a PDLC element or an SPD element.

Description

(1) They depict:

(2) FIG. 1 a cross-section through an embodiment of the composite pane according to the invention,

(3) FIG. 2 a diagram of the reflectance of an embodiment of the composite pane according to the invention as a function of the light transmittance of the intermediate layer.

(4) FIG. 1 depicts 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 that are joined to one another via a thermoplastic intermediate layer 3. The composite pane has a size of approx. 1 m.sup.2 and is intended for use as a roof panel of a passenger car, with the outer pane 1 intended to face the external environment and the inner pane 2 intended to face the vehicle interior. The outer pane 1 has an outer-side surface I and an interior-side surface II. The inner pane 2 has an outer-side surface III and an interior-side surface IV. The outer-side surface I and III face the external environment in the installed state; the interior-side surfaces II and IV face the vehicle interior in the installed position. The interior-side surface II of the outer pane 1 and the outer-side surface III of the inner pane 2 face one another. The outer pane 1 and the inner pane 2 contain soda lime glass and have in each case a thickness of 2.1 mm. The thermoplastic intermediate layer 3 contains or is made of polyvinyl butyral (PVB) and has a thickness of 0.76 mm.

(5) 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 circumferential frame-shaped coating-free region with a width of 8 mm. The coating-free region is hermetically sealed by bonding with the thermoplastic intermediate layer 3. The sun protection coating 4 is thus advantageously protected against damage and corrosion. The sun protection coating 4 comprises, for example, at least two functional layers that at least contain silver or are made of silver and have a layer thickness between 10 nm and 20 nm, with each functional layer arranged between two dielectric layers made of silicon nitride with a thickness of 40 nm to 70 nm.

(6) A thermal-radiation-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 further comprises additional dielectric layers above and below the functional layer made, in particular, of Al-doped SiO.sub.2 and Si.sub.3N.sub.4.

(7) The sun protection coating 4 results in reduced heating of the vehicle interior and of the inner pane 2 due to the reflection of infrared radiation. On the one hand, the thermal-radiation-reflecting coating 5 reduces the radiation of thermal radiation by the composite pane into the vehicle interior, in particular with high outside temperatures. On the other hand, thermal-radiation-reflecting coating 5 reduces the radiation of thermal radiation out of the vehicle interior with low outside temperatures.

(8) FIG. 2 shows the light reflectance of the reflecting coating (low-E layer) of certain composite glass panes with different values for the transmittance index A as a function of the light transmittance of the intermediate layer 3 made of PVB. The diagram is discussed in connection with the example.

(9) In the following, the invention is explained in detail using a nonrestrictive exemplary embodiment with reference to the accompanying figures.

EXAMPLE

(10) TABLE-US-00001 TABLE 1 TL [%] TL [%] TL [%] Low-E TL [%] RL [%] IRR glass PVB glass Product Side 4 A a) 76 36 27.2.sup.a 9.9 3.3 0.08 76 8 27.sup.a   2.2 3.1 0.08 b) 76 28 39.5.sup.b 11 3.5 0.05 76 8 39.5.sup.b 3.2 3.3 0.05 c) 76 23 54.5.sup.c 12 3.8 0.04 76 8 54.5.sup.c 4.4 3.5 0.04 d) 76 13 76.9.sup.d 10 3.9 0.03 76 8 76.9.sup.d 6.3 3.8 0.03 e) 76 8 91.3.sup.e 7.4 3.9 0.02 76 8 91.3.sup.e 7.4 3.9 0.02 Legend: IRR glass: outer pane 1 having sun protection coating 4 PLC 2.1 mm glass pane (Saint-Gobain) having sun protection coating 4, including three functional silver layers PVB: intermediate layer 3 tinted PVB film with different TL Low-E glass: inner pane 2 having thermal-radiation-reflecting coating 5 glass panes (Saint-Gobain) with different light transmittance, in each case with thermal-radiation-reflecting coating 5, including a functional ITO layer a) VG10 glass, 2.1 mm b) VG20 glass, 2.1 mm c) VG 40 glass, 2.1 mm d) TSA4+ glass, 2.1 mm e) PLC glass, 2.1 mm Product: Complete composite pane RL side 4: Reflectance, as defined above A: Transmittance Index, as defined above

(11) It can be seen that the advantageous reflectance of less than 6%, preferably of less than 4% can be achieved with the combinations listed in Table 1. In addition, it can be seen that with high transmittance indices of 0.05 to 0.08, high variability of transmittances of the PVB films used is possible without significantly impacting the RL on the side 4. The smaller the transmittance index, the lower the variability in the transmittance of the PVB used, without the RL on side 4 departing from the preferred range.

(12) This can also be seen in FIG. 2.

(13) A composite pane with dark VG10 2.1 mm glass has a transmittance index A of 0.08 (diamond-shaped symbol in FIG. 2). A composite pane with lighter PLC 2.1 mm glass has a transmittance index A of 0.02 (three-lined X symbol in FIG. 2).

(14) FIG. 2 shows that with increasing light transmittance of the intermediate layer 3, the light reflectance of the reflecting coating (low-E layer) of all composite glass panes with the different values for the transmittance index A increases. For composite glass panes with a high transmittance index A, e.g., 0.08, the increase in the light reflectance of the reflecting coating (low-E layer) rises more slowly with increasing light transmittance of the intermediate layer 3 than for those with a low transmittance index A, e.g., 0.02.

COMPARATIVE EXAMPLE

(15) TABLE-US-00002 TABLE 2 TL [%] TL [%] TL [%] Low-E TL [%] RL [%] IRR-glass PVB glass Product Side 4 A a) 76 36 10 3.5 3.1 0.22

(16) The Comparative Example differs from the Example a, variant with 36% TL of the intermediate layer only in that the thickness of the inner pane made of VG10-glass was 3.9 mm instead of 2.1 mm. It can be seen that the transmittance index A here is clearly outside the targeted range. A similar result can be expected if the degree of tinting of the inner pane were increased instead of its thickness.

LIST OF REFERENCE CHARACTERS

(17) (1) outer pane (2) inner pane (3) thermoplastic intermediate layer (4) sun protection coating (5) thermal-radiation-reflecting coating/low-E coating (I) outer-side surface (outer surface) of (1) (II) interior-side surface (inner surface) of (1) (Ill) outer-side surface (outer surface) of (2) (IV) interior-side surface (inner surface) of (2)