COATED GLAZING

Abstract

A coated glazing includes a transparent glass substrate, and a coating located on the glass substrate. The coating is provided with at least the following layers in sequence starting from the glass substrate: a first layer having a refractive index of more than 1.6, an optional second layer having a refractive index that is less than the refractive index of the first layer, a third layer based on tin dioxide doped with antimony, niobium and/or neodymium, and a fourth layer based on titanium dioxide, wherein the fourth layer is photocatalytic.

Claims

1.-16. (canceled)

17. A coated glazing comprising: a transparent glass substrate, and a coating located on the glass substrate, wherein the coating comprises at least the following layers in sequence starting from the glass substrate: a first layer having a refractive index of more than 1.6, an optional second layer having a refractive index that is less than the refractive index of the first layer, a third layer based on tin dioxide doped with antimony, niobium and/or neodymium, and a fourth layer based on titanium dioxide, wherein the fourth layer is photocatalytic.

18. The coated glazing according to claim 17, wherein the coating consists of the first layer, the second layer, the third layer and the fourth layer.

19. The coated glazing according to claim 17, wherein the first layer has a thickness of at least 5 nm, but at most 40 nm.

20. The coated glazing according to claim 17, wherein the second layer has a thickness of at least 5 nm, but at most 40 nm.

21. The coated glazing according to claim 17, wherein the third layer has a thickness of at least 130 nm, but at most 365 nm.

22. The coated glazing according to claim 17, wherein the fourth layer has a thickness of at least 8 nm, but at most 40 nm.

23. The coated glazing according to claim 17, wherein the first layer is based on an oxide of a metal, preferably wherein the first layer is based on tin dioxide, tin oxide, niobium oxide, titanium dioxide or tantalum oxide, most preferably wherein the first layer is based on tin dioxide.

24. The coated glazing according to claim 17, wherein the second layer is based on an oxide of a metalloid, preferably wherein the second layer is based on silicon dioxide or silicon oxynitride, most preferably wherein the second layer is based on silicon dioxide.

25. The coated glazing according to claim 17, wherein the coated glazing exhibits a maximum visible light transmittance of 70%, preferably a maximum visible light transmittance of 60%, more preferably a maximum visible light transmittance of 55%, most preferably a maximum visible light transmittance of 50%.

26. The coated glazing according to claim 17, wherein the coated glazing exhibits an a* coordinate in reflection on the film side of at least −10, but at most 4, and a b* coordinate in reflection on the film side of at least −25, but preferably at most −7.

27. The coated glazing according to claim 17, wherein the coated glazing exhibits an a* coordinate in transmission of at least −10, but at most 5, and a b* coordinate in transmission of at least −10, but at most 5.

28. The coated glazing according to claim 17, wherein the coating has a specific photocatalytic activity in accordance with ISO/DIS 10678:2010 of greater than 0.4 nmol/cm.sup.2h, preferably greater than 0.5 nmol/cm.sup.2h, more preferably greater than 0.6 nmol/cm.sup.2h, even more preferably greater than 0.7 nmol/cm.sup.2h, most preferably greater than 0.8 nmol/cm.sup.2h.

29. The coated glazing according to claim 17, wherein the transparent glass substrate is a clear transparent glass substrate.

30. The coated glazing according to claim 17, wherein the coated glazing further comprises a second coating located on an opposing major surface of the glass substrate.

31. A coated glazing comprising: a clear transparent glass substrate, and a coating located on the glass substrate, wherein the coating comprises at least the following layers in sequence starting from the glass substrate: a first layer having a refractive index of more than 1.6, wherein the first layer is based on tin dioxide, and wherein the first layer has a thickness of at least 5 nm, but at most 35 nm; a second layer having a refractive index that is less than the refractive index of the first layer, wherein the second layer is based on silicon dioxide, and wherein the second layer has a thickness of at least 10 nm, but at most 40 nm; a third layer based on antimony doped tin dioxide, wherein the third layer has a thickness of at least 130 nm, but at most 365 nm; and a fourth layer based on titanium dioxide, wherein the fourth layer is photocatalytic, and wherein the fourth layer has a thickness of at least 10 nm, but at most 25 nm.

Description

[0091] The invention will now be further described by way of the following specific embodiments, which are given by way of illustration and not of limitation, with reference to the accompanying drawing in which:

[0092] FIG. 1 is a schematic view, in cross-section, of a coated glazing in accordance with certain embodiments of the present invention, and

[0093] FIG. 2 is a CIELAB colour chart of a coated glazing in accordance with certain embodiments of the present invention in comparison with a known coated glazing.

[0094] FIG. 1 shows a cross-section of a coated glazing 1 according to certain embodiments of the present invention. Coated glazing 1 comprises a transparent float glass substrate 2 that has been sequentially coated using CVD with a layer based on tin dioxide 3, a layer based on silicon dioxide 4, a layer based on antimony doped tin oxide 5 and a layer based on titanium dioxide 6. The CVD may be carried out in conjunction with the manufacture of the glass substrate in the float glass process.

EXAMPLES

[0095] Examples 1-4 according to the invention were prepared using atmospheric pressure CVD as part of the float glass process. The transparent glass substrate used for each Example was clear soda-lime-silica glass with a thickness of 6 mm for Examples 1-3 and 4 mm for Example 4. Comparative Example 1 was commercially available Pilkington Activ™ Blue, of 4 mm thickness.

[0096] The coating for each Example according to the invention consisted of the following four layers starting from the glass substrate: SnO.sub.2/SiO.sub.2/SnO.sub.2:Sb/TiO.sub.2.

[0097] The SnO.sub.2 layer was deposited over the glass surface using the following components: [0098] N.sub.2 carrier gas, O.sub.2, dimethyltin dichloride, and H.sub.2O.

[0099] The SiO.sub.2 layer was deposited over the glass surface using the following components: [0100] N.sub.2 carrier gas, He carrier gas, O.sub.2, C.sub.2H.sub.4, and SiH.sub.4.

[0101] The SnO.sub.2:Sb layer was deposited over the glass surface using the following components: [0102] N.sub.2 and He carrier gas, O.sub.2, dimethyltin dichloride, 30-50 wt % triphenyl antimony in ethyl acetate, and H.sub.2O.

[0103] The TiO.sub.2 layer was deposited over the glass surface using the following components: [0104] Titanium tetrachloride in ethyl acetate (ratio EtOAc:TiCl.sub.4 1.8-2.2).

[0105] The optical properties of the resultant coated glazing were determined using a HunterLab™ Ultrascan Pro spectrophotometer. The layer thicknesses of the Examples were determined by scanning electron microscopy (SEM) using an FEI Nova NanoSEM™ 450 and EDAX Octane plus EDS detector with TEAM software. The optical properties and layer thicknesses of the Examples are shown below in Tables 1 and 2:

TABLE-US-00001 TABLE 1 Optical properties for Examples according to the invention and a Comparative Example Transmittance Film Side Reflectance Glass Side Reflectance Example % a* b* % a* b* % a* b* 1 48.3 −2.6 −4.0 14.8 −3.4 −10.0 9.5 −1.5 −11.6 2 48.3 −2.4 −3.5 16.4 −3.6 −9.2 10.3 −2.7 −10.7 3 49.1 −2.4 −3.8 15.3 −3.8 −9.3 9.9 −2.2 −10.7 4 45.0 −1.0 −1.3 17.3 −5.0 −16.6 9.6 2.2 −14.6 Comparative 58.6 −6.8 −2.5 15.1 −3.1 −13.9 10.9 −1.4 −14.0 Example 1

TABLE-US-00002 TABLE 1 Layer thicknesses for Examples according to the invention and a Comparative Example Layer Thicknesses (nm) Example SnO.sub.2 SiO.sub.2 SnO.sub.2:Sb TiO.sub.2 1 21.1 19.6 204.5 15.9 2 21.5 20.2 197.7 18.4 3 22.2 19.6 193.9 16.3 4 14.6 29.2 139.7 23.7 Comparative — 30.0 — 17.3 Example 1

[0106] Table 1 shows that the coated glazings according to the present invention, Examples 1-4, afford an aesthetically pleasing level of visible light transmittance and reflectance from both sides. Moreover, the coated glazings also exhibit an attractive blue colouration in both transmission and reflection. The slight differences in optical properties between Examples 1-3 on one hand and Example 4 on the other are due to Example 4 having a thicker TiO.sub.2 layer. The fact that the coatings have been deposited via CVD means that they are more robust than PVD coatings.

[0107] The comparison between the colour properties of Example 4 and those of Comparative Example 1 is depicted in the CIELAB chart of FIG. 2. Example 4 has a similar level of blueness (negative b*) to Comparative Example 1 in transmission but is desirably far less green (negative a*). The film side colour in reflection of Example 4 is slightly bluer and greener but comparable to that of Comparative Example 1. The glass side colour in reflection of Example 4 is the same level of blue and slightly red (positive a*) rather than slightly green compared to Comparative Example 1. Since both the film side and glass side reflectance of Example 4 is so low, the colour in reflection is less critical than the colour in transmission. Overall, the less green colouration in transmission and the similar level of blue colouration in both forms of reflection in comparison with Comparative Example 1 means that Example 4 is generally more attractive to observers.

[0108] Example 4 and Comparative Example 1 were tested for photocatalytic activity according to ISO/DIS 10678:2010. The coating of Example 4 was found to exhibit a specific photocatalytic activity of 0.69 nmol/cm.sup.2h and the coating of Comparative Example 1 achieved a value of 1.43 nmol/cm.sup.2h. Whilst the coating of Example 4 exhibits lower photocatalytic activity than Comparative Example 1, nevertheless it provides an acceptable level of performance.

[0109] The invention is not restricted to the details of the foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.