Glass article having an anti-reflection coating

Abstract

The glass article includes a glass substrate having a coating formed thereon. The coating includes a first antireflective layer deposited on the glass substrate, the first layer having a refractive index of 1.6 or greater and a thickness less than λ / (4*n). A second antireflective layer is deposited on the first antireflective layer, the second antireflective layer having a thickness greater than the thickness of the first antireflective layer and a refractive index less than the refractive index of the first antireflective layer. The glass article exhibits a total visible light reflectance of less than 6.0%.

Description

Background Art

[0001] The present invention relates to a coated glass article. More specifically, the present invention relates to a glass article having an antireflection coating.

[0002] Windows and touch screen electronic devices are often made of glass. Excessive reflection from the glass in windows and touch screen devices can sometimes be undesirable. To improve the performance of windows or the readability and usability of devices, it is advantageous to provide glass that exhibits low visible light reflection and high visible light transmittance.

Summary of the Invention

[0003] The glass article includes a glass substrate having a coating formed thereon. The coating includes a first antireflection layer deposited on the glass substrate, and the first layer has a refractive index of 1.6 or more and a thickness less than λ / (4*n). A second antireflection layer is deposited on the first antireflection layer, and the second antireflection layer has a thickness greater than the thickness of the first antireflection layer and a refractive index less than the refractive index of the first antireflection layer. This glass article exhibits a total visible light reflectance of less than 6.0%.

Brief Description of the Drawings

[0004] The above and other advantages of the present invention will become readily apparent to those skilled in the art by considering the following detailed description in light of the accompanying drawings.

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0005] It should be understood that, unless explicitly specified otherwise, various alternative orientations and process sequences are possible. It should also be understood that the specific layers, articles, methods, and processes illustrated in the accompanying drawings and described below in the specification are merely exemplary embodiments of the concepts of the present invention. Accordingly, specific dimensions, orientations, or other physical characteristics associated with the disclosed embodiments should not be considered limiting unless otherwise explicitly stated.

[0006] In one embodiment, a glass article 10 is provided. With reference to FIGS. 1 and 2, an embodiment of the glass article 10 will be described below. The embodiment of the glass article 10 can be utilized as a single glass sheet. In such an embodiment, the glass article 10 is utilized as part of a window assembly. In another embodiment, the glass article 10 can be utilized as a display assembly. However, it should be understood that the embodiment of the glass article 10 can be utilized in other architectural, electronic, residential, commercial, photovoltaic, automotive, and aerospace applications.

[0007] The glass article 10 includes a glass substrate 12. Embodiments of the glass substrate 12 are shown, for example, in FIGS. 1 and 2. The thickness of the glass substrate 12 can vary between embodiments. In some embodiments, the glass substrate 12 is not limited to a specific thickness. However, in certain embodiments, the glass substrate 12 can have a thickness of 20.0 millimeters (mm) or less. Preferably, the glass substrate 12 can have a thickness of 0.5 to 20.0 mm. In some embodiments, the glass substrate 12 can have a thickness of 2.0 to 20.0 mm.

[0008] The transparency or absorption characteristics of the glass substrate 12 can vary among embodiments of the glass article 10. For example, in some embodiments, the glass substrate 12 is transparent. In embodiments where the glass substrate 12 is transparent, the glass substrate 12 may exhibit a total visible light reflectance (D65 light source, 10-degree field of view) of 7.0% to 9.0%. In other embodiments, the glass substrate 12 may preferably have a low iron content that enables the glass substrate 12 to exhibit a high visible light transmittance. In some embodiments, the glass substrate 12 may comprise 0.15 wt% or less of Fe 2 O 3 (total iron). As used herein, the phrase "total iron" refers to the total weight of iron oxide (FeO + Fe 2 O 3 ) contained in the glass. More preferably, the glass substrate 12 comprises 0.1 wt% or less of Fe 2 O 3 (total iron), even more preferably 0.02 wt% or less of Fe 2 O 3 (total iron). In one embodiment, the glass substrate 12 may comprise 0.012 wt% of Fe 2 O 3 (total iron). In these embodiments, the glass substrate 12 may exhibit a total visible light transmittance of 91% or more in the CIELAB color scale system (C light source, 10-degree field of view). Further, the color of the glass substrate 12 can vary among embodiments. In one embodiment, the glass substrate 12 can be substantially transparent. In still other embodiments, the glass substrate 12 can be thinly colored or colored.

[0009] The glass substrate 12 can be a conventional glass composition known in the art. However, the glass substrate 12 is preferably soda-lime-silica glass. When the glass substrate 12 is soda-lime-silica glass, the glass substrate 12 comprises 68 - 74 wt% of SiO 2 , 0 - 3 wt% of Al 2 O 3 , 0 - 6 wt% of MgO, 5 - 14 wt% of CaO, 10 - 16 wt% of Na 2 O, 0 - 2 wt% of SO 3, 0.005 to 2 wt% of Fe 2 O 3 and 0 to 5 wt% of K 2 O. The glass may also contain other additives, such as refining agents that will typically be present in amounts up to 2%. In these embodiments, the glass substrate 12 can be a float glass ribbon. In embodiments where the glass substrate 12 is part of a float glass ribbon, the glass substrate 12 can be clear float glass. In some of these embodiments, the clear float glass can mean a glass having a composition defined in relevant standards such as BS EN 572-1:2012+A1:2016 and BS EN 572-2:2012. However, the glass substrate 12 can be another composition, such as a borosilicate or aluminosilicate composition, for example.

[0010] The coating 14 is formed on the glass substrate 12. The coating 14 is of an anti-reflection type in that it enables the glass article 10 to exhibit a lower visible light reflection than the visible light reflection exhibited by the glass substrate 12 alone. Advantageously, the coating 14 is also configured to provide more visible light transmission through the glass article 10 than a known design.

[0011] Preferably, the coating 14 is formed directly above the first major surface 16 of the glass substrate 12. When the coating 14 is formed directly above the glass substrate 12, there is no intervening coating between the coating 14 and the glass substrate 12. The second major surface 18 of the glass substrate 12 and the opposite side of the glass article 10 may be uncoated. The coating 14 is anti-reflection in order to enable the glass article 10 to exhibit a lower visible light reflection than the visible light reflection exhibited by the glass substrate 12.

[0012] In one embodiment, the coating 14 is pyrolytic. As used herein, the term "pyrolytic" may refer to a coating or layer that is chemically bonded to a glass substrate or another layer. Preferably, the coating 14 is formed under dynamic deposition conditions. In these embodiments, the glass substrate 12 is moving when the coating 14 is formed thereon or above it. Preferably, the glass substrate 12 moves at a predetermined speed, for example, greater than 3.175 m / min (125 inches / min) when the coating 14 is being formed. In one embodiment, the glass substrate 12 moves at a speed of 3.175 m / min (125 inches / min) to 12.7 m / min (600 inches / min) when the coating 14 is being formed. In these embodiments, one or more of the coating layers 20-26 may be formed in conjunction with the manufacture of the glass substrate 12. Preferably, the glass substrate 12 is manufactured using a known float glass manufacturing process.

[0013] The coating 14 comprises two or more layers, including the antireflection layers 24 and 26. Preferably, the coating 14 comprises three or more layers, including the barrier layer 22 and the antireflection layers 24 and 26. In some embodiments, the coating 14 comprises four or more layers and has layers 20 and 22 that function as an iridescence suppressing intermediate layer between the glass substrate 12 and the antireflection layers 24 and 26. In one embodiment, the coating 14 may consist of four layers 20, 22, 24 and 26. In this embodiment, there is no layer intervening between the layers 20, 22, 24, 26, and no layer intervening between the first layer 20 and the glass substrate 12.

[0014] Thus, in some embodiments, the coating 14 includes a first iridescence suppressing layer 20 deposited on the glass substrate 12. More specifically, the layer 20 is deposited on the first major surface 16 of the glass substrate 12. In one embodiment, the layer 20 is deposited directly above the first major surface 16 of the glass substrate 12. When the layer 20 is deposited directly above the first major surface 16 of the glass substrate 12, there is no layer intervening between the layer 20 and the first major surface 16 of the glass substrate 12.

[0015] Preferably, the first anti-iridescent layer 20 has a refractive index of 1.6 or more. In certain embodiments, the refractive index of layer 20 is 1.8 or more. In such an embodiment, the refractive index of layer 20 is from 1.8 to 2.0. In another embodiment, the refractive index of layer 20 is from 2.1 to 2.5. It should be noted that the refractive index values described herein are reported as average values over 400 - 780 nm of the electromagnetic spectrum.

[0016] Preferably, the first anti-iridescent layer 20 is thermally decomposable. In certain embodiments, layer 20 comprises an inorganic metal oxide. In some embodiments, layer 20 comprises tin oxide (SnO 2 ). When layer 20 comprises tin oxide, it is preferred that layer 20 comprises tin and oxygen. However, in these embodiments, layer 20 may also comprise other components including trace or more of other elements such as, for example, carbon. As used herein, the term "trace" refers to an amount of a component of the coating layer that constitutes less than 0.01 wt% of the coating layer. In certain embodiments, layer 20 may consist essentially of tin oxide. In other embodiments, layer 20 may comprise niobium oxide (Nb 2 O 5 ), titanium dioxide (TiO 2 ), tantalum oxide (Ta 2 O 5 ) or another transparent metal oxide. Tin oxide, niobium oxide, titanium dioxide and tantalum oxide are preferred metal oxides because each has a relatively high refractive index and electrical resistance. It should be noted that it is preferred that the electrical resistance of layer 20 is not reduced by adding a dopant such as, for example, fluorine or other materials to layer 20. Therefore, it is preferred that layer 20 is not doped.

[0017] Layer 20 has a thickness of 50 nanometers (nm) or less. Preferably, the thickness of layer 20 is 30 nm or less. In certain embodiments, the thickness of layer 20 is from 5 to 25 nm.

[0018] The second anti-rainbow layer 22 can be deposited on top of, preferably directly on top of, the first anti-rainbow layer 20. Thus, layer 20 separates layer 22 from the glass substrate 12. When layer 22 is deposited directly on top of layer 20, there is no intervening layer between layer 20 and layer 22. In certain embodiments, layer 22 is pyrolyzable.

[0019] Preferably, layer 22 has a thickness of 50 nm or less. In some embodiments, layer 22 has a thickness greater than the thickness of layer 20. Preferably, the thickness of layer 22 is 20 - 50 nm.

[0020] The second anti-rainbow layer 22 has a refractive index smaller than that of layer 20. In some embodiments, layer 22 has a refractive index of 1.6 or less. In one embodiment, the refractive index of layer 22 is 1.2 - 1.6. In other embodiments, the refractive index of layer 22 is 1.2 - 1.5.

[0021] In certain embodiments, it is preferred that layer 22 has a relatively high electrical resistance. In these embodiments, the second layer may preferably comprise an oxide of silicon. In such one embodiment, layer 22 comprises silicon dioxide (SiO 2 ). In these embodiments, layer 22 comprises silicon and oxygen. Layer 22 may also contain trace amounts of one or more additional components, such as carbon for example. Thus, in certain embodiments, layer 22 may consist essentially of silicon dioxide. However, other materials exhibiting relatively high electrical resistance and a desirable refractive index may be suitable for use in the second layer.

[0022] Thus, in certain embodiments, layers 20 and 22 form an anti-rainbow intermediate layer between the glass substrate 12 and the anti-reflection layers 24 and 26. The anti-rainbow intermediate layer is advantageous in enabling the glass article 10 to exhibit intermediate colors in transmission and reflection. In this embodiment, the thickness of the anti-rainbow intermediate layer formed by layers 20 and 22 together may preferably be about 1 / 6 to about 1 / 12 of the design wavelength of 500 nm.

[0023] In other embodiments where it is not particularly advantageous for the glass article 10 to exhibit an intermediate color in transmission and reflection, the anti-iridescence layers 20 and 22 may be omitted (not shown). In still other embodiments, the anti-iridescence layer 20 may be omitted, but the layer 22 may be included (not shown) so as to function as a barrier layer between the glass substrate 12 and the first anti-reflection layer 24. In that case, the layer 22 will reduce the haze exhibited by the otherwise coated glass article 10.

[0024] The first anti-reflection layer 24 is deposited on the glass substrate 12 and, unless omitted, on the layer 22. In embodiments including the layer 22, the layer 24 is preferably deposited directly on top of the layer 22. In that case, the layer 22 separates the layer 24 from the layer 20. When the layer 24 is deposited directly on top of the layer 22, there is no intervening layer between the layer 24 and the layer 22. The layer 24 is preferably pyrolytic.

[0025] Preferably, the first anti-reflection layer 24 has a refractive index of 1.6 or greater. In certain embodiments, the refractive index of the layer 24 is 1.8 or greater. In one embodiment, the refractive index of the layer 24 is from 1.8 to 2.0. In other embodiments, the refractive index of the layer 24 is 2.0 or greater. In these embodiments, the refractive index of the layer 24 can be from 2.1 to 2.4.

[0026] In certain embodiments, the layer 24 comprises an inorganic metal oxide. In some embodiments, the layer 24 comprises tin oxide (SnO 2 ). Tin oxide is a preferred material due to its relatively high refractive index and electrical resistance. Other materials having desirable refractive indices and electrical resistances suitable for use in the layer 24 are niobium oxide (Nb 2 O 5 ) and tantalum oxide (Ta 2 O 5) and thus, in some embodiments, layer 24 comprises niobium oxide or tantalum oxide. Other inorganic metal oxide materials may be suitable for use in layer 24. Also, it is preferred that the electrical resistance of layer 24 is not reduced, for example, by adding a dopant such as fluorine or other materials to layer 24. Therefore, layer 24 is preferably undoped.

[0027] The first antireflection layer 24 has a thickness of less than λ / (4*n), where λ is equal to the design wavelength in the visible spectrum and n is equal to the refractive index of layer 24. Preferably, the design wavelength λ is generally selected at the center of the visible light region of the electromagnetic spectrum or at 550 nm. Layer 24 preferably has a refractive index of 1.6 or more. In certain embodiments, the refractive index of layer 24 is 1.8 or more. In one embodiment, the refractive index of layer 24 is from 1.8 to 2.0. In another embodiment, the refractive index of layer 24 is from 2.1 to 2.4.

[0028] Under the conditions specified above, the first antireflection layer 24 will have a thickness of less than 70 nm. In one embodiment, layer 24 has a thickness of 5 to 60 nm. Preferably, when layer 24 comprises tin oxide, layer 24 has a thickness of 20 to 60 nm. Even more preferably, when layer 24 comprises tin oxide, layer 24 has a thickness of 20 to 40 nm. When layer 24 comprises niobium oxide or tantalum oxide, layer 24 preferably has a thickness of 5 to 40 nm.

[0029] The second antireflection layer 26 is deposited on top of, preferably directly on top of, the first antireflection layer 24. When layer 26 is deposited directly on top of layer 24, there is no intervening layer between layer 24 and layer 26. In some embodiments, layer 26 can be the outermost layer of coating 14. When layer 26 is the outermost layer of coating 14, layer 26 forms the outer surface 28 of the glass article 10.

[0030] In one embodiment, as shown in FIG. 1, the second anti-reflection layer 26 has a thickness greater than that of the first anti-reflection layer 24. Preferably, the thickness of layer 26 is 80 nm or more. In some embodiments, the thickness of layer 26 is 80 - 125 nm. In one embodiment, the thickness of layer 26 is 80 - 110 nm.

[0031] The second anti-reflection layer 26 has a refractive index smaller than that of the first anti-reflection layer 24. In some embodiments, layer 26 has a refractive index of 1.6 or less. In one embodiment, the refractive index of layer 26 is 1.2 - 1.6. In other embodiments, the refractive index of layer 26 can be 1.2 - 1.5.

[0032] In one embodiment, the second anti-reflection layer 26 comprises an oxide of silicon. Preferably, layer 26 comprises silicon dioxide (SiO 2 ). In these embodiments, layer 26 comprises silicon and oxygen. Layer 26 can also include one or more additional trace components such as, for example, carbon. Thus, in certain embodiments, layer 26 can consist essentially of silicon dioxide. However, other materials that exhibit relatively high electrical resistance and low refractive index can be suitable for use in layer 26.

[0033] The above embodiments provide a glass article 10 exhibiting anti-reflection properties. The reflectance of the glass article 10 is further discussed below with respect to its total visible light reflectance. To describe the glass article 10, the total visible light reflectance refers to the percentage of visible light reflected from the glass article 10 as measured from side 30 (coating side) of the glass article 10 having a coating 14 formed on the surface of the glass substrate 12. The total visible light reflectance is described herein according to the CIELAB color scale system using a D65 light source and a 10-degree field of view, and can be measured using a commercially available spectrophotometer such as a Perkin Elmer Lambda950.

[0034] Advantageously, the glass article 10 exhibits a total visible light reflectance of less than 6.0% (D65 light source, 10-degree field of view). Preferably, the glass article 10 exhibits a total visible light reflectance of 5.5% or less (D65 light source, 10-degree field of view). In one embodiment, the glass article 10 may exhibit a total visible light reflectance of 4.0% to 5.5% (D65 light source, 10-degree field of view).

[0035] In other embodiments, the glass article 10 exhibits a total visible light reflectance of 5.0% or less (D65 light source, 10-degree field of view). In such an embodiment, the glass article 10 may exhibit a total visible light reflectance of 4.0% to 5.0% (D65 light source, 10-degree field of view).

[0036] The glass article 10 may also exhibit a high visible light transmittance. The visible light transmittance of the glass article 10 is further discussed below with respect to the total visible light transmittance. As discussed herein, the total visible light transmittance refers to the percentage of visible light passing through the glass article 10 as measured from the coating side 30 of the glass article 10. The total visible light transmittance is described herein according to the CIELAB color scale system using a D65 light source, 10-degree field of view, and can be measured using a commercially available spectrophotometer such as a Perkin Elmer Lambda950. In one embodiment, the glass article 10 exhibits a total visible light transmittance of 90% or more (D65 light source, 10-degree field of view). Preferably, the glass article 10 exhibits a total visible light transmittance of 92% or more, more preferably 94% or more (D65 light source, 10-degree field of view).

[0037] The glass article 10 may also exhibit other advantageous properties. For example, when the layers 20 and 22 are included as an anti-iridescence intermediate layer, the glass article 10 may exhibit an intermediate color with respect to visible light reflected from the coating side 30 of the glass article 10 when viewed at an incident angle of 90 degrees to the glass article 10. The color of the visible light reflected from the coating side 30 of the glass article 10 may be referred to herein as the "reflection color". The reflection color is described herein according to the CIELAB color scale system using a D65 light source and a 10-degree field of view. The reflection color may be measured using a commercially available spectrophotometer such as a Perkin Elmer Lambda950. Also, for the purpose of describing the embodiments of the glass article 10 disclosed herein, the intermediate color of the visible light reflected from the coating side 30 of the glass article 10 has an a* value (D65 light source, 10-degree field of view) in the range of -6 to 6 and a b* value (D65 light source, 10-degree field of view) in the range of -6 to 6. Preferably, the glass article 10 exhibits a reflection color in the range of about -4 to 6 for the a* value (D65 light source, 10-degree field of view) and a reflection color in the range of about -3 to 3 for the b* value (D65 light source, 10-degree field of view).

[0038] Also, the glass article 10 may exhibit a low haze value, particularly in embodiments including the layer 22. As discussed herein, the term "haze" refers to the percentage of incident visible light that scatters when passing through the glass article 10. Also, as discussed herein, the haze exhibited by the glass article 10 is measured from the coating side 30 of the glass article 10. In one embodiment, the glass article 10 may exhibit a haze of 0.5% or less. Preferably, the glass article 10 exhibits a haze of 0.4% or less. In some embodiments, the haze exhibited by the glass article 10 is 0.1 to 0.4%. The haze exhibited by the glass article 10 may be measured using a commercially available haze meter such as a BYK-Gardner Haze Guard Plus.

[0039] In certain embodiments, the glass article 10 can be utilized within a touch screen electronic device. The touch screen electronic device can be of the projected capacitance touch, optical, or infrared type. When the glass article 10 is utilized within a touch screen electronic device, the glass article 10 is provided to the device such that the coating 14 faces outward from the device, and when the touch screen electronic device is in use, the user controls the device by touching the coating 14. In these embodiments, it is preferred that the glass article 10 exhibits a high sheet resistance. In such an embodiment, the glass article 10 exhibits a sheet resistance greater than, for example, 1.0×10 5 Ω / sq. The glass article 10 exhibits a sheet resistance greater than, for example, 1.0×10 5 Ω / sq. by appropriate selection of the composition and thickness of each of the layers 20 - 26. The sheet resistance exhibited by the glass article 10 is measured at the coating side 30 of the glass article 10. The sheet resistance exhibited by the glass article 10 can be measured using the four - point probe method and a commercially available four - point probe.

[0040] As described above, the coating 14 can be formed in conjunction with the manufacture of the glass substrate 12 in a known float glass manufacturing process. The float glass manufacturing process is typically carried out using float glass equipment such as the equipment 32 shown in FIG. 3. However, it should be understood that the float glass equipment 32 described herein is merely an example of such equipment.

[0041] As shown in FIG. 3, the float glass equipment 32 can include a waterway section 33 along which molten glass 34 is sent from a melting furnace to a float bath section 36 where a glass substrate is formed. In this embodiment, the glass substrate is referred to as a glass ribbon 38. The glass ribbon 38 is a preferred substrate on which a coating is formed. However, it should be understood that the glass substrate is not limited to being a glass ribbon.

[0042] The glass ribbon 38 advances from the bus section 36 through the adjacent annealing rail 40 and cooling section 42. The float bus section 36 includes a bottom 44 that contains a molten tin bath 46 therein, a roof 48, opposing side walls (not shown), and end walls 50, 52. The roof 48, side walls, and end walls 50, 52 together define an enclosure 54 in which a non-oxidizing atmosphere is maintained to prevent oxidation of the molten tin 46.

[0043] During operation, the molten glass 34 flows downward in a controlled amount along the water channel section 33 below the adjustment twill 56 onto the surface of the tin bath 46. On the molten tin surface, the molten glass 34 spreads laterally under the influence of gravity and surface tension, as well as under certain mechanical influences, and advances across the tin bath 46 to form the glass ribbon 38. The glass ribbon 38 is removed from the bus section 36 on the lift-out roll 58 and then conveyed through the annealing rail 40 and cooling section 42 on aligned rolls. The deposition of the coating 14 is preferably carried out in the float bus section 36, but the deposition can also be further carried out along the glass manufacturing line, for example, in the gap 60 between the float bus 36 and the annealing rail 40, or within the annealing rail 40.

[0044] As shown in FIG. 2, two coating devices 62, 64 are shown within the float bus section 36. The coating 14 can be formed using the coating devices 62, 63, 64, 65, and each coating device can be used to deposit one of the coating layers 20 - 26. For example, in one embodiment, layer 20 is deposited using the first coating device 62, layer 22 is deposited using the second coating device 63, layer 24 is deposited using the third coating device 64, and layer 26 is deposited using the fourth coating device 65.

[0045] A suitable non-oxidizing atmosphere, generally nitrogen, or a mixture of nitrogen and hydrogen under nitrogen domination, is maintained in the float bath section 36 to prevent oxidation of the molten tin 46 provided with the float bath. The atmospheric gas enters through a conduit 70 operably coupled to the distribution manifold 72. The non-oxidizing gas is introduced at a rate sufficient to compensate for normal losses and maintain a slight positive pressure about 0.001 to about 0.01 atmospheres higher than the ambient atmospheric pressure in order to prevent the intrusion of outside air. For the purpose of explaining the present invention, the above pressure range is considered to correspond to normal atmospheric pressure.

[0046] Preferably, the coating 14 is formed at substantially atmospheric pressure. Thus, the pressure within the float bath section 36, the annealing rail 40 and / or the gap 60 between the float bath 36 and the annealing rail 40 can be substantially atmospheric pressure.

[0047] The heat for maintaining the desired temperature period within the float bath section 36 and the enclosure 54 is provided by a radiant heater 74 within the enclosure 54. The atmosphere within the rail 40 is usually atmospheric air. This is because the cooling section 42 is not enclosed and thus the glass ribbon 38 is open to the ambient atmosphere. Subsequently, it is possible to cool the glass ribbon 38 to the ambient temperature. To cool the glass ribbon 38, the ambient air can be directed towards the glass ribbon 38 by a fan 76 of the cooling section 42. A heater can also be provided within the annealing rail 40 (not shown) to gradually lower the temperature of the glass ribbon 38 as it is carried through over a predetermined period.

Example

[0048] The following examples are presented only for the purpose of further explaining and disclosing embodiments of glass articles.

[0049] Examples of glass articles within the scope of the present invention are described below and illustrated in Tables 1 and 2. In Table 1, the glass article within the scope of the present invention is Ex1. Comparative example C1, which is not considered part of the present invention, is also described below and shown in Table 1. Examples Ex1 and C1 were modeled. The characteristics shown for each are predictive.

[0050] The following conditions apply to the glass articles of Ex1 and C1. The glass articles of Ex1 and C1 each include a glass substrate. The glass substrate has a soda-lime-silica composition and a thickness of 6 millimeters (mm). A coating is provided on the first major surface of each glass substrate. Each coating includes a first layer, a second layer, a third layer, and a fourth layer.

[0051] For C1, the first layer is directly above the first major surface of the glass substrate. The first layer comprises tin oxide and has a thickness of 15 nm. The second layer is directly above the first layer. The second layer comprises silicon dioxide and has a thickness of 27 nm. The third layer is directly above the second layer. The third layer comprises tin oxide (SnO 2 ) and has a thickness of 130 nm. The fourth layer is directly above the third layer. The fourth layer comprises silicon dioxide and has a thickness of 85 nm. Thus, the glass article of C1 has a glass / SnO 2 / SiO 2 / SnO 2 / SiO 2 arrangement.

[0052] For Ex1, the first layer is directly above the first major surface of the glass substrate. The first layer comprises tin oxide and has a thickness of 15 nm. The second layer is directly above the first layer. The second layer comprises silicon dioxide and has a thickness of 27 nm. The third layer is directly above the second layer. The third layer comprises undoped tin oxide (SnO 2 ) and has a thickness of 30 nm. The fourth layer is directly above the third layer. The fourth layer comprises silicon dioxide and has a thickness of 85 nm. Thus, the glass article of Ex1 has a glass / SnO 2 / SiO 2 / SnO 2 / SiO 2 It becomes an array.

[0053] Table 1 shows the total visible light transmittance (Tvis) (D65 light source, 10-degree field of view), total visible light reflectance (Rf) (D65 light source, 10-degree field of view), and reflected color (Ra*, Rb*) (D65 light source, 10-degree field of view) of the glass articles of Ex1 and C1. The total visible light transmittance and total visible light reflectance are expressed as percentages.

[0054]

Table 1

[0055] As shown in Table 1, the glass article of Ex1 exhibits improved reflectance and transmittance characteristics when compared with the glass article of C1. It should also be noted that the glass article of Ex1 showed an intermediate color for the visible light reflected from the coating side of the glass article.

[0056] In Table 2, the glass article within the scope of the present invention is Ex2. A comparative example C2 that is not considered a part of the present invention is also described below and illustrated in Table 2.

[0057] The following experimental conditions are applied to Ex2 and C2. As the glass substrate is formed and moves in conjunction with the manufacturing process of float glass, the coating is deposited on the first main surface of the glass substrate. Each glass substrate has a soda-lime-silica composition and a thickness of 3.2 mm.

[0058] In the case of Ex2 and C2, the coating was formed by depositing a first layer, a second layer, a third layer, and a fourth layer. Each layer is pyrolytic and was formed using an APCVD process.

[0059] In the case of C2, the first layer is directly above the first main surface of the glass substrate. The first layer comprises tin oxide and has a thickness of 12 nm. The second layer is directly above the first layer. The second layer comprises silicon dioxide and has a thickness of 25 nm. The third layer is directly above the second layer. The third layer comprises fluorine-doped tin oxide (SnO 2 :F) and has a thickness of 130 nm. The fourth layer is directly above the third layer. The fourth layer comprises silicon dioxide and has a thickness of 85 nm. Thus, the glass article of C2 has a glass / SnO 2 / SiO 2 / SnO 2 :F / SiO 2 arrangement.

[0060] In the case of Ex2, the first layer is directly above the first main surface of the glass substrate. The first layer comprises tin oxide and has a thickness of 12 nm. The second layer is directly above the first layer. The second layer comprises silicon dioxide and has a thickness of 25 nm. The third layer is directly above the second layer. The third layer comprises undoped tin oxide (SnO 2 ) and has a thickness of 30 nm. The fourth layer is directly above the third layer. The fourth layer comprises silicon dioxide and has a thickness of 85 nm. Thus, the glass article of Ex2 has a glass / SnO 2 / SiO 2 / SnO 2 / SiO 2 arrangement.

[0061] Table 2 shows the total visible light transmittance (Tvis) (D65 light source, 10-degree field of view), total visible light reflectance (Rf) (D65 light source, 10-degree field of view), and reflected color (Ra*, Rb*) (D65 light source, 10-degree field of view) of the glass articles of Ex2 and C2. The total visible light transmittance was measured on the coating side of each glass article using a Perkin Elmer Lambda 950 spectrophotometer. The total visible light transmittance is expressed as a percentage. The total visible light reflectance and the reflected color on the coating side of each glass article were also measured using a Perkin Elmer Lambda 950 spectrophotometer. The total reflectance of visible light is expressed as a percentage.

[0062]

Table 2

[0063] As shown in Table 2, the glass article of Ex2 exhibits substantially the same total visible light reflectance as the glass article of C2. However, the glass article of Ex2 exhibits a total visible light transmittance that is 2% higher than that of the glass article of C2. Also, the glass article of Ex2 exhibited an intermediate color with respect to the visible light reflected from the coating side of the glass article.

[0064] Additional examples from Ex3 to Ex13 are described below and shown in Table 3. Here, the first anti-rainbow layer is omitted and the second layer functions as a barrier layer. The examples from Ex1 to Ex13 were modeled. The characteristics shown by each are predictive.

[0065] Each of the glass articles from Ex3 to Ex13 has a glass / SiO 2 / SnO 2 / SiO 2 arrangement. The glass substrate has a soda-lime-silica composition and has a thickness of 6 millimeters (mm). The thickness (nm) and characteristics of the coating layer are shown in Table 3.

[0066]

Table 3

[0067] As shown in Table 3, the glass articles from Ex3 to Ex13 exhibit improved reflectance and transmittance characteristics when compared to the glass article of C1, and improved transmittance characteristics when compared to the glass article of C2. However, the glass articles from Ex3 to Ex13 exhibited a color of visible light reflected from the coating side of the glass article that is a weaker intermediate color compared to the colors of Ex1 and Ex2.

[0068] Furthermore, the modeled Ex3 to Ex13 can be modified by removing the SiO 2 barrier layer, resulting in a glass / SiO 2 / SnO2 / SiO 2 An array of glass articles results. In that case, the predicted properties shown in Table 3 are the same for each example, but the haze shown in the examples so modified will increase from the haze shown by the examples including the barrier layer.

[0069] The foregoing description is to be regarded as merely illustrative of the principles of the invention. Further, since many modifications and changes will readily occur to those skilled in the art, it is not desirable to limit the invention to the exact construction and process shown and described herein. Accordingly, all suitable modifications and equivalents may be regarded as being within the scope of the invention as defined by the following claims.

Claims

1. A glass article comprising a glass substrate and a coating formed on the glass substrate, wherein the coating comprises: a first antireflection layer deposited on the glass substrate, the first antireflection layer comprising undoped tin oxide and having a refractive index of 1.6 or more and a thickness of less than 550 nm / (4*n) (where n represents the refractive index of the first antireflection layer); a second antireflection layer deposited on the first antireflection layer, the second antireflection layer having a thickness greater than the thickness of the first antireflection layer and a refractive index less than the refractive index of the first antireflection layer; and wherein the glass article exhibits a total visible light reflectance of less than 6.0%; the glass article further comprising an iridescence suppressing intermediate layer between the glass substrate and the first antireflection layer. Glass article.

2. The glass article according to claim 1, wherein the glass article exhibits a total visible light reflectance of 5.5% or less, preferably 4.0% to 5.5%.

3. The glass article according to claim 1, wherein the glass article exhibits a reflected color of an intermediate color.

4. The glass article according to claim 1, wherein the refractive index of the first antireflection layer is 2.0 or more, preferably 2.1 to 2.

5.

5. The glass article according to claim 1, wherein the thickness of the first antireflection layer is less than 70 nm.

6. The glass article according to claim 1, wherein the thickness of the first antireflection layer is 20 nm or more and 60 nm or less.

7. The glass article according to claim 1, wherein the first antireflection layer comprises tin oxide and has a thickness between 20 nm and 50 nm.

8. The glass article according to claim 1, wherein the second antireflection layer has a thickness of 80 nm or more, preferably 80 nm or more and 125 nm or less, most preferably 80 nm or more and 110 nm or less.

9. The glass article according to claim 1, wherein the refractive index of the second antireflection layer is 1.6 or less, preferably 1.2 to 1.6, more preferably 1.2 to 1.

5.

10. The glass article according to claim 1, wherein the second antireflection layer comprises silicon dioxide.

11. The glass article according to claim 1, wherein the second antireflection layer is the outermost layer of the glass article.

12. The anti-rainbow intermediate layer includes a first anti-rainbow layer having a refractive index of 1.6 or more, and a second anti-rainbow layer deposited on the first anti-rainbow layer. The second anti-rainbow layer has a refractive index smaller than that of the first anti-rainbow layer. The glass article according to claim 1.

13. The refractive index of the first anti-rainbow layer is 2.1 to 2.

5. The glass article according to claim 12.

14. The first anti-rainbow layer includes tin oxide. The glass article according to claim 12.

15. The first anti-rainbow layer has a thickness of 50 nm or less. The glass article according to claim 12.

16. The first anti-rainbow layer has a thickness of 5 nm or more and 25 nm or less. The glass article according to claim 12.

17. The second anti-rainbow layer is deposited directly on the first anti-rainbow layer. The glass article according to claim 12.

18. The second anti-rainbow layer has a thickness greater than that of the first anti-rainbow layer. The glass article according to claim 12.

19. The second anti-rainbow layer has a thickness of 50 nm or less. The glass article according to claim 12.

20. The second anti-rainbow layer has a thickness of 5 nm or more and 25 nm or less. The glass article according to claim 12.

21. The refractive index of the second anti-rainbow layer is 1.6 or less, preferably 1.2 to 1.6, more preferably 1.2 to 1.

5. The glass article according to claim 12.

22. The second anti-rainbow layer includes silicon dioxide. The glass article according to claim 12.

23. The first antireflection layer is deposited directly on the second anti-rainbow layer. The glass article according to claim 12.

24. The coating consists of the first anti-rainbow layer, the second anti-rainbow layer, the first antireflection layer, and the second antireflection layer. The glass article according to claim 12.

25. The glass article according to claim 1 further includes a barrier layer between the glass substrate and the first antireflection layer.

26. The barrier layer has a thickness of 50 nm or less. The glass article according to claim 25.

27. The barrier layer includes silicon dioxide. The glass article according to claim 25.

28. The coating consists of the barrier layer, the first antireflection layer, and the second antireflection layer. The glass article according to claim 25.

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