DE112009003493T5 - Primer layers conferring improved overcoat functionality - Google Patents

Abstract

A coated article includes a substrate and a first coating formed over at least a portion of the substrate. The first coating contains an oxide mixture that contains oxides of at least two of P, Si, Ti, Al and Zr. A functional coating is formed over at least a portion of the first coating. The functional coating is selected from an electrically conductive coating and a photoactive coating. In one embodiment, the functional coating contains fluorine-doped tin oxide. In another embodiment, the functional coating contains titanium dioxide.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority over U.S. Serial No.s. 12 / 273.617; 12 / 273,623 and 12 / 273,641, all filed on Nov. 19, 2008, and all three applications are hereby incorporated by reference in their entirety.

GENERAL PRIOR ART

1. Field of the invention

This invention relates generally to coated articles, and more particularly to multi-layer coated articles having a functional overcoat and at least one undercoat layer.

2. Technical considerations

Multilayer coated articles are used in numerous applications. An example is in the field of thin-film solar cells. A typical solar cell includes a substrate such as a glass plate with a transparent conductive film (first electrode). A semiconductor film having a photoelectric conversion material is deposited on the transparent conductive film. The cell contains another substrate with a transparent conductive film (second electrode). An electrolyte could be trapped between the two electrodes. When the photoelectric conversion material absorbed on the semiconductor film is irradiated, electrons generated by the irradiation move through the semiconductor film and into one of the transparent conductive films. For example, the electrons may move through the first electrode, through an electrical lead, and to the other electrode. For solar cells, it is important for photoelectric conversion efficiency that the electrons move as quickly as possible through the first conductive film to the other electrode. That is, it is desirable if the surface resistance of the transparent conductive film is low. If the electrons do not move rapidly, reunification of the electrons with the photoelectric conversion material (commonly referred to as "reverse current" or "countercurrent") may occur. It is also desirable if the conductive film is highly transparent so that the maximum amount of solar radiation can go to the photoelectric conversion material. Therefore, it would be desirable to provide a coated article for a solar cell that enhances electron flow through a transparent conductive film. That is, a transparent conductive film with low surface resistance.

Another example of an area where coated articles are used is the field of photocatalytic articles. It is known to apply a photocatalytic coating, such as titanium dioxide, to a substrate to obtain a coated article having self-cleaning properties. When exposed to certain electromagnetic radiation, such as ultraviolet radiation, the photocatalytic coating interacts with organic contaminants on the coating surface to degrade or decompose the organic contaminants. However, conventional photocatalytic articles have a relatively high visible light reflectance and therefore may be unsuitable for use in some architectural applications. Additionally, conventional photocatalytic coatings may be subject to degradation by so-called "sodium ion poisoning" caused by sodium ions diffusing from the underlying glass substrate into the photocatalytic coating. Further, conventional photocatalytic coatings tend to have dazzling effects that degrade the aesthetic appearance of the coated article.

Therefore, it would be desirable to provide a coated article having a primer layer positioned between a substrate and a functional overcoat (such as, but not limited to, a conductive photovoltaic, transparent conductive coating or a photocatalytic coating) other than just Block for a sodium ion diffusion, but also improves the performance of the coated article. For example, performance could be increased by lowering the reflectance of the coated article and / or providing color suppression on the article and / or increasing the functionality of the cover layer. For example, in photovoltaic applications, the primer layer might lower the surface resistance of the capping layer (eg, a transparent conductive layer) to increase the flow of electrons. In photocatalytic applications, the primer layer could increase the photocatalytic activity of the photocatalytic coating.

BRIEF SUMMARY OF THE INVENTION

A coated article includes a substrate and a first coating formed over at least a portion of the substrate. The first coating comprises oxides of at least two of P, Si, Ti, Al and Zr. A functional coating is formed over at least a portion of the first coating. In a non-limiting embodiment, the first coating comprises at least oxides of Ti and Si. In another non-limiting embodiment, the first coating comprises at least oxides of Ti, Si and P. In a further non-limiting embodiment, the first coating comprises at least oxides of Ti, Si and Al. Other embodiments may include any combination of two or more of these materials. Examples of functional coatings include, but are not limited to, photoactive coatings (such as photocatalytic coatings and / or photo-hydrophilic coatings), and electrically conductive coatings. The functional coating may be applied over a first coating with any combination of the above components.

Another coated article includes a glass substrate and a first coating formed over at least a portion of the substrate. The first coating comprises oxides of at least two of P, Si, Ti, Al and Zr. A functional coating is formed over at least a portion of the first coating. The functional coating is selected from titanium dioxide and fluorine-doped tin oxide.

A method for producing a coated article includes providing a glass substrate; Forming a first coating over at least a portion of the glass substrate by CVD by directing a first coating composition onto the glass substrate, the first coating composition comprising a silica precursor, a titania precursor and a silica accelerator comprising at least one accelerator material having at least one of P, Al and Zr includes; and forming a functional coating over at least a portion of the first coating by CVD by directing a second coating composition onto the glass substrate, wherein the second coating composition comprises a fluorine-doped tin oxide precursor composition or a titania precursor composition.

Another coated article comprises a substrate and a first coating formed over at least a portion of the substrate. The first coating comprises a mixture of oxides comprising oxides of at least two of P, Si, Ti, Al and Zr. A conductive coating is formed over at least a portion of the first coating. The conductive coating includes oxides of one or more of Zn, Fe, Mn, Al, Ce, Sn, Sb, Hf, Zr, Ni, Zn, Bi, Ti, Co, Cr, Si or In, or an alloy of two or more of these materials.

A method of lowering the surface resistivity of a conductive coating comprises providing a substrate; Forming a first coating over at least a portion of the substrate, the first coating comprising oxides of at least two of P, Si, Ti, Al, and Zr; and forming a conductive coating over at least a portion of the first coating.

One method of increasing haze and / or increasing the visible light transmission of a coated article involves providing a substrate; Forming a first coating over at least a portion of the substrate, the first coating comprising oxides of at least two of P, Si, Ti, Al, and Zr; and forming a functional coating over at least a portion of the first coating.

Another coated article comprises a substrate and a first coating formed over at least a portion of the substrate. The first coating comprises a mixture of oxides comprising oxides of at least two of P, Si, Ti, Al and Zr. A photoactive coating is formed over at least a portion of the first coating.

A photoactive article comprises a glass substrate and a first coating formed over at least a portion of the substrate. The first coating comprises a mixture of silica, titania and alumina. A photoactive functional coating comprising titanium dioxide is formed over at least a portion of the first coating.

A method for increasing the photocatalytic activity of a photoactive coating comprises providing a substrate; Forming a first coating over at least a portion of the substrate, wherein the first coating comprises oxides of at least two of P, Si, Ti, Al and Zr; and forming a photoactive coating over at least a portion of the first coating.

A method for producing a photoactive article comprises providing a glass substrate; Forming a first coating on at least a portion of the glass substrate by CVD by directing a first coating composition onto the glass substrate, the first coating composition comprising tetraethyl orthosilicate, titanium isopropoxide, and dimethylaluminum isopropoxide; and forming a photoactive coating over at least a portion of the first coating by CVD by directing a second coating composition onto the glass substrate, the photoactive coating comprising titanium dioxide.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description, in conjunction with the accompanying drawings, provides a thorough understanding of the invention.

1 Figure 3 is a side sectional view (not to scale) of a coated article having the features of the invention;

2 Figure 12 is a graph of surface resistance versus [Sn] for fluorine doped tin oxide coatings formed directly on glass or on a primer of the invention;

3 Figure 4 is a graph of percent transmission versus wavelength for fluorine doped tin oxide coatings formed directly on glass or on a primer of the invention;

4 , Figure 3 is a graph of reflectance versus titanium dioxide thickness for the coated articles of Example 5; and

5 FIG. 12 is a graph of a color change for the coated article of Example 6. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used herein, spatial or directional terms such as "left,""right,""inward,""outside,""above,""below," and the like, refer to the invention as illustrated in the figures , However, it should be understood that the invention is capable of various alternative orientations and, therefore, such terms are not to be considered as limiting. Further, as used herein, all numbers indicating dimensions, physical properties, processing parameters, amounts of ingredients, reaction conditions and the like used in the specification and claims are to be understood to be in all instances by the term " about "are modified. Unless otherwise indicated, therefore, the numerical values set forth in the following description and claims may vary depending on the desired properties to be achieved by the present invention. Lastly, and not as an attempt to limit the application of equivalence to the scope of the claims, any numerical value should be construed, at least in light of the number of significant digits indicated, and by the use of normal rounding techniques. Furthermore, all ranges given herein should be understood to include the values at the beginning and end of the range and all subranges subsumed therein. For example, a specified range of "1 to 10" should be understood to include all intervening portions between (and including) the minimum value (s) of 1 and (the) the maximum value (s) of 10; that is, all sub-regions starting with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g. B. 1 to 3.3, 4.7 to 7.5, 5.5 to 10 and the like. Further, the terms "formed over,""depositedover," or "provided over," as used herein mean formed on, deposited on or provided for, but not necessarily in direct contact with, a surface. For example, a coating layer "formed" over a substrate does not exclude the presence of one or more other coating layers or films of the same or different composition formed between the formed coating layer and the substrate. As used herein, the terms "polymer" or "polymer" include oligomers, homopolymers, copolymers and terpolymers, e.g. For example, polymers formed from two or more types of monomers or polymers. The terms "visible region" or "visible light" refer to electromagnetic radiation having a wavelength in the range of 380 nm to 760 nm. The terms "infrared region" or "infrared radiation" refer to electromagnetic radiation having a wavelength in the range of more as 760 nm to 100,000 nm. The terms "ultraviolet range" or "Ultraviolet radiation" means electromagnetic energy having a wavelength in the range of 300 nm to less than 380 nm. The terms "microwave range" or "microwave radiation" refer to electromagnetic radiation having a frequency in the range of 300 megahertz to 300 gigahertz. In addition, all documents, such as, but not limited to, granted patents and patent applications referred to herein are to be considered "full reference" in their entirety. In the following discussion, the refractive index values are those for a reference wavelength of 550 nanometers (nm). The term "film" refers to a coating area having a desired or selected composition. A "layer" comprises one or more "films". A "coating" or "coating stack" comprises one or more "layers".

A coated object 10 with the features of the invention is in 1 shown. The object 10 contains a substrate 12 with at least one main surface. A first coating (primer layer) 14 The invention is formed over at least a part of the main surface. A second coating (functional coating) 16 is over at least part of the first coating 14 educated. While specific exemplary embodiments are described, it is to be understood that one or more of the features of the invention contained in these embodiments may be combined with one or more features of the other embodiments, and that the invention is not is limited to the specific exemplary embodiments described below.

In the general practice of the invention, the substrate 12 contain any desired material with any desired properties. For example, the substrate 12 transparent, translucent or opaque to visible light. By "transparent" is meant a transmittance of visible light of more than 0% to 100%. As an alternative, the substrate 12 translucent or impermeable. By "translucent" is meant that electromagnetic energy (eg, visible light) can pass through, but this energy is scattered so that objects on the side are not clearly visible to the viewer. By "opaque" is meant a transmission of visible light of 0%. Examples of suitable materials include, but are not limited to, plastic substrates (such as acrylic polymers such as polyacrylates, polyalkyl methacrylates such as polymethyl methacrylates, polyethyl methacrylates, polypropyl methacrylates and the like; polyurethanes; polycarbonates; polyalkyl terephthalates such as polyethylene terephthalate (PET), polypropylene terephthalates, polybutylene terephthalates, and the like Polysiloxane-containing polymers, or copolymers of any monomers for their preparation, or any mixtures thereof); Metal substrates such as, but not limited to, galvanized steel, stainless steel and aluminum; ceramic substrates; like tile substrates; Glass substrates; or any mixtures or combinations of the above. For example, the substrate may contain conventional soda lime silicate glass, borosilicate glass or lead glass. The glass can be clear glass. By "clear glass" is meant a non-tinted or non-tinted glass. Alternatively, the glass may be a tinted or otherwise colored glass. The glass may be a tempered or heat treated glass. As used herein, the term "heat treated" means tempered or at least partially annealed. The glass may be of any type, such as conventional float glass, and may have any composition with any optical properties, e.g. For example, any value of visible light transmittance, ultraviolet transmittance, infrared transmittance and / or solar energy transmittance. By "float glass" is meant glass produced by a conventional float process in which molten glass is deposited on a molten metal bath and controllably cooled to form a float glass ribbon. Although not limiting for the invention, examples of glass suitable for the substrate are shown in FIG U.S. Patent No. 4,746,347 ; 4,792,536 ; 5,030,593 ; 5,030,594 ; 5,240,886 ; 5,385,872 and 5,393,593 described. Non-limiting examples of glass that can be used for the practice of the invention contain Solar Green ^® -, Solextra ^® -, GL-20 ^® -, GL-35 ^TM -, solar bronze ^® -, Starphire ^® -, Solarphire ^® -, Solarphire PV ^® - and Solargray® ^® - glass, all of which are commercially available from PPG Industries Inc. of Pittsburgh, Pennsylvania. The glass may have a smooth surface or, alternatively, may have a rough or textured surface. In a non-limiting embodiment, the glass surface may have a surface roughness (RMS) in the range of 100 nm to 5 mm.

The substrate 12 can have any desired dimensions, e.g. B. length, width, shape or thickness. For example, the substrate 12 be flat or curved or may have both flat and curved parts. In a non-limiting embodiment, the substrate may be 12 a thickness in the range of 1 mm to 10 mm, such as 1 mm to 5 mm, such as 2 mm to 4 mm, such as 3 mm to 4 mm.

In a non-limiting embodiment, the substrate may be 12 have a high visible light transmittance at a reference wavelength of 550 nanometers (nm). By "high visible light transmittance", a visible light transmittance at 550 nm becomes equal to or greater than 85%, such as greater than or equal to 87%, such as greater than or equal to 90%, greater than or equal to 91%, greater than or equal to 92%.

The first coating (primer layer) 14 gives the coated object 10 various performance advantages, as described in detail below. In a non-limiting embodiment of the invention, the first coating 14 be a homogeneous coating. By "homogeneous coating" is meant a coating in which the materials are distributed randomly throughout the coating. As an alternative, the first coating 14 multiple coating layers or films include (such as two or more separate coating films). As another alternative, the first coating 14 be a gradient layer. By "gradient layer" is meant a layer having two or more components, wherein the concentration of the components changes (or is stepped) continuously with the distance to the substrate.

In a non-limiting embodiment, the first coating comprises 14 a mixture of two or more oxides selected from oxides of silicon, titanium, aluminum, zirconium and / or phosphorus. The oxides may be present in any proportions. In a non-limiting embodiment, the first coating comprises 14 a mixture of silica and titania, wherein the silica is present in the range of 0.1 weight percent (wt%) to 99.9 wt% and the titanium dioxide is in the range of 99.9 wt% to 0.1 % By weight is present. The first coating 14 may be a homogeneous coating. As an alternative, the first coating 14 a gradient coating wherein the relative proportions of silica and titania vary throughout the coating. For example, the first coating 14 predominantly silica in the region adjacent to the substrate surface and primarily titanium dioxide at the outer region of the first coating 14 be.

As discussed above, the first coating 14 Mixtures of at least two oxides containing elements selected from silicon, titanium, aluminum, zirconium and / or phosphorus. Such mixtures include, but are not limited to, titanium dioxide and phosphorus oxide; Silica and alumina; Titanium dioxide and alumina; Silica and phosphorus oxide; Titanium dioxide and phosphorus oxide; Silica and zirconia; Titanium dioxide and zirconium dioxide; Alumina and zirconia; Alumina and phosphorus oxide; Zirconia and phosphorus oxide; or any combination of the above materials. The relative proportions of the oxides may be present in any desired amount, such as from 0.1% to 99.9% by weight of one material and from 99.9% to 0.1% by weight of the other material ,

In addition, the first coating 14 Mixtures of at least three oxides, such as, but not limited to, three or more oxides with elements selected from silicon, titanium, aluminum, zirconium and / or phosphorus. Examples include, but are not limited to, mixtures comprising silica, titania and phosphorus oxide; Silica, titania and alumina; and silica, titania and zirconia. In a non-limiting embodiment, the first coating comprises 14 a mixture of silica and titania with at least one other oxide selected from alumina, zirconia and phosphorus oxide. The relative proportions of the oxides may be present in any desired amount, such as from 0.1% to 99.9% by weight of a material, from 99.9% to 0.1% by weight of a second material and 0.1% to 99.9% by weight of a third material.

A special first coating 14 of the invention comprises a mixture of silica, titania and phosphorus oxide. The silica may be present in the range of 30% by volume (vol.%) To 80% by volume. The titanium dioxide may be present in the range of 5% to 69% by volume. The phosphorus oxide may be present in the range of 1% to 15% by volume.

The first coating 14 may be any desired thickness, such as, but not limited to, 10 nm to 120 nm, such as 30 nm to 80 nm, such as 40 nm to 80 nm, such as 30 nm to 70 nm.

The second coating (cover layer) 16 includes a functional coating. Examples of a functional coating useful in the invention include, but are not limited to, conductive coatings, solar control coatings, low emissivity coatings, and photoactive coatings.

In a non-limiting embodiment, the second coating comprises 16 at least one electrically conductive oxide layer, such as a doped oxide layer. For example, the second coating 16 contain one or more oxide materials, such as, but not limited to, one or more oxides of one or more of Zn, Fe, Mn, Al, Ce, Sn, Sb, Hf, Zr, Ni, Zn, Bi, Ti, Co, Cr, Si or in or one Alloy of two or more of these materials, such as zinc stannate. The second coating 16 may also contain one or more dopants, such as, but not limited to, F, In, Al and / or Sb. In one non-limiting embodiment, the second coating is 16 a fluorine doped tin oxide coating, wherein the fluorine is present in the coating precursor materials in an amount of less than 20 weight percent, based on the total weight of the precursor materials, such as less than 15 weight percent, such as less than 13 weight percent, such as less than 10% by weight, such as less than 5% by weight. The second coating 16 may be amorphous, crystalline or at least partially crystalline.

In a non-limiting embodiment, the second coating comprises 16 fluorine-doped tin oxide having a thickness greater than 200 nm, greater than 250 nm, greater than 350 nm, greater than 380 nm, greater than 400 nm, and greater than 420 nm. In a non-limiting embodiment, the thickness is Range from 350 nm to 420 nm.

The primer layer 14 The invention gives the topcoat 16 (e.g., fluorine doped tin oxide) has a surface resistance of less than 15 ohms per square (Ω / □), such as less than 14 Ω / □, such as less than 13.5 Ω / □, such as less than 13 Ω / □, such as less than 12 Ω / □, such as less than 11 Ω / □, such as less than 10 Ω / □.

In another non-limiting embodiment, the second coating 16 be a photoactive coating. The adjective or adverb "photoactive" refers to the photogeneration of a hole-electron pair when irradiated at a particular frequency, e.g. B. Ultraviolet ("UV") light. The photoactive coating may be photocatalytic, photoactive hydrophilic, or both. By "photocatalytic" is meant a coating having self-cleaning properties, ie, a coating which, when exposed to a particular electromagnetic radiation, such as UV, interacts with organic contaminants on the coating surface to degrade and decompose the organic contaminants. By "photoactively hydrophilic" is meant a coating for which the contact angle of a water drop on the coating decreases over time as a result of the electromagnetic radiation of the coating in the photoabsorption band of the material. For example, after a radiation exposure of sixty minutes in the photoabsorption band of the 24 w / m ² gauge material at the coating surface, the contact angle may decrease to less than 15 °, such as less than 10 °, and become superhydrophilic, e.g. B. decrease to less than 5 °. Although photoactive, the coating need not necessarily be photocatalytic to the extent that it is self-cleaning, ie, could not be sufficiently photocatalytic to decompose organic matter such as dirt on the coating surface in an appropriate or economically useful period of time. For example, the photocatalytic activity may be less than 4 x 10 ^-3 per centimeter minute (cm ^-1 min ^-1 ), such as less than 3 x 10 ^-3 cm ^-1 min ^-1 , such as less than 2 x 10 ^-3 cm ^-1 min ^-1 , such as less than 1 x 10 ^-3 cm ^-1 min ^-1 .

The photoactive coating may include at least one photoactive coating material and optionally at least one additive or dopant configured to affect the photoactivity of the coating as compared to that of the coating without dopant material. The photoactive coating material may include at least one oxide, such as, but not limited to, one or more oxides or oxide semiconductors such as titanium oxides, silicon oxides, aluminum oxides, iron oxides, silver oxides, cobalt oxides, chromium oxides, copper oxides, tungsten oxides, zinc oxides, zinc / tin oxides. Strontium titanate and mixtures thereof. The oxide may include oxides, superoxides or suboxides of the element. The oxide may be crystalline or at least partially crystalline. In an exemplary coating of the invention, the photoactive coating material is titanium dioxide. Titanium dioxide exists in an amorphous form and three crystalline forms, i. h., in the crystalline anatase, rutile and brookite forms. The titania of the Anastas phase is particularly useful because it has strong photoactivity, while also having excellent resistance to chemical attack and physical durability. However, the rutile phase or combinations of the anatase and / or rutile phases with the brookite and / or amorphous phase are also acceptable for the present invention.

Examples of photoactive coating dopants useful in the invention include, but are not limited to, one or more of chromium (Cr), vanadium (V), manganese (Mn), copper (Cu), iron ( Fe), magnesium (Mg), scandium (Sc), yttrium (Y), niobium (Nb), molybdenum (Mo), ruthenium (Ru), tungsten (W), silver (Ag), lead (Pb), nickel ( Ni), rhenium (Re), tin (Sn) and / or any mixtures or combinations thereof in either elemental or ionic state.

In a non-limiting embodiment, the second coating comprises 16 Titanium dioxide having a thickness greater than 10 nm, such as greater than 20 nm, greater than 30 nm, greater than 40 nm, and larger than 50 nm, such as greater than 60 nm, such as greater than 70 nm, greater than 80 nm, greater than 90 nm, and greater than 100 nm, such as in the range from 10 nm to 150 nm.

In a non-limiting embodiment, the first coating 14 the invention the subject 10 with a second titanium dioxide coating 16 with a reflectance in the visible range of less than 23%, such as less than 20%, such as less than 19%, less than 18%, less than 17%, less than 16%, less than 15%, and less than 14%, less than 12%, less than 11%, less than 10%.

The first coating 14 and / or second coating 16 may be over at least part of the substrate 12 by any conventional method such as, but not limited to, spray pyrolysis, chemical vapor deposition (CVD) or magnetron sputtering vacuum deposition (MSVD). In the spray pyrolysis method, an organic or metal-containing precursor composition having one or more oxide precursor materials, e.g. As precursor materials for titanium dioxide and / or silica and / or alumina and / or phosphorus oxide and / or zirconium dioxide, carried in suspension, z. An aqueous or nonaqueous solution, and directed onto the surface of the substrate while the substrate is at a sufficiently high temperature to cause decomposition of the precursor composition and formation of a coating on the substrate. The composition may contain one or more dopant materials. In a CVD method, a precursor composition in a carrier gas, e.g. As a nitrogen gas, carried and directed to the heated substrate. in the MSVD method, one or more metal-containing targets are sputtered under reduced pressure in an inert or oxygen-containing atmosphere to deposit a sputter coating over the substrate. The substrate may be heated during or after the coating to cause crystallization of the sputtered coating to form the coating.

In a non-limiting practice of the invention, one or more CVD coating apparatus (s) may be used at one or more positions in a conventional float glass ribbon manufacturing process. For example, a CVD coating apparatus may be used while the float glass ribbon is moving through the tin bath after exiting the tin bath before entering the cooling furnace as it moves through the cooling furnace or after leaving the cooling furnace. Because the CVD method is capable of coating a moving float glass ribbon but can still withstand the harsh environment associated with making the float glass ribbon, the CVD method is particularly well suited for depositing coatings on the float glass ribbon in the molten tin bath. U.S. Patent No. 4,853,257 ; 4,971,843 ; 5,536,718 ; 5,464,657 ; 5,714,199 and 5,599,387 describe CVD coating apparatuses and methods that can be used in the practice of the invention to coat a float glass ribbon in a molten tin bath.

In one non-limiting embodiment, one or more CVD coater may be disposed in the tin bath over the tin melt pool. As the float glass ribbon moves through the tin bath, the vaporized precursor composition may be added to a carrier gas and directed onto the top surface of the belt. The precursor composition decomposes to form a coating (eg, first coating 14 and / or second coating 16 ) on the tape. In one non-limiting embodiment, the coating composition is deposited on the belt at a location where the temperature of the belt is less than 1300 ° F (704 ° C), such as less than 1250 ° F (677 ° C), such as less than 1200 ° F (649 ° C) as less than 1190 ° F (643 ° C) as less than 1150 ° F (821 ° C) as less than 1130 ° F (610 ° C) as in the range of 1190 ° F up to 1200 ° F (643 ° C to 649 ° C). This is when depositing a second coating 16 (For example, fluorine-doped tin oxide) with reduced surface resistance particularly useful, since the lower the deposition temperature is the lower the surface resistance obtained.

For example, the composition comprises for forming a first coating 14 which includes silica and titania, both a silica precursor and a titania precursor. A non-limiting example of a silica precursor is tetraethyl orthosilicate (TEOS).

Examples of titania precursors include, but are not limited to, oxides, suboxides or superoxides of titanium. In one embodiment, the titania precursor material may include one or more titanium alkoxides such as, but not limited to, titanium methoxide, ethoxide, propoxide, butoxide, and the like; or isomers thereof, e.g. For example, titanium isopropoxide, tetraethoxide and the like. Exemplary precursor materials useful in the practice of the invention include, but are not limited to, tetraisopropyl titanate (TPT). Alternatively, the titania precursor material may be titanium tetrachloride. Examples of alumina precursors include, but are not limited to, Dimethylaluminum isopropoxide (DMAP) and aluminum tri-sec-butoxide (ATSB). In a non-limiting embodiment, the dimethylaluminum isopropoxide may be prepared by mixing trimethylaluminum and aluminum isopropoxide at a molar ratio of 2: 1 in an inert atmosphere at room temperature. Examples of phosphorus oxide precursors include, but are not limited to, triethyl phosphite. Examples of zirconia precursors include, but are not limited to, zirconium alkoxides.

A first coating 14 with a combination of silica and titania offers advantages over previous oxide combinations. For example, the combination of a low refractive index material such as silica (refractive index of 1.5 at 550 nm) with a high refractive index material such as titanium dioxide (refractive index of 2.4 at 550 nm) enables the refractive index variation of the first coating 14 between these two extremes by varying the amount of silica and titania. This is especially useful when the first coating 14 provided with color or iris suppression properties.

The deposition rate of titania is usually much faster than that of silica. Under typical deposition conditions, this limits the amount of silica to not more than about 50% by weight, which in turn limits the lower refractive index range of the resulting silica / titania coating. Therefore, a doping material may be added to the silica and titania precursor composition to accelerate the deposition rate of silica. The dopant forms part of the resulting oxide mixture and therefore can be selected to impart improved performance to the resulting coating. Examples of dopants useful in the practice of the invention include, but are not limited to, materials containing one or more of phosphorus, alumina and zirconium to form oxides of these materials in the resulting coating. Examples of phosphorus oxide precursor materials include triethyl phosphite. Examples of alumina precursor materials include aluminum tri-sec-butoxide (ATSB) and dimethylaluminum isopropoxide (DMAP). Examples of zirconia precursors include zirconium alkoxide.

EXAMPLES

example 1

This example demonstrates the use of a primer layer of the invention as a color suppression layer for a titanium dioxide overcoat. The undercoat layer was a combination of silica, titania and phosphorus oxide.

The primer layer was applied to a glass substrate by a chemical vapor deposition process using a laboratory blade. Then a titania coating was deposited on the primer. Table 1 shows the coating configurations (composition and thickness) for Samples 1-4. The primer was deposited as a multi-film layer with three primer films; a first primer film over the glass substrate, a second primer film over the first primer film, and a third primer film over the second primer film. The multilayer configuration simulates a graded primer layer. Table 1 Sample 1 Sample 2 Sample 3 Sample 4 Thickness of the first primer [nm] 13 11 29 13 Vol .-% phosphorus oxide in the first primer 5 10 5 5 Vol .-% silica in the first primer 75 80 70 75 Vol .-% titanium dioxide in the first primer 20 10 25 20 Thickness of the second primer [nm] 23 33 21 27 Vol .-% phosphorus oxide in the second primer 2 2 2 2 Vol .-% silica in the second primer 49 58 48 62 Vol .-% titanium dioxide in the second primer 49 40 50 36 Thickness of the third primer [nm] 21 18 15 23 Vol .-% phosphorus oxide in the third primer 5 11 5 5 Vol .-% silica in the third primer 75 80 70 70 Vol .-% titanium dioxide in the third primer 20 9 25 25 Thickness of the upper titanium dioxide coating [nm] 115 121 113 118

Table 2 shows the reflected color performance data for Samples 1-4 and Comparative Samples (titania-coated glass plates without primer layer). The color data were modeled with conventional TFCalc ^® software for the coated side of the substrate at 065, 10 ° Observer. Table 2 Sample 1 115 nm TiO ₂ Sample 2 121 nm TiO ₂ Sample 3 113 nm TiO ₂ Sample 4 118 nm TiO ₂ a * -6.6 17.17 -4.1 -3.5 -6.6 21.3 -4.2 10.4 b * -9.2 -41.4 -12.5 -38.7 -7.7 -40.9 -12.8 -40.7 L * 50.8 42.4 50.8 46.2 51.3 41.5 50.6 44.1

Through the primer layer, this sample has a generally lower (more negative) a * value and a higher (more positive) b * value compared to the article without a primer layer.

Example 2

This example demonstrates the use of a primer layer of the invention to impart improved photoactivity to a titanium dioxide overcoat. The undercoat layer comprised silica, titania and phosphorus oxide.

Both the primer layer and the overcoat (titanium dioxide) were formed by chemical vapor deposition processes. The phosphorus oxide precursor was triethyl phosphite (TEP). The precursor for silica was tetraethyl orthosilicate (TEOS). The precursor for titania in both the primer layer and topcoat was tetraisopropyl titanate (TPT). Table 3 shows the deposition parameters for Samples 5-9. Table 3 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Molar ratio of TEP / TEOS 1.25 1.25 0.5 0.5 N / A Molar ratio of TPT / TEOS 0.25 0.5 0.25 0.5 N / A Vol .-% TEOS of the total flux for the primer layer 0.11 0.12 0.18 0.12 N / A Vol .-% TEP of the total flux for the primer layer 0.14 0.15 0.09 0.06 N / A Vol .-% TPT of the total flux for the primer layer 0.03 0.06 0.05 0.06 N / A Vol .-% TPT of the total flux for the functional coating 0.257 0.257 0.257 0.257 0.257

Table 4 shows the layer thicknesses for Samples 5-9. Table 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Phosphorus oxide [microgram / cm ² ] 1.5 2.1 1.5 1.2 N / A Titanium dioxide [microgram / cm ² ] 34.4 38.4 36.0 37.0 30.2 Thickness of primer layer [nm] 37.4 98.9 52.5 83.3 0 Thickness of functional titanium dioxide coating [nm] 132 132 129 121 129

Table 5 shows the results of a conventional stearic acid test for Samples 5-9. The stearic acid test is in U.S. Patent No. 6,027,766 which is incorporated herein by reference. As can be seen, the article having the primer layer of the invention had higher photocatalytic activity than the article without a primer layer (Sample 9). Table 5 PCA (× 10 ^-3 cm ^-1 min ^-1 ) Sample 5 121 Sample 6 121 Sample 7 112 Sample 8 92 Sample 9 61

Example 3

This example demonstrates the use of a primer layer of the invention to reduce the surface resistivity of a fluorine doped tin oxide liner.

The undercoat layer was a silica, titania, phosphorus oxide undercoat layer deposited by CVD. The precursors used were TEOS (silica), TPT (titanium dioxide), and TEP (phosphorus oxide).

Fluorine doped tin oxide coatings of different thickness were deposited on the primer layer and also on uncoated glass (as comparative samples). The surface resistivity of both coatings, as measured by the R-Chek + 4 point meter, commercially available from Electronic Design To Market, Inc., was compared. The amount of [Sn] was determined by X-ray fluorescence, which corresponds to the thickness of the fluorine-doped tin oxide coatings. 2 shows that the surface resistance of fluorine doped tin oxide coatings on a primer layer of the invention is on average 1 to 3 ohms / square lower than that of fluorine doped tin oxide coatings of the same thickness on glass. In 2 the open squares and dotted lines show fluorine-doped tin oxide on glass. The closed circles and solid lines show the fluorine doped tin oxide coatings on the primer layer of the invention. The primer layer (composition and thickness) was the same for each sample.

Example 4

A piece of clear glass (12 inches by 24 inches, 30 cm by 61 cm) was coated with the precursors described above using a CVD process. Half of the glass was coated with a fluorine-doped tin oxide coating directly on the glass and the other half of the glass was coated with a silica, titania, phosphorus undercoat and a fluorine doped tin oxide topcoat.

Samples were cut from each part of the glass plate and analyzed as described below.

(1) X-ray fluorescence (XRF) data

The XRF data in Table 6 shows a similar amount of [Sn] for both coatings (somewhat higher in the case of the FTO / UL coating stack). Table 6 Only FTO FTO / UL Without [P] 0.09 0.56 0.09 [Ti] 0 1.87 0 [Sn] 145.8 147 0.2

(2) turbidity and permeability

The samples were also tested for haze and permeability. The results are shown in Table 7. The transmission spectra are in 4 shown. The haze was higher and the transmission was also higher for the fluorine doped tin oxide (FTO) / primer layer (UL) coating stack compared to the fluorine doped tin oxide (FTO) coating directly on glass. Thus, the undercoat layer of the invention also provides a way to increase the haze and permeability of a coated article. This could be useful in the field of solar cells, where increased turbidity increases the absorption path of the electromagnetic energy, which in turn provides an improved opportunity for absorption of electromagnetic energy. Table 7 Only FTO FTO / UL cloudiness 0.89% 1.77% permeability 80.78% 81.37%

(3) surface resistance

Surface resistivity data are shown in Table 8. The FTO / UL coating had a surface resistance that was 1.5 ohms / square lower than that of an FTO coating on glass. Table 8 Only FTO FTO / UL 13.55 ohms / square 12.05 ohms / square

(4) coating thickness

The FTO coating thickness was somewhat thicker in the case of FTO coating on glass (356 nm) versus FTO on the UL (FTO top coat 334 nm), as determined by the etching method.

(5) Coating porosity

The coatings were viewed using Scanning Electron Microscopy (SEM). Numerous small holes were observed in the FTO coating directly on glass. No holes were noted in the FTO / UL coating stack.

(6) surface roughness

The surface roughness was determined by atomic force microscopy (AFM) for areas of 10 microns (μm) by 10 μm; 5 μm by 5 μm; and 1 μm by 1 μm. The results are shown in Table 9. The surface roughness was higher in the case of the FTO / UL coating stack than for FTO directly on glass. Increased surface roughness increases coating haze and thus increases the absorption path of all impacting electromagnetic energy. Table 9 sample RMS roughness (nm) Ra roughness (nm) Only FTO 10 μm × 10 μm 13.39 10.69 FTO / UL 10 μm × 10 μm 17.45 13.74 Only FTO 5 μm × 5 μm 12.53 9.99 FTO / UL 5 μm × 5 μm 18.03 14.09 Only FTO 1 μm × 1 μm 8.99 7.18 FTO / UL 1 μm × 1 μm 9.96 8.03

Example 5

This example demonstrates the effect of a primer layer of the invention on the reflectance of a coated article.

4 Fig. 10 shows the change in reflectance for a 10 nm to 120 nm TiO ₂ coating on clear glass (dotted line diamond) and for the same TiO ₂ layer on a primer layer of the invention on clear glass. The primer layer was 13 nm 75% SiO ₂ -20% TiO ₂ -5% P ₂ O ₅ / SiO ₂ 23 nm 49% -49% TiO ₂ 2% P ₂ O ₅ / SiO ₂ 21 nm 75% -20% TiO ₂ -5% P ₂ O ₅ (closed circle and solid line). The TiO ₂ thickness varies from 10 nm to 120 nm at 5 nm intervals.

4 shows that as the functional TiO ₂ coating thickness on glass is increased, the reflectance varies widely (ie, 11.7% <R <38.8%). However, when the functional TiO 2 coating is deposited on the primer layer, the reflectance changes are much lower (ie, in the range of 17.2% to 27.4%). This shows that with the variation in topcoat thickness, the reflectance of the entire coating stack with a backsize coating is not as sensitive as without a backsize coating.

In some areas, the reflectance with a primer layer of the invention could be significantly reduced. Table 10 shows the difference in reflectance for titania values of 55 nm and 165 nm. Table 10 Reflectance without underlay Reflectance with underlay 55 nm TiO ₂ 38.8% 26.4% 165 nm TiO ₂ 35.6% 25.5%

Example 6

This example demonstrates the effect of a primer layer of the invention on the color (e.g., a * and b *) of an article.

5 shows the change of a * and b * for 10 nm to 120 nm TiO ₂ on clear glass (open diamond with dotted line) and for the same coating on a primer layer (13 nm 75% SiO ₂ -20% TiO ₂ -5% P ₂ O ₅ / SiO ₂ 23 nm 49% -49% TiO ₂ 2% P ₂ O ₅ / SiO ₂ 21 nm 75% -20% TiO ₂ -5% P ₂ O ₅₎ on a clear glass (closed circle and solid line) , The TiO ₂ thickness varies from 10 nm to 120 nm at 5 nm intervals.

5 shows that as the functional TiO ₂ coating thickness increases, the color (a * and b *) of the undoped TiO ₂ coating varies greatly (-24 <a * <+37, and -42 <b * <+34 ). However, when the functional TiO ₂ coating is deposited on a primer layer as described above, a * and b * change to a lesser extent (in the range of -8 <a * <+ 12, and -10 <b * <+ 7) , This means that with the variation in topcoat thickness, the color of the entire coating stack with a backing layer of the invention is not as sensitive as without backing.

Example 7

This example demonstrates the effect of a gradient undercoating layer of silica and titania on the photocatalytic activity of a titanium dioxide overcoat (120 nm thick).

Table 11 shows the compositions of two gradient primer layers. Table 11 Average TiO ₂ (%) Average SiO ₂ (%) Estimated thickness (nm) XRD results a * b * R (%) Sample 10 68.9 31.1 23 Amorphous -0.937 -8.174 14.51 Sample 11 68.1 31.9 32 Amorphous -1.129 -7.904 15.81

Table 12 shows the effect of the two primer layers of Table 11 on the photocatalytic activity of a 120 nm thick titanium dioxide overcoat as compared to the titanium dioxide without primer layers. [Ti] units are micrograms / cm ² . Table 12 [Ti] amount by XRF (μg / cm ² ) PCA (× 10 ^-3 cm ^-1 min ^-1 ) [Ti] _primer [Ti] _primer + topcoat [Ti] _topcoat Sample 12 TiO ₂ coating on sample 10 56.5 4.10 34,60 30.50 Sample 13 TiO ₂ coating on sample 11 577 4.60 35.40 30,80 Sample 14 TiO ₂ coating on clear glass 51.6 N / A 32,70 32,70

It will be apparent to those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed in the foregoing specification. Therefore, the particular embodiments described in detail herein are merely illustrative and do not limit the scope of the invention, the full scope of which is determined by the appended claims and all equivalents thereof.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4746347 [0024]
• US 4792536 [0024]
• US 5030593 [0024]
• US 5030594 [0024]
• US 5240886 [0024]
• US 5385872 [0024]
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Claims (20)

A coated article comprising: a substrate; a first coating formed over at least a portion of the substrate, the first coating comprising oxides of at least two of P, Si, Ti, Al, and Zr; and a functional coating formed over at least a portion of the first coating, wherein the functional coating is selected from an electrically conductive coating and a photoactive coating. The article of claim 1, wherein the first coating comprises at least oxides of Ti and Si. The article of claim 1, wherein the first coating comprises at least oxides of Ti, Si and P, The article of claim 1, wherein the first coating comprises at least oxides of Ti, Si and Al. The article of claim 1, wherein the first coating comprises 30-80 vol.% Silica, 1-15 vol.% Phosphorus oxide, and 5-69 vol.% Titanium dioxide. The article of claim 1, wherein the first coating has a thickness in the range of 10 nm to 120 nm, such as 30 nm to 70 nm. The article of claim 1, wherein the first coating is a gradient coating. The article of claim 1, wherein the first coating is a multilayer coating comprising: a first layer comprising 5-10% by volume of phosphorus oxide, 70-80% by volume of silica and 10-25% by volume of titanium dioxide having a thickness in the range of 11 nm to 29 nm; a second layer comprising 2% by volume of phosphorus oxide, 48-62% by volume of silica and 36-50% by volume of titanium dioxide having a thickness in the range of 21 nm to 33 nm; and a third layer comprising 5-11% by volume of phosphorus oxide, 70-80% by volume of silica and 9-25% by volume of titanium dioxide having a thickness in the range of 15 nm to 23 nm. The article of claim 1, wherein the functional coating is a conductive coating comprising oxides of one or more of Zn, Fe, Mn, Al, Ce, Sn, Sb, Hf, Zr, Ni, Zn, Bi, Ti, Ca, Cr , Si and In or an alloy of two or more of these materials. The article of claim 9, wherein the functional coating comprises at least one dopant selected from F, In, Al and Sb. The article of claim 10, wherein the functional coating comprises fluorine-doped tin oxide. The article of claim 1, wherein the functional coating is a photoactive coating comprising titanium dioxide. The article of claim 1, wherein the article has a color in the range of -10 ≤ a * ≤ 2 and -15 ≤ b * ≤ 0. The article of claim 1, wherein the article has an a * in the range of -8 to -4.4, a b * in the range of -12.6 to -5.2, and an L * in the range of 50.5 to 52, 3 has. The article of claim 12, wherein the titanium dioxide has a thickness of at least 10 nm, such as in the range of 113 nm to 121 nm. The article of claim 1 wherein the first coating comprises oxides of Si, Ti and P and the functional coating is selected from titanium dioxide and fluorine doped tin oxide. The article of claim 1, wherein the first coating comprises a mixture of silica, titania, and alumina and the functional coating comprises titania. A method of making a coated article, comprising: providing a glass substrate; Forming a first coating over at least a portion of the glass substrate by CVD by directing a first coating composition onto the glass substrate, the first coating composition comprising a silica precursor, a titania precursor, and a silica accelerant comprising at least one accelerating material with at least one of P, Al, and Zr includes; and forming a functional coating over at least a portion of the first coating by CVD by directing a second coating composition onto the glass substrate, the second coating composition comprising a fluorine doped tin oxide precursor composition or a titania precursor composition. The method of claim 18, wherein the first coating is deposited as a gradient coating. The method of claim 18, wherein the first coating is deposited as a multilayer coating.

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