Photoactive coating, coated article, and method of making same

Photoactive coatings, coated products, and methods of making the same

Cross-reference to related applications. This application is a partial continuation of U.S. Application No. 10/075,316 (Greenberg et al., entitled "Photocatalytically activated self-cleaning appliances", filed on February 14, 2002), the latter being in April 1999 Divisional of U.S. Application No. 09/282,943 (now U.S. Patent No. 6,413,581) filed on the 1st, the latter being the division of U.S. Application No. 08/899,257 (now U.S. Patent No. 6,027,766) filed on July 23, 1997 The latter claims the priority of U.S. Provisional Application Serial No. 60/040,566 filed on March 14, 1997, and all applications and patents are hereby incorporated by reference into the present invention. This application also claims the priority of U.S. Provisional Application Serial No. 60/305,191 filed on July 13, 2001, which is also incorporated herein by reference.

1. Field of the present invention The present invention relates to a method for depositing a photoactive coating on a substrate (eg, a glass sheet or continuous float glass ribbon), a method for increasing the photoactivity of the coating, and a method for manufacturing according to these methods Into the product.

2. Technical issues For many substrates, such as glass substrates such as architectural windows, automotive glass, and aircraft windows, it is ideal for good visibility that the surface of the substrate is basically free of surface contamination for the longest possible duration. Such as common organic and inorganic surface contaminants. Usually, this means that these surfaces are cleaned frequently. This cleaning operation is usually performed by manually wiping the surface with or without the help of chemical cleaning solutions. The solution is labor, time, and/or cost intensive. Therefore, substrates, especially glass substrates, need to have a surface that is easier to clean than existing glass substrates, which reduces the need for manual cleaning or the frequency thereof.

Some semiconducting metal oxides are known to be incorporated into coatings to provide photoactive (hereinafter "PA") coatings. The term "photoactive" or "photoactively" refers to the photogenerating effect of hole-electron pairs when they are irradiated with radiation having a specific frequency, usually ultraviolet ("UV") light. Above certain minimum thicknesses, these PA coatings are usually photocatalytic (hereinafter "PC"). "Photocatalysis" refers to a coating with self-cleaning properties, that is, when the coating is exposed to certain electromagnetic radiation, such as UV, it interacts with organic pollutants on the surface of the coating to degrade or decompose the organic pollutants. In addition to their self-cleaning properties, these PC coatings are also generally hydrophilic, that is, they are wetted by water with a water contact angle of generally less than 20 degrees. The hydrophilicity of the PC coating helps reduce fogging, that is, the accumulation of water droplets on the coating, and fogging reduces the visibility of visible light through and through the coated substrate.

Generally, the thicker these PC coatings, the better the photoactivity, that is, the shorter the time for at least to destroy or decompose organic contaminants on the coating. In order to increase the photocatalytic activity of the coating, a photocatalytic enhancement promoter has been incorporated into the coating, for example, as reported in US Patent No. 6,603,363. Whether these known promoters increase the photocatalytic activity of the coating generally depends at least in part on where the promoter is located in the coating structure, that is, the surface of the coating or the body of the coating. The position of the promoter in the coating again depends on the method of depositing the coating. For example, in US Patent No. 6,603,363, the photocatalytic activity of a titanium dioxide coating is increased by covering the titanium dioxide coating with a thin metal layer of platinum, rhodium, silver, or palladium. US Patent No. 5,854,169 discloses increasing the photocatalytic activity of a titanium dioxide coating by adding a promoter containing palladium, platinum, rhodium, ruthenium, tungsten, molybdenum, gold, silver, or copper. However, these promoters are usually deposited near the coating surface instead of being introduced into the coating body, making the deposition process more difficult and time-consuming.

In order to achieve the previously required levels of coating thickness, photocatalytic activity, surface roughness, and coating porosity, many PC coatings are deposited by sol-gel technology. In a typical sol-gel process, an uncrystallized colloidal suspension (sol) is coated on a substrate at or near room temperature to form a gel, and then heated to form a crystalline coating. For example, US Patent No. 6,013,372 discloses a method for forming a hydrophilic, photocatalytic, and self-cleaning method by blending photocatalyst particles in a metal oxide layer and applying the blend to a substrate through a sol-gel process. coating.

However, conventional sol-gel coating methods are economically or practically unsuitable for certain use conditions or substrates. For example, in the conventional float glass process, the float glass ribbon in the molten metal bath is too hot to accept the sol due to the evaporation or chemical reaction of the solvent used for the sol. Conversely, if the sol is applied to a substrate lower than the specific temperature at which the catalyst in the crystalline form is formed, the sol-coated substrate is reheated to a temperature sufficient to form the crystalline photocatalyst. These cooling and reheating operations may require significant investment in equipment, energy, and operating costs, and may significantly reduce production efficiency. In addition, the sodium-containing substrate, such as soda lime glass, is reheated to a temperature sufficient to form a crystalline photocatalyst, which increases the possibility of sodium ions in the substrate to migrate to the coating. This migration can lead to what is commonly referred to as "sodium ion poisoning" of the deposited coating. These sodium ions can reduce or destroy the photocatalytic activity of the PC coating. In addition, the sol-gel process usually produces thick coatings, eg, a few microns thick, which can adversely affect the optical and/or aesthetic properties of the coated article. Generally, as the thickness of the PC coating increases, the transmittance and reflectance of the coating experience a series of minimum and maximum values due to optical interference effects. The reflection and transmission colors of the coating also change due to these optical effects. Therefore, coatings thick enough to provide the required self-cleaning properties may have undesirable optical properties.

Therefore, it is advantageous to provide a method for depositing a PA coating with a photocatalytic enhancement co-catalyst compatible with conventional float glass processes and/or to provide articles made according to the method, the method and/or The product reduces or eliminates at least some of the above-mentioned defects.

Summary of the invention In one aspect of the invention, a method of forming at least a PA coating includes depositing a precursor composition on at least a portion of the surface of a substrate. The precursor composition includes a photoactive coating precursor material, such as a metal oxide or semiconducting metal oxide precursor material. In one embodiment, the precursor material is a titanium dioxide precursor material. The precursor composition also includes at least one other precursor material having at least one photoactivity enhancing material. In one embodiment, the photoactivity enhancing material is at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, or any mixture or combination thereof or containing one or more of the above metals Of any material. Sufficient amounts of other precursor materials are added to the composition such that the molar ratio of the selected metal to titanium in the applied photocatalytic coating is about 0.001 to about 0.05. The at least PA coating leads to at least hydrophilicity of the coating on the substrate, such as photoactive hydrophilicity, and may also lead to sufficient photocatalytic activity to be a PC coating.

Another method of forming the photoactive coating includes depositing the precursor composition by chemical vapor deposition onto at least a portion of the float glass ribbon in the molten metal bath. The precursor composition includes a photoactive coating precursor material and at least one other precursor material containing a dopant, which enhances the photoactivity of the photoactive coating relative to the photoactive coating without the dopant .

Another method of forming at least a PA coating includes depositing a precursor composition onto at least a portion of the surface of the substrate. The precursor composition includes at least one titanium dioxide precursor material. In one embodiment, the titanium dioxide precursor material includes titanium and oxygen, such as at least one titanium alkoxide, such as but not limited to titanium methoxide, titanium ethoxide, titanium propoxide, titanium butoxide, and the like or isomers thereof , Such as but not limited to titanium isopropoxide. In another embodiment, the titanium dioxide precursor material comprises titanium tetrachloride. In one embodiment, the precursor composition further includes at least one other organometallic precursor having at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, or mixtures or combinations thereof material. In one embodiment, the other precursor materials may be oxides, alkoxides, or mixtures thereof. Exemplary organometallic precursor materials include, but are not limited to, trialkyl borate, strontium alkoxide, lead alkyl, zirconium alkoxide, lanthanum alkoxide, strontium ethoxide, strontium 2-ethylhexanoate, hexafluoroacetylacetone Strontium, strontium isopropoxide, strontium methoxide, strontium tantalum ethoxide, strontium titanium isopropoxide, triethyl borate (also known as triethoxyborane or triethyl borate), other borate esters such as triborate -n-butyl ester, triisopropyl borate, tetra-n-butyl lead, zirconium 2-methyl-2-butoxide, and lanthanum isopropoxide, and mixtures thereof.

Other methods of depositing photoactive, for example, photocatalytic and/or photoactive hydrophilic coatings on substrates include arranging chemical vapor deposition coating equipment on a float glass ribbon in a float chamber and combining the precursor composition The belt is guided by the coating equipment. The precursor composition includes a titanium dioxide precursor material and at least one other precursor material having at least one metal selected from boron, strontium, lead, barium, calcium, hafnium, lanthanum, or any mixture or combination thereof. Sufficient other precursor materials are added to the composition such that the molar ratio of the selected metal to titanium in the applied photocatalytic coating is from about 0.001 to about 0.05. The substrate is heated to a temperature sufficient to decompose the precursor material to form a photoactive coating.

A method for increasing the photocatalytic activity of a titanium dioxide coating is provided. The method includes adding at least one metal selected from the group consisting of boron, strontium, zirconium, lead, barium, calcium, hafnium, and lanthanum to the titanium dioxide coating so that the molar ratio of the selected metal to titanium in the photocatalytic coating is about 0.001 to about 0.05.

One method for forming a photocatalytic coating includes depositing a precursor composition on at least a portion of a substrate. The precursor composition includes titanium tetrachloride, an organic oxygen source, and a boron-containing precursor material.

The article of the present invention includes a substrate having at least one surface and a photocatalytic coating deposited on at least a portion of the surface of the substrate. The photocatalytic coating includes titanium dioxide and at least one other material containing at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and any mixture or combination thereof. The amount of the other materials present in the coating is such that the molar ratio of the selected metal to the titanium in the photocatalytic coating is about 0.001 to about 0.05.

The present invention provides the following technical solutions: (1) A method for forming a photoactive coating, comprising the steps of: depositing a precursor composition on at least a part of the float glass ribbon in a molten metal bath by chemical vapor deposition, and the front The body composition includes: a photoactive coating precursor material; and at least one other precursor material containing a dopant that increases the light of the photoactive coating relative to the photoactive coating without the dopant. active.

(2) The method according to (1) above, wherein the photoactive coating precursor material contains a titanium dioxide precursor material.

(3) The method according to (2) above, wherein the titanium dioxide precursor material is selected from titanium alkoxides, titanium tetrachloride, and mixtures thereof.

(4) The method according to (3) above, wherein the titanium alkoxide is selected from the group consisting of titanium methoxide, titanium ethoxide, titanium tetraethoxide, titanium propoxide, titanium butoxide, isomers thereof, and mixtures thereof.

(5) The method according to (3) above, wherein the titanium alkoxide is selected from titanium isopropoxide, titanium tetraethoxide, and mixtures thereof.

(6) The method according to (1) above, wherein the at least one other precursor material contains an organometallic alkoxide.

(7) The method according to (6) above, wherein the at least one other precursor material contains at least one transition metal alkoxide having a boiling point of less than 200°C.

(8) The method according to the above (6), wherein the organometallic alkoxide is selected from the alkoxides of boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and mixtures thereof.

(9) The method according to (1) above, wherein at least one other precursor material is selected from trialkyl borate, strontium alkoxide, lead alkyl, zirconium alkoxide, lanthanum alkoxide, strontium ethoxide, 2-ethylhexyl Strontium acid, strontium hexafluoroacetylacetonate, strontium isopropoxide, strontium methoxide, strontium tantalum ethoxide, strontium titanium isopropoxide, triethyl borate, tetra-n-butyl lead, 2-methyl-2-butanol Zirconium, lanthanum isopropoxide, and mixtures thereof.

(10) The method according to (1) above, wherein the photoactive coating is photocatalytic.

(11) The method according to (1) above, wherein the photoactive coating is photoactive and hydrophilic.

(12) The method according to (2) above includes adding sufficient other precursor materials so that the molar ratio of dopant to titanium in the applied photoactive coating is 0.001-0.05.

(13) A method of forming a photoactive coating, comprising the steps of: depositing a precursor composition on at least a part of the surface of a substrate, the precursor composition comprising: a titanium dioxide precursor material; and at least one having a boiling point lower than Metal alkoxide at 200°C.

(14) The method according to (13) above, wherein the metal alkoxide includes a metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and mixtures thereof.

(15) The method according to (13) above, wherein the titanium dioxide precursor material is selected from titanium alkoxides, titanium tetrachloride, and mixtures thereof.

(16) A method of forming a photoactive coating, comprising the steps of: depositing a precursor composition on at least a part of the surface of a substrate, the precursor composition comprising: a titanium dioxide precursor material; and at least one material selected from the group consisting of: Other precursor materials of metals such as boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and mixtures thereof; and adding sufficient other precursor materials to the composition so that the selected metal and titanium are in the light applied The molar ratio in the active coating is 0.001-0.05.

(17) The method according to (16) above, wherein the titanium dioxide precursor material is selected from titanium tetrachloride, titanium alkoxide, and mixtures thereof.

(18) The method according to (17) above, wherein the titanium dioxide precursor material is selected from titanium isopropoxide and titanium tetraethoxide.

(19) The method according to the above (16), wherein at least one other precursor material is selected from trialkyl borate, strontium alkoxide, lead alkyl, zirconium alkoxide, lanthanum alkoxide, strontium ethoxide, 2-ethylhexyl Strontium acid, strontium hexafluoroacetylacetonate, strontium isopropoxide, strontium methoxide, strontium tantalum ethoxide, strontium titanium isopropoxide, triethyl borate, tetra-n-butyl lead, 2-methyl-2-butanol Zirconium, lanthanum isopropoxide, and mixtures thereof.

(20) The method according to (16) above, wherein the titanium dioxide precursor material is titanium isopropoxide, and the other precursor materials are soluble in titanium isopropoxide.

(21) The method according to (16) above, wherein the boiling point of the other precursor material is lower than 200°C.

(22) The method according to (16) above, comprising: heating the titanium dioxide precursor material and the other precursor material to a temperature sufficient to evaporate the precursor material; and introducing the vaporized precursor composition into the carrier gas so that the vaporized precursor The ratio of the material to the carrier gas is 0.01% by volume to 0.06% by volume.

(23) The method according to (16) above includes depositing the photocatalytic coating by a process selected from the group consisting of chemical vapor deposition, magnetron sputtering vacuum deposition, and spray pyrolysis.

(24) The method according to (16) above, wherein the substrate is a float glass ribbon in a float chamber and the method includes depositing the precursor composition on the float glass ribbon in the float chamber by chemical vapor deposition.

(25) The method according to (16) above includes depositing sufficient precursor composition so that the photocatalytic coating has a thickness of 50 angstroms to 2000 angstroms.

(26) The method according to (16) above, including depositing an intermediate layer between the substrate and the photocatalytic coating.

(27) The method according to (26) above, wherein the intermediate layer is an anti-reflection layer.

(28) The method according to (27) above, wherein the anti-reflection layer contains at least one of aluminum oxide, tin oxide, indium oxide, silicon oxide, silicon oxycarbide, and silicon oxynitride.

(29) The method according to (26) above, wherein the intermediate layer is a sodium ion diffusion barrier layer.

(30) The method according to (29) above, wherein the barrier layer includes at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, aluminum oxide, fluorine-doped aluminum oxide, and aluminum nitride.

(31) A method for forming a photocatalytic coating, including the step of depositing a precursor composition on at least a part of the surface of a substrate, the precursor composition comprising titanium isopropoxide and at least one selected from triethyl borate Esters, strontium isopropoxide, tetra-n-butyl lead, zirconium 2-methyl-2-butoxide, and other organometallic precursor materials of lanthanum isopropoxide.

(32) The method according to (31) above, including adding enough other organometallic precursor materials to the composition so that the molar ratio of the metal of the organometallic precursor material to titanium in the applied photocatalytic coating is 0.001-0.05.

(33) A method for depositing a photocatalytic coating on a substrate, comprising the steps of: setting a chemical vapor deposition coating device above the float glass ribbon in the float chamber; and transferring the precursor composition from the coating device Directed on the belt, the precursor composition includes a titanium dioxide precursor material and at least one other precursor material having a metal selected from the group consisting of boron, strontium, lead, barium, calcium, hafnium, lanthanum, and mixtures thereof; and Sufficient other precursor materials are added to the composition so that the molar ratio of the selected metal to titanium in the applied photocatalytic coating is 0.001-0.05; and heating the substrate to a temperature sufficient to decompose the precursor materials to form the photocatalytic coating Floor.

(34) A method for increasing the photocatalytic activity of a titanium dioxide coating, including the step of adding at least one metal selected from the group consisting of boron, strontium, zirconium, lead, barium, calcium, hafnium, and lanthanum to the titanium dioxide coating, so that all The molar ratio of the selected metal to titanium in the photocatalytic coating is 0.001-0.05.

(35) A method for forming a photocatalytic coating, comprising the steps of depositing a precursor composition on at least a part of the substrate, the precursor composition comprising titanium tetrachloride, an organic oxygen source, and a boron-containing precursorBody material. Body material.

(36) The method according to (35) above, wherein the organic oxygen source is an alkyl ester having a C2-C10 alkyl group.

(37) The method according to (35) above, wherein the precursor material contains triethyl borate.

(38) The method according to (35) above, including directly depositing the photocatalytic coating on the surface of the substrate.

(39) The method according to (35) above, including depositing an intermediate coating between the surface of the substrate and the photocatalytic coating.

(40) The method according to (39) above, wherein the intermediate coating layer contains at least one of tin oxide, aluminum oxide, and zirconia.

(41) An article, comprising, a substrate having at least one surface; and a photocatalytic coating deposited on at least a portion of the surface of the substrate, wherein the photocatalytic coating contains titanium dioxide and at least one containing at least one Other materials from metals such as boron, strontium, zirconium, lead, barium, calcium, hafnium, and lanthanum, and the amount of the other materials present in the coating is such that the selected metal and titanium are in the photocatalytic coating The molar ratio is 0.001-0.05.

(42) The article according to (41) above, wherein the substrate is selected from glass, plastic, and ceramic.

(43) The product according to (41) above, wherein the product is monolithic.

(44) The product according to (41) above, wherein the product is laminated.

(45) The product according to (41) above, wherein the product is at least one lattice of a heat-insulating glass unit and the base material is a heat-insulating glass unit.

(46) The article according to (41) above, wherein the substrate is selected from annealed glass, tempered glass, and heat-reinforced glass.

(47) The product according to (41) above, wherein the product is an architectural transparent body.

(48) The article according to (41) above, wherein the photocatalytic coating is deposited directly on the surface of the substrate.

(49) The article according to (41) above, wherein the photocatalytic coating contains at least part of titanium dioxide in the anatase phase.

(50) The article according to (41) above, wherein the photocatalytic coating contains at least part of titanium dioxide in a rutile phase.

(51) The article according to (41) above, wherein the photocatalytic coating is deposited by a process selected from the group consisting of chemical vapor deposition, magnetron sputtering vacuum deposition, and spray pyrolysis.

(52) The article according to (41) above, wherein the substrate includes at least one surface having tin diffused therein.

(53) The article according to (41) above, wherein the photocatalytic coating has a thickness of 50 angstroms to 2000 angstroms.

(54) The article according to (41) above, wherein the substrate is a float glass ribbon and the process is selected from chemical vapor deposition and spray pyrolysis.

(55) The article according to (41) above, comprising at least one intermediate layer between the surface of the substrate and the photocatalytic coating.

(56) The article according to (55) above, wherein the intermediate layer is an anti-reflection layer.

(57) The article according to (55) above, wherein the intermediate layer is a sodium ion diffusion barrier layer.

(58) The article according to (56) above, wherein the anti-reflection layer contains at least one of aluminum oxide, tin oxide, indium oxide, silicon oxide, silicon oxycarbide, and silicon oxynitride.

(59) The article according to (57) above, wherein the barrier layer contains tin oxide, silicon oxide, titanium oxide, zirconium oxide, fluorine-doped tin oxide, aluminum oxide, magnesium oxide, zinc oxide, cobalt oxide, chromium oxide, oxide Iron, and at least one of its mixtures.

Description of the drawings Figure 1 is a cross-sectional view (not to scale) of a part of the substrate on which the photoactive coating of the present invention is deposited;

Figure 2 is a side view (not to scale) of a coating process for applying the photoactive metal oxide coating of the present invention to a glass ribbon in a molten metal bath used in a float glass process; and Figure 3 is an introduction Side view (not to scale) of the insulating glass unit featuring the present invention.

Description of the invention The spatial or directional terms used herein, such as "inner", "outer", "above", "below", "top", "bottom", and similar terms refer to the present invention as shown in the drawings. However, it can be understood that the present invention can present various alternative orientations, and therefore, these terms should not be considered as limiting. In addition, all numbers representing dimensions, physical properties, process parameters, component amounts, reaction conditions, etc. used in the specification and claims should be understood as being modified by the term "about" in all cases. Therefore, unless stated to the contrary, the numerical values given in the following description and claims are approximate values that can be varied according to the required performance to be obtained by the present invention. At least, and not intended to limit the application of the principle of equivalence to the scope of the claims, each value should be interpreted at least according to the recorded significant figures and through the application of ordinary rounding techniques. In addition, all ranges disclosed herein should be understood to include any and all sub-ranges contained therein. For example, the range "1-10" should be considered to include any and all sub-ranges between (and inclusive) a minimum value of 1 and a maximum value of 10; that is, starting with a minimum value of 1 or more and ending at 10. All subranges ending or lower, for example, 5.5-10. In addition, the term "deposited on" or "provided on" as used herein means to be deposited or provided on a surface but not necessarily in contact with it. For example, the coating "deposited on the substrate" does not exclude the presence of one or more other coating films with the same or different composition between the deposited coating and the substrate. In addition, all percentages disclosed herein are "weight" unless expressed to the contrary. All photocatalytic activity values discussed herein are those determined by the conventional stearic acid test described in U.S. Patent No. 6,027,766, which is incorporated herein by reference. All root mean square roughness values are those that can be determined by atomic force microscopy by measuring root mean square (RMS) roughness on a surface area of 1 square micrometer. In addition, all mentions of "incorporating the present invention as a reference" are hereby understood as being fully incorporated into the present invention.

Referring now to Figure 1, an article 20 having the features of the present invention is shown. The article 20 includes a substrate 22 having a first surface 21 and a second surface 60. The substrate 22 does not limit the present invention and may be any material having any desired characteristics, such as an opaque or transparent substrate. "Transparent" means that the visible light transmittance is greater than 0% to 100%. "Opaque" means having a visible light transmittance of 0%. "Visible light" refers to electromagnetic energy having a wavelength of 400 nanometers (nm) to 800 nm. Examples of suitable substrates include, but are not limited to, plastic substrates (such as polyacrylate, polycarbonate, and polyethylene terephthalate (PET)); metal substrates; glazed or ceramic substrates Material; glass substrate; or a mixture or combination thereof. For example, the substrate 22 may be conventional uncolored soda lime glass, that is, "transparent glass", or may be colored or otherwise colored glass, borosilicate glass, leaded glass (leaded glass). glass), tempered, untempered, annealed, or heat strengthened glass. The glass can be of any kind, such as conventional float glass, flat glass, or float glass ribbon, and can have any optical properties, such as any value of visible transmission, ultraviolet transmission, infrared transmission, and/or total solar energy transmission Any composition. The types of glass suitable for the present invention are described in, for example, U.S. Patent Nos. 4,746,347; 4,792,536; 5,240,886; 5,385,872; and 5,393,593, but this is not considered to be limiting. For example, the substrate 22 may be a float glass tape, a glass lattice of a building window, a skylight, a window pane of a heat-insulating glass unit, a mirror, a shower door, a glass appliance (such as a glass table top or a glass cabinet), or used for conventional Car windshield ply, side or rear window, car roof, or aircraft glass window, to name a few.

The photoactivity-enhancing (hereinafter "PE") coating 24 of the present invention can be deposited on at least a portion of the substrate 22, for example, on all or a portion of the main surface of the substrate 22, such as on all or a portion of the surface 21 or the surface 60. In the embodiment given, the PE coating 24 is deposited on the surface 21 as shown. The term "increased photoactivity" as used herein refers to a photoactive material or coating, including at least one cocatalyst or dopant that is relatively free of cocatalyst for increasing the photoactivity of the coating. The PE coating 24 can be photocatalytic, photoactive hydrophilic, or both. "Photoactive hydrophilic" refers to a coating in which the contact angle of water droplets on the coating decreases over time as the coating is exposed to electromagnetic radiation. For example, after 60 minutes of exposure to UVA 340 from Q-Panal Company (Cleverand, Ohio) with an intensity of 24W/m2, the contact angle on the surface of the PE coating can be reduced to less than 15 Degrees, such as values below 10 degrees, and can become superhydrophilic, e.g., drop below 5 degrees. Although photoactive, the coating 24 need not be photocatalytic to the extent that it is self-cleaning, that is, it may not be photocatalytic enough to decompose the organic materials on the coating surface within a reasonable or economically useful time. Grime.

As described above, the PE coating 24 includes (1) a photoactive coating material and (2) a photoactivity enhancing cocatalyst or dopant. The photoactive coating material (1) may include at least one metal oxide, such as, but not limited to, one or more metal oxides or semiconducting metal oxides, such as various titanium oxides, silicon oxides, aluminum oxides, and iron oxides. , Silver oxide, cobalt oxide, chromium oxide, copper oxide, tungsten oxide, zinc oxide, zinc oxide/tin oxide, strontium titanate, and mixtures thereof. The metal oxide may include the oxide, super-oxide or suboxide of the metal. In one embodiment, the metal oxide is crystalline or at least partially crystalline. In an exemplary coating of the present invention, the photoactive coating material is titanium dioxide. Titanium dioxide exists in an amorphous form and three crystalline forms, namely, anatase, rutile and brookite crystalline forms. Anatase titanium dioxide is particularly useful because of its strong light activity, while also having excellent chemical resistance and excellent physical durability. However, the rutile phase, or the combination of anatase and/or rutile phase and brookite and/or amorphous phase are also acceptable for the present invention.

The photoactivity-enhancing cocatalyst (2) can be a coating that has relatively no cocatalyst to increase the photoactivity of the resulting coating, for example, any material that has photocatalytic activity and/or photoactive hydrophilicity. In an exemplary embodiment, the promoter includes at least one material having at least one component selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and/or a mixture or combination thereof. The presence of the promoter in the PE coating 24 is sufficient to increase the photoactivity of the coating, such as photocatalytic activity and/or photoactive hydrophilicity, without adversely affecting the required coating properties, such as reflectance, light transmission Degree, color, etc. For example, in the PE coating 24 mainly containing anatase titanium dioxide, the co-catalyst can be present in such an amount that the molar ratio of the selected co-catalyst (eg, the metal of the co-catalyst) to titanium in the PE coating 24 is 0.001-0.05 , Such as 0.005-0.03, such as 0.01±0.005. In addition, in the present invention, the promoter is not necessarily concentrated on or near the coating surface 21, but can be deposited such that it is dispersed or introduced into the bulk of the coating 24.

The PE coating 24 should be thick enough to provide an acceptable degree of photoactivity for the desired purpose, such as photocatalytic activity and/or photoactive hydrophilicity. There is no absolute value that makes the PE coating 24 "acceptable" or "unacceptable", because whether the PE coating 24 has an acceptable degree of photoactivity greatly depends on the purpose and conditions when the PE coated article is being used. And the selection of performance standards that match the purpose varies. However, the thickness required to achieve the photoactive hydrophilic PE coating 24 may be significantly lower than the thickness required to achieve a commercially acceptable level of photocatalytic self-cleaning activity. For example, in one embodiment, the PE coating 24 may have a thickness of 10 angstroms to 5000 angstroms, where a thicker coating in this range may have photocatalytic self-cleaning activity and hydrophilicity for at least a certain period of time. As the coating becomes thinner within this range, the photocatalytic self-cleaning activity generally decreases in terms of performance and/or duration. As the coating thickness decreases in the range such as 50 angstroms-3000 angstroms, such as 100 angstroms-1000 angstroms, such as 200 angstroms-600 angstroms, such as 200 angstroms-300 angstroms, the photocatalytic self-cleaning activity may not be measurable but the photoactivity Hydrophilicity can still exist in the presence of selected electromagnetic radiation.

In another aspect of the present invention, the outer surface 25 (ie, the surface facing away from the substrate) of the PE coating 24 can be smoother than previously known self-cleaning coatings, while maintaining photoactive hydrophilicity and/or photocatalytic activity. For example, the PE coating 24, especially the top or outer surface 25 of the coating, may have a diameter of less than 5 nm, such as less than 4.9 nm, such as less than 4 nm, such as less than 3 nm, such as less than 2 nm, such as Below 1nm, such as 0.3nm-0.7nm RMS surface roughness (even for the above range, such as thin coatings within 200 angstroms to 300 angstroms).

In another aspect of the present invention, the PE coating 24 can be made more dense than previously known hydrophilic, self-cleaning coatings. For example, the PE coating 24 may be substantially non-porous. "Substantially non-porous" means that the coating is dense enough so that the coating can withstand the conventional hydrofluoric acid test, in which a drop of 0.5% by weight (wt.%) hydrofluoric acid (HF) aqueous solution is placed on the coating at room temperature Top and cover with watch glass for 8 minutes (mins). The HF was then rinsed off and the coating was visually inspected for damage. An alternative HF dip test is described in Industrial Engineering Chemistry and Research, Vol. 40, No. 1, page 26, 2001 (Charles Greenberg), which is incorporated herein by reference. The denser PE coating 24 of the present invention provides more protection against chemical attack to the underlying substrate than the previous self-cleaning coating with more pores, and is harder than the previous self-cleaning coating using sol-gel And more scratch resistant.

The PE coating 24 can be directly deposited on the surface 21 of the substrate 22 shown in FIG. 1, that is, on the surface in contact therewith. Even for substrates containing sodium, such as soda lime glass, if the coating is applied by the following in-bath method, for example, the thin PE coating 24 of the present invention below 1000 angstroms should not be due to the sodium in the substrate. And become non-photoactive. Therefore, without using the sodium barrier layer between the glass and the PE coating 24 of the present invention, soda lime glass can be made to be more easily cleaned. If necessary, such a conventional sodium barrier layer can be used.

Alternatively, one or more other layers or coatings may be inserted between the PE coating 24 and the substrate 22. For example, the PE coating 24 may be the outer or outermost layer of the multilayer coating layer present on the substrate 22 or the PE coating 24 may be embedded in this multilayer layer as one of the layers other than the outermost layer. Inside. "Outer layer" refers to a layer that receives sufficient excitation electromagnetic radiation, such as ultraviolet radiation, so as to provide a coating that has sufficient photoactivity to be at least photoactive and hydrophilic if not necessarily photocatalytic. In one embodiment, the PE coating 24 is the outermost coating on the substrate 22.

The PE coating 24 of the present invention can be applied to the substrate 22 by any conventional method, such as spray pyrolysis, chemical vapor deposition (CVD), or magnetron sputtering vacuum deposition (MSVD) by one or more methods. form. In the spray pyrolysis method, there are (1) a metal oxide precursor material, such as a titanium dioxide precursor material, and (2) at least one photoactivity-enhancing precursor material, that is, a co-catalyst material, such as an organometallic precursor. The organic or metal-containing precursor composition of the bulk material is carried in an aqueous suspension, such as an aqueous solution, and directed to the surface of the substrate 22, while the substrate 22 is at a high enough temperature so that the precursor composition decomposes and A PE coating 24 is formed on the substrate 22. In the CVD method, the precursor composition is carried in a carrier gas, such as nitrogen, and directed to the substrate 22. In the MSVD method, one or more metal-containing cathode targets are sputtered in an inert or oxygen-containing atmosphere under reduced pressure to deposit a sputter coating on the substrate 22. The substrate 22 may be heated during or after the coating process to crystallize the sputtered coating to form the PE coating 24. For example, one cathode can be sputtered to provide the metal oxide precursor material (1) and the other cathode can be sputtered to provide the promoter material (2). Alternatively, a single cathode that has been doped with the desired promoter may be sputtered to form the PE coating 24.

Each method has advantages and limitations, depending on the required characteristics of the PE coating 24 and the type of glass manufacturing process. For example, in a conventional float glass process, molten glass is poured into a pool of molten metal (such as tin) in a bath of molten metal (such as tin) to form a continuous float glass ribbon. The temperature of the float glass ribbon in the tin bath is generally 1203°C (2200°F) (at the supply end of the bath) to 592°C (1100°F) (at the exit end of the bath). The float glass ribbon is taken out of the tin bath and annealed in an annealing furnace, that is, controlled cooling, and then cut into glass sheets having the desired length and width. The temperature of the float glass ribbon between the tin bath and the annealing furnace is generally 480°C (896°F) -580°C (1076°F) and the temperature of the float glass ribbon in the annealing furnace is generally 204°C (400°F) ) -557°C (1035°F) (peak). U.S. Patent Nos. 4,466,562 and 4,671,155 (herein incorporated by reference herein) provide a discussion of the float glass process.

CVD and spray pyrolysis methods are preferred in float glass processes over MSVD methods because they are more compatible with coating continuous substrates, such as float glass ribbons, at elevated temperatures. Exemplary CVD and spray pyrolysis coating methods are described in US Patent Nos. 4,344,986; 4,393,095; 4,400,412; 4,719,126; 4,853,257; and 4,971,843, which are incorporated herein by reference.

In the present invention, one or more CVD coating devices can be used at several points in the float glass ribbon manufacturing process. For example, the CVD coating device can be used when the float glass ribbon passes through the tin bath, after it leaves the tin bath, before it enters the annealing furnace, when it passes through the annealing furnace, or after it leaves the annealing furnace. Because the CVD method can coat float glass ribbons that are still subject to movement in the harsh environment associated with the manufacture of float glass ribbons, the CVD method is particularly suitable for providing PE coating 24 on float glass ribbons in a molten tin bath. U.S. Patent Nos. 4,853,257; 4,971,843; 5,536,718; 5,464,657; 5,714,199; and 5,599,387 (herein incorporated by reference) describe CVD coatings that can be used in the present invention to coat float glass ribbons in molten tin baths Device and method.

For example, as shown in FIG. 2, one or more CVD coaters 50 may be located in the tin bath 52 above the molten tin pool 54. As the float glass ribbon 56 moves through the tin bath 52, the evaporated precursor composition (ie, the photoactive coating precursor material (1), such as the metal oxide precursor material, and the photoactivity-enhancing co-catalyst material ( 2) For example, organometallic precursor materials) can be added to the carrier gas and on the top surface 21 of the guide belt 56. The precursor composition decomposes to form the PE coating 24 of the present invention. The promoter material (2) can be at least partially soluble in the coating precursor material (1) under the required deposition conditions, such as completely soluble in the coating precursor material (1). Any amount of the promoter material (2) required to achieve the required amount of photoactivity, such as photoactive hydrophilicity and/or photocatalytic activity, can be added, mixed, or dissolved in the coating precursor material (1) in. For example, the co-catalyst material may be an organometallic material with a boiling point lower than 200°C, such as an alkoxide material (e.g., a transition metal alkoxide). Alternatively, two separate precursors can be evaporated separately and combined.

Exemplary coating precursor materials (1) (eg, titanium dioxide precursor materials) that can be used in the present invention to form the titanium dioxide PE coating 24 by the CVD method include, but are not limited to, titanium oxides, suboxides, or Super-oxide. In one embodiment, the precursor material (1) may be one or more titanium alkoxides, such as but not limited to titanium methoxide, titanium ethoxide, titanium propoxide, titanium butoxide, and the like or isomers thereof. Exemplary precursor materials suitable for the present invention include, but are not limited to, titanium tetraisopropoxide (Ti(OC3H7)4) (hereinafter "TTIP") and titanium tetraethoxide (Ti(OC2H5)4) (hereinafter "TTEt "). Alternatively, the titanium dioxide precursor material (1) may be titanium tetrachloride.

The co-catalyst (eg, dopant) material can be any material that increases or affects the photoactivity of the resulting coating in a desired manner, such as photocatalytic activity and/or photoactive hydrophilicity. The promoter material may include one or more of boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and/or any mixture or combination thereof. For example, the co-catalyst material may include one or more of trialkyl borate, strontium alkoxide, lead alkyl, zirconium alkoxide, lanthanum alkoxide, strontium ethoxide, strontium 2-ethylhexanoate, strontium hexafluoroacetylacetonate , Strontium isopropoxide, strontium methoxide, strontium tantalum ethoxide, strontium titanium isopropoxide, triethyl borate (also called triethoxyborane or triethyl borate), other borate esters such as tri-n borate -Butyl ester, triisopropyl borate, tetra-n-butyl lead, zirconium 2-methyl-2-butoxide, lanthanum isopropoxide, and/or any mixture or combination thereof. Exemplary carrier gases that can be used in the CVD method of the present invention include but are not limited to air, nitrogen, oxygen, ammonia, and mixtures thereof. The concentration of the precursor composition in the carrier gas can vary with the specific precursor composition used. However, for a coating having a thickness of about 200 angstroms, it is expected that the concentration of the precursor composition in the carrier gas is usually 0.01% by volume to 0.1% by volume, for example, 0.01% by volume to 0.06% by volume, for example, 0.015% by volume to 0.06 % By volume; for example, 0.019% by volume -0.054% by volume.

For the CVD method (and the spray pyrolysis method discussed below), the temperature during the process of forming the PE coating 24 on the substrate 22 (such as float glass ribbon 56) should be such that the metal-containing precursor composition decomposes and A coating having a desired amount of photoactivity, such as photocatalytic activity, photoactive hydrophilicity, or both, is formed. The lower limit of this temperature range is greatly affected by the decomposition temperature of the selected precursor composition. For the titanium-containing precursor described above, the lower limit of the temperature of the substrate 22 that provides sufficient precursor composition to decompose is generally in the range of 400°C (752°F) to 500°C (932°F). The upper limit of this temperature range is affected by the method of coating the coated substrate. For example, if the substrate 22 is a float glass ribbon 56 and the PE coating 24 is applied to the float glass ribbon 56 in the molten tin bath 52 during the manufacture of the float glass ribbon 56, the float glass ribbon 56 can reach more than 1000°C (1832°F) temperature. The float glass ribbon 56 can be thinned or changed in size (such as stretched or compressed) when the temperature exceeds 800°C (1472°F). If the PE coating 24 is applied to the float glass ribbon 56 before or during thinning, the PE coating 24 may crack or shrink accordingly when the float glass ribbon 56 is stretched or compressed. Therefore, the PE coating 24 can be applied when the float glass ribbon 56 is dimensionally stable (except for thermal shrinkage during cooling), for example, below 800°C (1472°F) (for soda lime glass), and the float glass ribbon 56 is at a temperature that decomposes metal-containing precursors, for example, over 400°C (752°F).

For spray pyrolysis, US Patent Nos. 4,719,126; 4,719,127; 4,111,150; and 3,660,061 (herein incorporated by reference herein) describe spray pyrolysis devices and methods that can be used in conventional float glass ribbon manufacturing processes. Although the spray pyrolysis method is very suitable for coating moving float glass ribbons like the CVD method, spray pyrolysis has more complicated equipment than CVD equipment and is usually used between the outlet end of the tin bath and the inlet end of the annealing furnace.

Exemplary metal-containing precursor compositions that can be used in the present invention to form PE coatings by spray pyrolysis methods include relatively water-insoluble organometallic reactants, especially metal acetylacetonates, which are spray-milled or wet-milled to particles The size is below 10 microns and is suspended in an aqueous medium through the use of chemical wetting agents. A suitable metal acetylacetonate precursor material for forming a PE coating containing titanium dioxide is titanyl acetylacetonate (TiO(C5H7O2)2). For example, the photoactivity-enhancing cocatalyst as described above can be mixed with or dissolved in the acetylacetonate precursor material. In one embodiment, the relative concentration of the metal acetylacetonate and the cocatalyst precursor material in the aqueous suspension is 5-40% by weight of the aqueous suspension. The wetting agent can be any relatively low foaming surfactant, including anionic, nonionic or cationic compositions. In one embodiment, the surfactant is non-ionic. The amount of wetting agent added is usually 0.24% by weight, but may be 0.01% to 1% or more. The aqueous medium can be distilled water or deionized water. Aqueous suspensions for pyrolytic deposition of metal-containing films are described in U.S. Patent No. 4,719,127, especially column 2, line 16 to column 4, line 48, which is incorporated herein by reference.

Those skilled in the art can understand that the bottom surface 60 of the float glass ribbon placed directly on the molten tin (usually called the "tin side") has tin diffused in the surface, and the tin absorption pattern provided on the tin side is different. On the opposite surface 21 that is not in contact with the molten tin (usually referred to as the "air side"). The PE coating of the present invention can be formed on the air side of the float glass ribbon by the CVD method as described above while it is carried on the tin, and after it leaves the tin bath, it can be formed on the float glass by CVD or spray pyrolysis. The air side of the ribbon is formed, and/or is formed on the tin side of the float glass ribbon by a CVD method after it leaves the tin bath.

As an alternative to including oxygen in the atmosphere of the tin bath to form an oxide coating, the precursor composition may itself include one or more organic oxygen sources. The organic oxygen may be, for example, an ester or a carboxylic acid ester, such as an alkyl ester in which the alkyl group has β-hydrogen. Suitable esters may be alkyl esters with C2-C10 alkyl groups. Exemplary esters that can be used in the present invention are described in WO 00/75087, which is incorporated herein by reference.

For MSVD, U.S. Patent Nos. 4,379,040; 4,861,669; 4,900,633; 4,920,006; 4,938,857; 5,328,768; and 5,492,750 (herein incorporated by reference herein) describe the sputter coating of metal oxide films to substrates (including glass substrates) ) On the MSVD device and method. The MSVD process is generally not suitable for providing a PE coating on the float glass ribbon during the manufacturing process, because among other reasons, the MSVD process requires pressure reduction during the sputtering operation, which makes it difficult to form a reduction on the continuously moving float glass ribbon. Pressure. However, the MSVD method can be used to deposit the PE coating 24 onto a substrate 22, such as a glass sheet. The substrate 22 can be heated to a temperature of 400°C (752°F) to 500°C (932°F), so that the MSVD sputter coating on the substrate crystallizes during the deposition process, which eliminates subsequent heating operations. Heating the substrate during the sputtering process is generally not preferable because the additional heating operation during the sputtering process can reduce throughput. Alternatively, the sputtered coating can be crystallized directly in the MSVD coating device without post-heat treatment by using high-energy plasma, but again due to its tendency to reduce the throughput of the MSVD coater, this may not be preferable.

An exemplary method of using the MSVD method to provide a PE coating (especially a PE coating of 300 angstroms or less and having an RMS surface roughness of 2 nm or less) is to sputter the co-catalyst-containing coating onto the substrate, The coated substrate is removed from the MSVD coater, and the coated substrate is then heat treated to crystallize the sputtered coating. For example, but not limiting the present invention, in one embodiment, at least one photoactivity enhancing promoter selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and/or mixtures thereof is doped The target of titanium metal of the material can be sputtered in an argon/oxygen atmosphere with 5-50%, such as 20% oxygen, at a pressure of 5-10 mTorr, so that the substrate 22 is sputtered and deposited with a desired thickness. Doped with titanium dioxide coating. The deposited coating did not crystallize. The coated substrate is removed from the coater and heated to a temperature of 400°C (752°F)-600°C (1112°F) for a sufficient time to promote the formation of a crystalline form of titanium dioxide to generate photoactivity. Generally, at least one hour at a temperature of 400°C (752°F)-600°C (1112°F) is sufficient. If the substrate 22 is a glass sheet cut from a float glass ribbon, the PE coating 24 may be sputter deposited on the air side and/or the tin side.

The substrate 22 with the PE coating 24 deposited by CVD, spray pyrolysis, or MSVD methods may subsequently be subjected to one or more post-coating annealing operations. It can be understood that the annealing time and temperature can be affected by several factors, including the composition of the substrate 22, the composition of the PE coating 24, the thickness of the PE coating 24, and whether the PE coating 24 is in direct contact with the substrate 22 or Whether it is one layer of the multilayer laminate on the substrate 22.

Regardless of whether the PE coating 24 is provided by a CVD process, a spray pyrolysis process, or an MSVD process, where the substrate 22 includes sodium ions that can migrate from the substrate 22 to the PE coating 24 deposited on the substrate 22, the sodium ions can pass Form inert compounds while consuming titanium, for example, by forming sodium titanate or by causing photo-excited charge recombination to inhibit or destroy the photoactivity of the PE coating 24, for example, photocatalytic activity and/or photoactive hydrophilicity . Therefore, a conventional sodium ion diffusion barrier (SIDB) layer can be deposited on the substrate before the PE coating 24 is deposited. Suitable SIDB layers are discussed in detail in U.S. Patent No. 6,027,766, which is incorporated herein by reference and therefore will not be discussed in detail herein. By post-coating heating, a sodium barrier layer can be used for sodium-containing substrates, such as soda lime glass. For the application of the PE coating 24 of the present invention in a molten metal bath, the sodium barrier layer is optional.

The PE coating 24 of the present invention can become photoactive when exposed to electromagnetic radiation in the light absorption band of the coating, for example, photocatalytic and/or photoactive hydrophilic. The "light absorption band" refers to the range of electromagnetic radiation that is absorbed by a material to make the material photoactive. In one embodiment, the coating 24 becomes photoactive when exposed to electromagnetic radiation in the ultraviolet range of the electromagnetic spectrum, for example, from 300 nm to 400 nm. Ultraviolet radiation sources include natural sources, such as solar radiation, and man-made sources such as black light or ultraviolet light sources such as UVA-340 light sources.

As shown in FIG. 1, in addition to the PE coating 24 of the present invention, one or more functional coatings 46 may be deposited on the substrate 22. For example, the functional coating 46 may be deposited on the major surface 60 of the substrate 22 opposite to the surface 21. The term "functional coating" as used herein refers to a coating that changes one or more of the physical properties of the substrate on which it is deposited, such as optical, thermal, chemical or mechanical properties, and is not intended to be used during subsequent processing. Remove from the substrate. The functional coating 46 may have one or more functional coating films with the same or different compositions or functions. The term "layer" or "film" as used herein refers to a coating area having a desired or selected coating composition. The film can be uniform, non-uniform, or have a graded composition change. If the outer surface or part (that is, the surface or part furthest from the substrate), the inner surface or part (that is, the surface or part closest to the substrate), and the part between the outer and inner surfaces have substantially the same composition, The film is "uniform". When moving from the inner surface to the outer surface, if the film has one or more components in substantially increasing fractions and one or more other components in substantially decreasing fractions (and vice versa), the film is "graded of". If the film is not uniform or graded, then the film is "non-uniform." The "coating" is composed of one or more "films".

The functional coating 46 may be a conductive coating, such as, for example, the conductive heating window coating disclosed in U.S. Patent Nos. 5,653,903 and 5,028,759, or a single-film or multi-film coating that can be used as an antenna. Likewise, the functional coating 46 may be a solar control coating, for example, a visible, infrared or ultraviolet energy reflecting or absorbing coating. Examples of suitable solar control coatings are, for example, in U.S. Patent Nos. 4,898,789; 5,821,001; 4,716,086; 4,610,771; 4,902,580; 4,716,086; 4,806,220; 4,898,790; 4,834,857; 4,948,677; 5,059,295; Found in. Similarly, the functional coating 46 may be a low emissivity coating. "Low-emissivity coating" refers to visible wavelength energy, for example, 400nm-780nm can transmit through the coating but reflect longer wavelength solar infrared energy and/or thermal infrared energy and is generally used to improve the thermal insulation performance of architectural glass windows. "Low emissivity" refers to an emissivity lower than 0.4, such as lower than 0.3, for example, lower than 0.2. Examples of low emissivity coatings are, for example, in U.S. Patent Nos. 4,952,423 and 4,504,109 and British reference document GB Found in 2,302,102. The functional coating 46 may be a single-layer or multi-layer coating and may contain one or more metals, non-metals, semi-metals, semiconductors, and/or alloys, compounds, composites, combinations, or blends thereof. For example, the functional coating 46 may be a single-layer metal oxide coating, a multi-layer metal oxide coating, a non-metal oxide coating, or a multi-layer coating.

Examples of functional coatings suitable for use in the present invention may be SUNGATE(R) and SOLARBAN(R) series coatings (available from PPG Industries, Inc. (Pittsburgh, Pennsylvania)). These functional coatings usually include one or more anti-reflective coating films containing dielectric or anti-reflective materials, such as metal oxides or metal alloy oxides, which are usually transparent to visible light. The functional coating 46 may also include an infrared reflective film containing a reflective metal, such as a precious metal such as gold, copper or silver, or a combination or alloy thereof, and may further include a base film or a base film on and/or under the metal reflective layer. Barrier films, such as titanium, are known in the art.

The functional coating 46 can be deposited in any conventional manner, such as but not limited to magnetron sputter vapor deposition (MSVD), chemical vapor deposition (CVD), spray pyrolysis (ie, pyrolytic deposition), atmospheric pressure CVD (APCVD) ), low pressure CVD (LPCVD), plasma enhanced CVD (PEVCD), plasma assisted CVD (PACVD), thermal or electron beam evaporation, cathodic arc deposition, plasma spray deposition, and wet chemical deposition (eg, sol-condensation Glue, silver mirror method, etc.). For example, U.S. Patent Nos. 4,584,206, 4,900,110, and 5,714,199 (herein incorporated by reference herein) disclose methods and apparatuses for depositing metal-containing films on the bottom surface of a glass ribbon by chemical vapor deposition. This known device can be located downstream of the molten tin bath in the float glass process, so that a functional coating is provided under the glass ribbon, that is, on the side opposite to the PE coating of the present invention. Alternatively, one or more other CVD coaters may be located in the tin bath to deposit the functional coating on or under the PE coating 24 on the float glass ribbon. In one embodiment, if the functional coating is applied to the PE coating side of the substrate, the functional coating is applied in a tin bath before the PE coating. If the functional coating is on the side 60 opposite to the PE coating, the functional coating can be applied to the tin side of the substrate 22 after the tin bath in the float process as described above, for example, by CVD or MSVD. In another embodiment, the PE coating 24 can be deposited on all or a portion of the surface 60 and the functional coating 46 can be deposited on all or a portion of the surface 21.

An exemplary article of the present invention is given in the form of an insulating glass (IG) unit 30 in FIG. 3. The insulating glass unit has a first pane 32 isolated from the second pane 34 by an isolation component (not shown) and fixed in place by a sealant system, forming a cavity between the two panes 32, 34. The first pane 32 has a first surface 36 (No. 1 surface) and a second surface 38 (No. 2 surface). The second pane 34 has a first surface 40 (No. 3 surface) and a second surface 42 (No. 4 surface). The first surface 36 may be the outer surface of the IG unit, that is, the surface exposed to the environment, and the second surface 42 may be the inner surface, that is, the surface that forms the interior of the structure. Examples of IG units are disclosed in U.S. Patent Nos. 4,193,236; 4,464,874; 5,088,258; and 5,106,663, which are incorporated herein by reference. In one embodiment shown in Figure 3, the PE coating 24 may be located on the No. 1 or No. 4 surface, such as the No. 1 surface. The PE coating 24 reduces fogging and makes the IG unit 30 easier to clean and maintain. In this embodiment, one or more optional functional coatings 46 as described above can be deposited on at least a portion of the No. 2, No. 3, or No. 4 surface.

The advantages of the present invention over the sol-gel method of forming a self-cleaning coating include the method of forming a thin, dense, PE film on the substrate, which is different from the generally thicker, porous, self-cleaning method obtained by the sol-gel coating method. Clean the coating. Because the PE coatings of the present invention can be thin, for example, less than 1000 angstroms, such as less than 600 angstroms, they are aesthetically acceptable as transparent coatings on glass substrates. Another advantage is that the method of providing a PE coating according to the present invention avoids the need to reheat the substrate after applying the coating or coating precursor, which is required by currently available sol-gel methods. This not only makes the method less expensive and more effective, such as lower equipment cost, lower energy cost, and lower production time, but also significantly reduces the possibility of sodium ion migration and therefore the PE coating of the present invention The sodium ion of 24 is poisoned. Further, the method of the present invention is easy to be used to form a PE coating on a continuously moving substrate, such as a glass float belt, while the currently available sol-gel method is not easy to adapt.

The following embodiments of the present invention are given for illustration, and therefore the present invention is not limited thereto.

Example A PE coating of titanium dioxide and selected dopants was made by CVD as described below to evaluate the effect of dopants on the photoactivity of the PE coating.

A PE coating with a thickness of about 600 angstroms was deposited on a 3.3 mm thick transparent float glass specimen at a temperature of 1250°F (676°C) under normal pressure through a CVD coater with a commercially available Sierratherm CVD furnace. In one set of experiments (Experiment A), the PE coating was deposited directly on the glass specimen. In another set of experiments (Experiment B), the PE coating was deposited on a 700 angstrom thick tin oxide layer previously deposited on the test piece.

In each experiment, the titanium dioxide precursor material was titanium isopropoxide and the carrier gas was nitrogen. Exemplary dopant precursor materials are as follows:

A dopant precursor material is added to form the resulting PE coating, wherein the molar ratio of the dopant metal to titanium is 0.001, 0.01, and 0.05. For each test, the concentration of the precursor composition (eg, titanium isopropoxide and dopant precursor material) in the carrier gas was maintained at 0.17% by volume.

As a reference point, an undoped titanium dioxide coating (600 angstroms thick) was deposited directly on the float glass test piece (reference 1) and the test piece with a 700 angstrom tin oxide layer (reference 2). These undoped coatings were tested for photocatalytic activity according to the conventional stearic acid test described in US Patent No. 6,027,766. Determine the following photocatalytic activity level (the unit of "activity" level is 10-3 cm-1/min (cm-1/min)):

Table I below shows the activity of the PE coating deposited directly on the glass specimen and deposited on the tin oxide layer. The unit of all values is 10-3 cm-1/min. The crystal structure of the titanium dioxide coating deposited directly on the glass was found to be anatase by x-ray diffraction. The crystal structure of the coating deposited on the tin oxide layer was found to contain both anatase and rutile titanium dioxide.

It can be seen from Table I that, relative to Reference 1, at dopant/Ti molar ratios of 0.001 and 0.01, B, Zr, Pb, and Sr dopants all increase the photocatalytic activity of the coating directly deposited on the glass. The photocatalytic activity level decreases from 0.01 to 0.05 dopant/Ti molar ratio.

On the other hand, W and Ta show lower activity levels relative to reference 1 at each dopant/Ti molar ratio tested.

In addition, as shown in Table I, except for Pb, all samples showed lower activity levels when deposited on the tin oxide layer. The ability of Pb to enhance photocatalytic activity in the presence of rutile titanium dioxide seems to indicate a different enhancement mechanism than other dopants.

According to the disclosed tendency, it can be inferred that hole-doping titanium dioxide can increase the photocatalytic activity. This can be seen from the fact that Sr, Zr, and B all have a positive effect (increase the photocatalytic activity), while Ta and W have a side effect (decrease the photocatalytic activity). There are fewer valence electrons than Ti, and the metal present on the Ti site in the crystal lattice can be hole-doped with titanium dioxide. Boron can exist on the oxygen site, and it can act as a positive hole and also have the effect of doping these sites. For dopants with more valence electrons, the situation seems to be the opposite. Zirconium, which has the same number of valence electrons as Ti, is less electronegative than Ti, and therefore should have a positive effect due to the electron-withdrawing ability of oxygen. The hole doping of the crystal lattice makes it easier for holes or electrons generated when absorbing electromagnetic radiation to move to the surface of the coating and react with contaminants. Under this hypothesis, other dopants that should increase the photocatalytic activity should be La, Ba, Ca, and Hf (Hf has the same number of valence electrons as Zr but has even lower electronegativity).

Those skilled in the art can understand that the present invention can be improved without departing from the basic principles disclosed in the above description. Therefore, the specific embodiments described in detail herein are only illustrative and do not limit the scope of the present invention, while the latter is entirely given by the appended claims and any and all equivalents thereof.