Photoactive coating, coated article, and method of making same

[Technical field]

【0001】

(Cross-reference to related applications) This application is filed on July 23, 1997, claiming the benefit of US Provisional Application No. 60 / 040,566 filed on March 14, 1997, US Application No. 08 / 899,257. A division of U.S. Pat. No. 6,027,766 (now U.S. Pat. No. 6,027,766) filed on April 1, 1999, a division of U.S. Application No. 09 / 282,943 (now U.S. Pat. No. 6,413,581), filed on February 14, 2002. A continuation of Greenberg et al.'S US Patent No. 10 / 075,316 entitled "Photocatalytically-Activated Self-Cleaning Appliances". All of these applications and patents are incorporated herein by reference. The present application also claims the benefit of US Provisional Application No. 60 / 305,191 filed on 13 July 2001, which is also incorporated herein.

【0002】

(1. Field of Invention) The present invention relates to a method for adhering a protective coating on a substrate (for example, a glass sheet or a continuous float glass ribbon), a method for increasing the photoactivity of the coating, and further, these methods. Regarding articles manufactured by.

[Background technology]

【0003】

(2. Technical considerations) For many substrates, such as glass substrates, such as architectural windows, automotive transparency, and aircraft windows, in order to obtain good visibility, on the surface of the substrate. It is desirable that the surface contaminants, such as ordinary organic and inorganic surface contaminants, are virtually free for as long as possible. By convention, this means that these surfaces are cleaned frequently. This cleaning operation is typically performed by manually wiping the surface with or without the help of a chemical cleaning solution. This approach is effort, time and cost intensive. Therefore, there is a need for a substrate, particularly a glass substrate, that is easier to clean than existing glass substrates and has a surface that reduces the need or frequency of such cleaning.

【0004】

It is known that some semiconductor metal oxides can be incorporated into the coating to provide a photoactive (hereinafter "PA") coating. The term "photoactive" or "photoactively" is related to the photogeneration of hole-electron pairs when irradiated with radiation of a specific frequency, usually ultraviolet ("UV") light. doing. Above a certain minimum thickness, these PA coatings are typically photocatalytic (hereinafter "PC"). "Photocatalytic" is a self-cleaning property that interacts with organic pollutants on the surface of the film when exposed to constant electromagnetic radiation, such as UV. It refers to a coating that disintegrates or decomposes organic pollutants. In addition to their self-cleaning properties, these PC coatings are also typically hydrophilic, i.e., they are also water wet by having a contact angle with water generally less than 20 degrees. The hydrophilicity of the PC coating helps reduce fogging or water droplet accumulation on the coating, which can reduce visible light transmission and visibility through the coating substrate.

【0005】

In general, the thicker these PC coatings are, the better the photoactivity, i.e., the shorter the time required to at least destroy or decompose the organic pollutants on the coating. In order to increase the photocatalytic activity of the coating, co-catalysts that enhance the photocatalytic activity have been incorporated into the coating, as reported in US Pat. No. 6,603,363. Whether or not these known co-catalysts increase the photocatalytic activity of the coating is at least partly in the location of the co-catalyst in the coating structure, i.e. on the coating surface or in the coating body. It depends on whether it is in. The position of the co-catalyst in the coating depends on the method by which the coating is attached. For example, in US Pat. No. 6,603,363, the photocatalytic activity of a titanium dioxide coating is enhanced by covering the titanium dioxide coating with a thin metal layer of platinum, rhodium, silver, or palladium. US Pat. No. 5,854,169 discloses that the photocatalytic activity of a titanium dioxide coating is increased by the addition of a cocatalyst containing palladium, platinum, rhodium, ruthenium, tungsten, molybdenum, gold, silver, or copper. However, these co-catalysts are typically adhered near the surface of the coating and are not incorporated into the coating body, which makes the adhesion process more difficult and time consuming.

【0006】

In order to achieve the desired levels of film thickness, photocatalytic activity, surface roughness, and coating porosity described above, many PC coatings have been adhered by the sol-gel process. In a typical sol-gel process, the uncrystallized colloidal suspension (sol) is coated on the substrate at or near room temperature to form a gel, which is then heated to form a crystallized coating. Form. For example, US Pat. No. 6,013,372 is a hydrophilic, photocatalytic, self-cleaning coating formed by blending photocatalytic particles into a layer of metal oxide and applying the blend to a substrate by the sol-gel process. Is disclosed.

【0007】

However, conventional sol-gel coating methods are not economically or practically compatible with certain application conditions or substrates. For example, in the usual float glass method, the float glass ribbon in the molten metal bath may be too hot to accept the sol due to evaporation or chemical reaction of the solvent used in the sol. Conversely, when the sol is applied to a substrate below the singular temperature that forms the crystalline form of the catalyst, the sol-coated substrate must be reheated to a temperature sufficient to form a crystallized photocatalyst. It doesn't become. Such cooling and reheating operations can require significant investment equipment, energy, and handling costs, and can significantly reduce manufacturing efficiency. In addition, reheating the sodium-containing substrate, eg, soda lime silica glass, to a temperature sufficient to form a crystallized photocatalyst increases the chances of sodium ions in the substrate moving into the coating. This transition is the "sodium ion poisoning" of the adherent coating. What is commonly referred to as "poisoning)" may result. The presence of these sodium ions may reduce or destroy the photocatalytic activity of the PC coating. In addition, the sol-gel process typically produces thick coatings, eg, a few microns thick, which can adversely affect the optical and / or architectural properties of the coated article. Typically, as the thickness of the PC coating increases, the light transmittance and reflectance of the coating experience a minimum and maximum pair due to the optical interference effect. The reflected and transmitted colors of the coating also fluctuate due to these optical effects. Therefore, a film thickness sufficient to provide the desired self-cleaning may have undesired optical properties.

[Disclosure of Invention]

[Problems to be Solved by the Invention]

【0008】

Therefore, it would be beneficial to provide a method of adhering a PA coating with a photocatalytic co-catalyst that is compatible with the conventional float glass method and / or an article manufactured according to that method. , The method and / or the article reduces or eliminates at least some of the above drawbacks.

[Means for solving problems]

【0009】

(Overview of the Invention) In one aspect of the invention, at least the method of forming a PA coating comprises attaching the precursor composition onto at least a portion of the surface of the substrate. The precursor composition comprises a photoactive coating precursor material such as a metal oxide or a semiconductor metal oxide precursor material. In one aspect, the precursor material is a titania precursor material. The precursor composition further comprises at least one other precursor material having at least one photoactivity enhancing material. In one embodiment, the reinforcing material is at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, or a mixture or combination thereof, or one of the above metals. Any material containing one or more. To the composition, this other precursor material is added in sufficient amount so that the molar ratio of the selected metal to titanium in the applied photocatalytic coating is in the range of about 0.001 to about 0.05. ing. At least the PA coating produces at least hydrophilicity, eg, photoactive hydrophilicity, of the coating on the substrate, and may also produce sufficient photocatalytic activity to be a PC coating. A further method of forming a photoactive coating involves depositing the precursor composition onto at least a portion of a float glass ribbon in a molten metal bath by chemical vapor deposition. The precursor composition comprises a photoactive coating precursor material and at least one other precursor material containing a dopant that increases the photoactivity of the photoactive coating over the photoactivity of a dopant-free photoactive coating.

【0010】

Another method of forming a coating of at least PA comprises attaching the precursor composition onto at least a portion of the surface of the substrate. The precursor composition comprises at least one titania precursor material. In one aspect, the titania precursor material contains titanium and oxygen; for example, at least one titanium alkoxide, such as, but not limited to, titanium methoxydo, titanium ethoxydo, titanium propoxide, titanium. Buttoxides and the like, or isomers thereof, such as, but not limited to, titanium isopropoxide. In another embodiment, the titania precursor material comprises titanium tetrachloride. In one embodiment, the precursor composition further comprises at least one other metal having at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, or mixtures or combinations thereof. Contains organic metal precursor material. In one embodiment, the other precursor material can be an oxide, an alkoxide, or a mixture thereof. Exemplary organometallic precursor materials are, but are not limited to, trialkyl borate, strontium alkoxide, alkyl lead, zirconium alkyl alkoxide, lanthanum alkoxide, strontium ethoxydo, strontium-2-ethylhexanoate, strontium hexanoate. Fluoroacetylacetonate, strontium isopropoxide, strontium methoxyde, strontium tantalumoxide, strontium titanium isopropoxide, triethyl borate (also called triethoxybolan or triethyl borate ester), other borates, such as tri Includes -n-butylborate, triisopropylborate, tert-n-butyl lead, zirconium-2-methyl-2-butoxide, and lanthanumisopropoxide, and mixtures thereof.

【0011】

A further method of depositing a photoactive, eg, photocatalytic and / or photoactively hydrophilic, coating onto a substrate is to place a chemical vapor deposition coating device above the float glass ribbon in the float chamber. And it involves directing the precursor composition from the coating device onto the ribbon. The precursor composition comprises a titania precursor material and at least one other precursor material having at least one metal selected from boron, strontium, lead, barium, calcium, hafnium, lanthanum, or mixtures or combinations thereof. Includes. This other precursor material is added to the composition well so that the molar ratio of the selected metal to titanium in the applied photocatalytic coating is in the range of 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.

【0012】

A method for increasing the photocatalytic activity of a titania coating is provided. This method adds at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, and lanthanum to the titania coating, and the molar ratio of the selected metal to titanium in the photocatalytic coating. Includes addition so that it is in the range of about 0.001 to about 0.05.

【0013】

The method of forming a photocatalytic coating comprises attaching the precursor composition onto at least a portion of the substrate. The precursor composition comprises titanium tetrachloride, an organic oxygen source and a boron-containing precursor material.

【0014】

Articles of the invention include a substrate having at least one surface and a photocatalytic coating adhered on at least a portion of the surface of the substrate. The photocatalytic coating contains titania and at least one additive material containing at least one metal selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum, and mixtures or combinations thereof. Includes. The additive material is present in the coating in such an amount that the molar ratio of the selected metal to titanium in the photocatalytic coating is in the range of about 0.001 to about 0.05.

【0015】

(Explanation of Drawings) FIG. 1 is a cross-sectional view (not proportionally proportional) of a part of the substrate having the photoactive coating of the present invention adhered thereto; [0016].

FIG. 2 is a cross-sectional view (not proportional) of the coating process for applying the photoactive metal oxide coating of the present invention onto a glass ribbon in a molten metal bath for the float glass method; [0017]

FIG. 3 is a cross-sectional view (not proportionally proportional) of the heat insulating glass unit incorporating the features of the present invention.

【0018】

(Details of the Invention) When used herein, terms indicating space or orientation, such as "inside," "outside," "top," "bottom," "top," "bottom," are shown in the drawings. As you can see, it is related to the present invention. However, it should be understood that the present invention can envision various alternative indications and therefore such terms should not be construed in a limited way. Furthermore, all numbers used in the specification and claims to describe dimensions, physical features, process parameters, amounts of components, reaction conditions, etc. are all changed by the term "about". It should be understood that it is to be done. Thus, unless otherwise indicated, the numbers described in the following claims and claims are approximate numbers that can vary depending on the intended properties that may be obtained by the present invention. At least, and not as a constraint on the application of the doctrine of equivalents to the claims, each number should be interpreted at least in light of the number of significant figures reported and by the application of conventional rounding techniques. .. Moreover, all ranges disclosed herein should be understood to enclose any and all subranges contained herein. For example, the defined range of "1-10" should be construed to include any and all subranges between the minimum value of 1 and the maximum value of 10; that is, from a minimum value of 1 or greater. All subranges that start and end with a maximum value of 10 or less, for example 5. Includes 5-10. Furthermore, when used herein, the term "attached on" or "given on" is attached or applied on a surface but does not necessarily have to be in contact with the surface. Means. For example, a coating "adhered on" a substrate does not preclude the presence of one or more other coatings of the same or different composition located between the adherent coating and the substrate. In addition, all percentages disclosed herein are by "weight" unless otherwise indicated. All values of photocatalytic activity discussed herein have been measured by the conventional stearic acid test described in US Pat. No. 6,027,766 incorporated herein. All root mean square roughness values are measurable by measuring root mean square (RMS) roughness on a surface area of 1 square micrometer by atomic force microscopy. It should also be understood that all material "incorporated" herein is incorporated in its entirety.

【0019】

Although described with reference to FIG. 1, an article 20 having the characteristics of the present invention is shown therein. Article 20 includes a substrate 22 having a first surface 21 and a second surface 60. The substrate 22 is not limited to the present invention, but may be of any desired material having any desired properties such as an opaque or transparent substrate. "Transparent" means having a visible light transmittance greater than 0% to 100% visible light transmittance. "Opaque" means having a visible light transmittance of 0%. "Visible light" means electromagnetic energy having wavelengths in the range of 400 nanometers (nm) to 800 nm. Examples of suitable substrates include, but are not limited to, plastic substrates (eg, polyacrylate, polycarbonate, and polyethylene terephthalate (PET)); metal substrates; enamel or ceramic substrates: glass substrates; or mixtures or combinations thereof. .. For example, the substrate 22 can be uncolored ordinary soda lime silica glass, i.e. "transparent glass", or colored or otherwise colored glass, borosilicate glass, leaded glass. glass), tempered glass, non-tempered glass, annealed glass, or heat strengthened can be glass). The glass can be of any type, such as regular float glass, flat glass, or float glass ribbon, and any optical property, eg, any value of visible light transmittance, ultraviolet transmittance, infrared transmission. It can be of any composition with rate and / or total solar energy transmission. The types of glass suitable for practicing the present invention are not intended to be limited, but are described in US Pat. Nos. 4,746,347, 4,792,536, 5,240,886, 5,385,872, and 5,393,593. For example, substrate 22 is a float glass ribbon, a glass plate for a building window, a skylight, a section of a heat insulating glass unit, a mirror, a shower door, glass furniture (eg, a glass table top or, to name just a few examples. It can be a glass cabinet), or a regular automobile front glass, ply for side or back windows, or a transparent material for an aircraft.

【0020】

The photoactively-enhanced (hereinafter PE) coating 24 of the present invention is on at least a portion of the substrate 22, eg, on all or part of the main surface of the substrate 22, eg, surface 21 or It can be adhered on all or part of the surface 60. In the illustrated embodiment, the PE coating 24 is shown adhered onto the surface 21. As used herein, the term "photoactivity enhancement" is a material or coating that is photoactive and at least one cocatalyst or dopant that increases the photoactivity of the coating over the photoactivity of the coating without a cocatalyst. Refers to said material or coating containing. The PE coating 24 can be photocatalytic, photoactively hydrophilic, or both. "Photoactively hydrophilic" means such a coating in which the contact angle of water droplets on the coating decreases over time as a result of exposing the coating to electromagnetic radiation within the light absorbing band of the material. For example, the contact angle can be reduced to a value less than 15 °, for example less than 10 °, and 24 W / m on the PE coating surface.²After 60 minutes of exposure to UV light from a light source sold under the trade name UVA340 by Q Panels, Cleveland, Ohio, which has the intensity of, it can become superhydrophilic, eg, reduced to less than 5 °. Even with photoactivity, the coating 24 does not necessarily have to be photocatalytic to the extent that it is self-cleaning, i.e., organic material-like stains on the coating surface are reasonable or economical. It does not have to be sufficiently photocatalytic to decompose within an effective time.

【0021】

As described above, the PE coating 24 contains (1) a photoactive coating material and (2) a photoactivity enhancing cocatalyst or dopant. The photoactive coating material (1) is at least one metal oxide, such as, but not limited to, one or more metal oxides or semiconductor metal oxides, such as titanium oxide, silicon oxide, aluminum oxide. , Iron oxide, silver oxide, cobalt oxide, calcium oxide, copper oxide, tungsten oxide, zinc oxide, zinc / tin oxide, strontium titanate, and mixtures thereof. Metal oxides include metal oxides, peroxides or suboxides. In one aspect, the metal oxide is crystalline or at least partially crystalline. In one exemplary coating of the invention, the photoactive coating material is titanium dioxide. Titanium dioxide exists in amorphous and three crystalline forms: anatase, rutile and brookite crystalline forms. Anatase phase Titanium dioxide is particularly effective because it exhibits strong photoactivity but also has excellent chemical resistance and excellent physical durability. However, combinations of the rutile phase or anatase and / or the rutile phase with the brookite and / or amorphous phase are also acceptable in the present invention.

【0022】

The photoactivity-enhancing cocatalyst (2) can be any material that increases the photoactivity of the resulting coating, eg, photocatalytic activity and / or photoactive hydrophilicity, than that of a coating without a cocatalyst. In one exemplary embodiment, the co-catalyst comprises at least one material having at least one component selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lanthanum and / or mixtures or combinations thereof. To do. The co-catalyst is in the PE coating in an amount sufficient to increase the photoactivity of the coating, such as photocatalytic activity and / or photoactive hydrophilicity, without adversely affecting the desired coating performance such as reflectance, transmittance, color, etc. Exists in. For example, in a PE coating 24 containing mainly anatase titanium dioxide, the co-catalyst has a molar ratio of the selected co-catalyst (eg, the metal of the co-catalyst) to titanium in the PE coating 24 in the range 0.001 to 0.05, for example. It can be present in an amount in the range of 0.005 to 0.03, for example 0.01 ± 0.005. Also, in the practice of the present invention, the co-catalyst does not necessarily have to be concentrated on or near the coating surface 21, but rather may be adhered in such a way that it is dispersed or incorporated into the body of the coating 24. it can.

【0023】

The PE coating 24 should be thick enough to provide acceptable levels of photoactivity, such as photocatalytic activity and / or photoactive hydrophilicity, for the intended purpose. There is no absolute value that makes the PE coating 24 "acceptable" or "unacceptable", because whether or not the PE coating 24 has an acceptable level of photoactivity is the purpose for which the PE coating article is used. This is because it varies greatly depending on the conditions and the performance standard selected to meet the purpose. However, the thickness of the PE coating 24 to achieve photoactive hydrophilicity can be much thinner than that required to achieve commercially acceptable levels of photocatalytic self-cleaning activity. .. For example, in one embodiment, the PE coating 24 can have a thickness in the range of 10 Å to 5000 Å, but the thicker coating in this range is not only hydrophilic but also photocatalytic self for at least a period of time. It can have a cleaning activity. When the coating is thinner in this range, the photocatalytic self-cleaning activity typically decreases in proportion to implementation and / or duration. Photocatalytic self-cleaning activity may be unmeasurable when the film thickness decreases within the range of 50 Å to 3000 Å, for example 100 Å to 1000 Å, for example 200 Å to 600 Å, for example 200 Å to 300 Å. Although it may not be, photoactive hydrophilicity can still be present in the presence of selected electromagnetic radiation.

【0024】

In another aspect of the invention, the outer surface 25 of the PE coating 24 (ie, the surface farther from the substrate) is far more than a known self-cleaning coating while still maintaining photoactive hydrophilicity and / or photocatalytic activity. Can be smooth. For example, the PE coating 24, especially the top or outer surface 25 of the coating, has an RMS surface roughness of less than 5 nm, eg, less than 4.9 nm, eg, less than 4 nm, eg, 3 nm, even for thin coatings in the above range, such as 200 Å to 300 Å. It can have less than, eg, less than 2 nm, eg, less than 1 nm, eg 0.3 nm to 0.7 nm.

【0025】

In yet another aspect of the invention, the PE coating 24 can be made more densely than the conventionally known hydrophilic self-cleaning coatings. For example, the PE coating 24 can be substantially non-porous. "Substantially non-porous" means that the coating is dense enough to withstand a normal hydrofluoric acid test, in which 0.5% by weight hydrofluoric acid on the coating. Drop 1 drop of (HF) aqueous solution and cover with a watch glass at room temperature for 8 minutes. The HF is then wiped off and the coating is visually inspected for damage. Alternative HF immersion tests are incorporated herein by Charles Greenberg, Industrial Engineering Chemistry & Research, Vol. 40, No. 1, p. 6 (2001). Year). The dense PE coating 24 of the present invention provides better protection of the underlying substrate from chemical attack than conventional porous self-cleaning coatings, and better than conventional sol-gel applied self-cleaning coatings. It is also harder and more scratch resistant.

【0026】

The PE coating 24 can be adhered directly onto, or in surface contact with, the surface 21 of the substrate 22 as shown in FIG. Even with sodium-containing substrates such as soda lime silica glass, the thin PE coating 24 of the present invention, for example less than 1000 Å, is photoactive due to the sodium in the substrate when the coating is applied by the in-bath method described below. It cannot disappear. Therefore, the ease of cleaning the soda lime silica glass can be obtained without using a sodium barrier layer between the glass and the PE coating 24 of the present invention. In some cases, such conventional sodium barrier layers can also be used.

【0027】

Alternatively, one or more other layers or coatings may be interposed between the PE coating 24 and the substrate 22. For example, the PE coating 24 can be the outer or outermost layer in a multi-layer stack of coatings existing on top of the substrate 22, or the PE coating 24 is one of the layers of the non-outermost stack in such a multi-layer stack. Can be embedded as a stack. The "outer layer" means a layer that receives at least sufficient excitation electromagnetic radiation, eg, ultraviolet light, to impart sufficient photoactivity to the coating to be photoactively hydrophilic, if not necessarily photocatalytic. In one aspect, the PE coating 24 is the outermost coating on the substrate 22.

【0028】

The PE coating 24 of the present invention can be prepared by any of the usual methods, for example, spray pyrolysis, chemical vapor deposition (CVD), or magnetron sputtered vacuum. It can be formed by one or more of deposition) (MSVD). In the spray pyrolysis method, an organic having (1) a metal oxide precursor material such as a titania precursor material and (2) at least one photoactivity enhancing precursor material or co-catalyst material such as an organic metal precursor material. Alternatively, the metal-containing precursor composition is carried in the form of an aqueous suspension, eg, an aqueous solution, and at a temperature high enough for the substrate 22 to decompose the precursor composition and form a PE coating 24 on the substrate 22. In the meantime, it is directed towards the surface of the substrate 22. In the CVD method, the precursor composition is carried in a carrier gas such as nitrogen gas and directed towards substrate 22. In the MSVD method, one or more metal-containing cathode targets are sputtered under reduced pressure in an inert or oxygen-containing atmosphere in order to deposit a sputtered coating onto the substrate 22. The substrate 22 can be heated during or after coating to cause crystallization of the sputter coating to form the PE coating 24. For example, one cathode can be sputtered to impart the metal oxide precursor material (1) and another cathode can be sputtered to impart the co-catalyst material (2). Alternatively, a single cathode pre-doped with the desired co-catalyst can be sputtered to form the PE coating 24.

【0029】

Each method has advantages and restrictions depending on the desired properties of the PE coating 24 and the type of glass processing method. For example, in a conventional float glass method, molten glass is poured onto a pool of molten metal, eg tin, in a molten metal (tin) bath to form a continuous float glass ribbon. The temperature of the float glass ribbon in the tin bath generally ranges from 1203 ° C (2200 ° F) at the delivery end of the bath to 592 ° C (1100 ° F) at the outlet end of the bath. The float glass ribbon is removed from the tin bath and cut into glass sheets of the desired length and width after being slowly cooled, i.e., after being controlledly cooled in an annealing lehr. Will be done. The temperature of the float glass ribbon between the tin bath and the slow-cooling hood is generally in the range of 480 ° C (896 ° F) to 580 ° C (1076 ° F), and the float glass ribbon in the slow-cooling hood. Temperatures generally range from 204 ° C (400 ° F) to 557 ° C (1035 ° F) peaks. U.S. Pat. Nos. 4,466,562 and 4,671,155 (incorporated herein) discuss the float glass method.

【0030】

The CVD and spray pyrolysis methods may be preferred over the MSVD method in the float glass method as they are compatible with high temperature coating of continuous substrates such as float glass ribbons. Illustrative CVD and spray pyrolysis coating methods are described in US Pat. 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.

【0031】

In practicing the present invention, one or more CVD coating devices can be used at several points in the float glass ribbon manufacturing process. For example, a CVD coating device moves when a float glass ribbon moves through a tin bath, after it leaves the tin bath, before it enters a slow cooling basin, or when it moves through a slow cooling basin. Can be used when, or after it has exited the slow cooling. Since the CVD method can withstand the harsh environment associated with float glass ribbon manufacturing and coat moving float glass ribbons, the CVD method puts a PE coating 24 on top of the float glass ribbon in a molten tin bath. Especially well suited for granting. U.S. Pat. Nos. 4,853,257, 4,971,843, 5,536,718, 5,464,657, 5,714,199, and 5,599,387 incorporated herein by reference are used in the practice of the present invention to coat a float glass ribbon in a molten tin bath. Describes the CVD coating equipment and methods that can be used.

【0032】

For example, as shown in FIG. 2, one or more CVD devices 50 can be placed in the tin bath 52 above the molten tin pool 54. As the float glass ribbon 56 moves through the tin bath 52, the vaporized precursor composition (ie, the photoactive film precursor material (1), for example, the metal oxide precursor material and the photoactivity enhancing co-catalyst material. (2) (eg organic metal precursor material) can be added to the carrier gas and directed onto the top surface 21 of the ribbon 56. The precursor composition decomposes to form the PE coating 24 of the present invention. The co-catalyst material (2) can be at least partially soluble in the coating precursor material (1), eg, completely soluble in the coating precursor material (1) under the desired degradation conditions. Is. The required amount of photoactivity, eg, photoactive hydrophilicity and / or the required amount of co-catalytic material (2) to achieve photocatalytic activity, is added to or mixed with the coating precursor material (1). It can be solubilized in it. For example, the co-catalyst material can be an organometallic material, such as an alkoxide material having a boiling point of less than 200 ° C (eg, a transition metal alkoxide). Instead, two separate precursors can be vaporized and combined separately.

【0033】

An exemplary coating precursor material (1) (eg, titania precursor material) that can be used in the practice of the present invention to form the titanium dioxide PE coating 24 by the CVD method is, but is not limited to, the oxidation of titanium. Includes substances, suboxides, or peroxides. In one embodiment, the precursor material (1) can be one or more titanium alkoxides, titanium ethoxyoxides, titanium propoxides, titanium butoxides and the like, or isomers thereof. Examples of precursor materials suitable for practicing the present invention are not limited, but titanium tetraisopropoxide (Ti (OC)).₃H₇)₄) (Hereinafter "TTIP") and Titanium Tetraethoxydo (Ti (OC)₂H₅)₄) (Hereinafter, "TTEt"). Alternatively, the titania precursor material (1) can be titanium tetrachloride.

【0034】

The co-catalyst (eg, dopant) material can also be any material that enhances or influences the photoactivity of the resulting coating, eg, photocatalytic activity and / or photoactive hydrophilicity, in a desired manner. .. The co-catalyst can include one or more of boron, strontium, zirconium, lead, barium, calcium, hafnium, lantern and / or a mixture or combination thereof. For example, co-catalyst materials are trialkyl borate, strontium alkoxide, alkyl lead, zirconium alkyl alkoxide, lanthanum alkoxide, strontium ethoxyoxide, strontium-2-ethylhexanoate, strontium hexafluoroacetylacetonate, strontium isopropoxide, strontium. Methoxydo, strontium tantalumoxide, strontium titanium isopropoxide, triethyl borate (also called triethoxybolan or triethyl borate ester), other borates such as tri-n-butylborate, triisopropylborate, tert-n -Can include one or more of butyl lead, zirconium-2-methyl-2-butoxide, lanthanum isopropoxide, and / or a mixture or combination thereof. Illustrated 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 depending on the specific precursor composition used. However, for coatings with a thickness of about 200 Å, the concentration of precursor composition in the carrier gas will typically be in the range of 0.01% to 0.1% by volume, for example 0.01% to 0.06% by volume. For example, 0.015 volume% to 0.06 volume%; for example, 0.019 volume% to 0.054 volume%.

【0035】

For the CVD method (similarly, spray pyrolysis described below), the temperature of the substrate 22 when forming the PE coating 24 on it decomposes the metal-containing precursor composition and the desired amount of photoactivity, For example, it should be within the range of forming a coating having photocatalytic activity, photoactive hydrophilicity, or both. The lower limit of this temperature range is greatly influenced by the decomposition temperature of the selected precursor composition. For the titanium-containing precursors listed above, the lower limit temperature of the substrate 22 that results in sufficient decomposition of the precursor composition is generally in the range of 400 ° C (752 ° F) to 500 ° C (932 ° F). .. The upper limit of this temperature range may be affected by the substrate coating method. For example, if the substrate 22 is a float glass ribbon 56 and the PE coating 24 is applied to the float glass ribbon in the molten tin bath 52 during the manufacture of the float glass ribbon 56, the float glass ribbon 56 is 1000 °. It can reach temperatures above C (1832 ° F). The float glass ribbon 56 can be elongated or sized at temperatures above 800 ° C (1472 ° F). If the PE coating 24 is applied to the float glass ribbon 56 before or during elongateding, the PE coating 24 may crack or wrinkle as the float glass ribbon 56 is stretched or compressed, respectively. Therefore, the PE coating 24 is when the float glass ribbon 56 is dimensionally stable (other than heat shrinkage due to cooling), for example, less than 800 ° C (1472 ° F) for soda lime silica glass and float. It can be applied, for example, above 400 ° C (752 ° F) when the glass ribbon 56 is at a temperature that decomposes the metal-containing precursor.

【0036】

For spray pyrolysis, US Pat. Nos. 4,719,126, 4,719,127, 4,111,150, and 3,660,061 incorporated herein describe spray pyrolysis equipment and methods that can be used with conventional float glass ribbon manufacturing processes. There is. Like the CVD method, the spray pyrolysis method is well suited for coating moving float glass ribbons, but the spray pyrolysis has more complex equipment than the CVD equipment, and usually has a tin bath outlet and slow cooling. Used between the entrance ends of the gama.

【0037】

Illustrative metal-containing precursor compositions that can be used in the practice of the present invention to form PE coatings by spray pyrolysis include relatively water-insoluble organometallic reactants, in particular metal acetylacetonate compounds. , It is jet milled or wet milled to a particle size of less than 10 microns and suspended in an aqueous medium by the use of a chemical wetting agent. Suitable metal acetylacetone precursor materials for forming titanium dioxide-containing PE coatings are titanylacetylacetoneate (TiO (C).₅H₇O₂)₂). The photoactivity enhancing co-catalyst as described above can be mixed with or solubilized in the acetylacetone precursor material. In one aspect, the relative concentrations of the metal acetylacetonate and the co-catalyst precursor material in the aqueous suspension range from 5-40% by weight of the aqueous suspension. The wetting agent may be any relatively low foaming surfactant, including anionic, nonionic or cationic compositions. In one aspect, the surfactant is nonionic. Wetting agents are typically added at 0.24% by weight, but can range from 0.01% to 1% or more. The aqueous medium may be distilled or non-distilled water. Aqueous suspensions for the thermal decomposition of metal-containing coatings are described in US Pat. No. 4,719,127, which is incorporated herein by reference, particularly in column 2, lines 16-4, line 48.

【0038】

As will be appreciated by those skilled in the art, the bottom surface 60 (usually referred to as the "tin side") of a float glass ribbon, which is directly supported by molten tin, has tin diffused into it. It gives the tin side a different tin adsorption pattern than the opposite surface 21 (usually referred to as the "air side") that is not in contact with the molten tin. The PE coating of the present invention is subjected to the CVD method on the air side of the float glass ribbon by the CVD method as described above while the float glass ribbon is supported on the tin, and / or after the float glass ribbon is taken out of the tin bath. Alternatively, it can be formed on the air side of the float glass ribbon by either the spray thermal decomposition method and / or on the tin side of the float glass ribbon by the CVD method after the float glass ribbon has left the tin bath.

【0039】

Instead of including oxygen in the atmosphere of the tin bath to form the oxide film, the precursor composition itself can contain one or more sources of organic oxygen. The organic oxygen can be, for example, an ester or a carboxylate ester, for example, an alkyl ester having an alkyl group having β-hydrogen. Suitable ester is C₂~ C₁₀It can be an alkyl ester having an alkyl group. Illustrative esters that can be used in the practice of the present invention are described in WO 00/75087, which is incorporated herein by reference.

【0040】

With respect to MSVD, US Pat. Nos. 4,379,040, 4,861,669, 4,900,633, 4,920,006, 4,938,857, 5,328,768, and 5,492,750, which are incorporated herein by reference, have a metal oxide film on the substrate, including the glass substrate. Describes the MSVD apparatus and method for sputter coating. The MSVD method is generally not suitable for applying a PE coating on a float glass ribbon during the manufacture of a float glass ribbon, because, among many circumstances, the MSVD method requires decompression during the sputtering operation. That is because it is difficult to form on a continuously moving float glass ribbon. However, the MSVD method is acceptable for depositing the PE coating 24 on the substrate 22, eg, a glass sheet. The substrate 22 is heated to a temperature in the range of 400 ° C (752 ° F) to 500 ° C (932 ° F) so that the MSVD sputtered coating on the substrate crystallizes during the adhesion process, thereby eliminating subsequent heating operations. Can be done. Heating the substrate during sputtering is generally undesirable, because additional heating operations during sputtering may reduce the amount of processing. Alternatively, the sputtered coating can be crystallized directly in the MSVD coating equipment and without subsequent heat treatment by using a high energy plasma, but again its tendency to reduce the throughput through the MSVD coating. Therefore, this may also be undesirable.

【0041】

An exemplary method of using the MSVD method to provide a PE coating (particularly a PE coating of 300 Å or less with an RMS surface roughness of 2 nm or less) is to sputter a cocatalyst-containing coating onto the substrate and this coating substrate. Is removed from the MSVD coater, and then the coated substrate is heat treated to crystallize the sputtered coating. For example, but not limiting the invention, in one embodiment for at least one photoactivity enhancer selected from boron, strontium, zirconium, lead, barium, calcium, hafnium, lantern, and / or mixtures thereof. The target of the titanium metal doped with the co-catalyst material has argon / oxygen with 5-50% oxygen, for example 20% oxygen, to deposit the desired thickness of the doped titanium dioxide film on the substrate 22. It can be spattered in an atmosphere with a pressure of 5-10 milittles. The film when attached is not crystallized. The coating substrate is removed from the coating and promotes the formation of crystalline forms of titanium dioxide for photoactivity at temperatures in the range 400 ° C (752 ° F) to 600 ° C (1112 ° F). It is heated for a sufficient time. Generally, a temperature in the range of 400 ° C (752 ° F) to 600 ° C (1112 ° F) is sufficient for at least 1 hour. When the substrate 22 is a glass sheet cut from a float glass ribbon, the PE coating 24 can be sputtered onto the air side and / or the tin side.

【0042】

The substrate 22 having the PE coating 24 adhered by the CVD method, the spray pyrolysis method or the MSVD method can then undergo one or more post-coating slow cooling operations. As will be recognized, the time and temperature of slow cooling are 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. Alternatively, it can be influenced by several factors, including whether or not it is a single layer of a multi-layer stack on the substrate 22.

【0043】

Contains sodium ions that allow the substrate 22 to migrate from the substrate 22 into the PE coating 24 adhered onto the substrate 22, regardless of whether the PE coating 24 is provided by CVD, spray pyrolysis, or MSVD. If so, the sodium ions are photoactive, eg, photocatalyst, of the PE coating 24 by forming an inert compound while consuming titanium, for example, by forming sodium titanate or by recombination of photoexcited charges. May inhibit or destroy active and / or photoactive hydrophilicity. Therefore, it is possible to attach a conventional sodium ion diffusion barrier (SIDB) layer onto the substrate before the PE coating 24 is attached. Suitable SIDB layers are discussed in detail in US Pat. No. 6,027,766, which is incorporated herein by reference, and will not be discussed in detail here. In combination with post-coating heating, a sodium barrier layer for sodium-containing substrates such as soda lime silica glass can be utilized. When applying the PE coating 24 of the present invention in a molten metal bath, the sodium barrier layer is optional.

【0044】

The PE coating 24 of the present invention can be photoactive, eg, photocatalytic and / or photoactively hydrophilic, when exposed to electromagnetic radiation within the light absorption band of the coating. "Light absorption band" means the range of electromagnetic radiation absorbed by a material to make it photoactive. In one aspect, the coating 24 is photoactive when exposed to electromagnetic radiation in the ultraviolet region of the electromagnetic spectrum, eg, 300 nm to 400 nm. UV sources include natural sources such as solar radiation, and artificial light sources such as dark light sources or UV sources such as UVA-340 light sources.

【0045】

As shown in FIG. 1, in addition to the PE coating 24 of the present invention, one or more functional coatings 46 can be adhered on or over the substrate 22. For example, the functional coating 46 can be attached over the main surface 60 of the substrate 22 on the opposite side of the surface 21. As used herein, the term "functional coating" is a coating that alters the physical properties of one or more of the substrates to which it is attached, eg, optical, thermal, chemical or mechanical properties. A coating that is not intended to be removed from the substrate during subsequent processing. The functional coating 46 can have one or more functional coatings of the same or different composition or function. As used herein, the term "layer" or "coating" refers to the coating area of the intended or selected coating composition. The coating can be homogeneous, heterogeneous, or have a gradient composition change. The outer surface or part (ie, the surface or part farthest from the substrate), the inner surface or part (ie, the surface or part closest to the substrate), and the part between the outer and inner surfaces have substantially the same composition. When has, the coating is "homogeneous". A fraction in which the film substantially increases one or more components and a fraction in which one or more other components substantially decrease as the film moves from the inner surface to the outer surface and vice versa. When having, the coating is "gradient". A film is "inhomogeneous" when it is neither homogeneous nor gradient. A "coating" is composed of one or more "coatings".

【0046】

The functional coating 46 is an electrically conductive coating, eg, an electrically conductive heated window coating as disclosed in US Pat. Nos. 5,653,903 and 5,028,759, or a single or multiple coating that can function as an antenna. , Can be. Similarly, the functional coating 46 can be a coating for controlling solar radiation, for example, a coating that reflects or absorbs visible light, infrared or ultraviolet energy. Examples of suitable solar radiation control coatings are, for example, U.S. Pat. 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. It can also be found in and in US Patent Application No. 09 / 058,440. Similarly, the functional coating 46 can be a low emissivity coating. A "low emissivity coating" allows visible wavelength energies such as 400nm to 780nm to be transmitted through the coating, but reflects and represents longer wavelengths of solar and / or thermal infrared energy. It is intended to improve the thermal insulation of architectural glass. "Low emissivity" means emissivity less than 0.4, for example less than 0.3, for example less than 0.2. Examples of low emissivity coatings can be found, for example, in US Pat. Nos. 4,952,423 and 4,504,109 and UK Pat. No. 2,302,102. The functional coating 46 can be a single-layer or multi-layer coating, and one or more metals, non-metals, semimetals, semiconductors, and / or alloys, compounds, composites, combinations or blends thereof. Can include. For example, the functional coating 46 can be a single-layer metal oxide coating, a multi-layer metal oxide coating, a non-metal oxide coating, or a multi-layer coating.

【0047】

Examples of suitable functional coatings for use with the present invention are commercially available from PPG Industries, Inc. of Pittsburgh, PA for SUNGATE® and SOLARBAN® family dressings. .. Such functional coatings typically include one or a dielectric or antireflection material, such as a metal oxide or an oxide of a metal alloy, which is typically transparent to visible light. Includes more anti-reflection coatings. The functional coating 46 can also include infrared reflective coatings containing reflective metals such as precious metals such as gold, copper or silver, or combinations or alloys thereof, and is also known to those skilled in the art. An undercoat or barrier coating, such as titanium, can be placed above and / or below the metal reflective layer as described above.

【0048】

The functional coating 46 is in any conventional manner, for example, but not limited to, magnetron sputter deposition (MSVD), chemical vapor deposition (CVD), spray thermal decomposition (ie, thermal deposition), atmospheric pressure CVD. (APCVD), Low Pressure CVD (LPCVD), Plasma-enhanced CVD (PEVCD), Plasma Assisted (plasma) Assisted) can be adhered by CVD (PACVD), thermal or electron beam evaporation, cathode arc adhesion, plasma spray adhesion, and wet chemical deposition (eg, solgel, mirror silver plating, etc.). For example, US Pat. Nos. 4,584,206, 4,900,110, and 5,714,199 incorporated herein disclose methods and devices for depositing a metal-containing film on the bottom surface of a glass ribbon by chemical vapor deposition. Such known devices can be placed downstream of the molten tin bath in the float glass method to impart a functional coating on the underside of the glass ribbon, i.e. on the side opposite to the PE coating of the present invention. Alternatively, one or more separate CVD coaters can be placed in the tin bath to attach the functional coat either above or below the PE coat 24 on the float glass ribbon. In one embodiment when 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 opposite side 60 of the PE coating, the functional coating is applied to the tin side of the substrate 22 by, for example, CVD or MSVD, after the tin bath in the float method as discussed above. Can be done. In another embodiment, the PE coating 24 can be attached over the whole or part of the surface 60, and the functional coating 46 can be attached over the whole or part of the surface 21.

【0049】

An exemplary article of manufacture of the present invention is shown in FIG. 3 in the form of an insulating glass (IG) unit 30. The insulating glass unit separates the first glass 32 from the second compartment 34 by a spacer assembly (not shown) and sealant to form a chamber between the two compartments 32, 34. It is held and held in the correct position by the system. The first glass 32 has a first surface 36 (number 1 surface) and a second surface 38 (number 2 surface). The second glass 34 has a first surface 40 (number 3 surface) and a second surface 42 (number 4 surface). The first surface 36 can be the outer surface of the IG unit, i.e. the surface exposed to the outside world, and the second surface 42 can be the inner surface, i.e. the surface forming the interior of the structure. it can. Examples of IG units are disclosed in US Pat. Nos. 4,193,236, 4,464,874, 5,088,258, and 5,106,663, which are incorporated herein by reference. In one aspect shown in FIG. 3, the PE coating 24 can be located on the surface of number 1 or number 4, for example, on the surface of number 1. The PE coating 24 reduces fogging and makes the IG unit 30 easier to clean and maintain. In this embodiment, one or more of the optional functional coatings 46 as described above can be attached onto at least a portion of the surface of number 2, number 3, or number 4.

【0050】

The advantage of the present invention over the sol-gel method for forming a self-cleaning film is that a thin, dense PE film is placed on the substrate, unlike the generally thicker porous self-cleaning film obtained by the sol-gel coating method. The ability to form can be mentioned. Since the PE coatings of the present invention can be thin, eg, less than 1000 Å, eg less than 600 Å, they are architecturally acceptable for use as transparent coatings on glass substrates. Yet another advantage is that the method of providing a PE coating in accordance with the present invention avoids the need to reheat the substrate after application of the coating or coating precursor as required by the currently available sol-gel process. .. This not only makes the method of the present invention cheaper and more efficient, eg, lower equipment cost, lower energy cost and shorter manufacturing time, but also the sodium ion transfer of the PE coating 24 of the present invention. And, in turn, significantly reduce the chance of sodium ion poisoning. Furthermore, while the methods of the invention are readily adaptable to the formation of PE coatings on moving continuous substrates such as glass float ribbons, the currently available sol-gel methods are not so easily adaptable.

【0051】

The following examples of the invention are presented for illustration purposes, which does not limit the invention.

[Example 1]

【0052】

The PE coating of titanium dioxide and the selected dopant was prepared by CVD as described below to evaluate the effect of the dopant on the photoactivity of the PE coating.

【0053】

A PE coating about 600 Å thick is a 3.3 mm thick rectangular plate of clear float glass at a CVD temperature of 1250 ° F (676 ° C) by a CVD coater with a commercially available Sierratherm CVD furnace. Adhered on a state test piece (coupon). In one set of experiments (Experiment A), the PE coating was adhered directly onto a rectangular plate of glass. In another set of experiments (Experiment B), the PE coating was deposited on a 700 Å thick tin oxide layer pre-attached onto a rectangular plate-shaped specimen.

【0054】

In each experiment, the titanium dioxide precursor material was titanium isopropoxide, and the carrier gas was nitrogen. Illustrated dopant precursor materials were:<u style="single">Dopant metal</u><u style="single">Dopant precursor material</u>Boron Triethyl Borate Strontium Strontium Isopropoxide Lead Tetra-n-Butyl Lead Zirconium Zirconium-2-Methyl-2-butoxide [0055]

Dopant precursor materials were added to form such PE coatings in which the molar ratio of dopant metal to titania in the resulting PE coating was 0.001, 0.01, and 0.05. The concentration of precursor composition (eg, titanium isopropoxide and dopant precursor material) in the carrier gas was 0.17% by volume for each experiment.

【0056】

As a reference point, an undoped titania coating (600 Å thickness) was directly attached onto the rectangular plate-shaped test piece of float glass (reference 1), and the rectangular plate-shaped test piece having a 700 Å tin oxide layer. Adhered to the top (criteria 2). These undoped coatings were tested for photocatalytic activity according to the conventional stearic acid test described in US Pat. No. 6,027,766. The following photocatalytic activity levels were measured (the "activity" level is 10^-3cm^-1(Shown in minutes):<img file="JP2004535922A_D0001.tif" /> 【0057】

Table 1 below shows the activity of the PE coating directly attached to the rectangular plate-shaped test piece of glass and attached to the tin oxide layer. All values are 10^-3cm^-1Shown in / minute units. The crystal structure of the titania coating directly attached to the glass was found to be anatase by X-ray diffraction. It was found that the crystal structure of the film adhered on the tin oxide layer contained both anatase and rutile titania.<u style="single">table 1</u><img file="JP2004535922A_D0002.tif" /> 【0058】

As can be seen from Table 1, all dopants B, Zr, Pb, and Sr have photocatalytic activity of the coating directly adhered to the glass at dopant / Ti molar ratios of 0.001 and 0.01 compared to Criterion 1. , Increased. The level of photocatalytic activity diminished as the dopant / Ti molar ratio went from 0.01 to 0.05.

【0059】

On the other hand, both W and Ta showed lower levels of activity compared to Criterion 1 in both dopant / Ti molar ratios.

【0060】

Except for Pb, all samples showed lower levels of activity when attached onto the tin oxide layer, also as shown in Table 1. The ability of Pb to enhance photocatalytic activity in the presence of rutile titania appears to suggest an enhancement mechanism different from other dopants.

【0061】

From the disclosed trends, it is assumed that doping titania with holes increases photocatalytic activity. This can be seen from the fact that Sr, Zr, and B all have a positive effect (increase photocatalytic activity), while Ta and W have a negative effect (decrease photocatalytic activity). Metals that have less valence electrons than Ti and are found at Ti sites in the crystal lattice will hole-dope titania. Boron may be present at oxygen sites, which may also have the effect of doping these sites as holes. The opposite is true for dopants with higher valence electrons. Zirconium, which has the same number of valence electrons as Ti, is still less electronegative than Ti, so it has a positive effect due to its ability to attract oxygen electrons. Doping holes in the lattice will facilitate the migration of either holes or electrons generated by the absorption of electromagnetic radiation to the surface of the coating and react with contaminants. Under this hypothesis, the other dopants that should enhance photocatalytic activity should be La, Ba, Ca, and Hf (Hf has the same number of valence electrons as Zr, but with smaller electron negatives. is there).

【0062】

Those skilled in the art will readily recognize that the present invention can be modified without departing from the concepts disclosed above. Therefore, the specific embodiments described in detail herein are merely exemplary and do not limit the scope of the invention, the invention should be given the scope of claims and all equivalent scope thereof. ..

[Simple explanation of drawings]

【0063】

FIG. 1 is a cross-sectional view (not proportionally proportional) of a part of the substrate having the photoactive coating of the present invention.

FIG. 2 is a cross-sectional view (not proportionately proportional) of a coating process for applying the photoactive metal oxide coating of the present invention onto a glass ribbon in a molten metal bath for the float glass method.

FIG. 3 is a cross-sectional view (not proportionally proportional) of an insulating glass unit incorporating the features of the present invention.

[Explanation of symbols]

【0064】

20 Article 21 First surface (upper surface) of substrate 22 Substrate 24 PE coating 25 Outer surface of PE coating 46 Functional coating 60 Second surface (bottom surface) of substrate 30 Insulation glass (IG) unit 32 First glass 34 Second glass 36 First surface of first glass 38 Second surface of first glass 40 First surface of second glass 42 Second surface of second glass 50 CVD coating device 52 Tin bath 54 Tin pool 56 Float glass ribbon