Photocatalytic-activated self-cleaning article and method of making the same

Photocatalytic activated self-cleaning product and preparation method thereof

This application claims the priority of U.S. Provisional Application No. 60/040566 filed on March 14, 1997. The U.S. Provisional Application No. 60/040565 filed on March 14, 1997 and the U.S. General Application No. 08/899265 entitled "Photocatalytic Activation Self-Cleaning Device" by Greenberg et al., filed on the same day as this application Relevant, and they are incorporated into this specification as a reference.

The invention relates to a method for depositing a photocatalytically activated self-cleaning coating on a substrate (such as a glass plate and a continuous float glass ribbon), and relates to preventing the photocatalytically activated self-cleaning coating deposited on a substrate containing sodium ions from being poisoned by sodium ions The method and the article made according to the method.

For many substrates (such as glass substrates), the surface of the substrate needs to be kept "clean", that is, without surface impurities, such as ordinary organic or inorganic surface impurities. In the traditional sense, this means cleaning these surfaces frequently. This cleaning work is generally carried out manually or by mechanical devices. Either method is very laborious, time-consuming and/or expensive. People need a substrate with a surface that is self-cleaning or at least easy to clean, which can eliminate or alleviate the need for manual or mechanical cleaning.

It is known that a titanium dioxide (TiO2) coating can provide a photocatalytically activated self-cleaning (hereinafter referred to as "PASC") surface on a substrate. Publications involving the formation of PASC titanium dioxide coatings on glass substrates include US5595813 and "Photooxidized self-cleaning transparent titanium dioxide film on glass", Paz et al., J. Mater. Res., Vol. 10, No. 11.pp .2842-48 (Nov. 1995). In addition, the catalogues of patents and articles usually related to the photocatalytic oxidation of organic compounds are included in the "Bibliography of Work on the Photocatalytic Removal of Hazardous Compounds from Water and Air" (Bibliography of Work on the Photocatalytic Removal of Hazardous Compounds from Water and Air). ), D. Blake, National Renewable Energy Laboratory (May 1994) and updated in October 1995 and updated in October 1996.

The existing method for coating a PASC coating (such as a titanium dioxide PASC coating) on a substrate is the sol-gel method. Using the sol-gel method, an uncrystallized colloidal suspension (sol) based on an alcohol solvent can be sprayed, sprayed or dipped on the substrate at room temperature or approximately room temperature. Then the substrate is heated to a temperature of about 100-800°C (212-1472 degrees Fahrenheit), thereby causing the PASC coating to adhere to the substrate and/or to crystallize the PASC coating; thereby forming a crystalline PASC coating on the substrate ( gel).

What restricts the use of sol-gel PASC coatings is that the sol-gel coating method is economically uneconomical or does not match certain coating conditions or substrates in practice. For example, when a PASC coating needs to be formed on the glass ribbon during the manufacturing process of the float glass ribbon, the glass ribbon is too hot to accept the sol, which partly depends on the solvent used in the sol solution. For many solvents used in this sol-gel process, it is necessary to cool the hot float glass plate to room temperature before applying the sol, and then heat the float glass plate enough to crystallize the sol into a PASC coating temperature. Such cooling and reheating operations require a large investment in equipment, require energy and operating costs, and greatly reduce production efficiency.

If there are sodium ions in the substrate and these sodium ions will migrate from the substrate to the PASC coating, the PASC activity of the PASC coating will be greatly reduced or destroyed. This process is called sodium poisoning or sodium ion poisoning. For many substrates containing sodium ions, the rate at which sodium ions migrate into the coating will increase as the substrate temperature increases. Therefore, another limitation of the sol-gel coating method is that reheating the substrate increases the chance of sodium ion migration, which in turn increases the sodium ion poisoning of the PASC coating.

Another limitation of forming a PASC coating by the sol-gel method is the thickness of the coating, for example, a few microns (10-6 m) thick. PASC coatings of this thickness can adversely affect the optical and/or aesthetic properties of PASC-coated articles.

As can be seen from what has been said above, people need a product with a PASC coating deposited thereon without the above-mentioned defects and a method for depositing a PASC coating.

The present invention relates to a PASC product, which includes a substrate with at least one surface and a PASC coating, such as titanium dioxide. The PASC coating is selected from chemical vapor deposition (hereinafter referred to as "CVD"), spraying Pyrolysis and magnetron sputtering vacuum deposition ("MSVD") is a method of deposition on the surface of the substrate. The invention also relates to a method of manufacturing the article.

The present invention also relates to a PASC product, which includes a sodium ion migration barrier (hereinafter referred to as "SIDB") layer deposited on the surface of the substrate with at least one surface, such as tin oxide, titanium dioxide, aluminum oxide layer and mixtures thereof And a PASC layer, such as a titanium dioxide layer, deposited on the SIDB layer. The PASC coating and SIDB layer are each deposited by a method selected from CVD, spray pyrolysis, and MSVD. The invention also relates to a method of manufacturing the article.

Figure 1 is a partial front view of a substrate with a PASC coating deposited thereon.

Figure 2 is similar to Figure 1 and shows the SIDB layer between the substrate and the PASC coating.

Figure 3 shows a schematic diagram of selected parts of the CVD coater.

Figure 4 shows a schematic view of selected parts of the spray pyrolytic coater.

Referring now to Figure 1, there is shown an article 20 having the features of the present invention. The article 20 includes a substrate 22 on which a PASC coating 24 is deposited. The base 22 is not limited to the present invention and may include a glass base, such as a glass plate or a continuous float glass ribbon, a plastic base, a metal base, and a glazed base.

The PASC coating 24 may be directly on the substrate 22 as shown in FIG. 1 or there may be other layers between the PASC coating 24 and the substrate 22, for example, including but not limited to the SIDB layer as shown in FIG. 2 and described in detail below. 26. In addition, as those skilled in the art can understand, the PASC coating 24 can be the outermost layer of the multilayer laminate on the substrate 22, or the PASC coating 24 can be embedded as a non-outermost layer. In the multi-layer stack, the condition is that sufficient light radiation can pass through the coating deposited on the PASC coating 24, so that the PASC coating 24 is photocatalytically activated and the active radiation can pass through the coating deposited on the PASC coating 24, Thus, it reacts with organic impurities present on the outermost layer of the multilayer stack.

The PASC coating 24 can be any coating that can be photocatalytically activated to self-clean and can be deposited by a CVD method, a spray pyrolysis method, or an MSVD method. For example, but not limited to the present invention, this PASC coating 24 may include one or more metal oxides, such as titanium oxide, iron oxide, silver oxide, copper oxide, tungsten oxide, aluminum oxide, silicon oxide, and tin oxide. Zinc oxide, molybdenum oxide, zinc oxide, zinc oxide/tin oxide, strontium titanate, and mixtures thereof. The metal oxide may include oxides, metal peroxides or suboxides.

The preferred PASC coating 24 is a titanium dioxide coating. Titanium dioxide exists in amorphous and three crystalline forms, namely anatase, rutile and brookite crystal forms. Anatase-type titanium dioxide is preferred because it has strong PASC activity, while also having excellent chemical resistance and excellent physical stability. In addition, anatase titanium dioxide has a high transmittance in the visible light region, which makes a thinner anatase coating with excellent optical properties. Rutile titanium dioxide also has PASC activity. The combination of anatase and/or rutile and brookite and/or amorphous phases is feasible for the present invention, provided that the combination has PASC activity.

The PASC coating 24 must be thick enough to provide proper PASC activity. There is no absolute value that can make the PASC active coating 24 "appropriate" or "inappropriate", because whether the PASC coating has proper PASC activity is mainly determined by the purpose and conditions of the PASC coated product and the choice according to the purpose. Performance standards. Generally, thicker PASC coatings produce higher PASC activity. But thinner coatings are also different. For example, when the product requires a higher transmittance for optical or aesthetic reasons, a thinner coating is preferred; with a thinner coating, the surface of the product The surface impurities on the surface can be easily removed, the coating will be exposed to basic radiation and/or the PASC coating 24 will be exposed to sodium poisoning, which will be described in detail below. For more applications, preferably the PASC coating is at least about 200 angstroms, preferably at least about 400 angstroms, and more preferably about 500 angstroms. It has been found that when the substrate 22 is a piece of glass and the PASC coating 24 is an anatase titanium dioxide PASC coating formed directly on float glass by the CVD method, a thickness of at least about 500 angstroms provides about 2×10-3-5 ×10-3/cm·min PASC reaction speed (for the removal of stearic acid test film on the surface of the widely used PASC coating, when the PASC coating is directed to a light source with an intensity of about 20 watts/square meter , As provided by Q-Panel Company of Cleveland, Ohio, when exposed to ultraviolet radiation from a light source sold under the trademark UVA-340).

According to the present invention, a thinner, such as less than 1 micron (10-6 m), more preferably less than 0.5 micron PASC coating is formed on the substrate surface 22 by spraying pyrolysis, CVD or MSVD. In the spray pyrolysis method, the metal-containing precursor is carried in an aqueous suspension, such as an aqueous solution, while in the CVD method, the carrier is carried in a carrier gas, such as nitrogen, and directed to the surface of the substrate 22, At the same time, the substrate 22 is at a sufficiently high temperature to decompose the metal-containing precursor and form a PASC coating 24 on the substrate 22. In the MSVD method, a metal-containing cathode target is sputtered under negative pressure in an inert or oxygen-containing atmosphere to deposit a sputtered layer on the substrate 22. The substrate 22 during the coating process or after the coating process is heated to crystallize the sputtered layer to form the PASC coating 24.

Each method has advantages and limitations. For example, the CVD method and the pyrolysis method are preferred to the spray pyrolysis method. This is because the aqueous solution of the spray pyrolysis method will cause the presence of OH- ions in the PASC coating 24. The formation of crystals is inhibited in the PASC coating 24, thereby reducing the activity of the PASC coating. The CVD method and the pyrolysis method are preferred to the MSVD method because it can be compatible with coating continuous substrates, such as float glass ribbons, at higher temperatures. The CVD, spray pyrolysis, and MSVD methods used to deposit the PASC coating 24 will be described in detail below. As people can understand, spray pyrolysis and CVD methods can be used to deposit thinner (eg, hundreds of angstroms) metal oxide coatings (including titanium dioxide layers) on the substrate. These coatings are disclosed in US4344986, 4393095, 4400412, 4719126, 4853257 and 4,971,843, which are incorporated herein by reference.

Metal-containing precursors that can be used in the present invention to form a titanium dioxide PASC coating by a CVD method include, but are not limited to, titanium tetrachloride (TiCl4), titanium tetraisopropoxide (Ti(OC3H7)4) (hereinafter referred to as "TTIP") and tetraethoxy titanium (Ti(OC2H5)4) (hereinafter referred to as "TTEt"). The carrier gas that can be used in the CVD method includes, but is not limited to, air, nitrogen, oxygen, ammonia, and mixtures thereof. The preferred carrier gas is nitrogen and the metal-containing precursor is TTIP. Generally, for the above three metal-containing precursors, the concentration of the metal-containing precursor in the carrier gas is 0.1%-0.4% by volume. However, as those skilled in the art understand, for other For metal-containing precursors, these concentrations can vary.

Metal-containing precursors that can be used in the present invention to form PASC coatings by spray pyrolysis include relatively water-insoluble organometallic reagents, especially metal acetylacetonates, which are jet-pulverized or wet-milled to a particle size of less than about 10 particles (10-6m) and use a chemical wetting agent to be suspended in an aqueous medium. The metal acetylacetonate suitable for forming the titanium dioxide PASC coating is titanium oxide acetylacetonate (TiO(C5H7O2)2). The relative concentration of the metal acetylacetonate in the aqueous suspension is preferably about 5-40% by weight of the aqueous suspension. The humectant can be any relatively low foaming surfactant, including anionic, nonionic or cationic compositions, although nonionic ones are preferred. The humectant is typically added in an amount of about 0.24% by weight, but can be about 0.01% to 1% or more. The aqueous medium is preferably distilled water or deionized water. Aqueous suspensions for pyrolytic deposition of metal-containing films are disclosed in US 4,719,127, particularly in the second column, line 16 to column 4, line 48, which article is incorporated herein by reference.

For CVD and spray pyrolysis, the temperature of the substrate during the formation of the PASC coating must be such that the metal-containing precursor can decompose and form a PASC active (for example, a crystalline phase for a metal oxide PASC coating) Coating. As one can understand, the lower limit of the temperature range is mainly affected by the decomposition temperature of the selected metal-containing precursor. For the aforementioned titanium-containing precursor, the lowest temperature of the matrix 22 that fully decomposes the precursor is in the range of about 400°C (752°F) and about 500°C (932°F). The upper limit of this temperature range is affected by the coated substrate. For example, when the substrate 22 is a float glass ribbon and the PASC coating 24 is applied to the float glass ribbon in the process of manufacturing the float glass ribbon, the float glass can reach a temperature exceeding 1000°C (1832°F) temperature. Float glass ribbons generally shrink or deform (e.g., extend or shrink) at temperatures above 800°C (1472 degrees Fahrenheit). If the PASC coating 24 is applied before or during the shrinkage of the float glass, the PASC coating 24 may break or creep when the float glass ribbon extends or shrinks. Therefore, when implementing the present invention, it is preferable that the float glass ribbon is dimensionally stable, for example, for soda lime silica glass, it is lower than about 800°C (1472 degrees Fahrenheit) and the float glass ribbon is in a position that can decompose the metal-containing precursor. When the temperature is higher than about 400°C (752°F), PASC coating is applied.

The formation of the PASC coating 24 by CVD or spray pyrolysis is particularly suitable for the manufacture of float glass ribbons. Generally, float glass ribbons are made by melting glass batch materials in a furnace and conveying the clarified molten glass onto a molten tin bath. The molten glass on the tin bath is drawn from the tin bath as a continuous glass ribbon, while its size is changing, and is controllably cooled to form a dimensionally stable float glass ribbon. The float glass ribbon is removed from the tin bath and moved through the annealing furnace by a conveyor belt to anneal the float glass ribbon. Then the annealed float glass ribbon is moved on a conveyor roller through a cutting station, where the glass ribbon is cut into glass plates with the required length and width. US4466562 and 4671155 disclose float glass processes, which are incorporated herein by reference.

The temperature of the float glass ribbon on the tin bath is usually about 1093.3°C (2000°F) at the delivery end of the tin bath and about 538°C (1000°F) at the outlet end of the tin bath. The temperature of the float glass ribbon between the tin bath and the annealing furnace is usually about 480°C (896°F)-580°C (2076°F); the temperature of the float glass ribbon in the annealing furnace is usually about 204°C (400 degrees Fahrenheit) -557°C (1035 degrees Fahrenheit).

US4853257, 4971843, 5536718, 5464657 and 5599387 describe CVD coating devices and methods. These documents are incorporated herein by reference. These devices and methods can be used to implement the present invention for coating float glass in the manufacturing process of float glass. Glass ribbon. Since the CVD method can coat a moving float glass ribbon (at this time, the glass ribbon is also subjected to the harsh environment related to the manufacture of float glass), the CVD method is particularly suitable for forming a PASC coating on the float glass ribbon 24 . The CVD coating device can be used at several locations in the float glass manufacturing process, for example, when the float glass ribbon leaves the tin bath and moves through the tin bath, before it enters the annealing furnace, when it moves through The annealing furnace or the CVD coating device is used after it leaves the annealing furnace.

As those skilled in the art can understand, the concentration of the metal-containing precursor in the carrier gas, the flow velocity of the carrier gas, the velocity of the float glass ("linear velocity"), the relative value of the CVD coating device to the float glass The surface area of the glass surface, the surface area and flow velocity of the exhausted carrier gas passing through the exhaust pipe of the CVD coating device, more specifically, the ratio of the exhaust velocity through the exhaust pipe to the carrier gas input velocity through the CVD coating unit, That is, the "exhaust gas mix ratio" and the temperature of the float glass ribbon are parameters that may affect the final thickness and morphology of the PASC coating 24 formed on the float glass ribbon by the CVD method.

US4719126, 4719127, 4111150 and 3660061 describe spray pyrolysis devices and methods that can be used with the float glass manufacturing process, which documents are incorporated herein by reference. Although the spray pyrolysis method similar to the CVD method is particularly suitable for coating the moving float glass ribbon, the spray pyrolysis method has a more complicated device than the CVD device and is usually between the outlet end of the tin bath and the inlet end of the annealing furnace. Used between.

As those skilled in the art can understand, the composition and concentration of the aqueous suspension for pyrolysis spraying, the linear velocity of the float glass ribbon, the number of pyrolysis spray guns, the spray pressure or volume, the spraying style and the float during deposition The temperature of the glass is a parameter that affects the final thickness and morphology of the PASC coating 24 formed on the float glass ribbon by the pyrolytic spraying method.

As those skilled in the art can understand, the surface of the float glass ribbon on the molten tin bath (commonly referred to as the "tin side") has diffused tin in the surface, which makes the tin side have tin absorption The pattern, which is different from the opposite side that is not in contact with molten tin (usually called the "air side"). This feature is in "Chemical Properties of Float Glass Surface", Seiger, J., "Journal of Amorphous Solid State", Vol.19, pp.213-220 (1975); "The diffusion of tin on the bottom surface of float glass: Synthesis", Columbin L. et al., "Journal of Amorphous Solid State", vol.38&39, pp551-556 (1980); and "Determining the oxidation state of tin in float glass by Mossbauer spectroscopy, the depth curve of Sn2+ and Sn4+, and the diffusion of oxygen Coefficient", Wiliams, KFE et al., "Journal of Amorphous Solid State", Vol.211, pp.164-172 (1997), these documents are incorporated herein by reference. As those skilled in the art understand, the PASC coating 24 can be formed on the air side of the float glass ribbon by the CVD method when the float glass ribbon is supported on the tin bath; it can be formed by the CVD method or thermal spraying. The solution is formed on the air side of the float glass ribbon after it leaves the tin bath and can be formed on the tin side of the float glass ribbon after it leaves the tin bath by the CVD method. When the PASC coating 24 is formed on the tin side of the float glass ribbon, it can be considered that the tin/tin oxide present in the glass surface will act as the SIDB layer 26 on which the PASC coating 24 is located.

US4379040, 4861669, 4900633, 4920006, 4938857, 5328768 and 5492750 describe MSVD devices and methods, which are incorporated herein by reference. These devices and methods are used for sputtering metal oxide films on substrates, including glass substrates. The MSVD method is generally not suitable for forming a PASC coating on the float glass ribbon during the float glass manufacturing process. This is because the MSVD method requires negative pressure during the sputtering process, which is difficult to form on the continuously moving float glass ribbon. However, the MSVD method easily deposits the PASC coating 24 on the substrate 22, such as a glass plate. As understood by those skilled in the art, the substrate 22 can be heated to a temperature of about 400°C (752°F)-500°C (932°F), so that the MSVD sputtered coating on the substrate is deposited Crystallization in the process, thus eliminating the need for subsequent heating process. Heating the substrate during the sputtering process is not a preferred method because the additional heating process will reduce the yield. In addition, the sputtered coating can be crystallized in the MSVD coating device directly and without subsequent heat treatment by using high-energy plasma. However, this method is not a preferred method because the production of the MSVD coating device will be reduced.

The preferred method of using the MSVD method to form the PASC coating is to sputter the coating on the substrate, remove the coated substrate from the MSVD coater and heat the coated substrate to crystallize the sputtered coating The PASC coating 24 is formed. For example, but not limited to the present invention, using the MSVD method, the titanium metal target is at a pressure of about 5-10 millitorr (0.67-1.33Pa) with about 5-50%, preferably about 20% oxygen. In an argon/oxygen atmosphere, a titanium dioxide coating having a desired thickness is sputtered and deposited on the substrate 22. The deposited coating is uncrystallized. The coated substrate is removed from the coating machine and heated to about 400°C (752°F)-600°C (1112°F), and kept for a period of time to fully promote the formation of the crystalline form of titanium dioxide PASC, thus having PASC activity. Usually at least one hour at a temperature of about 400°C (752°F)-600°C (1112°F) for one hour. When the substrate is a glass plate cut from a float glass ribbon, the PASC coating 24 may be sputter deposited on the air side and/or the tin side.

Then, the substrate 22 with the PASC coating 24 formed by CVD, spray pyrolysis or MSVD deposition can be subjected to one or more post-PASC coating annealing treatments to increase the self-cleaning activity of the PASC coating 24. It is believed that this post-PASC coating annealing increases the self-cleaning activity of the PASC coating 24 by promoting the formation of the desired PASC crystalline phase. As one can understand, the annealing time and temperature are affected by several factors, including the composition of the substrate 22, the composition of the PASC coating 24, the thickness of the PASC coating 24, and whether the PASC coating 24 is directly on the substrate 22 or It is one of the multi-layer stacks on the substrate 22. It has been determined that when the substrate 22 is a piece of float glass and the PASC coating is 400 angstroms or 625 angstroms, an anatase titanium dioxide layer formed by spray pyrolysis, annealing at 500°C (932°F) for less than 13 minutes can increase PASC active.

As mentioned above, when the PASC coating is formed by CVD, spray pyrolysis or MSVD, if the substrate 22 contains sodium ions that can migrate from the substrate 22 to the PASC coating deposited on the substrate 22, these Sodium ions form inactive compounds and consume titanium at the same time, for example, by forming sodium titanate or by recombining photo-activated charges to inhibit or destroy the photocatalytic activity of the PASC coating.

It has been found that the PASC coating can be formed on the substrate 22 containing sodium ions without loss of photocatalytic activity. This is achieved by: 1) subjecting part of the PASC coating to limited local sodium ion poisoning; and/or 2) providing an SIDB layer 26. These two methods will be described in detail below.

It has been found that when the PASC coating exceeds the minimum limit value, the PASC activity will not be damaged by the migration of sodium ions, even when the substrate is at a temperature sufficient to allow sodium ions to migrate from the substrate to the PASC coating. Sodium substrate surface. Although the mechanism of this result is not fully understood, it can be considered that when the thickness of the PASC coating exceeds the minimum thickness, the sodium ions can only migrate through part of the PASC coating when the substrate temperature exceeds the temperature at which sodium ions can migrate. thickness. Then when the substrate temperature drops below the temperature at which sodium ions can migrate, the sodium ion migration will stop or "freeze", resulting in no sodium ion poisoning in the thickness of the PASC coating opposite to the substrate surface and the PASC activity can be maintained. As those skilled in the art can understand, the minimum thickness of this PASC coating varies with the stated parameters, such as but not limited to the time the substrate is kept at a temperature higher than the temperature at which sodium ions can migrate, and the use of PASC products And the degree of PASC activity required. It has been found that for a titanium dioxide PASC coating deposited by CVD on a piece of soda-lime-silica flat glass, the thickness of the PASC coating should be at least about 250 angstroms, preferably at least about 400 angstroms, and more preferably at least about 500 angstroms. Therefore, a sufficient part of the PASC coating 24 can remain free from sodium ion poisoning and maintain its PASC activity.

Now referring to FIG. 2, in another method for preventing sodium ion poisoning of the PASC coating 24, there is a SIDB layer 26 between the PASC coating 24 and the substrate 22. The SIDB layer 26 may be the only layer between the PASC coating 24 and the substrate 22, or it may be a layer in a multi-layer stack. When a multi-layer stack is used, there is no need to contact the SIDB layer 26 with the substrate 22, as long as the SIDB layer 26 is located between the PASC coating 24 and the substrate 22 to prevent sodium ions from migrating from the substrate 22 to the PASC coating 24.

The SIDB layer 26 may be formed of amorphous or crystalline metal oxides, including but not limited to cobalt oxide, chromium oxide and iron oxide, tin oxide, silicon oxide, titanium oxide, zirconium oxide, fluorine-doped tin oxide, aluminum oxide, magnesium oxide, Zinc oxide and its mixtures. Mixtures include, but are not limited to, magnesium oxide/aluminum oxide and zinc oxide/tin oxide. As understood by those skilled in the art, metal oxides may include metal oxides, peroxides, or suboxides. Although the thickness of the SIDB layer to prevent sodium ion poisoning of the PASC coating varies with several factors, including the time the substrate is maintained at a temperature higher than the temperature at which sodium ions migrate, the speed of sodium ion migration from the substrate, and sodium ion migration Through the speed of the SIDB layer, the thickness of the PASC coating and the degree of photocatalytic activity required for a certain application, typically for most applications, the thickness of the SIDB layer should be at least about 100 angstroms, preferably at least It is about 250 angstroms, more preferably at least 500 angstroms, to prevent sodium ion poisoning of the PASC coating. The SIDB layer may be deposited on the substrate 22 by CVD, spray pyrolysis, or MSVD method. When a spray pyrolysis method or a CVD method is used, it is preferable to maintain the substrate 22 at at least about 400° C. (752 degrees Fahrenheit) to ensure that the metal-containing precursor decomposes, thereby forming the SIDB layer. The SIDB layer can also be formed by other methods, including the sol-gel method. As mentioned above, the sol-gel method does not match the float glass ribbon manufacturing process.

The tin oxide SIDB layer can be deposited on the substrate by spray pyrolysis by forming an aqueous suspension of dibutyltin difluoro (C4H9) 2SnF2 and water and coating the aqueous suspension on the substrate by spray pyrolysis. Generally, the aqueous suspension contains 100-400 g dibutyltin difluoro/liter of water. A wetting agent can be added as a suspension accelerator. In the process of preparing the aqueous suspension, dibutyltin difluoride can be ground to an average particle size of 1-10 microns (10-6m). Preferably, the aqueous suspension is stirred vigorously so that the particles are uniformly distributed in the suspension. The aqueous suspension is delivered to the surface of the substrate by spray pyrolysis, and the surface of the substrate is heated to at least about 400°C (752°F), preferably about 500-700°C (932-1292°F), thereby The aqueous suspension is decomposed to form a tin oxide SIDB layer. As people can understand, the thickness of the SIDB layer formed by this method will be affected by the coating line speed, the concentration of dibutyltin difluoride in the aqueous suspension, and the spraying speed.

In addition, the tin oxide SIDB layer may be formed on a substrate by a CVD method from a metal-containing precursor such as trichloromonobutyltin vapor (hereinafter referred to as "MBTTCL") in an air carrier gas mixed with water vapor. MBTTCL steam may be present in the air carrier gas coated on the substrate at a concentration of at least about 0.5%, when the substrate is at a temperature sufficient to decompose the tin-containing layer, for example, at least about 400°C (952°F), preferably The ground is about 500-800°C (932-1472 degrees Fahrenheit), thereby forming a tin oxide SIDB layer. As one can understand, the thickness of the SIDB layer formed by this method is affected by the coating linear velocity, the concentration of MBTTCL vapor in the air carrier gas, and the carrier gas flow velocity.

The SIDB layer formed by the MSVD method is disclosed in U.S. Patent Application Serial No. 08/597543 (filed on February 1, 1996 under the name "Alkali Metal Diffusion Barrier Layer"), which is incorporated herein by reference, which discloses alkali metal Formation of diffusion barrier. The barrier layer mentioned therein is usually effective at a thickness of about 20-180 angstroms, and when the density of the barrier layer increases, its effect will also increase.

The PASC coating of the present invention is usually photocatalytically activated to form self-cleaning when exposed to ultraviolet light, such as the electromagnetic spectrum of 300-400 nanometers. Ultraviolet radiation sources include natural light sources, such as solar radiation and artificial light sources, such as black light or ultraviolet light sources, such as UVA-340 light sources. When artificial ultraviolet light sources are used under test conditions to determine how the PASC coating reacts with natural ultraviolet radiation, as people understand, UVA-340 has a light energy distribution that is very close to the solar light source, while the black light source is not so close. In this way, UVA-340 light source can be used to estimate the PASC coating when exposed to sunlight very closely.

The ultraviolet radiation intensity is calibrated to an intensity of at least about 20 watts per square meter on the coated surface to be tested. The intensity can be calibrated, for example, by an ultraviolet light meter, such as the ultraviolet light meter sold by Ultraviolet Products, Inc., of San Gabriel, Ca under model J-221. It is preferable to place the light source in a position perpendicular to the coated surface to be tested.

The UV radiation source and the PASC coating can be placed on each other such that the UV radiation first passes through the PASC coating and then through the substrate (ie, the front or "coating side"). When passing the ultraviolet radiation from the substrate, the PASC coating and the ultraviolet radiation source can be placed so that the ultraviolet radiation first passes through the substrate and then the PASC coating (ie, the back or "substrate side"). In another solution, one or more ultraviolet radiation sources can be placed on the side of the substrate with the PASC coating on one or both surfaces.

As people can understand, due to the influence of many factors, it is difficult to accurately determine the preferred ultraviolet radiation source or intensity or the relative position of the ultraviolet radiation source/PASC coating/substrate. These factors include: the purpose of use of the PASC coating, such as indoor or outdoor, the selected ultraviolet light source, such as natural or artificial, the influence of seasonal or geographic factors when the ultraviolet radiation source is natural, and the required ultraviolet radiation Exposure time, the incident angle of the ultraviolet radiation relative to the PASC coating surface, the speed of PASC activity required, the degree of reflection or absorption of the ultraviolet radiation by the substrate and/or the surface of the substrate or any other coating on the PASC coating, and the amount to be removed Impurities, the thickness of the PASC coating, the composition of the PASC coating, the possibility of sodium ion poisoning, and whether there is a SIDB layer. However, it has been found that when measured at the surface of the PASC coating by an ultraviolet radiation source located on the surface of the PASC coating, an ultraviolet radiation intensity of about 5-100 watts/square meter, preferably at least about 20 watts/square meter, can produce enough In order to form suitable PASC activity, it can be used in a variety of self-cleaning applications.

It is useful to be able to measure and compare the PASC effect or the activity of the PASC coating to evaluate the PASC activity of the PASC coating. A known commercially available organic impurity can be coated on the PASC coating, and after photocatalytic activation of the PASC coating, the ability of the PASC coating to remove the organic impurities can be observed and measured. Stearic acid CH3(CH2)16COOH is a standard organic "impurity" for testing the PASC activity of PASC coatings. This is because stearic acid is a carboxylic acid with a long hydrocarbon chain, so it is present in conventional impurities, such as household Good "model molecules" for molecules in oil and garbage. Stearic acid can be applied as a thin test film on the PASC coating by conventional techniques, including dip coating, spray coating, and spin coating. Generally speaking, a stearic acid test film with a thickness of about 100-200 angstroms can provide a suitable test film. Stearic acid can be applied as a solution of stearic acid in a methanol solution and it has been found that a solution with a concentration of about 6 x 10-3 moles of stearic acid per liter of solution is suitable.

The PASC activity of the PASC coating can be achieved by coating the PASC coating with a stearic acid film (when applied to the PASC coating, the film usually appears as a light brown coating) to turn the stearic acid film to a suitable strength Exposure to UV radiation for a suitable time and visually inspect the stearic acid film to see if the stearic acid film has completely disappeared or compared to the part of the stearic acid film coated on the PASC coating but not exposed to UV radiation. It is quantitatively estimated whether the blackness of the fatty acid film decreases.

The PASC activity of the PASC coating can also be quantitatively determined by measuring the integrated intensity of the hydrocarbon of stearic acid (hereinafter referred to as "CH") existing on the PASC coating to extend the vibration absorption band. The integrated intensity is equivalent to the thickness of the stearic acid film remaining on the surface of the PASC coating, and the removal of the stearic acid film by self-cleaning by photocatalytic activation will cause the intensity of the CH extension vibration band to decrease. In the presence of the CH bond in stearic acid will absorb infrared radiation which is different from ultraviolet radiation, and it will not photocatalytically activate the PASC coating. This absorption usually occurs between 2800-3000 nm-1 wavenumber, and can pass Fourier Tranform Infrared Spectrophotometer (hereinafter referred to as "FTIR spectrophotometer") to measure. The FTIR can be equipped with a detector, such as a deuterated triglycine surface detector (hereinafter referred to as "DTGS detector") or a mercury-cadmium-telluride detector (hereinafter referred to as "MCT detector"). The MCT detector is preferred because it can provide a higher signal-to-noise ratio than the DTGS detector. This is important when the substrate and/or coatings other than the PASC coating absorb the infrared radiation used by the spectrophotometer to generate the absorption spectrum. When infrared radiation is absorbed by the substrate and/or other coatings, the intensity of the infrared radiation beam that passes through the stearic acid film, PASC coating and substrate and reaches the detector is significantly reduced. Combine this with the low concentration of stearic acid present on the surface of the PASC coating (which produces very weak infrared radiation absorption characteristics) and the infrared radiation signal obtained is not particularly strong. Therefore, an instrument equipped with an MCT detector provides a spectrum whose signal-to-noise ratio is approximately higher than that of a DTGS detector. When measuring the PASC activity of the stearic acid test film deposited on the film and the substrate that can transmit the infrared radiation beam, the infrared radiation beam can be transmitted through the film and the substrate to the detector located on the opposite side of the test sample. When the film or substrate cannot allow infrared radiation to pass through, the infrared radiation beam can be directed at the surface at a certain angle, pass through the stearic acid test film and be reflected by the substrate to reach the detector. The latter method is known as reflection infrared spectroscopy.

The PASC reaction rate of the PASC coating can be determined by measuring the speed at which the PASC coating reacts to remove the stearic acid film when the PASC coating is exposed to actinic radiation. Furthermore, the reduction rate of the integrated intensity of the CH extension vibration characteristic (proportional to the surface coverage) with the cumulative time of exposure to actinic (UV) radiation provides the PASC reaction speed. For example, an FTIR spectrophotometer is used to determine the initial PASC activity of a test film of stearic acid present on the PASC coating. For the initial PASC activity determination, the PASC coating can be exposed to ultraviolet radiation or not. Then, the PASC coating coated with stearic acid was exposed to ultraviolet radiation for a certain period of time, and at the end, the second PASC activity measurement was performed with an FTIR spectrophotometer. The integrated intensity of the CH extension vibration in the second measurement may be lower than that in the first time because part of the stearic acid test film was removed due to exposure to ultraviolet radiation. For these two measurements, the integrated intensity of CH extensional vibration can be plotted against time, and its slope is the PASC response speed. Although two points are sufficient to provide the curve, several measurements were performed during the PASC activity determination process to provide a more accurate curve. Although the exposure time to UV radiation during the FTIR measurement can be unchanged or can be changed when the PASC activity measurement is accumulated twice or more (when it is the cumulative time of UV radiation exposure used to draw the curve), when measuring the PASC reaction speed At this time, the intensity and direction of the ultraviolet radiation (coating side or substrate side) remain unchanged for all PASC measurements.

The PASC reaction speed can be described in units of cm-1 min-1, and the higher the value, the greater the PASC activity. There is no absolute value that makes the PASC coating "suitable" or "unsuitable", because whether the PASC coating has the appropriate PASC level depends mainly on the purpose of the PASC coated product and the performance standards selected for this purpose. For most applications, a PASC activity of at least about 2×10-3, preferably at least about 5×10-3/cm·min is required.

It is useful to measure the thickness of the PASC coating, so that the PASC activity of the PASC coating prepared according to the present invention can be completely determined and compared. This is because the thickness of the PASC coating will affect the photocatalytic activity, which can be seen from the following examples prove. The thickness of the PASC coating 24 and the /SIDB layer 26 (if present) can be determined by Variable Angle Spectroscopic Ellipsometry (hereinafter referred to as "VASE") or by the measurement result of the edge-removed curve in the measurement film, or estimated by the interference color , As known in the art.

The particle size of the PASC coating 24 and the /SIDB layer 26 (if present) can be calculated from X-ray diffraction (hereinafter referred to as "XRD") through the Scherrer relationship. This relationship is known in the art, and its content can be found in "Methods for X-ray Diffraction Analysis of Polycrystalline and Amorphous Materials", Klug and Alexander, John Wiley & Sons, Inc. (1954), Chapter 9.

The following embodiments of the present invention are for illustration, and the present invention is not limited to these embodiments.

Example 1 The PASC activity of the 2100 angstrom PASC coating formed by the CVD method and the titanium dioxide PASC coating with a thickness of about 2100 angstroms was investigated in the following manner. The CVD method was used to deposit a PASC coating on the substrate 22, which is the air side of a soda lime silica float glass plate sold under the trademark SOLEX(R) glass by PPG Industries, Pittsburgh, Pennsylvania. Referring to Figure 3, the measured width of the Solex® glass sheet is about 5.5 inches, the length is about 12 inches, and the thickness is about 0.016 inches (14 cm wide × 30.5 cm long × 0.4 cm thick) and is coated with CVD as shown in Figure 3 The device is coated with titanium dioxide PASC coating. The CVD coater generally includes the three regions shown in FIG. 3, which are separated by vertical dashed lines 90 and 92. The three areas include a preheating area 94, a coating area 96, and an annealing area 98. The Solex(R) glass sheet (hereinafter referred to as the base 22) is moved on the endless conveyor belt 102 in the direction indicated by the arrow through three areas.

The substrate 22 moves into the preheating zone 94 and is preheated to about 649° C. (about 1200 degrees Fahrenheit) by a plurality of heaters 106 located above and below the conveyor belt 102. The substrate 22 is moved into the CVD coating area 96 through the conveyor belt 102. As people understand, the CVD coating area 96 includes at least one coating unit 97. In order to deposit more than one coating layer sequentially, the coating area 96 may include a plurality of coating units 97. The coating unit 97 includes support subsystems and controls such as gas delivery subsystem, liquid delivery subsystem, temperature control, exhaust subsystem and control, and temperature and pressure monitoring subsystems. None of the units are shown in the figure. The gas delivery subsystem controls the flow of carrier gas to the surface of the substrate 22. Nitrogen is used as the carrier gas. The incoming nitrogen flow was controlled to 113°C (approximately 235°F) by a heater not shown. NH3 is contained in the carrier gas at 20% of the total flow rate. The exhaust air velocity is 125% of the incoming air velocity. The metal-containing precursor used to deposit the titanium dioxide PASC coating on the substrate 22 is TTIP, which is 0.4% of the total gas flow volume and is fed at a temperature of about 113°C (about 235°F). The total gas flow of N2, NH3, and TTIP steam passing through the CVD coater 88 is 75 standard liters/minute. The linear speed of the conveyor belt 102 is about 50 inches (127 cm) per minute, and the width of the coating unit opening is about 3/16 inches (0.48 cm). The substrate 22 is maintained at about 554° C. (1030 degrees Fahrenheit) while the coating layer 24 is deposited on the substrate 22 under the coating unit 97 to form a coating sample 100. A titanium dioxide PASC coating 24 with a thickness of approximately 2100 angstroms (measured by VASE) was formed on the coated sample 100.

Then the coated sample 100 is advanced into the annealing zone 98, where it is annealed from the starting temperature of about 549°C (1020°F) to the final temperature of about 121°C (250°F) in about 26 minutes. .

XRD analysis was performed on sample 100 coated with PASC. The particle size of the PASC coating 24 was determined to be about 309 angstroms (calculated using Sherrel's relationship). The coated sample 100 showed a strong absorption peak corresponding to anatase titanium dioxide in the XRD pattern.

A stearic acid film was coated on the PASC-coated sample 100 to measure its photocatalytic activity. The stearic acid/methanol solution has a concentration of about 6×10-3 moles of stearic acid per liter of solution. The stearic acid solution is sucked into the center of the sample 100 at a rate of about 2 ml/10 seconds, while passing through The coated sample 100 is rotated at a speed of about 1000 revolutions per minute, and the stearic acid flows to the entire surface of the coated sample 100 by centrifugal force, thereby forming a stearic acid film with a generally uniform thickness on the surface of the coated sample 100 , Its thickness is about 100-200 angstroms. Since the thickness of the stearic acid layer is not fixed along the length of the coated sample 100, the term "usual" is used here, but due to the effect of centrifugal force, the thickness is the thickest at the end of the coated sample 100, and in the center Thinnest. As people understand, the stearic acid solution concentration, rotation speed, sample size and liquid absorption speed can be changed to obtain a stearic acid coating with a desired thickness. When measured by calibrating the IR intensity with a quartz crystal microbalance, the average thickness of the stearic acid test film is about 150 angstroms under the above parameters.

The sample 100 coated with the stearic acid test film/titanium dioxide PASC coating was exposed to ultraviolet radiation from a black light source perpendicular to the coating side of the sample 100, and the intensity at the surface of the PASC coating 24 was about 20 watts/square meter. Accumulate for about 30 minutes to induce the photocatalytic activation of the stearic acid film to self-clean. The FTIR spectrophotometer equipped with an MCT detector was used to perform regular FTIR spectrophotometric measurements within a cumulative UV exposure period of 30 minutes to quantitatively determine the photocatalytic activity. Furthermore, the sample 100 coated with the stearic acid test film/PASC is exposed to ultraviolet radiation for a certain period of time, and then the coated sample 100 is placed in an FTIR spectrophotometer, where the measurement is performed on stearic acid The integrated area under the CH absorption band determines PASC activity. The coated sample 100 was again exposed to ultraviolet radiation for a period of time to remove additional stearic acid, after which another FTIR measurement was performed. This process is repeated to obtain the point of the integrated IR absorption of the CH extension vibration versus the cumulative UV exposure time, the slope of which provides the PASC speed of the stearic acid test film/titanium dioxide PASC coated sample 100. As it is understood, all measurements are performed on approximately the same area of the coated sample 100 to minimize the influence of the thickness variation of the stearic acid film as described above. The measured photocatalytic reaction rate is 3.53×10-3/cm·min, which is close to the value of PASC coated substrates (such as quartz glass substrates) containing little or no sodium ions, which indicates that the thickness of the titanium dioxide PASC coating is sufficient to overcome Sodium ion poisoning.

Example 2 Formation of 700-800 Angstrom PASC coating by CVD method In the same manner as in Example 1, a titanium dioxide PASC coating with a thickness of about 700-800 Angstrom was deposited on a glass substrate by CVD method. The differences are as follows Say.

The glass composition used in Example 2 was 3 mm (0.12 inch) thick transparent (ie, low-iron soda lime silica) glass. The preheating temperature in Example 2 is 593°C (1100°F). The TTIP concentration in Example 2 is 0.1%, and the total flow rate is 50 standard liters/minute. NH3 is contained in the carrier gas at 24% of the total flow rate. The line speed is 30 inches/minute (76.2 cm/minute). The mouth width is 1/16 inch. The thickness of the titanium dioxide PASC coating 24 is estimated from the interference color, which is a technique known in the art for measuring the thickness of the film, and it is determined to be approximately 700-800 angstroms.

The stearic acid test film was coated on the titanium dioxide PASC coating in the same manner as in Example 1, and after exposure to UV light in the same manner as in Example 1, PASC active FTIR was periodically performed during a 33-hour accumulation period. Spectrophotometric determination. After measurement, the photocatalytic reaction rate is about 0.17×10-3/cm·min.

The decrease in PASC activity in Example 2 can be considered to be due to the difference in the thickness of the titanium dioxide coating between Examples 1 and 2 (about 2100 angstroms vs. about 700-800 angstroms). Furthermore, it can be considered that the PASC reaction rate of Example 2 is lower than that of Example 1. This is because the percentage of the total thickness of the titanium dioxide coating used for the titanium dioxide PASC coating is greater than that of Example 1, and sodium ions diffuse to The thickness in the titanium dioxide coating of Example 2 is increased. It can be considered that sodium ions migrated from the glass sample into the PASC coating of Example 2 in the annealing furnace 44. By comparing Example 1 and Example 2, a conclusion can be drawn that when there is no SIDB layer, a thicker PASC coating is less prone to sodium ion poisoning, thereby maintaining a higher PASC activity.

Example 3 Formation of PASC coating on SIDB layer by CVD method In this example, the influence of the presence of tin dioxide SIDB layer on PASC activity was studied. Furthermore, a tin oxide SIDB layer was formed on the air side of four pieces of float glass and some physical characteristics of the SIDB layer were investigated. Then, a titanium dioxide SIDB layer was formed on the other 16 float glass sheets by the CVD method, and each layer of the titanium dioxide SIDB layer was coated with a titanium dioxide PASC coating by the CVD method. Cut a sample from each of the 16 float glass sheets coated with the PASC/SIDB layer, and coat the 16 samples with a stearic acid test film, and coat the 16 blocks with a stearic acid test film/titanium dioxide PASC coating /The sample of the tin dioxide SIDB layer was exposed to ultraviolet radiation and the PASC reaction rate of the sample was measured. 3A. Research on the SIDB layer The SIDB layer was coated on the air side of four pieces of glass by the CVD method using the coating device described in Example 1. These glass pieces were cut on the soda-lime-silica float glass ribbon Coming out, its size is about 5 inches × 12 inches × 0.16 inches thick (12.7cm × 30.48cm × 0.4cm). Furthermore, the SIDB layer is a tin dioxide SIDB layer, and the concentration of the precursor containing the metal, the water vapor concentration, the CVD linear velocity, the preheating temperature, and the thickness of the SIDB layer on the tin dioxide SIDB layer are studied. The metal-containing precursor used to form the SIDB layer of tin dioxide by the CVD method on all four pieces of glass is MBTTCL vapor, which is mixed with water vapor in an air carrier gas.

By directing MBTTCL vapor to the air side of the glass sheet at a concentration of about 1.5% in the air carrier gas and water vapor at a concentration of about 1.5% in the air carrier gas, the CVD method and device described in Example 1 were used in the fourth The first piece of glass is coated with a tin oxide SIDB layer. The preheating temperature of the glass sheet is about 648°C (1200 degrees Fahrenheit), and the linear velocity is about 50 inches (127 cm) per minute. The thickness of the tin oxide SIDB layer thus formed is approximately 3500 angstroms as measured by VASE. The resistance and particle size of the SIDB layer were measured, and the results were about 4.6×10-3 ohm·cm and 198 angstroms, respectively.

Similarly, the second piece of glass is coated with a tin oxide SIDB layer, but the line speed is reduced to about 20 inches (50.8 cm)/min and the vapor concentration of MBTTCL in the air carrier gas is reduced to about 0.5%, and the water vapor is in the air carrier gas. The concentration in is reduced to about 0.5%. The preheat temperature is maintained at approximately 648°C (1200°F). The thickness of the tin oxide SIDB layer thus formed was about 4340 angstroms as measured by VASE. The resistance is about 3.9×10-3 ohm·cm, and the particle size is about 185 angstroms.

The third piece of glass was similarly coated with a tin oxide SIDB layer, but the preheating temperature was reduced to about 480°C (900°F) and the line speed was increased to about 50 inches (127 cm) per minute. The concentration of MBTTCL is about 1.5%, and the concentration of water vapor in the air carrier gas is about 1.5%. The obtained tin oxide SIDB layer has a coating thickness of about 1000 angstroms measured by VASE, a resistance of about 3.8×10-2 ohm·cm, and a particle size of about 59 angstroms.

The third glass is similarly coated with a tin oxide SIDB layer, but the preheat temperature is maintained at about 480°C (900°F) and the line speed is reduced to about 20 inches (50.8 cm)/minute. The concentration of MBTTCL is about 0.5%, and the concentration of water vapor in the air carrier gas is about 0.5%. The obtained tin oxide SIDB layer has a coating thickness of about 1010 angstroms measured by VASE, a resistance of about 2×10-2 ohm·cm, and a particle size of about 78 angstroms.

From the above content, it can be concluded that in the above-mentioned temperature range, concentration, linear velocity and SIDB layer thickness, although the resistance or particle size can be changed, all four pieces of glass have a cassiterite structure. 3B. Form a titanium dioxide PASC coating on the tin oxide SIDB layer by the CVD method. Another 16 pieces of float glass with a size of 5 inches × 12 inches × 0.16 inches (12.7 cm × 30.48 cm × 0.4 cm) are each used in the implementation. The CVD coater and process described in Example 3A coats the tin oxide SIDB layer and the CVD coating equipment and process described in Example 1 are then used to coat the titanium dioxide PASC coating. For this coating operation, the online CVD process uses a pair of continuous coating units (one for the SIDB layer and the other for the PASC coating). The PASC coating on the SIDB layer makes it difficult (if impossible) to analyze the SIDB layer separately. Therefore, it can be considered that the PASC coated on the tin oxide layer has the same characteristics as the non-overcoating described in section 3A above. The tin oxide layer has the same properties, although the SIDB layer and the PASC coating are applied to 16 glass sheets under various specific coating parameters which will be described in detail below and listed in Table 1 below.

Generally speaking, 16 tin oxide SIDB layers are deposited from metal-containing precursors of MBTTCL vapor mixed with water vapor (also carried in air) in an air carrier gas. The MBTTCL steam temperature is maintained at approximately 160°C (320°F). The total flow rate is about 60 standard liters/minute, and the discharge mix ratio is 115%. The mouth width is 0.16 cm (1/16 inch). The specific coating parameters that can be changed for the SIDB layer in this embodiment include the preheat zone 94 temperature, linear velocity, MBTTCL concentration, water vapor concentration, and SIDB layer thickness. Shown in Table 1 below are the coating parameters of the tin dioxide SIDB layer and the desired SIDB layer thickness of each of the 16 pieces of glass. The actual thickness measurement has not been obtained, and the desired thickness is based on the results obtained in section 3A above. According to the preheating temperature and line speed, the 16 slices in Table 1 are divided into four groups, each with four slices.

On each of the 16 pieces of glass coated with SIDB layer, a titanium dioxide PASC coating was again coated, which was deposited by the second coating unit located downstream of the first SIDB coating unit, TTIP containing metal in nitrogen carrier gas The vapor precursor is directed onto the surface of the glass sheet coated with the SIDB layer through the second coating unit. NH3 was added to the TTIP/carrier gas mix for use on 8 of the 16 glass. For all 16 pieces of glass, the carrier gas is maintained at approximately 113°C (235°F). Sixteen pieces of glass were annealed as in Example 1. Keep the TTIP steam temperature at approximately 104.4°C (220°F). Shown in Table 2 below are the titanium dioxide PASC coating parameters for 16 pieces of glass. According to the preheating temperature and line speed, in Table 2, 16 pieces of glass are divided into 4 groups, 4 pieces in each group.

*The preheating temperature here refers to the temperature of the preheating zone 94. There is only one preheating operation, and the preheating temperature listed above is the glass in the preheating zone when the glass sheet moves through the CVD coater 88 before entering the annealing zone 98 and receives the SIDB layer for the first time and then performs PASC coating. The elevated temperature of the flakes.

**1/16 inch = 0.16cm, 3/16 inch = 0.48cm

Shown in Table 3 below are the properties of each of the 16 selected glass sheets after applying the PASC coating as described in Table 2. The thickness of the PASC coating has not been measured, but due to changes in other parameters such as linear velocity and precursor concentration, it is estimated that there are changes in each group. However, surface roughness and particle size are measured to correlate PASC activity with roughness and particle size. The surface roughness measurement is estimated by the measurement result of an atomic force microscope (hereinafter referred to as "AFM") made of PASC coating. It has been found that there are large changes in surface roughness and particle size and the crystalline phase changes with the preheating temperature.

*The particle size cannot be measured. This is because the anatase peaks (samples 1, 2, 5, 6, 8, 9 and 14) are not detected in the X-ray diffraction pattern or the peaks are too wide and weak to be measured (Sample 3, 4, 7 and 15). 3C. The PASC activity test of 16 substrates describes a 1 inch x 4 inch (2.54 cm x 10.16 cm) sample or test strip at the center of each of 16 PASC/SIDB-coated glass plates. Each of the 16 test pieces was spin-coated with the stearic acid test film as described in Example 1. Then 16 test strips were exposed to ultraviolet radiation from a black light source with an intensity of 20 W/m 2 for 7 hours to induce photocatalytic activation of the self-cleaning stearic acid test film.

Since the thickness of the stearic acid test film varies along the length of the 1 inch × 4 inch (2.54 cm × 10.16 cm) test strip (that is, as mentioned above and can be seen by visual observation of the interference color change along the length of the test strip) The effect of centrifugal force when stearic acid drops in the center of the rotating test strip, there is a thicker stearic acid film at the end of the test strip, and a thinner stearic acid film at the center of each strip) , FTIR spectrophotometer equipped with MCT detector was used to test the photocatalytic activity at the ends of 16 test strips. Table 4 shows the PASC reaction speed obtained from the FTIR spectrophotometric test for each pair of tests performed on 16 test strips.

It can be clearly seen from Table 4 that for some test strips, there is a very obvious difference in the activity at both ends of the test strip. This difference can be considered to be related to the uneven thickness of the stearic acid film on the test strip.

See Table 4, there appears to be no relationship between the deposition conditions and the PASC activity of the PASC coating on the SIDB layer. According to the activity on the left side of the test strip, the three most active test strips shown in Table 4 are samples 13, 10, and 14. Bars 13, 10, and 14 correspond to a higher preheat temperature of 1200 degrees Fahrenheit (648.8°C). If the PASC activity is used for arraying, the remaining 13 test strips show mixed preheating temperature and other coating parameters, which indicates that the presence of the sodium ion diffusion barrier can prevent the PASC coating from being poisoned by sodium ions and can be used in the coating A wider range of conditions and parameters can be obtained while still obtaining photocatalytic activity.

Example 4 Formation of PASC coating by spraying pyrolysis method In this example, different thicknesses of titanium dioxide PASC coatings were coated on glass sheets by spraying pyrolysis method to study the influence of PASC coating thickness on PASC activity.

The air side of three float glass sheets with dimensions of 4 inches×4 inches×0.16 inches (10.16 cm×10.16 cm×4 cm) was sprayed and pyrolyzed with a titanium dioxide PASC coating.

The base part of the pyrolytic spraying device used to coat the PASC coating on the glass sheet is shown in FIG. 4. The spraying pyrolysis device includes a preheating zone 120 and a pyrolysis spraying zone 122. The glass sheet 126 is conveyed on an unshown conveyor into the preheating zone 120, where it is heated by a plurality of electric heaters 130 to a temperature of about 600-700°C (1112-1292 degrees Fahrenheit). The glass sheet 126 is then transported back to a vibrating nozzle 132, which is placed about 10 inches (25.4 cm) above the air side of the glass sheet 126. The aqueous suspension of the organometallic coating agent 134 is kept suspended in the mixing chamber 138 by the stirrer 136. The aqueous suspension 134 is moved through the straw 140 into the nozzle 132, where it is mixed with compressed air in a conventional manner (from the compressed air). The air source 142, which is moved to the nozzle 132 through the suction pipe 144). The spray pattern 146 is formed when the water suspension 134/compressed air mixture is sprayed from the nozzle 132 onto the surface of the glass sheet 126 and pyrolyzed on the glass sheet 126 to form the PASC coating 24. Then, the PASC-coated glass sheet 126 was cooled in the air.

For this embodiment, the selected organometallic coating reagent is titanyl acetylacetonate and the speed of the aqueous suspension delivered to the surface of the three glass sheets 126 is controlled to form a certain thickness on each glass sheet. PASC coating. The thicknesses are respectively 400 angstroms, 725 angstroms and 1000 angstroms. All other coating parameters were kept unchanged to determine the effect of the PASC coating thickness on the photocatalytic activity of the titanium dioxide PASC coating (without SIDB barrier) deposited on transparent float glass by spray pyrolysis.

Table 5 shows the specific coating parameters for this example.

After depositing the titanium dioxide PASC coating, the three pieces were cut into four test strips measuring 1 inch x 4 inches (2.54 cm x 10.16 cm), and there were 12 test strips in total.

The test strips from the three original glass sheets were each subjected to X-ray diffraction analysis. From this analysis, it can be found that all the test strips of the three glass sheets in this example have strong X-ray diffraction lines, which match those of anatase titanium dioxide.

In order to evaluate the photocatalytic activity of the three glass sheets, the test strips from the three glass sheets were coated with a stearic acid test film by the process described in Example 1. Then the three test strips were exposed to ultraviolet radiation from a black light source, the light source was perpendicular to the coated surface of each test strip, the radiation intensity was 20 watts/square meter, and the cumulative time was 7 hours. As mentioned above, an FTIR spectrophotometer equipped with an MCT detector was used to quantitatively determine the photocatalytic reaction rate of the three test strips. Table 5 shows the photocatalytic reaction rate of the three glass sheets.

From the above content, it can be inferred that the PASC coating formed by spraying pyrolysis technology can obtain a lower but acceptable photocatalytic reaction rate without sodium ion poisoning of the PASC coating. It can also be inferred that a thicker PASC coating can lead to a higher PASC activity, as demonstrated by Sample C in Table 5.

Example 5 Comparison of the PASC coating formed by spraying pyrolysis with and without SIDB layer and the effect of PASC coating annealing in the experimental substrate provided 8 glass sheets on the glass sheet With a PASC coating formed by spray pyrolysis, to evaluate the presence and absence of the SIDB layer, the thickness of the PASC coating, and the influence of the substrate temperature on the PASC reaction rate of the PASC coating during the deposition of the PASC coating.

Furthermore, the air side of 4 of the 8 4mm Solex® float glass sheets are coated with a 500 angstrom thick tin dioxide SIDB layer, which has been sprayed and pyrolyzed from dibutyltin difluoride And the aqueous suspension of the wetting agent. The tin dioxide SIDB layer was coated by the spray pyrolysis device and process as described in Example 4. After coating the SIDB layer, the glass sample was cooled to room temperature, and the four glass sheets and the remaining four glass sheets were each coated with a titanium dioxide PASC coating on the SIDB layer, and cooled to room temperature. It is worth noting that the four SIDB-coated glass sheets that were cooled to room temperature between the coating of the SIDB layer and the PASC coating and then heated again before coating the PASC coating were prepared in this way. The reason is that The laboratory pyrolysis spray device used in this experiment only has one spray pyrolysis station, so it needs to be converted from a dibutyltin difluoride suspension (providing SIDB layer) to a titanium oxide acetylacetonate suspension (providing PASC coating). This intermediate cooling step can be omitted in the preferred coating machine. For example, the dual spray pyrolysis station can sequentially apply the SIDB layer and the PASC coating to a moving substrate, such as a continuous float glass ribbon, without any intermediate Cooling step.

After all 8 glass sheets coated with PASC coating were cooled to room temperature, as described in Example 1, a stearic acid film was coated on the glass sheets and then exposed to ultraviolet radiation from a UVA 340 light source, which was placed in It is perpendicular to the coating side of the glass sheet coated with the stearic acid test film/PASC coating, thereby providing a strength of 20 watts/square meter on the surface of the PASC coating. The process described in Example 1 was used to quantitatively determine the PASC reaction rate for removing the stearic acid test film. The PASC reaction rate is recorded in the 0.00 minute column in Table 6 below. It can be seen that the 0.00 minute parameter refers to the glass sheet with PASC coating thereon after being cooled to room temperature and not annealed, rather than the cumulative time of UV exposure.

The effect of annealing time on the removal of stearic acid was tested in the following manner. By scrubbing the surface with a scrubbing cloth soaked in methanol until no stearic acid film or fog is visible, the residual stearic acid test film is washed away from the PASC coating of the 8 glass plates. Then, each of the 8 glass sheets was placed in a furnace maintained at a temperature of about 500° C. (932 degrees Fahrenheit) for about 3 minutes, thereby heating the glass sheets. Turn off the furnace heat, open the furnace door and cool the glass sheets in the furnace to room temperature. The slow cooling rate in the furnace provides annealing. Then, the test film of stearic acid was again coated on each glass plate and exposed to ultraviolet radiation, and the PASC reaction rate was measured in the same manner as described above for the unannealed PASC coating in this example. As mentioned above, the residual stearic acid test film on the surface of the glass sheet was rinsed again, and the glass sheet was heated for another 10 minutes and the glass sheet was slowly cooled in the furnace in the same manner, resulting in a cumulative heating time of 13 minutes, and then The stearic acid test film was repeatedly coated and the PASC reaction rate was measured as described above. This process was repeated again to obtain a cumulative heating time of 73 minutes, and then slowly cooled in a furnace for annealing.

Table 6 below shows the PASC reaction rate for the SIDB layer and PASC coating properties of 8 glass sheets (DK) and the relative cumulative annealing time.

*PASC reaction rate (×10-3/cm·min) for removing stearic acid. The photocatalytic analysis result shown in Table 6 tells us that there is no barrier layer with a thickness of about 625 angstroms of titanium dioxide (Sample I) The PASC activity of the thinner 400 angstrom PASC coating (Sample K) on the SIDB layer can be achieved. It is worth noting that for sample K, the SIDB layer is subjected to an intermediate cooling and said subsequent reheating operation. This reheating operation can reduce the effect of the SIDB layer for sample K, which may have higher PASC activity.

The sample K in Table 6 also shows that the annealing time has a significant effect on the PASC reaction rate. After 3 minutes of annealing, the PASC activity of sample K increased from about 4.64 to 12.29×10-3/cm·min, but then decreased in another annealing. It can be considered that the anatase phase of the titanium dioxide coating is formed during the annealing process when the PASC activity is measured for 3 minutes and there is no obvious sodium ion poisoning due to the presence of tin oxide surface in the SIDB layer. Although not limited to a specific theory, it can be considered that a too long accumulation time of continuous annealing may induce sodium ion poisoning, unless there is a SIDB layer, which causes the PASC activity of sample K to decrease.

The above-mentioned embodiments are used to illustrate the present invention, but not to limit the present invention.

Although the above methods of providing PASC coating have been described in conjunction with providing such a coating on a continuously moving substrate such as a continuous float glass ribbon in the substrate manufacturing process, it should be understood that these methods can be used downstream of the substrate manufacturing process. . For example, a PASC coating may be provided on a substrate including but not limited to glass as part of the process of bending and/or tempering the substrate. For example, when the glass substrate is heated for subsequent bending and/or tempering, the above-mentioned spray pyrolysis or CVD or MSVD technique can be coated with or without SIDB PASC coating before bending/tempering. CVD and spray pyrolysis can be used when the glass substrate is heated to the bending/tempering temperature. The PASC coating with or without the SIDB layer can be applied to the glass substrate in the post-bending/tempering reheating operation by any one of CVD, spray pyrolysis, or MSVD.

It can be considered that there is a difference between the PASC coating prepared by the sol-gel method and the PASC coating prepared by the above method. For example, it can be considered that compared with PASC coatings made by CVD or spray pyrolysis, PASC coatings made by sol-gel method can be more porous, less dense, usually thicker, and are generally not suitable for transparency. It may contain more OH groups. As mentioned above, since OH groups will inhibit proper crystal formation in the PASC coating, which in turn reduces PASC activity, excess OH groups are inappropriate. It can be considered that the PASC coating prepared by CVD or spray pyrolysis has a finer particle structure than the coating prepared by the sol-gel method.

The advantages of the present invention over the sol-gel method used to form the PASC coating include the ability to form a thin and dense PASC film on the substrate, while the sol-gel coating method forms a thicker, porous coating. Since the PASC coatings of the present invention are thin, they are aesthetically more suitable as transparent coatings on glass substrates. Another advantage is that the method of providing a PASC coating of the present invention can avoid the need to reheat the substrate after applying the coating or coating precursor, as required by the current sol-gel method. This not only makes the method of the present invention cheaper and more effective, such as but not limited to less equipment cost, less energy cost and less production time, but also the PASC coating of the present invention causes sodium ion migration and sodium ion poisoning. Chances will fall. In addition, the method of the present invention is easily applicable to forming a PASC coating on a continuously moving substrate, such as a float glass ribbon, while the current sol-gel method is not easy to adapt.

Various changes should be included in the scope of the present invention, and the scope is determined by the following claims.