Photocatalytically-activated self-cleaning article and method of making same

Photocatalytically activated self-cleaning product and manufacturing method thereof

Cross-reference to related applications

This application claims the benefit of US Provisional Application Serial No. 60/040,566, filed March 14, 1997. U.S. Provisional Application No. 60/040,565, filed March 14, 1997, and U.S. Regular Application No. 08/899,265 to Greenberg et al. incorporated by reference.

The present invention relates to a method for depositing a photocatalytically activating self-cleaning coating on a substrate (eg, flat glass or continuous glass float ribbon), a method for preventing sodium ion poisoning of a photocatalytically activating self-cleaning coating deposited on a substrate containing sodium ions, and the method It relates to an article made according to the method.

For many substrates (eg, glass substrates), it is desirable to maintain a "clean state" free of surface contaminants such as conventional organic and inorganic surface soils. Conventionally, maintaining such a clean state has meant that the surface must be cleaned frequently. These cleaning operations were typically performed manually or by mechanical devices. This approach has been significantly labor intensive, time intensive and/or cost intensive. A need still exists for substrates having surfaces that are self-cleaning or at least prematurely clean, which eliminates or reduces the need for manual or mechanical cleaning.

titanium dioxide (TiO)<sb>2</sb>) coatings are known to provide a photocatalytically activated self-cleaning (hereinafter referred to as "PASC") surface on a substrate. For the formation of PASC titanium dioxide coatings on glass substrates, see US Pat. No. 5,595,813 and "Photooxidative Self-cleaning Transparent Titanium Dioxide films on Glass", Paz et al., J. Mater Res., Vol. 10, No. 11, pp. 2842-48 (Nov. 1995). Additionally, a list of general patents and products pertaining to the photocatalytic oxidation of organic compounds can be found in Bibliography of Work On The Photocatalytic Removal of Hazardous compounds from water and Air, D. Blake, National Renewable Energy Laboratory (May 1994) and in an October 1995 update and an October 1996 update].

A recently used method of applying PASC coatings (eg titanium dioxide PASC coatings) to substrates is the sol-gel method. When using the sol-gel method, an amorphous alcohol-solvent-based colloidal suspension (sol) is sprayed, spun or dip coated at approximately room temperature. The substrate is then heated to a temperature in the range of about 100 to 800° C. (212 to 1472° F.) to bond the PASC coating to the substrate or cause the PASC coating to crystallize to form a crystallized PASC coating (gel) on the substrate. .

One limitation in applying sol-gel PASC coatings is that the sol-gel process is not economically or practically compatible with certain application conditions or substrates. For example, if it is desired to provide a PASC coating to a float ribbon during fabrication of a coated article, the ribbon may overheat to allow a sol that is partially dependent on the solvent used in the sol solution. For many solvents used in the sol-gel process, it is required to cool the hot float ribbon to approximately room temperature and reheat the float ribbon to a temperature sufficient to crystallize the sol into a PASC coating prior to application of the sol. Such cooling and reheating operations entail significant investment costs in equipment, energy and operating costs and significantly reduce production efficiency.

When sodium ions are present in the substrate and the ions migrate from the substrate to the PASC coating, the PASC activity of the PASC coating may be significantly reduced or destroyed. This process is known as sodium poisoning or sodium ion poisoning. For many substrates containing sodium ions, the rate of movement of sodium ions into the coating increases with increasing substrate temperature. Thus, another limitation of the sol-gel coating method is the increased chance of sodium ions migrating when the substrate is reheated, i.e. sodium ion poisoning of the PASC coating.

Another limitation in the formation of PASC coatings by the sol-gel method is, for example, a few microns (10<sp>-6</sp>M) is in the thickness of the coating equal to the thickness. A PASC coating of this thickness adversely affects the optical and/or aesthetic properties of the PASC coated article.

As can be seen from the above art, there is a need for products made by depositing PASC coatings and for methods of depositing PASC coatings without the disadvantages known in the prior art.

Summary of the invention

The present invention relates to one or more surfaces; and a PASC coating e.g. titanium dioxide deposited on the surface of the substrate by a method selected from the group consisting of chemical vapor deposition (hereinafter referred to as "CVD"), spray pyrolysis and magnetron sputtered vacuum deposition (hereinafter referred to as "MSVD"). It relates to a PASC article comprising a substrate. The present invention also relates to a method for making the product.

The present invention also relates to one or more surfaces; a sodium ion diffusion barrier (hereinafter referred to as "SIDB") layer such as a tin oxide, titanium dioxide, aluminum oxide layer deposited on the surface of a substrate; and a substrate having a PASC coating, for example a titanium dioxide coating deposited over a SIDB layer. The PASC coating and the SIDB layer are each deposited by a method selected from the group consisting of CVD, spray pyrolysis and MSVD. The present invention also relates to a method for making the product.

1 is an elevational view of a portion of a substrate having a PASC coating dispersed therein;

FIG. 2 is a view similar to that of FIG. 1 showing the SIDB layer interposed between the substrate and the PASC coating.

3 schematically shows selected components of a CVD coater.

Figure 4 schematically shows selected components of the spray pyrolysis coater.

1 shows an article 20 having an aspect of the present invention. Article 20 includes a substrate 22 having a PASC coating 24 deposited thereon. The substrate 22 is not limited in the present invention and may include a glass substrate (eg, flat glass or continuous glass float ribbon), a plastic substrate, a metal substrate, and an enameled substrate.

The PASC coating 24 is applied directly over the substrate 22 shown in FIG. 1 or alternatively another layer is a PASC coating 24 and a substrate 22 comprising, but not limited to, a SIDB layer shown in FIG. 2 and described below. ) can be placed between As will further be appreciated by one of ordinary skill in the art, the PASC coating 24 may be the top layer of the coating of a multilayer stack present on the substrate 22, or the PASC coating 24 may provide sufficient actinic radiation to cover the PASC coating 24. A photocatalytic activator is provided so that it can penetrate any coating deposited on the PASC coating 24 and active radicals can penetrate the coating on which the PASC coating 24 is deposited and react with the organic soil present in the top layer of the multilayer stack. It may be embedded as one of the layers other than the top layer in the multilayer stack.

The PASC coating 24 can be any coating that can be photocatalytically activated, self-cleaning, and deposited by a CVD method, spray pyrolysis method, or MSVD method. Without being limited in the present invention, for example, PASC coating 24 may be formed of one or more metal oxides such as titanium oxide, iron oxide, silver oxide, copper oxide, tungsten oxide, zinc oxide, zinc oxide/tin oxide, strontium titanate and mixtures thereof. Metal oxides may include oxides, superoxides or suboxides of metals.

A preferred PASC coating 24 is a titanium dioxide coating. Titanium dioxide exists in amorphous and three crystalline forms: anatase, rutile and brookite crystalline form. Anatase-phase titanium dioxide is preferable because it exhibits strong PASC activity while exhibiting excellent resistance to chemical attack and excellent physical durability. In addition, the anatase phase titanium dioxide has a high transmittance in the visible region of the spectrum, providing a thin coating of anatase titanium dioxide with excellent optical properties. The rutile phase of titanium dioxide also exhibits PASC activity. Combinations of anatase and/or rutile phases with brookite and/or amorphous phases are acceptable in the present invention provided that the combination exhibits PASC activity.

The PASC coating 24 is sufficiently thick to provide an acceptable level of PASC activity. Whether a PASC coating has an acceptable level of PASC activity is largely determined by the application, the conditions under which the PASC coating product is used, and the performance standards selected in relation to the application. In general, a thick PASC coating provides a high degree of PASC activity. However, other considerations can be weighed against thick coatings, eg, if the product has high transmissivity for aesthetic or optical reasons, thick coatings are preferred; Surface soil on the surface of the article is easily removed in the case of a thick PASC coating of the article, the coating being exposed to substantial radiation and/or the PASC coating 24 being exposed to sodium ion poisoning, discussed in detail below. For a wide range of applications, it is desirable for the PASC coating to have a thickness of at least about 200 angstroms, preferably at least about 400 angstroms, more preferably at least about 500 angstroms. If the substrate 22 is a piece of float glass and the PASC coating 24 is an anatase titanium dioxide PASC coating formed directly on a piece of float glass by the CVD method, a thickness of about 500 Angstroms or greater is a PASC coating that allows the PASC coating to be used for a wide range of applications. Approx. 20 W/m from the surface<sp>2</sp>A light source having an intensity of [trade name: UVA-340; Source: approximately 2×10 for removal of stearic acid test film when exposed to ultraviolet light from the Q-Panel Company of Cleveland, Ohio].<sp>-3</sp> to about 5×10<sp>-3</sp>It has been found to provide PASC reaction rates in the range of /cm·min.

According to the invention, thin, for example 1 μ (10<sp>-6</sp>A coating of less than M), more preferably less than 0.5 μm, is formed on the substrate by spray pyrolysis CVD or MSVD methods. A metal-containing precursor is included in a carrier gas, such as nitrogen gas, in a CVD method in an aqueous suspension, such as an aqueous solution, in the spray pyrolysis method, and the substrate 22 decomposes the metal-containing precursor to form a PASC coating on the substrate 22 The metal-containing precursor is directed toward the surface of the substrate 22 while maintained at a temperature sufficient to form 24 . In the MSVD method, a sputter coating is deposited on a substrate 22 by sputtering a metal-containing cathode target under negative pressure in an inert or oxygen-containing atmosphere. The substrate 22 is heated during or after coating to crystallize the sputter coating to form the PASC coating 24 . Each method has advantages and limitations, for example, the spray pyrolysis method can reduce the PASC activity of the PASC coating 24 by inhibiting the formation of suitable crystallinity in the aqueous solution, thereby reducing the PASC coating 24 OH.<sp>-</sp> CVD methods and pyrolysis methods are preferred over spray pyrolysis methods because they can lead to the presence of ions. The CVD method and the pyrolysis method are preferred over the MSVD method because the MSVD method is compatible with coated continuous substrates such as glass float ribbons observed at elevated temperatures. The CVD method, the spray pyrolysis method, and the MSVD method of depositing the PASC coating 24 are discussed in more detail below. A thin (eg, several hundred Angstroms thick) metal oxide coating (including a titanium dioxide coating) can be deposited over a substrate using the spray pyrolysis method and the CVD method as described above. Such coatings 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.

In the practice of the present invention, the metal-containing precursor that can be used to form a titanium dioxide PASC coating by a CVD process is titanium tetrachloride (TiCl).<sb>4</sb>), titanium tetraisopropoxide (Ti(OC<sb>3</sb>H<sb>7</sb>)<sb>4</sb>) (hereinafter referred to as "TTIP") and titanium tetraisopropoxide (Ti(OC<sb>2</sb>H<sb>5</sb>)<sb>4</sb>) (hereinafter referred to as "TTEt"), but is not limited thereto. Carrier gases that may be used in the CVD process include, but are not limited to, air, nitrogen, oxygen, ammonia, and mixtures thereof. The preferred carrier gas is nitrogen and the preferred metal containing precursor is TTIP. The concentration of the metal containing precursor in the carrier gas generally ranges from 0.1 to 0.4 vol %, based on the volume of the three enumerated metal containing precursors, but as will be apparent to those skilled in the art, this concentration may vary for other metal containing precursors. have.

Metal-containing precursors that may be used to form PASC coatings in the practice of spray pyrolysis in the practice of the present invention include relatively water-insoluble organometal reactants, particularly metal acetylacetonate compounds, which contain about 10 μ (10<sp>-6</sp>M) jet milled or wet milled to a particle size below and suspended in an aqueous medium by use of a chemical wetting agent. A suitable metal acetylacetonate for forming a titanium dioxide coating is titanyl acetylacetonate (TiO(C<sb>5</sb>H<sb>7</sb>O<sb>2</sb>)<sb>2</sb>)am. The relative concentration of metal acetylacetonate in the aqueous suspension is about 5 to 40% by weight of the aqueous suspension. Wetting agents are relatively low concentrations of foaming surfactants comprising anionic, nonionic or cationic compositions, preferably nonionic surfactants. Wetting agents are typically added at about 0.24% by weight, but can be from about 0.01 to 1% or more. The aqueous medium is preferably distilled or deionized water. Aqueous suspensions for pyrolytic deposition of metal-containing films are particularly described in US Pat. No. 4,719,127 at column 2, line 16 to column 4, line 48, which is incorporated herein by reference.

In both the CVD method and the spray pyrolysis method, the temperature of the substrate 22 during the formation of the PASC coating 24 decomposes the metal-containing precursor so that the coating has PASC activity (eg, a crystalline phase to a metal oxide PASC coating). It should be within the temperature range that forms As is evident, the lower limit of this temperature range is mainly influenced by the decomposition temperature of the selected metal-containing precursor. For the titanium-containing precursor, the lowest temperature of the substrate 22 that provides sufficient decomposition of the precursor is within a temperature range of about 400° C. (752° F.) to about 500° C. (932° F.). The upper limit of this temperature range can be influenced by the substrate being coated. For example, if substrate 22 is a glass float ribbon and a PASC coating 24 is applied to the float ribbon during manufacture of the float ribbon, the float glass may reach temperatures in excess of 1000°C (1832°F). Float glass is typically attenuated or sized (eg stretched or compressed) at temperatures above 800° C. (1472° F.). If the PASC coating 24 is applied to the float glass prior to or during attenuation, the PASC coating 24 may crack or wrinkle as the float coating 24 is stretched or extruded, respectively. Accordingly, in the practice of the present invention it is preferred to apply a PASC coating if the float ribbon is dimensionally stable at temperatures below about 800° C. (1472° F.), for example for soda lime silica glass, the float ribbon being a metal containing precursor. is maintained at a temperature above, for example, about 400° C. (752° F.), at which it decomposes.

Formation of the PASC coating 24 by a CVD method or a spray pyrolysis method is particularly suitable for practice during manufacture of glass float ribbons. Glass float ribbons are generally made by melting glass batch material in a furnace and dispensing refined molten glass onto a bath of molten tin. The molten glass on the bath is pulled across the tin bath as a continuous glass ribbon while sizing and controlled cooling to form a dimensionally stable float ribbon. The float ribbon is annealed by removing the float ribbon from the tin bath and transferring the roll to a lehr. The annealed float ribbon is then moved to a cutting position on a conveyor roll where the ribbon is cut into panes of the desired length and width.

Float glass processes are discussed in US Pat. Nos. 4,466,562 and 4,671,155, which are incorporated herein by reference.

The temperature of the float ribbon in the tin bath generally ranges from about 1093.3° C. (2000° F.) at the dispensing end of the bath to about 538° C. (1000° F.) at the outlet end of the bath. The temperature of the float ribbon between the tin bath and the annealing ler generally ranges from about 480°C (896°F) to about 580°C (1076°F), and the temperature of the float ribbon at the annealing ler is typically about 204°C (400°C). ) to about 557° C. (1035° F.).

U.S. Pat. Nos. 4,853,257, 4,971,843, 5,536,718, 5,464,657, and 5,599,387, which are incorporated herein by reference, describe CVD coating apparatus and methods that can be used in the practice of the present invention to coat float ribbons during manufacture. are doing The CVD method is well suited for providing a PASC coating 24 on the float ribbon because the CVD method is capable of coating a moving float ribbon but can withstand the harsh environments associated with the manufacture of float ribbons. The CVD coating apparatus can be used in several aspects in the float ribbon manufacturing process. For example, a CVD cladding apparatus can be used to determine whether a float ribbon travels through a tin bath after exiting the tin bath, before exiting from the annealing ler, as it travels through an annealing ler, or after exiting the annealing ler. can be used

As will be apparent to those skilled in the art, the concentration of the metal-containing precursor in the carrier gas, the flow rate of the carrier gas, the velocity of the float ribbon (line velocity), the surface area of the CVD coating apparatus relative to the surface area of the float ribbon, the surface area of the CVD coating apparatus and the exhaust vent The flow rate of the carrier gas exhausted through It is influenced by the final thickness and morphology of the PASC coating 24 formed on the ribbon.

U.S. Patent Nos. 4,719,126, 4,719,127, 4,111,150 and 3,660,061, incorporated herein by reference, describe spray pyrolysis apparatus and methods that can be used in float ribbon manufacturing processes. Although spray pyrolysis methods such as CVD methods are suitable for coating moving glass float ribbons, spray pyrolysis is performed in more complex equipment than CVD equipment and is typically used between the outlet of the tin bath and the inlet of the annealing lery.

As will be apparent to those skilled in the art, the composition and concentration of the pyrolytically atomized aqueous suspension, the line speed of the float ribbon, the number of pyrolytic spray guns, the atomizing pressure and volume, the atomizing mode and the temperature of the float ribbon at the time of deposition are determined by spray pyrolysis. It affects the final thickness and morphology of the PASC coating 24 formed on the ribbon.

As is known to those skilled in the art, the surface of a glass float ribbon on molten tin (commonly referred to as the "tin side") diffuses tin to the surface providing the tin side in a different tin absorption pattern than the opposite surface that is not in contact with the molten tin. make it These characteristics are described in Chemical Characteristics of Float Glass Surfaces, Seiger, J., JOURNAL OF NON-CRYSTALLINE SOLIDS, Vol. 19, pp. 213-220 (1975); Penetration of Tin in The Bottom Surface of Float Glass; A Synthesis, Columbin L. et al., JOURNAL OF NON_CRYSTALLINE SOLIDs, Vol. 38 &amp; 39, pp. 551-556 (1980); and Tin Oxidation State, Depth Profiles of Sn<sp>2+</sp> and Sn<sp>4+</sp> and Oxgen Diffusivity in Float Glass by Mossbauer Spectroscopy, Williams, KFE et al, JOURNAL OF NON-CRYSTALLINE SOLIDS, Vol. 211, pp. 164-172 (1997), which is incorporated herein by reference. As will be apparent to those skilled in the art, the PASC coating 24 is deposited on the air side of the float ribbon while supported by (CVD method) on the tin bath, and on the air side of the float ribbon after exiting the tin bath by CVD or spray pyrolysis methods. It is formed on the tin side of the float ribbon after being discharged from the tin bath by the CVD method. When the PASC coating 24 is formed on the tin side of the float ribbon, the tin and/or tin oxide present on the glass surface acts as a SIDB layer 26 for the PASC coating placed thereon.

U.S. Patent Nos. 4,379,040, 4,861,669, 4,900,633, 4,920,006, 4,938,857, 5,328,768, and 5,492,750, which are incorporated herein by reference, are disclosed for sputtering a coated metal oxide film onto a substrate comprising a glass substrate. MSVD devices and methods are described. The MSVD method, among other methods, is generally incompatible with the provision of a PASC coating on the glass float ribbon during manufacturing as it requires negative pressure during sputtering operations, which is difficult to form on continuously moving float ribbons. However, the MSVD method may be acceptable for depositing a PASC coating 24 on a substrate 22 , eg, pane. As will be apparent to those skilled in the art, the substrate 22 is heated to a temperature in the range of about 400°C (752°F) to about 500°C (932°F) such that the MSVD sputtered coating on the substrate crystallizes during the deposition process, thereby eliminating subsequent heating operations. can be heated. Heating the substrate during sputtering is not a preferred method as additional heating operations during sputtering may reduce throughput. In addition, sputter coatings can be crystallized in the coating apparatus directly and without subsequent heat treatment by using a high energy plasma, but this is not the preferred method because of the reduced throughput through the MSVD coater.

A preferred method of providing a PASC coating using the MSVD method is to separate the coated substrate from the MSVD coater and then heat treat the coated substrate to crystallize the sputtered coating into a PASC coating (24). For example, but not limited by the present invention, argon/oxygen with about 5 to 50% oxygen, preferably about 20% oxygen at a pressure of about 5 to 10 mtorr (0.67 to 1.33 Pa) for sputtering for the MSVD method. A titanium metal target sputtered in the atmosphere deposits a titanium dioxide coating of the desired thickness over the substrate 22 . The deposited coating does not crystallize. The coated substrate is separated from the coater and at a temperature ranging from about 400° C. (752° F.) to about 600° C. (1112° F.) for a time sufficient to promote the formation of a PASC crystalline form of titanium dioxide that makes the PASC active. is heated In general, it is desirable to heat at a temperature in the range of about 400°C (752°F) to about 600°C (1112°F) for at least one hour. The PASC coating 24 may be sputter deposited from the air side and/or the tin side if the substrate 22 is a pane cut from a glass float ribbon.

Substrates 22 deposited by CVD, spray pyrolysis, or MSVD methods may subsequently be subjected to one or more post-PASC coating annealing operations to enhance the self-cleaning activity of the PASC coating 24 . This subsequent annealing operation of the PASC coating can increase the activity of the PASC coating 24 by promoting the formation of the desired PASC crystalline phase. Obviously the time and temperature of the annealing depends on the composition of the substrate 22 , the composition of the PASC coating 24 , the thickness of the PASC coating 24 , and whether or not the PASC coating 24 is present directly on the substrate 22 . or whether it is one layer of a multilayer stack over the substrate 22 . PASC activity when substrate 22 is a piece of float glass and the PASC coating is annealed the coating at 500° C. was measured to increase.

As discussed above, the sodium capable of transferring the substrate 22 from the substrate 22 to the PASC coating deposited on the substrate 22, whether the PASC coating is provided by a CVD method, a spray pyrolysis method, or an MSVD method. Sodium ions, when included, can inhibit or destroy the photocatalytic activity of PASC coatings by forming inactive compounds during titanium consumption, for example by forming sodium titanate or by generating recombination of photoexcitation charges.

The PASC coating can be formed over the sodium ion containing substrate 22 without loss of photocatalytic activity by 1) a portion of the PASC coating provides limited partial sodium ion poisoning and/or 2) provides a SIDB layer 26 turned out to be Each method is discussed in detail below.

When the thickness of the PASC coating exceeds the initial minimum value, sodium ion migration will result in sodium ion migration even when the PASC coating is deposited over the surface of the sodium ion-containing substrate while the substrate is maintained at a temperature sufficient to migrate sodium ions from the substrate to the PASC coating. It was found that PASC activity was not disrupted. Although the mechanism for this result is not fully understood, when the thickness of the PASC coating exceeds this minimum thickness, sodium ions are released over the entire thickness of the PASC coating for a time when the temperature of the substrate exceeds the temperature that allows sodium ions to migrate. It has been found that it can only move through fragments. Then, when the temperature of the substrate is lower than the temperature at which the sodium ions migrate, the movement of sodium ions stops or "freezes" occurs to increase the thickness of the PASC coating on the opposite side from the surface of the substrate so that there is no sodium ion poisoning and PASC activity can be maintained. create As will be apparent to one of ordinary skill in the art, the minimum thickness of such a PASC coating is not limited, but will vary depending on predictors such as the length of time the substrate is held above the temperature at which sodium ion migration occurs, the application in which the PASC article is placed and the PASC activity is desired or desired. . 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 Å, preferably at least about 400 Å to allow a sufficient fraction of the PASC coating to retain its PASC activity without sodium ion poisoning. , more preferably at least about 500 Å.

FIG. 2 shows another method of preventing sodium ion poisoning of the PASC coating in which a SIDB layer 26 is provided 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 one of a multilayer stack. When a multilayer stack is used, the SIDB layer 26 is not required to be in contact with the substrate 22 , provided that the SIDB layer 26 is located between the PASC coating 24 and the substrate 22 and is removed from the substrate 22 . Prevents sodium ion migration into the PASC coating 24 .

SIDB layer 26 is amorphous or crystalline comprising cobalt oxide, chromium oxide and iron oxide, tin oxide, silicon oxide, titanium oxide, zircon oxide, fluorine-doped tin oxide, aluminum oxide, magnesium oxide, zinc oxide, and mixtures thereof. It may be formed of a strong metal oxide, but is not limited thereto. Mixtures include, but are not limited to, magnesium/aluminum oxide and zinc/tin oxide. As will be apparent to those skilled in the art, metal oxides include oxides, superoxides or suboxides of metals. The thickness of the SIDB layer required to prevent sodium ion poisoning of the PASC coating depends on the time the substrate is held above the temperature at which sodium ion migration occurs, the rate of sodium ion migration from the substrate, the rate of sodium ion migration through the SIDB layer, and the thickness of the PASC coating. and the degree of photocatalytic activity required for a given application, typically most applications, the thickness of the SIDB layer is preferably at least about 100 Angstroms to prevent sodium ion poisoning of the PASC coating layer. should be greater than or equal to about 250 Angstroms, more preferably greater than or equal to about 500 Angstroms. The SIDB layer may be deposited on the substrate 22 by CVD, spray pyrolysis, or MSVD methods. If spray pyrolysis or CVD methods are used, the substrate 22 is preferably maintained at a temperature of at least about 400[deg.] C. (752[deg.] F.) to ensure decomposition of the metal containing precursor to form the SIDB layer. The SIDB layer can be formed by other methods, including sol-gel methods, which are incompatible with the manufacture of glass float ribbons.

dibutyltin difluoride (C<sb>4</sb>H<sb>9</sb>)<sb>2</sb>SnF<sb>2</sb> and a layer of tin oxide SIDB can be deposited on the substrate by spray pyrolysis by forming an aqueous suspension of water and applying the aqueous suspension to the substrate via spray pyrolysis. Wetting agents may be used as suspension enhancers. During the preparation of the aqueous suspension, 1 to 10 μm (10<sp>-6</sp>M) can be polished to an average particle size. Dispensing the aqueous suspension to the surface of the substrate by pyrolysis at a temperature above about 400° C. (752° F.), preferably about 500 to 700° C. (932 to 1292° F.), at which the aqueous suspension pyrolyzes to form a tin oxide SIDB layer. . Obviously, the thickness of the SIDB layer formed by the above method can be controlled by, among other variables, the coat line speed, the concentration of dibutyltin difluoride in the aqueous suspension and the spray rate.

In addition, the tin oxide SIDB layer can be formed on a substrate by a CVD method from a metal-containing precursor such as monobutyltintrichloride vapor (hereinafter referred to as "MBTTCL") in an air carrier gas mixed with water vapor. "MBTTCL" while the substrate is maintained at a temperature at which the tin-containing layer is deposited, e.g., at least about 400° C. (752° F.) to form a tin oxide SIDB layer, preferably between about 500 to 800° C. (932 to 1472° F.) "The vapor may be present at a concentration of about 0.5% or greater in the air carrier gas applied to the substrate. Obviously, the thickness of the SIDB layer formed by the above process can be controlled by the line speed of the coating, the concentration of MBTTCL vapor in the air carrier gas and the flow rate of the carrier gas, among other variables.

A SIDB layer formed by the MSVD method is described in U.S. Patent Application Serial No. 08/597,543, entitled "Alkali Metal Diffusion Barrier Layer," filed February 1, 1996, which is incorporated herein by reference, which is incorporated herein by reference. The formation of diffusion barriers is disclosed. The barrier layers disclosed in this document are generally effective at a thickness of about 20 to about 180 Angstroms, which has the effect of increasing the density of the barrier.

The PASC coatings of the present invention are typically photocatalytically activated upon exposure to radiation in the ultraviolet range of the electromagnetic spectrum, for example about 300 to 400 nm. natural sources such as natural light sources such as sunlight and artificial light sources of natural light, or ultraviolet light sources such as UVA-340 light sources. When using an artificial UV light source under test conditions that determine in a desired way the form in which the PASC coating reacts with perceptible natural UV light, the UVA-340 light source is used to perform the PASC coating upon exposure to sunlight and the UVA-340 used It has a distribution of quantum energy that more closely matches daylight than distribution of the quantum energy of a black light source that more closely approximates the light source.

The intensity of ultraviolet light is about 20 W/m from the coated surface of the coating being tested.<sp>2</sp> It is measured with more than one strength. The intensity is measured by a commercially available UV meter [trade name: BLACK-RAY<sp>R</sp>; Source: Ultraviolet Products, Inc., of san Gabriel, CA; Model name: J-221]. The light source is preferably positioned perpendicular to the cladding surface being tested.

The UV source and the PASC coating may be positioned relative to each other such that the UV radiation first penetrates the PASC coating and then the substrate (ie, the front or "side of the coating"). When UV light penetrates through the substrate, the PASC coating and the UV source may be positioned relative to each other such that the UV light first penetrates the substrate and then through the PASC coating (ie, the back or "substrate side"). In another embodiment, one or more UV sources may be located on each side of a substrate having a PASC coating on one or both sides of the surface.

As will be evident, it is difficult to specifically define a preferred UV source or UV intensity or relatively located UV source/PASC coating/substrate as a number of factors can be considered. These factors depend, among other things, on the use in which the PASC coating is used, eg for indoor or outdoor use; seasonal or geographic influences if the UV source is a natural source; the desired or expected duration of exposure to UV light; the angle of incidence of ultraviolet light on the surface of the PASC coating; the desired or expected rate of PASC activity; the extent to which ultraviolet radiation can be reflected or absorbed by the substrate and/or other coatings or layers present over the substrate or PASC coating; PASC coating thickness; contaminants to be removed; potential for sodium ion poisoning; and the presence or absence of a SIDB layer. However, about 5 to 100 W/m as measured at the surface of the PASC coating from an ultraviolet source disposed on the surface of the PASC coating.<sp>2</sp>, preferably about 20 W/m<sp>2</sp> It has been found that above UV intensity produces sufficient intensity to produce satisfactory PASC activity for many self-cleaning applications.

To evaluate the PASC activity of a PASC coating, it is useful to measure and compare the PASC effect or activity of the PASC coating. Known and readily available organic contaminants can be applied over the PASC coating, and the ability of the PASC coating to remove organic contaminants can be observed or measured upon photocatalytic activation of the PASC coating. Stearic acid, CH as a model organic "contaminant" for testing PASC activity of PASC coatings, as stearic acid is a carboxylic acid with long chain hydrocarbons and is therefore a good "model molecule" present as common contaminants such as kitchen oils and spores.<sb>3</sb>(CH<sb>2</sb>)<sb>16</sb>COOH is used. The stearic acid can be applied over the PASC coating as a thin test film using conventional techniques such as dipping, spraying, or spin coating. Stearic acid test films in the range of thicknesses generally from about 100 to about 200 Angstroms can provide suitable test films. Stearic acid can be applied as stearic acid in methanol solution and is about 6×10<sp>-3</sp>A solution of stearic acid at a concentration of mol/l was found to be satisfactory.

The PASC activity of the PASC coating is determined by topcoating the PASC coating with a stearic acid film (the stearic acid film usually appears as a light brown coating when applied over the PASC coating), and exposing the stearic acid film to UV light of the desired intensity for a desired period of time. After exposure, the stearic acid film without the use of another device for complete removal of the stearic acid test film or reduction of the darkening of the stearic acid film compared to the portion of the stearic acid film applied on the PASC coating but not exposed to UV light. It can be qualitatively evaluated visually by examining the

The PASC activity of PASC coatings can also be assessed quantitatively by measuring the integrated strength of the carbon-hydrogen stearic acid (hereinafter referred to as "CH") stretch vibration absorber present on the PASC coating. Since the integrated strength corresponds to the thickness of the stearic acid film remaining on the surface of the PASC coating, it is thought that the removal of the stearic acid film by photocatalytically activated self-cleaning results in a decrease in the CH stretch vibration band intensity. . Unlike UV, the CH bonds present in the IR-absorbing stearic acid do not photocatalytically activate the PASC coating. This absorption is generally between 2800 and 3000 cm.<sp>-1</sp>It appears at the frequency of , and can be measured with a Fourier Transform Infrared Spectrophotometer (hereinafter referred to as "FTIR Spectrophotometer"). The FTIR may be equipped with a detection system such as a deuterated triglycerin sulfate detection system (hereinafter referred to as "DTGS detection system") or a mercury-cadmium-telluride detection system (hereinafter referred to as "MCT detection system"). MCT detection systems are preferred because they provide a greater signal-to-noise ratio than DTGS detection systems. This can be important if the substrate and/or other coatings other than the PASC coating absorb the infrared light used to generate the absorption spectrum by the spectrophotometer. When the substrate and/or other coatings absorb infrared radiation, the infrared beam entering the detection system through the stearic acid film, the PASC coating and the substrate is greatly reduced. When this is combined with a low concentration of stearic acid which produces a very weak infrared absorption behavior present on the surface of the PASC coating, the resulting infrared signal becomes particularly very weak. Therefore, a device equipped with an MCT detection system provides a spectrum whose signal-to-noise ratio is approximately one order of magnitude higher than that of a device equipped with a DTGS detection system. When measuring PASC activity of a film through which an infrared beam can pass and a stearic acid test film deposited on a substrate, the infrared beam can pass through the film and substrate and enter a detection system located on the opposite side of the sample to be tested. If the film or substrate does not pass infrared radiation, the infrared radiation can be angled on the surface and reflected off the substrate without passing through the stearic acid test film and entering the detection system. This method is known as reflected IR spectroscopy.

The PASC kinetics can be determined by measuring the kinetics of the PASC coating to remove the stearic acid film when the PASC coating is exposed to actinic radiation. More specifically, the rate of decrease of the integrated intensity (directly proportional to the surface coating thickness) of the CH stretch oscillation behavior with the cumulative time of exposure to actinic radiation (hereafter referred to as ultraviolet) gives the PASC response rate. For example, initial PASC activity is measured by FTIR spectrophotometer on a test film of stearic acid present on a PASC coating. The PASC coating may or may not be exposed to UV light for the initial PASC activity measurement. The stearic acid-coated PASC coating is then exposed to UV light for a measurement time period, followed by a second PASC activity measurement with an FTIR spectrophotometer. The integrated intensity of the CH stretching oscillations in the second measurement is thought to be lower than in the first measurement because some of the stearic acid test film is removed upon UV exposure. From these two measurements, a curve of the integrated intensity versus time of the CH stretching oscillations is drawn, and the PASC response rate is obtained from the slope of the curve. Although two points are sufficient to draw a curve, it is preferable to measure several times during the PASC activity measurement process to draw a more accurate curve. The time of exposure to UV between FTIR measurements can either remain constant or change when two or more PASC activity measurements are accumulated (as in the cumulative UV exposure time used to draw the curve), but the intensity and orientation of the UV light (on the side of the coating) or the substrate side) must be constant in all PASC measurements when determining the PASC kinetics.

PASC reaction rate in cm<sp>-1</sp>minute<sp>-1</sp> It can be expressed in units, where a larger value indicates greater PASC activity. PASC coatings that have an acceptable level of PASC reaction rate may be considered "acceptable" or "unacceptable" because PASC coatings are highly dependent on the purpose for which the PASC-coated product is used and on the standard performance chosen for this purpose. "There is no absolute speed of making. For most applications, PASC activity is preferably about 2×10<sp>-3</sp> ㎝<sp>-1</sp>min<sp>-1 </sp>or more, more preferably about 5×10<sp>-3</sp> ㎝<sp>-1</sp>min<sp>-1 </sp>More than that.

In addition, since the thickness of the PASC coating can affect the photocatalytic activity, as shown in the examples below, the thickness of the PSSC coating was used to significantly determine and compare the PASC activity of the PASC coatings prepared according to the present invention. It is useful to measure As is known in the art, the thickness of the PASC coating 24 and/or the SIDB layer 26, if present, is determined by Variable Angle Spectroscopic Ellipsometry (hereinafter referred to as "VASE"). Alternatively, it can be determined from profilometer measurements of the measured loss edges in the film, or evaluated from the interference color.

The particle size of the PASC coating 24 and/or the SIDB layer 26, if present, can be calculated from X-ray diffraction (hereinafter referred to as "XRD") data using the Scherrer equation. This equation is known in the art and is described in "X-Ray Diffraction Procedures For Polycrystalline and amorphos materials, Klug and Alexander, John Wiley &amp; Sons, Inc., Chapter 9, 1954." .

The following examples are presented to illustrate the present invention and are not intended to limit the present invention.

<u>Example 1</u>

2100 Å thick PASC coating formed by CVD method

The PASC activity of a titanium dioxide PASC coating having a thickness of about 2100 Å was investigated as follows. The PASC coating was prepared using a CVD method on a soda lime-silica float commercially available from PPG Industries, Inc. of Pittsburgh, PA under the trade name SOLEX® glass. ) deposited on the substrate 22, which is the air side of the glass. In FIG. 3 , Solex glass was measured to have a width of about 5.5 inches, a length of about 12 inches, and a thickness of 0.016 inches (14 cm wide, 30.5 cm long and 0.4 cm thick) and is shown in FIG. 3 . Solex glass was coated with a titanium dioxide PASC coating using a CVD coater 88 as described. The CVD coater 88 generally consists of three zones shown in FIG. 3 divided by vertical dash lines 90 and 92 . The three zones are a preheat zone 94 , a cladding zone 96 , and an annealing zone 98 . The Solex glass, denoted as the substrate 22, was then moved through three zones on a continuous conveyor 102 in the direction of the arrow 104.

The substrate 22 was moved to a preheat zone 94 and preheated to a temperature of about 649° C. (about 1200° F.) using a plurality of heaters 106 positioned above and below the conveyor 102 . The substrate 22 was moved by a conveyor 102 to the CVD cladding zone 96 . As is evident, the CVD cladding zone 96 includes one or more cladding units 97 . For the successive deposition of one or more coatings, the cladding zone 96 may include a plurality of cladding units 97 . The cladding unit 97 includes sub-systems and control systems for maintenance, such as a gas delivery sub-system, a liquid delivery sub-system, a temperature control system, an exhaust sub-system and an exhaust control system, and a sub-system for monitoring temperature and pressure. included but not shown. The gas delivery sub-system controls the flow of carrier gas relative to the surface of the substrate 22 . Nitrogen gas was used as a carrier gas. The nitrogen stream inlet was controlled to a temperature of 113[deg.] C. (about 235[deg.] F.) with a heater, not shown. NH<sb>3</sb>was incorporated into the carrier gas at 20% of the total flow rate. The exhaust flow rate was 125% of the inlet flow rate. The metal containing precursor used to deposit the titanium dioxide PASC coating on the substrate 22 was TTIP present at 0.4% by volume of the total flow and also provided a temperature of about 113°C (about 235°F). N via CVD coater (88)<sb>2</sb>, NH<sb>3</sb> and the total flow of TTIP vapor was 75 l (standard condition)/min (standard liter per minute; slm). The line speed of the conveyor 102 was about 50 inches (127 cm)/min, and the width of the cladding unit slots was about 3/16 inches (0.48 cm). A coating 24 was deposited on the substrate 22 to form a coating sample 100 while maintaining the substrate 22 at a temperature of about 554° C. (1030° F.) while under the coating unit 97 . A titanium dioxide PASC coating 24 of about 2100 Angstroms thick (as measured by VASE) was formed on the coating sample 100 .

The coated sample 100 was then transferred to an annealing zone 98, where it was annealed for about 26 minutes from an initial temperature of about 549°C (1020°F) to a final temperature of about 121°C (250°F).

A PASC coated sample 100 was XRD analyzed. The particle size of the PASC coating 24 was determined to be about 309 A as calculated using Scherrer's equation. The coated sample 100 exhibited a strong peak in the XRD pattern corresponding to anatase titanium dioxide.

The PASC coated sample 100 was then overcoated with a stearic acid test film to measure its photocatalytic activity. About 6×10 per liter of solution<sp>-3</sp> A stearic acid/methanol solution having a molar stearic acid concentration is applied to the center of the sample 100 by pipetting the stearic acid solution at a rate of about 2 ml/10 seconds, and the coated sample 100 is applied to about 100 Spins were performed at a rate of rotations/min, wherein the stearic acid was centrifuged by centrifugal force to provide a film of stearic acid having a generally uniform thickness in the range of about 100 to 200 Angstroms on the surface of the coated sample 100 ( 100) across the surface. The term "generally" means that the thickness of the stearic acid layer is not constant along the length of the coated sample 100 , and the distal end of the coated sample 100 is the thickest and the center of the coated sample 100 is the thickest due to the applied centrifugal force. It is a term used because it is thin. As will be apparent, the stearic acid solution concentration, spin speed, sample size and pipetting speed described above can be modified to obtain a stearic acid coating of the desired thickness. In the above parameters, the average thickness of the stearic acid test film was about 150 Å, as determined by correcting the IR intensity with a quartz crystal microbalance.

The stearic acid test film/titanium dioxide PASC coated sample 100 was exposed to ultraviolet light from a black light source perpendicular to the coated surface of the coated sample 100, and about 20 W/m2 was applied to the surface of the PASC coating 24 for about 30 minutes cumulatively. It provided strength to induce photocatalytically activated self-cleaning of the stearic acid test film. The photocatalytic activity was quantitatively measured by obtaining periodic FTIR spectrophotometer measurements over a cumulative 30-minute UV exposure time using an FTIR spectrophotometer equipped with an MCT detection system. More specifically, the stearic acid test film/PASC coated sample 100 was exposed to ultraviolet light for a measurement time period, after which the coated sample 100 was mounted on an FTIR spectrophotometer and the area of integration below the CH absorption band of stearic acid. was measured to determine PASC activity. Coated sample 100 was again exposed to ultraviolet light for an additional measurement time period to remove additional stearic acid, followed by FTIR measurements again. This method was repeated to obtain a curve of the accumulated IR absorption intensity of the CH stretching vibration versus the cumulative exposure time to ultraviolet light and the PASC rate for the stearic acid test film/titanium dioxide PASC coated sample 100 was obtained from the slope of the curve. As is evident, all FTIR measurements were taken around the same area of the coated sample 100 to minimize the effect of the thickness variation of the stearic acid test film as described above. The photocatalytic reaction rate is 3.53×10 reaching the values of PASC-coated substrates (eg, quartz glass substrates) containing little or no sodium ions.<sp>-3</sp> ㎝<sp>-1</sp>min<sp>-1</sp>, and this figure indicates that a 2100 Å thick titanium dioxide PASC coating is sufficient to overcome sodium ion poisoning.

<u>Example 2</u>

700-800 Å thick PASC coating formed by CVD method

A titanium dioxide PASC coating 24 having a thickness of about 700 to 800 angstroms was deposited on a glass substrate through a CVD method in the same manner as in Example 1 except for the following.

The glass composition used in Example 2 was a 3 mm (0.12 inch) thick clear (ie, low in iron soda lime silica) glass. The preheat temperature of Example 2 was 593° C. (1100° F.). The TTIP concentration of Example 2 was 0.1% of the total flow rate of 50 slm. NH<sb>3</sb>was included in the carrier gas at 24% of the total flow rate. The line speed was 30 inches/min (76.2 cm/min). The slot width was 1/16 inch. The thickness of the titanium dioxide PASC coating 24 was evaluated from interference color, a technique known in the art for thin film thickness measurement, and was determined to be in the range of about 700 to 800 Angstroms.

The stearic acid test film was applied on the titanium dioxide PASC coating in the same manner as described in Example 1, and after exposure to ultraviolet (UV) light in the manner described in Example 1, a period of 33 h with a FTIR spectrophotometer. PASC activity was measured over the cumulative cycle. The photocatalytic reaction rate is about 0.17 × 10<sp>-3</sp> ㎝<sp>-1</sp>min<sp>-1</sp>was decided

The decrease in PASC activity of Example 2 is believed to be due to the difference between the titanium dioxide coating thickness of Example 1 and the titanium dioxide coating thickness of Example 2 (about 2100 Angstroms versus about 700-800 Angstroms, respectively). More specifically, the titanium dioxide PASC coating of Example 2 has a greater percent full thickness of the titanium dioxide PASC coating than the titanium dioxide PASC coating of Example 1, so that the depth of diffusion of sodium ions into the titanium dioxide coating of Example 2 is Therefore, it is considered that the reaction rate of Example 2 is slower than the reaction rate of PASC of Example 1. Sodium ions are believed to have migrated from the glass sample to the PASC coating of Example 2 in the annealing zone 44 . One conclusion that can be drawn from the comparison of Examples 1 and 2 is that in the absence of the SIDB layer, the thicker PASC coating retains higher PASC activity because it is less susceptible to sodium ion poisoning.

<u>Example 3</u>

PASC coating on SIDB layer formed by CVD method

In this example, the effect of the tin dioxide SIDB layer on PASC activity was investigated. More specifically, a tin dioxide SIDB layer was formed on the air side of four pieces of float glass and the specific physical properties of the SIDB layer were investigated. Then, an additional 16 pieces of float glass were provided with a titanium dioxide SIDB layer by CVD method, and each of the tin dioxide SIDB layers was again overcoated with a titanium dioxide PASC coating by CVD method. One sample was cut from each of 16 pieces of PASC coated/SIDB layer coated/float glass and these 16 samples were overcoated with stearic acid test film. Sixteen stearic acid test film coated/titanium dioxide PASC coated/tin dioxide SIDB layer coated/samples were exposed to UV light and PASC reaction rates were determined on these samples.

<u>3A. Investigation of the SIDB layer</u>

The SIDB layer was made of 4 pieces cut from a soda-lime-silica glass float ribbon having a width of about 5 inches, a length of 12 inches, and a thickness of 0.16 inches (12.7 cm wide, 30.48 cm long and 0.4 cm thick). It was deposited by the CVD method on the air side of the glass using the CVD apparatus described in Example 1. More specifically, the SIDB layer was a tin dioxide SIDB layer, and the effects of metal containing precursor concentration, water vapor concentration, CVD line speed, preheat temperature and SIDB layer thickness on the tin dioxide SIDB layer were investigated. The metal-containing precursor used to form the tin dioxide SIDB layer on all four pieces of glass by the CVD method was MBTTCL vapor, which was mixed with water vapor in an air carrier gas.

Tin dioxide was carried out by the CVD method and CVD apparatus of Example 1, with the first glass of the four pieces facing the air side of the piece of glass with an MBTTCL vapor concentration of about 1.5% and a water vapor concentration of about 1.5% in the air carrier gas. covered with a SIDB layer. The preheat temperature for this piece of glass was about 648° C. (1200° F.) and the line speed was about 50 inches (127 cm)/min. The thickness of the tin dioxide SIDB layer thus formed was about 3500 Å as measured by VASE. The resistivity and particle size of the SIDB layer were measured to be approximately 4.6 × 10, respectively.<sp>-3</sp>It was confirmed that Ω-cm and 198 Å.

A second piece of glass was tin dioxide, except that the line speed was reduced to about 20 inches (50.8 cm)/min, the MBTTCL vapor concentration in the air carrier gas was reduced to about 0.5%, and the water vapor concentration was reduced to about 0.5%. It was similarly coated with a layer of SIDB. The preheat temperature was maintained at about 648° C. (1200° F.). The thickness of the tin dioxide SIDB layer thus formed was about 4340 Å as measured by VASE. The resistivity is about 3.9×10<sp>-3</sp>Ω-cm and the particle size was about 185 Å.

A third piece of glass was similarly coated with a layer of tin dioxide SIDB, except that the preheat temperature was reduced to about 480° C. (900° F.) and the line speed was increased to about 50 inches (127 cm)/min. The MBTTCL concentration in the air carrier gas was about 1.5% and the water vapor concentration was about 1.5%. The resulting tin dioxide SIDB layer had a coating thickness of about 1000 Å as measured by VASE and about 3.5×10<sp>-2</sp>It had a resistivity of Ω-cm and a particle size of about 59 Å.

A fourth piece of glass was similarly coated with a layer of tin dioxide SIDB, except that the preheat temperature was maintained at about 480° C. (900° F.) and the line speed was reduced to 20 inches (50.8 cm)/min. The MBTTCL concentration in the air carrier gas was about 0.5% and the water vapor concentration was about 0.5%. The tin dioxide SIDB layer was about 1010 Å as measured by VASE, and about 2×10<sp>-2</sp>It had a resistivity of Ω-cm and a particle size of about 78 Å.

It was concluded that all four glass pieces had a tinite structure, although the resistivity or grain size could vary within the above temperature range, concentration, line speed and SIDB layer thickness.

<u>3B. Formation of a tin dioxide PASC coating formed on a tin dioxide SIDB layer by a CVD method</u>

5 16 additional float glass pieces, each measured as having a width of 12 inches, a length of 12 inches, and a thickness of 0.16 inches (12.7 cm wide, 30.48 cm long and 0.4 cm thick), are each described generally in Example 3A It was coated with a tin dioxide SIDB layer with a CVD coater and CVD method, and then further coated with a titanium dioxide PASC coat using the CVD coater and CVD method generally described in Example 1. For this coating operation, an online CVD method using a pair of successive coating units (a coating unit for the SIDB layer and a coating unit for the PASC coating) was used. Since the PASC coating on the SIDB layer makes the individual analysis of the SIDB layer difficult, if possible, both the SIDB layer and the PASC coating were applied to 16 pieces of glass under various specific coating parameters as described below and as shown in Table 1 below. Nevertheless, it was thought that the PASC topcoated tin dioxide layer had the same properties as the untopically coated tin dioxide layer described in 3A above.

In general, 16 layers of tin dioxide SIDB were also deposited from a metal containing precursor of MBTTCL vapor in an air carrier gas mixed with water vapor carried in air. The MBTTCL vapor temperature was maintained at about 160°C (320°F). The total flow rate was 60 slm and the exhaust matching ratio was 115%. The slot width was 0.16 cm (1/16 inch). Various specific covering parameters in the SIDB layer formed in this example included preheat zone 94 temperature, line speed, MBTTCL concentration, water vapor concentration and SIDB layer thickness. Table 1 below shows the tin dioxide SIDB layer coating parameters and estimated SIDB layer thicknesses for each of the 16 glass pieces. Actual thickness measurement was not performed, and the estimated thickness is based on the results obtained in 3A above. The 16 pieces in Table 1 below were divided into 4 groups of 4 substrates each based on preheat temperature and line speed.

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align="center" colname="1" morerows="0" nameend="7" namest="1">SnO<sb>2</sb> CVD coating parameters of sodium ion dispersion barrier layer</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">group number</entry><entry align="center" morerows="0" nameend="2" namest="2">sample number</entry><entry align="center" morerows="0" nameend="3" namest="3">Preheat temperature ()</entry><entry align="center" morerows="0" nameend="4" namest="4">Line speed (inches/min)</entry><entry align="center" morerows="0" nameend="5" namest="5">H<sb>2</sb>O concentration (vol%)</entry><entry align="center" morerows="0" nameend="6" namest="6">MBTTCL concentration (%)</entry><entry align="center" morerows="0" nameend="7" namest="7">Estimated SIDB layer thickness (Å)</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">I</entry><entry align="center" morerows="0" nameend="2" namest="2">1</entry><entry align="center" 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namest="6">0.5</entry><entry align="center" morerows="0" nameend="7" namest="7">4340</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">10</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">0.5</entry><entry align="center" morerows="0" nameend="6" namest="6">0.5</entry><entry align="center" morerows="0" nameend="7" namest="7">4340</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">11</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">0.5</entry><entry align="center" morerows="0" nameend="6" namest="6">0.5</entry><entry align="center" morerows="0" nameend="7" namest="7">4340</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">12</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">0.5</entry><entry align="center" morerows="0" nameend="6" namest="6">0.5</entry><entry align="center" morerows="0" nameend="7" namest="7">4340</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">IV</entry><entry align="center" morerows="0" nameend="2" namest="2">13</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">1.5</entry><entry align="center" morerows="0" nameend="6" namest="6">1.5</entry><entry align="center" morerows="0" nameend="7" namest="7">3500</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">14</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">1.5</entry><entry align="center" morerows="0" nameend="6" namest="6">1.5</entry><entry align="center" morerows="0" nameend="7" namest="7">3500</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">15</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">1.5</entry><entry align="center" morerows="0" nameend="6" namest="6">1.5</entry><entry align="center" morerows="0" nameend="7" namest="7">3500</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">16</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">1.5</entry><entry align="center" morerows="0" nameend="6" namest="6">1.5</entry><entry align="center" morerows="0" nameend="7" namest="7">3500</entry></row></tbody></tgroup></table></tables>

Each of the 16 SIDB-coated glass pieces was again placed downstream of the first SIDB-coated unit and nitrogen (N<sb>2</sb>) The metal containing precursor of the TTIP vapor carrier in the carrier gas was overcoated with a titanium dioxide PASC coating deposited from a second CVD coating unit leading to the SIDB layer coating surface of the glass piece. Ammonia (NH<sb>3</sb>) was added to the TTIP/carrier gas mixture of 8 out of 16 glass pieces. The carrier gas of all 16 pieces was maintained at a temperature of about 113° C. (235° F.). Sixteen pieces were annealed as in Example 1. The TTIP vaporizer temperature was maintained at about 104.4° C. (220° F.). Table 2 below shows the titanium dioxide PASC coverage parameters for 16 glass pieces. In Table 2 below, 16 pieces of glass were divided into 4 groups of 4 pieces each based on preheat temperature and line speed.

<tables id="2"><table colsep="0" frame="top" id="2" rowsep="0"><title /><tgroup align="left" cols="9" colsep="0" rowsep="0" xmlns="http://www.oasis-open.org/tables/exchange/1.0"><colspec align="left" char="0" charoff="0" colname="1" colnum="1" colsep="0" colwidth="789" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="2" colnum="2" colsep="0" colwidth="1408" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="3" colnum="3" colsep="0" colwidth="1409" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="4" colnum="4" colsep="0" colwidth="1409" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="5" colnum="5" colsep="0" colwidth="1263" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="6" colnum="6" colsep="0" colwidth="1057" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="7" colnum="7" colsep="0" colwidth="1282" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="8" colnum="8" colsep="0" colwidth="1094" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="9" colnum="9" colsep="0" colwidth="1169" rowsep="0" /><tbody valign="top"><row rowsep="0" valign="middle"><entry align="center" colname="1" morerows="0" nameend="9" namest="1">TiO<sb>2</sb> Photocatalytically Activated Self-Cleaning Coating Parameters</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">group number</entry><entry align="center" morerows="0" nameend="2" namest="2">sample number</entry><entry align="center" morerows="0" nameend="3" namest="3">preheat temperature<sp>*</sp> (℉)</entry><entry align="center" morerows="0" nameend="4" namest="4">Line speed (inches/min)</entry><entry align="center" morerows="0" nameend="5" namest="5">Total flow rate (/min)</entry><entry align="center" morerows="0" nameend="6" namest="6">Exhaust Matching (%)</entry><entry align="center" morerows="0" nameend="7" namest="7">TTIP concentration (%)</entry><entry align="center" morerows="0" nameend="8" namest="8">NH<sb>3</sb> Concentration (%)</entry><entry align="center" morerows="0" nameend="9" namest="9">Slot Width (inches)</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">I</entry><entry align="center" morerows="0" nameend="2" namest="2">1</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">2</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">3</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">4</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">II</entry><entry align="center" morerows="0" nameend="2" namest="2">5</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">6</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">7</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">8</entry><entry align="center" morerows="0" nameend="3" namest="3">900</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">III</entry><entry align="center" morerows="0" nameend="2" namest="2">9</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">10</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">11</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">12</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">20</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">IV</entry><entry align="center" morerows="0" nameend="2" namest="2">13</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">14</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">105</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">0</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">15</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">35</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.1</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">1/16</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">16</entry><entry align="center" morerows="0" nameend="3" namest="3">1200</entry><entry align="center" morerows="0" nameend="4" namest="4">50</entry><entry align="center" morerows="0" nameend="5" namest="5">75</entry><entry align="center" morerows="0" nameend="6" namest="6">125</entry><entry align="center" morerows="0" nameend="7" namest="7">0.4</entry><entry align="center" morerows="0" nameend="8" namest="8">20</entry><entry align="center" morerows="0" nameend="9" namest="9">3/16</entry></row><row rowsep="0" valign="middle"><entry align="left" colname="1" morerows="0" nameend="9" namest="1"><sp>*</sp> Here, the preheating temperature refers to the temperature of the preheating zone 94 . There is only one preheat operation, and the preheat temperature shown here is such that the glass piece passes through a CVD coater 88 before entering the annealing zone 98 and is first coated with a SIDB layer and then with a PASC coat. A preheat temperature equal to the temperature of these pieces increased in the preheat zone.</entry></row></tbody></tgroup></table></tables>

Table 3 below shows the selected properties of each of the 16 glass pieces after the PASC coating was applied as described in Table 2. PASC coating thickness was not measured, but is believed to vary within each group due to variations in other deposition parameters such as line speed and precursor concentration. However, the surface roughness and particle size of PASC coatings were determined to correlate PASC activity with roughness and particle size. Surface roughness measurements were evaluated based on Atomic Force Microscope (hereinafter referred to as "AFM") measurements made of the PASC coating. A large change was found in the crystalline phase as a function of surface roughness, particle size and preheat temperature.

<tables id="3"><table colsep="0" frame="top" id="3" rowsep="0"><title /><tgroup align="left" cols="5" colsep="0" rowsep="0" xmlns="http://www.oasis-open.org/tables/exchange/1.0"><colspec align="left" char="0" charoff="0" colname="1" colnum="1" colsep="0" colwidth="1592" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="2" colnum="2" colsep="0" colwidth="1592" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="3" colnum="3" colsep="0" colwidth="1705" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="4" colnum="4" colsep="0" colwidth="1759" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="5" colnum="5" colsep="0" colwidth="2594" rowsep="0" /><tbody valign="top"><row rowsep="0" valign="middle"><entry align="center" colname="1" morerows="0" nameend="5" namest="1">TiO<sb>2</sb> Photocatalytically activated self-cleaning coating properties</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">group number</entry><entry align="center" morerows="0" nameend="2" namest="2">sample number</entry><entry align="center" morerows="0" nameend="3" namest="3">Surface roughness (Rms)</entry><entry align="center" morerows="0" nameend="4" namest="4">Particle size (Å)</entry><entry align="center" morerows="0" nameend="5" namest="5">crystalline phase</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">I</entry><entry align="center" morerows="0" nameend="2" namest="2">1</entry><entry align="center" morerows="0" nameend="3" namest="3">4.13</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">2</entry><entry align="center" morerows="0" nameend="3" namest="3">5.18</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">3</entry><entry align="center" morerows="0" nameend="3" namest="3">7.87</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">Chuseok / rutile</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">4</entry><entry align="center" morerows="0" nameend="3" namest="3">7.84</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">Chuseok / rutile</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">II</entry><entry align="center" morerows="0" nameend="2" namest="2">5</entry><entry align="center" morerows="0" nameend="3" namest="3">6.39</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">6</entry><entry align="center" morerows="0" nameend="3" namest="3">4.38</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">7</entry><entry align="center" morerows="0" nameend="3" namest="3">5.99</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">Chuseok / rutile</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">8</entry><entry align="center" morerows="0" nameend="3" namest="3">7.50</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">III</entry><entry align="center" morerows="0" nameend="2" namest="2">9</entry><entry align="center" morerows="0" nameend="3" namest="3">14.71</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">10</entry><entry align="center" morerows="0" nameend="3" namest="3">15.58</entry><entry align="center" morerows="0" nameend="4" namest="4">277</entry><entry align="center" morerows="0" nameend="5" namest="5">anatase</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">11</entry><entry align="center" morerows="0" nameend="3" namest="3">23.08</entry><entry align="center" morerows="0" nameend="4" namest="4">121</entry><entry align="center" morerows="0" nameend="5" namest="5">anatase</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">12</entry><entry align="center" morerows="0" nameend="3" namest="3">16.93</entry><entry align="center" morerows="0" nameend="4" namest="4">166</entry><entry align="center" morerows="0" nameend="5" namest="5">anatase</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">IV</entry><entry align="center" morerows="0" nameend="2" namest="2">13</entry><entry align="center" morerows="0" nameend="3" namest="3">13.13</entry><entry align="center" morerows="0" nameend="4" namest="4">216</entry><entry align="center" morerows="0" nameend="5" namest="5">anatase</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">14</entry><entry align="center" morerows="0" nameend="3" namest="3">15.72</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">not measured</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">15</entry><entry align="center" morerows="0" nameend="3" namest="3">14.52</entry><entry align="center" morerows="0" nameend="4" namest="4">*</entry><entry align="center" morerows="0" nameend="5" namest="5">a little anatase</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">16</entry><entry align="center" morerows="0" nameend="3" namest="3">15.93</entry><entry align="center" morerows="0" nameend="4" namest="4">154</entry><entry align="center" morerows="0" nameend="5" namest="5">anatase</entry></row><row rowsep="0" valign="middle"><entry align="left" colname="1" morerows="0" nameend="5" namest="1">* The particle size was not measured because the peak corresponding to the anatase phase was not detected in the X-ray diffraction pattern (Samples 1, 2, 5, 6, 8, 9 and 14) or the peak was too broad and weak (Sample 3, 4, 7 and 15) could not be calculated.</entry></row></tbody></tgroup></table></tables>

<u>3C. Description of the PASC Activity Test of 16 Substrates</u>

One A sample or test strip of inches by 4 inches (2.54 cm by 10.16 cm) was cut in the center of each of 16 pieces of PASC coated/SIDB coated glass. Each of the 16 test strips was overcoated with a stearic acid test film as described in Example 1 by spin coating. Sixteen test strips were then exposed to ultraviolet light from a black light source at an intensity of 20 W/m over a cumulative cycle of 7 hours to induce photocatalytically activated self-cleaning of the stearic acid test film.

Because the thickness of the stearic acid test film varies along the length of the test strip of 1 inch by 4 inches (2.54 cm by 10.16 cm) (i.e., as described above and by the change of interference color along the length of the test strip, It is observed from the observation that when stearic acid falls to the center of the spinning test strip, the thickness of the stearic acid test film is thicker at each end of the test strip and thinner towards the center of each test strip) due to the centrifugal force affecting the stearic acid, photocatalytically Activity was measured at each end of each of the 16 test strips using an FTIR spectrophotometer equipped with an MCT detection system. The PASC kinetics obtained from the FTIR spectroscopy tests in each pair of tests performed on each of the 16 test strips are shown in Table 4 below.

<tables id="4"><table colsep="0" frame="top" id="4" rowsep="0"><title /><tgroup align="left" cols="4" colsep="0" rowsep="0" xmlns="http://www.oasis-open.org/tables/exchange/1.0"><colspec align="center" char="0" charoff="0" colname="1" colnum="1" colsep="0" colwidth="1677" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="2" colnum="2" colsep="0" colwidth="1677" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="3" colnum="3" colsep="0" colwidth="3260" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="4" colnum="4" colsep="0" colwidth="3260" rowsep="0" /><tbody valign="top"><row rowsep="0" valign="middle"><entry align="center" colname="1" morerows="0" nameend="4" namest="1">Photocatalytically activated self-cleaning activity of 16 test strips</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">group number</entry><entry align="center" morerows="0" nameend="2" namest="2">sample number</entry><entry align="center" morerows="0" nameend="3" namest="3">PASC activation rate (left side of test strip) (×10<sp>-3</sp>/cm min)</entry><entry align="center" morerows="0" nameend="4" namest="4">PASC activation rate (left side of test strip) (×10<sp>-3</sp>/cm min)</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">I</entry><entry align="center" morerows="0" nameend="2" namest="2">1</entry><entry align="center" morerows="0" nameend="3" namest="3">0.39</entry><entry align="center" morerows="0" nameend="4" namest="4">0.45</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">2</entry><entry align="center" morerows="0" nameend="3" namest="3">0.32</entry><entry align="center" morerows="0" nameend="4" namest="4">0.28</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">3</entry><entry align="center" morerows="0" nameend="3" namest="3">0.26</entry><entry align="center" morerows="0" nameend="4" namest="4">0.31</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">4</entry><entry align="center" morerows="0" nameend="3" namest="3">0.4</entry><entry align="center" morerows="0" nameend="4" namest="4">0.39</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">II</entry><entry align="center" morerows="0" nameend="2" namest="2">5</entry><entry align="center" morerows="0" nameend="3" namest="3">0.5</entry><entry align="center" morerows="0" nameend="4" namest="4">0.57</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">6</entry><entry align="center" morerows="0" nameend="3" namest="3">0.23</entry><entry align="center" morerows="0" nameend="4" namest="4">0.14</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">7</entry><entry align="center" morerows="0" nameend="3" namest="3">0.27</entry><entry align="center" morerows="0" nameend="4" namest="4">0.22</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">8</entry><entry align="center" morerows="0" nameend="3" namest="3">0.014</entry><entry align="center" morerows="0" nameend="4" namest="4">0.019</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">III</entry><entry align="center" morerows="0" nameend="2" namest="2">9</entry><entry align="center" morerows="0" nameend="3" namest="3">0.23</entry><entry align="center" morerows="0" nameend="4" namest="4">0.048</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">10</entry><entry align="center" morerows="0" nameend="3" namest="3">0.96</entry><entry align="center" morerows="0" nameend="4" namest="4">0.77</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">11</entry><entry align="center" morerows="0" nameend="3" namest="3">0.4</entry><entry align="center" morerows="0" nameend="4" namest="4">0.31</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">12</entry><entry align="center" morerows="0" nameend="3" namest="3">0.52</entry><entry align="center" morerows="0" nameend="4" namest="4">0.43</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="3" nameend="1" namest="1">IV</entry><entry align="center" morerows="0" nameend="2" namest="2">13</entry><entry align="center" morerows="0" nameend="3" namest="3">1.18</entry><entry align="center" morerows="0" nameend="4" namest="4">0.94</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">14</entry><entry align="center" morerows="0" nameend="3" namest="3">0.73</entry><entry align="center" morerows="0" nameend="4" namest="4">0.77</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">15</entry><entry align="center" morerows="0" nameend="3" namest="3">0.42</entry><entry align="center" morerows="0" nameend="4" namest="4">0.41</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="2" namest="2">16</entry><entry align="center" morerows="0" nameend="3" namest="3">0.25</entry><entry align="center" morerows="0" nameend="4" namest="4">0.35</entry></row></tbody></tgroup></table></tables>

It can be seen from Table 4 that the difference in activity between the two ends of the test strip in a particular test strip is very large. This difference is believed to be related to the non-uniform thickness of the stearic acid layer on the test strip.

In Table 4, there appears to be little correlation between the deposition conditions and the PASC activity of the PASC coating on the SIDB layer. As shown in Table 4, three of the most active test strips are samples 13, 10 and 14 based on the activity of the left side of the test strip. These strips 13, 10 and 14 correspond to a higher preheat temperature of 1200°F (648.8°C). If graded for PASC activity, the remaining 13 test strips in the grade were a mix of preheat temperature and other coating parameters reflecting the fact that the sodium ion diffusion barrier layer acts to prevent sodium ion poisoning of the PASC coating layer. can allow greater tolerance in coating conditions and parameters while still having photocatalytic activity.

<u>Example 4</u>

PASC coating formed by spray pyrolysis

In this example, glass pieces were coated with a titanium dioxide PASC coating of varying thickness by spray pyrolysis and the effect of PASC coating thickness on PASC activity was investigated.

Three pieces of float glass each 4 inches by 4 inches by 0.16 inches (10.16 cm by 10.16 cm by 4 mm) were air-faced with a titanium dioxide PASC coating by spray pyrolysis.

The basic components of a pyrolytic spraying apparatus used to apply a PASC coating on a piece of glass are shown in FIG. 4 . The spray pyrolysis apparatus included a preheat zone 120 and a pyrolysis spray zone 122 . Glass pieces 126 were transferred to preheat zone 120 on a conveyor not shown, where they were heated to a temperature in the range of about 600 to 700° C. (1112 to 1292° F.) using a number of electric heaters 130. The piece of glass 126 was then passed under an oscillating spray nozzle 132 located about 10 inches (25.4 cm) above the air side of the piece of glass 126 . An aqueous suspension (134) of the organometallic coating reagent was maintained in suspension with a stirrer (136) in the mixing chamber (138). The aqueous suspension 134 is transferred via tube 140 to a spray nozzle 132 , where by any conventional means (from a compressed air source 142 that has passed through tube 144 to spray nozzle 132 ). It was mixed with compressed air. When the aqueous suspension 134/compressed air mixture was sprayed from the nozzle 132 onto the surface of the glass piece 126, a spray pattern 146 was formed, which was pyrolyzed to form a PASC coating 24 on the glass piece 126. was formed. A piece of PASC coated glass 126 was cooled in air.

From this example, the free metal coating reagent selected was titanyl acetylacetonate and the rate of the aqueous suspension delivered to the surface of the three glass pieces 126 was controlled to provide a PASC coating thickness on each glass piece. The thicknesses were 400 Angstroms, 725 Angstroms and 1000 Angstroms. All other coating parameters were kept constant to determine the effect of PASC coating thickness on photocatalytic activity in titanium dioxide PASC coatings deposited by spray pyrolysis on clean float glass without SIDB barrier layer.

Table 5 below describes the specific coverage parameters for this example.

<tables id="5"><img file="KR100499549B1_D0001.tif" /></tables>

After deposition of the titanium dioxide PASC coating, each of the three glass pieces was cut into four 1-inch by 4-inch (2.54 cm by 10.16 cm) test strips, for a total of 12 test strips.

One test strip from each of the three original glass pieces was each subjected to X-ray diffraction analysis. From this analysis, it was confirmed by X-ray diffraction analysis that all three glass pieces of this example had strong X-ray diffraction lines corresponding to anatase titanium dioxide.

To evaluate the photocatalytic activity of the three glass pieces, one test strip from each of the three glass pieces was each overcoated with a stearic acid test film by the method described in Example 1. Three test strips were then exposed to ultraviolet light from a black light source positioned perpendicular to the covering surface of each test strip at 20 W/m 2 intensity over a cumulative time period of 7 hours. The photocatalytic reaction of each of the three test strips was quantitatively determined from FTIR spectroscopy using an MCT detection system as described above. Table 5 shows the photocatalytic reaction rates for three pieces of glass.

From the above, it is concluded that a low but acceptable level of photocatalytic reaction rates can be obtained in PASC coatings formed by the spray pyrolysis technique without sodium ion poisoning of PASC coatings. It was also concluded that thicker PASC coatings exhibited higher PASC activity, as described in Sample C in Table 5.

<u>Example 5</u>

Comparison of PASC coatings formed by spray pyrolysis with and without SIDB layer and investigation of effects on PASC coatings after annealing

In this experimental matrix, 8 pieces of glass were provided with a PASC coating by spray pyrolysis method, the effect of the presence and absence of the SIDB layer, the effect of the PASC coating thickness, and the substrate temperature at the time of deposition of the PASC coating on the PASC reaction rate of the PASC coating. was evaluated.

More specifically, each of the four air sides of the eight 4 mm Solex float glass pieces was treated with dibutyltin difluoride ((C<sb>4</sb>H<sb>9</sb>)<sb>2</sb>SnF<sb>2</sb>) and a wetting agent with a 500 Å thick layer of tin dioxide SIDB already deposited by spray pyrolysis with an aqueous suspension. A layer of tin dioxide SIDB was applied to the spray pyrolysis apparatus and method described in Example 4. After coating with the SIDB layer, the glass sample was cooled to room temperature, and each of these 4 glass pieces and the remaining 4 glass pieces were coated with a titanium dioxide PASC coating on the SIDB layer and cooled to room temperature. The laboratory pyrolysis atomization apparatus used in this experiment had only one atomization pyrolysis station, so that the dibutyltin difluoride suspension (to provide the SIDB layer) to the titanyl acetylacetonate suspension (to provide the PASC coating) was It should be noted that, since conversion is required, 4 pieces of SIDB layer coated glass were prepared in the form of cooling to room temperature between the application of the SIDB layer and the PASC coating and then reheating before applying the PASC coating. This intermediate cooling step would be omitted in the preferred coater, i.e. two spray pyrolysis stations would be provided to subsequently coat the SIDB layer and the PASC coating to a substrate moving like a continuous glass float ribbon without any such intermediate cooling step. .

After all eight pieces of PASC coated glass were cooled to room temperature, the pieces of glass were top coated with the stearic acid film described in Example 1, which was then applied to the PASC coated surface with a stearic acid test film to provide a 20 W/m2 strength. The /PASC coated glass pieces were exposed to UV light with a UVA 340 light source positioned perpendicular to the covering surface. The PASC reaction rate for removal of the stearic acid test film was quantitatively determined using the method as described in Example 1. This PASC reaction rate is recorded in Table 6 below the column indicated by 0.00 min. Note that the 0.00 min parameter indicates that the piece of glass with the PASC coating was not annealed after cooling to room temperature, not the UV cumulative exposure time period.

The effect of annealing time on stearic acid removal was investigated as follows. The residual stearic acid test film of the PASC coating of each of the eight glass pieces was removed by wiping the surface with a wiping cloth moistened with methanol until no stearic acid film or haze was observed. Each of the eight pieces of glass was then placed back in the furnace at about 500°C (932°F) for about 3 minutes to heat each piece. The furnace heat was turned off, the furnace door was opened, and each piece of glass was allowed to cool in the furnace to about room temperature. Annealed at a slow cooling rate in the furnace. Each piece of glass was then overcoated with a fresh stearic acid test film and exposed to ultraviolet light, and the PASC reaction rate was then determined in the same manner as for the unannealed PASC coating described above in this example. The residual stearic acid test film was again removed from the surface of each glass piece as described above, and each glass piece was heated for an additional 10 minutes and slowly cooled in a furnace in the same manner to undergo a cumulative heating time cycle of 13 minutes, The stearic acid test film was then reapplied as described above to determine the PASC reaction rate as described above. The process was repeated for another hour to obtain a cumulative heating time period of 73 minutes, followed by annealing by slow cooling in the furnace.

The properties of the SIDB layer and PASC coating for eight glass pieces (D to K), and the PASC kinetics versus cumulative annealing time are shown in Table 6 below.

<tables id="6"><table colsep="0" frame="top" id="5" rowsep="0"><title /><tgroup align="left" cols="8" colsep="0" rowsep="0" xmlns="http://www.oasis-open.org/tables/exchange/1.0"><colspec align="left" char="0" charoff="0" colname="1" colnum="1" colsep="0" colwidth="1330" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="2" colnum="2" colsep="0" colwidth="1330" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="3" colnum="3" colsep="0" colwidth="1330" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="4" colnum="4" colsep="0" colwidth="1430" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="5" colnum="5" colsep="0" colwidth="1430" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="6" colnum="6" colsep="0" colwidth="1347" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="7" colnum="7" colsep="0" colwidth="1347" rowsep="0" /><colspec align="center" char="0" charoff="0" colname="8" colnum="8" colsep="0" colwidth="1347" rowsep="0" /><tbody valign="top"><row rowsep="0" valign="middle"><entry align="center" colname="1" morerows="0" nameend="8" namest="1">Photocatalytically active kinetics of PASC coatings in the presence and absence of a sodium-ion diffusion barrier layer</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="1" nameend="1" namest="1">Sample</entry><entry align="center" morerows="1" nameend="2" namest="2">barrier layer</entry><entry align="center" morerows="1" nameend="3" namest="3">TiO<sb>2</sb> thickness</entry><entry align="center" morerows="1" nameend="4" namest="4">TiO<sb>2</sb> Glass temperature during coating</entry><entry align="center" colname="5" morerows="0" nameend="8" namest="5">Photocatalytic activity after annealing at 500° C. for the following times:<sp>*</sp></entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="5" namest="5">0.00<sp>**</sp>minute</entry><entry align="center" morerows="0" nameend="6" namest="6">3 minutes</entry><entry align="center" morerows="0" nameend="7" namest="7">13 minutes</entry><entry align="center" morerows="0" nameend="8" namest="8">73 minutes</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">D</entry><entry align="center" morerows="0" nameend="2" namest="2">does not exist</entry><entry align="center" morerows="0" nameend="3" namest="3">400Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1145℉</entry><entry align="center" morerows="0" nameend="5" namest="5">0.72</entry><entry align="center" morerows="0" nameend="6" namest="6">1.05</entry><entry align="center" morerows="0" nameend="7" namest="7">1.94</entry><entry align="center" morerows="0" nameend="8" namest="8">***</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">E</entry><entry align="center" morerows="0" nameend="2" namest="2">does not exist</entry><entry align="center" morerows="0" nameend="3" namest="3">625Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1145℉</entry><entry align="center" morerows="0" nameend="5" namest="5">0.69</entry><entry align="center" morerows="0" nameend="6" namest="6">1.05</entry><entry align="center" morerows="0" nameend="7" namest="7">1.67</entry><entry align="center" morerows="0" nameend="8" namest="8">2.97</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">F</entry><entry align="center" morerows="0" nameend="2" namest="2">500Å SnO<sb>2</sb></entry><entry align="center" morerows="0" nameend="3" namest="3">400Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1147℉</entry><entry align="center" morerows="0" nameend="5" namest="5">2.39</entry><entry align="center" morerows="0" nameend="6" namest="6">5.02</entry><entry align="center" morerows="0" nameend="7" namest="7">7.39</entry><entry align="center" morerows="0" nameend="8" namest="8">***</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">G</entry><entry align="center" morerows="0" nameend="2" namest="2">500Å SnO<sb>2</sb></entry><entry align="center" morerows="0" nameend="3" namest="3">625Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1152℉</entry><entry align="center" morerows="0" nameend="5" namest="5">2.23</entry><entry align="center" morerows="0" nameend="6" namest="6">5.35</entry><entry align="center" morerows="0" nameend="7" namest="7">8.74</entry><entry align="center" morerows="0" nameend="8" namest="8">5.13</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">H</entry><entry align="center" morerows="0" nameend="2" namest="2">does not exist</entry><entry align="center" morerows="0" nameend="3" namest="3">400Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1260℉</entry><entry align="center" morerows="0" nameend="5" namest="5">2.05</entry><entry align="center" morerows="0" nameend="6" namest="6">6.59</entry><entry align="center" morerows="0" nameend="7" namest="7">5.14</entry><entry align="center" morerows="0" nameend="8" namest="8">***</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">I</entry><entry align="center" morerows="0" nameend="2" namest="2">does not exist</entry><entry align="center" morerows="0" nameend="3" namest="3">625Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1260℉</entry><entry align="center" morerows="0" nameend="5" namest="5">4.71</entry><entry align="center" morerows="0" nameend="6" namest="6">7.99</entry><entry align="center" morerows="0" nameend="7" namest="7">9.95</entry><entry align="center" morerows="0" nameend="8" namest="8">5.39</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">J</entry><entry align="center" morerows="0" nameend="2" namest="2">500Å SnO<sb>2</sb></entry><entry align="center" morerows="0" nameend="3" namest="3">400Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1300℉</entry><entry align="center" morerows="0" nameend="5" namest="5">2.4</entry><entry align="center" morerows="0" nameend="6" namest="6">5.26</entry><entry align="center" morerows="0" nameend="7" namest="7">3.73</entry><entry align="center" morerows="0" nameend="8" namest="8">***</entry></row><row rowsep="0" valign="middle"><entry align="center" morerows="0" nameend="1" namest="1">K</entry><entry align="center" morerows="0" nameend="2" namest="2">500Å SnO<sb>2</sb></entry><entry align="center" morerows="0" nameend="3" namest="3">625Å</entry><entry align="center" morerows="0" nameend="4" namest="4">1280℉</entry><entry align="center" morerows="0" nameend="5" namest="5">4.64</entry><entry align="center" morerows="0" nameend="6" namest="6">12.29</entry><entry align="center" morerows="0" nameend="7" namest="7">5.57</entry><entry align="center" morerows="0" nameend="8" namest="8">4.4</entry></row><row rowsep="0" valign="middle"><entry align="left" colname="1" morerows="0" nameend="8" namest="1"><sp>*</sp> PASC reaction rate for stearic acid removal (×10<sp>-3</sp> /cm min)</entry></row></tbody></tgroup></table></tables>

The photocatalytic assay results shown in Table 6 suggest that the PASC activity of an approximately 625 Å thick titanium dioxide layer without a barrier layer (Sample I) can reach the PASC activity of a thinner 400 Å thick PASC coating on the SIDB layer (Sample K). do. It should be noted that the reheat operation in sample K with the SIDB layer subjected to an intermediate cooling and subsequent reheat operation as described may reduce the effect of the SIDB layer in sample K, which would otherwise have a higher PASC activity.

Sample K in Table 6 also indicates that the annealing time can have a significant effect on the PASC kinetics. After a 3 min annealing time, the PASC activity of Sample K was about 4.64×10<sp>-3</sp> ㎝<sp>-1</sp>min<sp>-1</sp>at about 12.29×10<sp>-3</sp> ㎝<sp>-1</sp>min<sp>-1</sp>increases to , but then drops upon further annealing. The anatase phase of the titanium dioxide PASC coating was formed when PASC activity was measured at 3 min and is believed to have formed without apparent sodium ion poisoning due to the presence of tin dioxide in the SIDB layer. Without wishing to be bound by this particular theory, continuing annealing for too long a cumulative time period may induce sodium ion poisoning, which will be explained by the decrease in PASC activity of sample K despite the presence of the SIDB layer.

The above examples are presented to illustrate the present invention, not to limit the present invention.

While the above method of providing a PASC coating has been described for providing such a coating on a continuously moving substrate, such as, for example, a continuous glass float ribbon during the manufacture of the substrate, these methods are also downstream of the substrate manufacturing method. It will be appreciated that the process may be used. For example, a PASC coating may be provided on a substrate including, but not limited to, a glass substrate as part of a method of bending and/or tempering the substrate. For example, when bending and/or tempering a glass substrate after heating, the PASC coating with or without a SIDB layer can be applied by spray pyrolysis, CVD techniques or MSVD techniques as described above prior to bending/tempering. CVD and spray pyrolysis methods can be used when heating a glass substrate to a bending/tempering temperature. The PASC coating may be applied to the glass substrate after a bending/tempering reheat operation by any CVD, spray pyrolysis or MSVD method, with or without the SIDB layer.

It is believed that there is a difference between PASC coatings prepared by the sol-gel method and PASC coatings prepared by the aforementioned method. For example, PASC coatings made by the sol-gel process may be more porous, less dense, generally thicker, and generally less suitable for use in transparent applications, and may be produced by CVD or spray pyrolysis processes. It may tend to contain more OH groups than prepared. As noted above, excess OH groups are less desirable because they can inhibit the formation of more suitable crystals in the PASC coating, thereby reducing PASC activity. It is believed that PASC coatings produced by CVD or spray pyrolysis methods will have a finer grain structure than those produced by sol-gel methods.

Advantages of the present invention over sol-gel methods for forming PASC coatings include the ability to form thin, dense PASC films on substrates as opposed to thicker and porous coatings obtained with sol-gel coating methods. Because the PASC coatings of the present invention are thin, they are aesthetically suitable for use as transparent coatings on glass substrates. Another advantage is that the process for preparing PASC coatings according to the present invention does not require reheating of the substrate after application of the coating or coating precursor, as is required by the sol-gel processes currently in use. For this reason, the method of the present invention is not only low cost and high efficiency, such as, but not limited to, low equipment cost, low energy cost and low production time, but also the potential for sodium ions to migrate and the sodium in the PASC coating of the present invention. Ion poisoning is greatly reduced. The method of the present invention is also suitable for forming PASC coatings on continuously moving substrates such as glass float ribbons where the sol-gel methods currently in use are not so readily suitable.

Various modifications are included within the scope of the present invention, which is defined by the following claims.