Photocatalyst activated self-cleaning article and method for manufacturing the same

<u style="single">Cross-reference of related applications</u> This application claims the provisional US patent application serial number (Serial No.) 60 / 040,566 filed on March 14, 1997. The provisional U.S. patent application serial number 60 / 040,565 filed on March 14, 1997 and the same day filing, entitled "Photocatalytically Activated Self-Cleaning Equipment," formal United States such as Greenberg. Patent application serial number 08 / 899,265 is relevant to this application and is incorporated herein by reference.<u style="single">Background of the invention</u><u style="single">Field of invention</u> The present invention is a method of attaching a photocatalytically-activated self-cleaning coating onto a substrate (eg, a glass sheet or a continuous float glass ribbon). The present invention relates to methods for preventing sodium ion poisoning of a photocatalytically activated self-cleaning coating adhered to a sodium ion-containing substrate, and articles manufactured according to those methods.

<u style="single">Description of related technology</u> For many substrates (eg, glass substrates), it is desirable that the surface of the substrate remains "clean", i.e. free of surface contaminants such as common organic and inorganic surface contaminants. Traditionally, this has meant that such surfaces often have to be cleaned. This cleaning operation is typically performed manually or with a mechanical device. Both methods are extremely labor intensive, time consuming and / or costly. There is a need for substrates that are self-cleaning or at least have a surface that is easy to clean, eliminating or reducing the need for such manual or mechanical cleaning.

Titanium dioxide (TiO₂) Coating is known to impart photocatalytic activation self-cleaning (hereinafter referred to as "PASC") on the substrate. Publications on forming a PASC titanium dioxide coating on a glass substrate include Photooxidative Self-cleaning Transparent, such as US Pat. No. 5,595,813 and Paz. Titanium Dioxide Films on Glass), J. Mater, Res., Vol. 10, No. 11, pp. 2842-48, Nov. (1995) is included. In addition, the library catalog of patents and treatises on photocatalytic oxidation of organic compounds is generally referred to by D. Bleke, "Bibliography of Work On The Photocatalytic Removal" by D. Bleke. It has been reported in the Hazardous Compounds from Water and Air) (May 1994, National Renewable Energy Laborafory), and the latest edition in October 1995 and the latest edition in October 1996.

A currently available method of applying a PASC coating (eg, titanium dioxide PASC coating) to a substrate is the sol-gel method. In the sol-gel method, an uncrystallized alcohol solvent-containing colloidal suspension (sol) is sprayed, rotated, or immersedly coated on a substrate at or near room temperature. The substrate is then heated to a temperature within the range of about 100 ° C to 800 ° C (212 ° F to 1472 ° F) to bond the PASC coating to the substrate and / or crystallize the PASC coating onto the substrate. A crystallized PASC coating (gel) is formed on the surface.

One limitation of PASC coating application by the sol-gel method is that the sol-gel coating method is either uneconomical or substantially incompatible with certain application conditions or substrates. For example, when one wants to apply a PASC coating on a float ribbon during its production, the ribbon is too hot, in part because the solvent used in the sol solution makes the sol unacceptable. For many solvents used in the sol-gel process, the high temperature float ribbon is cooled to near room temperature, after which the sol is applied and the float ribbon is heated to a temperature sufficient for the sol to crystallize into a PASC coating. It is necessary to reheat. Such cooling and reheating operations require substantial investment in equipment, energy and handling costs, and significantly reduce manufacturing efficiency.

The PASC activity of the PASC coating can be significantly reduced or eliminated if sodium ions are present in the substrate and migrate from the substrate to the PASC coating. This process is known as sodium poisoning or sodium ion poisoning. For many substrates containing sodium ions, the rate of transfer of sodium ions to the coating increases as the temperature of the substrate increases. Therefore, another limitation of the sol-gel coating method is that reheating of the substrate increases the chance of sodium ion migration, which in turn increases the sodium ion poisoning of the PASC coating.

Another constraint on forming a PASC coating by the sol-gel process is the thickness of the coating, eg, a few μ. Such a thick PASC coating can adversely affect the optical and / or aesthetic properties of the PASC coated article.

As can be seen from the above, there is a need for manufactured articles with PASC coatings and PASC coating attachment methods that do not have the drawbacks known in the art.

<p><u style="single">Outline of the invention</u> The present invention comprises a substrate having at least one surface and a group consisting of chemical vapor deposition (hereinafter referred to as "CVD"), spray pyrolysis, and magnetron sputtering vacuum deposition (hereinafter referred to as "MSVD") on the surface of the substrate. For PASC products having a PASC coating deposited by a method selected from, eg, titanium dioxide coating. The present invention also relates to a process for making such products.</p><p> The present invention relates to a substrate having at least one surface, a sodium ion diffusion barrier (hereinafter referred to as "SIDB") layer deposited on the surface of the substrate, for example, a layer of tin oxide, titanium dioxide, aluminum oxide, and a layer thereof. The mixture also relates to a PASC coating deposited on the SIDB layer, eg, a PASC product having a titanium dioxide coating. The PASC coating and SIDB layer are each deposited by a method selected from the group consisting of CVD, spray pyrolysis, and MSVD, respectively. The present invention also relates to a process for making such products.</p>

<p><u style="single">Description of preferred embodiments</u> With respect to FIG. 1, an article 20 having the features of the present invention is shown. Article 20 has a substrate 22 on which the PASC coating 24 is deposited. The substrate 22 is not limited to the present invention and includes glass substrates such as glass sheets or continuous float glass ribbons, plastic substrates, metal substrates, and enamel coated substrates.</p><p> The PASC coating 24 may be present directly on the substrate 22, as shown in FIG. 1, or otherwise, another layer may be interposed between the PASC coating 24 and the substrate 22. Often, these layers include, but are not limited to, the SIDB layer 26, which is shown in FIG. 2 and will be described in more detail later. Further, the PASC coating 24 may be the top layer of a multilayer laminate of coatings present on the substrate 22, or the PASC coating 24 may be such as one of the layers other than the top layer. It will be appreciated by those skilled in the art that it may be embedded in a multilayer laminate. However, sufficient chemical lines to photocatalytically activate the PASC coating 24 pass through any coating deposited on the PASC coating 24, and active radicals pass through the coating deposited on the PASC coating 24 and are multilayered. It shall be capable of reacting with organic contaminants present on the top layer of the laminate.</p><p> The PASC coating 24 may be any coating that is photocatalytically activated to self-clean and can be deposited by CVD, spray pyrolysis, or MSVD. For example, PASC coating 24 includes titanium oxide, iron oxide, silver oxide, copper oxide, tungsten oxide, aluminum oxide, silicon oxide, zinc tinate, molybdenum oxide, zinc oxide, zinc / tin oxide, strontium titanate, etc. And mixtures thereof, but the invention is not limited thereto. Metal oxides also include metal oxides, superoxides, or suboxides.</p><p> The preferred PASC coating 24 is titanium dioxide. Titanium dioxide exists in amorphous and three crystalline forms, namely the crystalline forms of anatase, rutile and brookite. Anatase phase Titanium dioxide is preferred. Because it exhibits strong PASC activity, yet has excellent resistance to chemical erosion and excellent physical durability. In addition, the anatase phase titanium dioxide has high permeability in the visible region of the spectrum, which gives a thin coating of anatase titanium dioxide with excellent optical properties. Rutile phase titanium dioxide also exhibits PASC activity. Combinations of anatase and / or rutile phase with brookite and / or amorphous phase are also acceptable in the present invention as long as the combination exhibits PASC activity.</p><p> The PASC coating 24 must be thick enough to give an acceptable level of PASC activity. There is no absolute value that makes PASC coating 24 "acceptable" or "unacceptable". This is because whether or not a PASC coating has an acceptable level of PASC activity is largely determined by the purpose and conditions in which the PASC coated article is used and the performance criteria selected in connection with that purpose. In general, the thicker the PASC coating, the greater the PASC activity. However, other considerations may focus on giving a thinner coating. For example, thinner coatings are preferred when the article must have greater transparency for aesthetic or optical reasons. Surface contaminants on the surface of the article are easily removed using a thin PASC coating. The coating is exposed to substantial irradiation and / or the PASC coating 24 may be subject to sodium ion poisoning, which is described in more detail below. For a wide variety of applications, the PASC coating is preferably at least about 200 Å, preferably at least about 400 Å, and even more preferably at least about 500 Å. 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 the piece of float glass by the CVD method, it is at least about 500 Å thick and has a wide range of applications. Approximately 20 W / m on an acceptable PASC coated surface²When the PASC coating is exposed to UV light from a light source such as the one sold by Q-Panel in Cleveland, Ohio under the trade name UVA-340, which has the strength of, about 2 × for the removal of the stearic acid test film. Ten^-3~ About 5 × 10^-3/cm^-1Minutes^-1It has been found to give PASC kinetics in the range of.</p><p> According to the present invention, a thin PASC coating, eg, thinner than 1μ, more preferably less than 0.5μ, is formed on the substrate 22 by spray pyrolysis, CVD or MSVD. In the spray pyrolysis method, the metal-containing precursor is carried as an aqueous suspension or an aqueous solution, and in the CVD method, it is carried by a carrier gas, for example, nitrogen gas, and sent toward the surface of the substrate 22. Meanwhile, the substrate 22 is kept at a temperature high enough to decompose the metal-containing precursor to form a PASC coating 24 on the substrate 22. In the MSVD method, the metal-containing cathode target is sputtered in an inert or oxygen-containing atmosphere under reduced pressure to deposit a sputtering coating on the substrate 22. The substrate 22 during or after coating is heated to crystallize the sputtering coating to form the PASC coating 24.</p><p> Each of these methods has advantages and restrictions, for example, the CVD method and the thermal decomposition method are preferred over the spray thermal decomposition method. Because the aqueous solution of the spray pyrolysis method is OH in PASC coating 24^-This results in the presence of ions, which in turn prevent proper crystal formation of the PASC coating 24, thereby reducing the PASC activity of the coating. The CVD method and the thermal decomposition method are preferable to the MSVD method. This is because it is suitable for coating continuous substrates used at elevated temperatures, such as float glass ribbons. CVD, spray pyrolysis and MSVD methods for depositing PASC coating 24 are discussed in more detail below. It will be appreciated that spray pyrolysis and CVD methods can be used to deposit a thin (eg, hundreds of Å thick) metal oxide coating (including titanium dioxide coating) on a substrate. .. 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 (these patents are incorporated herein by reference). ..</p><p> Titanium tetrachloride (TiCl) is a metal-containing precursor that can be used in the practice of the present invention to form a titanium dioxide PASC coating by the CVD method.₄), Titanium tetraisopropoxide [Ti (OC)₃H₇)₄] (Hereinafter referred to as "TTIP"), and titanium tetraethoxydo [Ti (OC)₂H₅)₄] (Hereinafter referred to as "TTEt"), but is not limited to them. Carrier gases used in the CVD method 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 metal-containing precursors in the carrier gas is generally in the range of 0.1% to 0.4% by volume for the three metal-containing precursors listed above, but these concentrations are for other metal-containing precursors. It will be acknowledged by those skilled in the art that it can be changed.</p><p> Since the PASC coating is formed by the spray thermal decomposition method, the metal-containing precursors that can be used in the practice of the present invention include relatively water-soluble organometallic reactants, especially metal acetylacetonate compounds. Milled with a jet mill or wet grinded to a particle size smaller than about 10 μm and suspended in an aqueous medium using a chemical wetting agent. A suitable metal acetylacetone to form a titanium dioxide PASC coating is titanylacetylacetone [TiO (C).₅H₇O₂)₂]. The relative concentration of metal acetylacetonate in the aqueous suspension is preferably in the range of about 5-40% by weight of the aqueous suspension. The wetting agent may be any surface active agent having a relatively low foaming property, and includes anionic, nonionic and cationic compositions, but nonionic is preferable. The wetting agent is typically added in an amount of about 0.24% by weight, but can range from about 0.01% to 1% or more. Distilled water or deionized water is preferable as the aqueous medium. Aqueous suspensions for pyrolyzing and depositing metal-containing membranes are incorporated herein by US Pat. No. 4,719,127, particularly column 2, lines 16-4, line 48 (which is incorporated herein by reference). )It is described in.</p><p> For both CVD and spray pyrolysis, the temperature of the substrate 22 decomposes the metal-containing precursor during the formation of the PASC coating 24 on it to have PASC activity (eg, for metal oxide PASC coatings). It must be within the range of forming the crystal phase). It will be appreciated that the lower limit of this temperature range is significantly affected by the decomposition temperature of the selected metal-containing precursor. For the titanium-containing precursors listed above, the minimum temperature of the substrate 22, which provides sufficient decomposition of the precursor, is within the temperature range of about 400 ° C (752 ° F) and about 500 ° C (932 ° F). is there. The upper limit of this temperature range is affected by the substrate to be coated. For example, if the substrate 22 is a float glass ribbon and the PASC coating 24 is applied to the float ribbon during its manufacture, the float glass may have reached temperatures above 1000 ° C (1832 ° F). is there. Float glass ribbons are usually thinned or sized (eg, stretched or compressed) at temperatures above 800 ° C (1472 ° F). If the PASC coating 24 is applied before or during the thinning of the float glass, the PASC coating 24 will crack or wrinkle when the float glass ribbons are stretched or compressed respectively. Therefore, when carrying out the present invention, in the case of soda lime silica glass, the float method ribbon is lower than, for example, about 800 ° C (1472 ° F) and the shape is stable, and the float method ribbon is, for example, about 400 ° C. It is preferred to apply the PASC coating when at temperatures higher than (752 ° F) to decompose metal-containing precursors.</p><p> Forming the PASC coating 24 by CVD or spray pyrolysis is particularly well suited to be performed during the manufacture of float glass ribbons. Generally, a float glass ribbon is manufactured by melting a glass batch material in a furnace and sending clarified molten glass onto a molten tin bath. The molten glass on the bath is pulled across the tin bath as a continuous glass ribbon, its size is determined, controlled cooling is performed, and a float method glass ribbon having a stable shape is formed. The float method ribbon is taken out of the tin bath, moved through a furnace by a conveyor roll, and the float method glass ribbon is annealed. The annealed float ribbon is then moved on a conveyor roll through the cutting position, where the ribbon is cut into glass sheets of the desired length and width. U.S. Pat. Nos. 4,466,562 and 4,671,155, which are incorporated herein by reference, discuss the glass float method.</p><p> Float ribbon temperatures on tin baths generally range from approximately 1093.3 ° C (2000 ° F) at the outlet end of the bath to approximately 538 ° C (1000 ° F) at the outlet end of the bath. .. The temperature of the float ribbon between the tin bath and the annealing furnace is generally in the range of about 480 ° C (896 ° F) to about 580 ° C (1076 ° F). Float ribbon temperatures in the annealing furnace generally range from about 204 ° C (400 ° F) to about 557 ° C (1035 ° F) peaks.</p><p> US Pat. Nos. 4,853,257, 4,971,843, 5,536,718, 5,464,657 and 5,599,387, which are incorporated herein by reference, are used to cover the float ribbon during its manufacture. A CVD coating device and method that can be used in the practice of the present invention are described. The CVD method can coat a moving float ribbon and yet can withstand the harsh environment associated with the manufacture of the float ribbon, so to give the float ribbon a PASC coating 24, CVD. The law is very suitable. Float method A CVD coating device may be used at some point in the ribbon manufacturing process. For example, a CVD coating device moves when a float ribbon is moving through a tin bath, or after it leaves the tin bath, or before it enters an annealing furnace, or it moves through an annealing furnace. It can be used when or after it has left the annealing furnace.</p><p> Metal content in carrier gas Concentration of precursor, flow rate of carrier gas, velocity (linear velocity) of float method ribbon, surface area of CVD coating device relative to surface area of float method ribbon, waste carrier through exhaust vent of CVD coating device The flow rate and surface area of the gas, in particular the ratio of the exhaust rate through the exhaust vent to the carrier gas introduction rate through the CVD coating, and the temperature of the float ribbon, known as the "exhaust matching ratio". Will be accepted by those skilled in the art to fall within the parameters that affect the final thickness and morphology of the PASC coating 24 formed on the float method ribbon by the CVD method.</p><p> U.S. Pat. Nos. 4,719,126, 4,719,127, 4,111,150 and 3,660,061 incorporated herein by reference describe spray pyrolysis equipment and methods that can be used with the float ribbon process. Has been done. Similar to the CVD method, the spray pyrolysis method is well suited for coating moving float glass ribbons, but the spray pyrolysis has a more complex device than the CVD device and is usually in a tin bath. Used between the outlet end and the inlet end of the annealing furnace.</p><p> The components and concentrations of the aqueous suspension to be spray pyrolyzed, the linear velocity of the float pyrolysis, the number of spray pyrolysis guns, the spray pressure or volume, the spray pattern, and the temperature of the float pyrolysis during deposition are determined by spray pyrolysis. It is as accepted by those skilled in the art that it falls within the parameters that affect the final thickness and morphology of the PASC coating 24 formed on the float method ribbon.</p><p> As is known to those skilled in the art, the surface of a float glass ribbon on molten tin (commonly referred to as the "tin side") has tin diffused throughout the surface, which is in contact with the molten tin. Gives the tin side a different tin absorption pattern than the surface on the opposite side (commonly referred to as the "air side"). This property is described in "Chemical Characteristics of Float Glass Surfaces" by 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", Journal of Non-crystalline Solids, Vol. 38 &amp; 39, pp. 551-556 (1980); and Williams KFE et al., "Tin Oxide State of Float Glass by Mesbauer Spectroscopy, Sn²⁺And Sn⁴⁺Depth Profiles of Sn²⁺ and Sn⁴⁺ and Oxygen Diffusivity in Float Glass by Mossbauer Spectroscopy), Journal of Non-crystalline Solids, Vol. 211, pp. 164-172 (1997) (these statements are incorporated herein by reference). .. The PASC coating 24 may be formed (by the CVD method) on the air side of the float method ribbon while supporting the ribbon on a tin bath, or by the CVD method or the spray pyrolysis method, the float method ribbon. It may be formed on the air side of the tin bath after it has left the tin bath, or it may be formed on the tin side of the float method ribbon by the CVD method after it has left the tin bath. , Will be recognized by those skilled in the art. 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 the SIDB layer 26 for the PASC coating 24 deposited on it. Is expected to do.</p><p> US Pat. Nos. 4,379,040, 4,861,669, 4,900,633, 4,920,006, 4,938,857, 5,328,768 and 5,492,750, incorporated herein by reference. Incorporates into) describes an MSVD apparatus and method for sputtering a metal oxide film on a substrate including a glass substrate. The MSVD method is not always suitable for applying a PASC coating on a float glass ribbon during its manufacture. This is because, among other things, the MSVD method requires decompression during the sputtering operation, which is difficult to form on a continuously moving float method ribbon. However, the MSVD method is acceptable for depositing the PASC coating 24 on a substrate 22, eg, a glass sheet. The substrate 22 is heated to a temperature in the range of 400 ° C (752 ° F) to about 500 ° C (932 ° F) to crystallize the MSVD sputtering coating on the substrate during the deposition process, thereby performing a subsequent heating operation. It will be appreciated by those skilled in the art that can be omitted. Heating the substrate during sputtering is not the preferred method. This is because performing additional heating operations during sputtering reduces productivity. Alternatively, the sputtering coating can be crystallized directly in the MSVD coating equipment and does not require post-heat treatment with high energy plasma, but again the productivity of the MSVD coating equipment tends to decrease. So this is also not the preferred method.</p><p> A preferred method of applying a PASC coating using the MSVD method is to sputter the coating onto the substrate, remove the coated substrate from the MSVD coating machine, and then heat the coated substrate to crystallize the sputtering coating and PASC. Cover with 24. For example, using the MSVD method, sputtering a titanium metal target at a pressure of about 5-10 millitorls (0.67 to 1.33 pascals) in an argon / oxygen atmosphere containing about 5-50%, preferably about 20% oxygen. A titanium dioxide coating having a desired thickness is sputter-deposited on the substrate 22. The as-deposited coating is not crystallized. The coated substrate is removed from the coating machine and promotes the formation of PASC crystalline titanium dioxide to PASC activity at temperatures in the range of about 400 ° C (752 ° F) to about 600 ° C (1112 ° F). Heat for sufficient time. Generally, the temperature in the range of about 400 ° C (752 ° F) to about 600 ° C (1112 ° F) is preferably at least 1 hour. When the substrate 22 is a glass sheet cut from a float glass ribbon, the PASC coating 24 can be sputter-deposited on the air side and / or the tin side.</p><p> The substrate 22 with the PASC coating 24 deposited by CVD, spray pyrolysis, or MSVD method is later subjected to one or more PASC coating post-annealing operations to increase the self-cleaning activity of the PASC coating 24. It is believed that such post-PASC coating annealing can increase the self-cleaning activity of the PASC coating 24 by promoting the formation of the desired PASC crystal phase. The annealing time and temperature can be determined by the composition of the substrate 22, the composition of the PASC coating 24, the thickness of the PASC coating 24, and the PASC coating 24 being formed directly on the substrate 22 or one of the multilayer laminates on the substrate. It will be recognized that it is affected by several factors, including whether or not it is a single layer. If substrate 22 is a piece of float glass and the PASC coating is 400 Å or 625 Å thick anatase titanium dioxide formed by spray pyrolysis, the coating should be annealed at 500 ° C (932 ° F) for up to 13 minutes. Has been determined to increase PASC activity.</p><p> As described above, whether the PASC coating is applied by the CVD method or the spray pyrolysis method or the MSVD method, the substrate 22 contains sodium ions, which are deposited on the substrate 22 from the substrate 22 in the PASC coating. Sodium ions of the PASC coating can be transferred to by forming an inert compound while consuming titanium, eg, by forming sodium titanate, or by causing photoexcited charge recombination. It may inhibit or eliminate photocatalytic activity.</p><p> The PASC coating 1) limits the sodium ion poisoning given to a portion of the PASC coating and / or 2) provides the SIDB layer 26 without causing a decrease in photocatalytic activity. , It has been found that a PASC coating can be formed on the sodium ion-containing substrate 22. Each method is described in detail below.</p><p> If the thickness of the PASC coating exceeds the minimum threshold, a PASC coating is deposited on the surface of the sodium ion-containing substrate while the substrate is at a temperature sufficient to cause the transfer of sodium ions from the substrate to the PASC coating. However, it has been found that the PASC activity is not extinguished by the movement of sodium ions. The mechanism of this result is not fully understood, but if the thickness of the PASC coating exceeds this minimum thickness, during the time the temperature of the substrate exceeds the temperature that allows the movement of sodium ions. It is believed that sodium ions can migrate because they are only part of the total thickness of the PASC coating. When the temperature of the substrate subsequently drops below the temperature at which sodium ions move, the movement of sodium ions ceases, i.e. is "frozen" at that location, and the sodium ions are applied to the PASC coating on the opposite side of the substrate surface. The result is that PASC activity can be maintained, leaving unpoisoned thickness. The minimum thickness of this PASC coating is such as (limited to them) the time the substrate is maintained above the temperature at which sodium ion transfer occurs, its application with PASC-manufactured articles, and the desired or required PASC activity. It will be appreciated by those skilled in the art that it will vary depending on the expected factors (not). In the case of Titanium Dioxide PASC Coated on a Soda Lime Silica Flat Glass, in order to provide enough PASC coating 24 parts not poisoned by sodium ions and maintain its PASC activity, PASC The coating thickness should have a minimum value of about 250 Å, preferably a minimum value of about 400 Å, and more preferably a minimum value of about 500 Å.</p><p> Next, with respect to FIG. 2, another method of preventing sodium ion poisoning of the PASC coating is to provide SIDB layer 26 between the PASC coating 24 and the substrate 22. The SIDB layer 26 may be the only layer between the PASC coating 24 and the substrate 22, or it may be one layer of the multilayer laminate. When using a multi-layer laminate, the SIDB layer 26 is in contact with the substrate 22 as long as the SIDB layer 26 is placed between the PASC coating 24 and the substrate 22 to prevent the transfer of sodium ions from the substrate 22 to the PASC coating 24. You don't have to be.</p><p> SIDB layer 26 contains cobalt oxide, chromium oxide, iron oxide, tin oxide, silicon oxide, titanium oxide, zirconium oxide, fluorine-doped tin oxide, aluminum oxide, magnesium oxide, zinc oxide, and mixtures thereof (but not limited to them). It can be formed from amorphous or crystalline metal oxides including. Mixtures include, but are not limited to, magnesium / aluminum oxide and zinc / tin oxide. It is recognized by those skilled in the art that metal oxides include metal oxides, superoxides, or suboxides. The thickness of the SIDB layer required to prevent sodium ion poisoning of the PASC coating is the time the substrate is maintained above the temperature at which sodium ion migration occurs, the rate at which sodium ions migrate from the substrate, and the sodium ions in the SIDB layer. Prevents sodium ion poisoning of the PASC coating layer for most applications, depending on a variety of factors, including the rate of movement through, the thickness of the PASC coating, and the photocatalytic activity required for the given application. In order to do so, the thickness of the SIDB layer should typically be in the range of at least about 100 Å, preferably at least about 250 Å, more preferably at least about 500 Å. The SIDB layer can be deposited on the substrate 22 by CVD, spray pyrolysis, or the MSVD method. When spray pyrolysis or CVD method is used, the substrate 22 should be maintained at a temperature of at least about 400 ° C (752 ° F) to ensure that the metal-containing precursor is decomposed to form the SIDB layer. preferable. The SIDB layer may be formed by other methods including the sol-gel method, and the sol-gel method as described above is incompatible with the production of the float method glass ribbon.</p><p> The tin oxide SIDB layer was prepared by spray pyrolysis to dibutyl tin difluoride, (C.₄ H₉)₂ SnF₂And an aqueous suspension of water can be formed and deposited on the substrate by applying the aqueous suspension onto the substrate by spray pyrolysis. Generally, the aqueous suspension typically contains 100-400 g of dibutyl tin difluoride per liter of water. A wetting agent may be used as the suspension accelerator. During the production of the aqueous suspension, dibutyl tin difluoride particles are ground to an average particle size of 1-10μ. The aqueous suspension is preferably agitated vigorously to give a uniform particle distribution in the suspension. The aqueous suspension is delivered by spray pyrolysis to a substrate surface at a temperature of at least about 400 ° C (752 ° F), preferably about 500 to 700 ° C (932 ° F to 1292 ° F), thereby being aqueous. The suspension is pyrolyzed to form a tin oxide SIDB layer. It can be seen that the thickness of the SIDB layer formed by this method is controlled by the coverage rate, the concentration of dibutyl tin difluoride in the aqueous suspension, and the spray rate, among other parameters. Let's go.</p><p> Alternatively, the tin oxide SIDB layer can be formed on the substrate from a metal-containing precursor such as monobutyltin trichloride vapor (hereinafter referred to as "MBTTCL") in an air carrier gas mixed with water vapor by the CVD method. it can. MBTTCL vapor is present in the air carrier gas applied on the substrate at a concentration of at least about 0.5%, while the substrate is at a temperature sufficient to cause the deposition of the tin-containing layer, eg, at least about 400 ° C (952 ° C). ° F), preferably about 500 ° C to 800 ° C (932 ° F to 1472 ° F) to form the tin oxide SIDB layer. It will be appreciated that the thickness of the SIDB layer formed by this method is controlled by the coverage velocity, the concentration of MBTTCL vapor in the air carrier gas and the flow rate of the carrier gas, among various parameters.</p><p> The SIDB layer formed by the MSVD method is described herein by US Patent Application Serial No. 08 / 597,543, filed February 1, 1996, entitled "Alkali Metal Diffusion Barrier Layer". Incorporation), which describes the formation of alkali metal diffusion layers. The diffusion layer described therein is generally effective at a thickness of about 20 Å to about 180 Å, and becomes more effective as the density of the barrier increases.</p><p> The PASC coating of the present invention is photocatalytically activated and self-cleaning by irradiating with radiation in the ultraviolet range of about 300 to 400 nm of the electromagnetic wave spectrum. UV sources include natural light sources such as solar and artificial light sources, such as UV light sources such as black light or UVA-340 light sources. When using an artificial UV source under test conditions, if you want to determine how the PASC coating reacts with natural UV, the UVA-340 light source is more sunlight than the photon energy distribution of the black light source. A UVA-340 light source can be used to have a photon energy distribution that better matches its distribution and to more precisely approximate how the PASC coating works when exposed to sunlight.</p><p> UV intensity is at least about 20 W / m on the surface of the coating to be tested²Calibrate to the strength of. For example, the strength is similar to that sold by Ultraviolet Products, Inc. in San Gabriel, California under the trade name BLACK-RAY under model code J-221. It can be calibrated with an ultraviolet meter. The light source is preferably located at right angles to the coated surface to be tested.</p><p> The UV source and PASC coating are arranged relative to each other so that the UV light first passes through the PASC coating and then through the substrate (ie, on the front or "cover side"). If the substrate passes UV light, the PASC coating and the UV source are arranged relative to each other so that the UV light first passes through the substrate and then through the PASC coating (ie, on the back side or "base side"). In yet another embodiment, one or more UV sources may be placed on each side of the substrate having the PASC coating on one or both surfaces.</p><p> It will be appreciated that it is difficult to specifically define the preferred UV source or UV intensity or the relative position of the UV source / PASC coating / substrate. Because many factors influence such considerations. These factors include, among other things, the purpose of using PASC coatings, eg indoor or outdoor use; selected UV sources, eg natural or artificial; seasonal or geographical effects when the UV source is natural; UV Desired or expected duration of irradiation; angle of incidence of UV light on the surface of the PASC coating; expected or desired PASC activity; the substrate and / or other coating or other coating present on the substrate or on the PASC coating. The extent to which UV light is reflected or absorbed by the layer; the contaminants required to be removed; the thickness of the PASC coating; the composition of the PASC coating; the potential for sodium ion poisoning; and the presence or absence of the SIDB layer. However, as measured on the surface of the PASC coating from an ultraviolet source located on the surface of the PASC coating, about 5-100 W / m²Within the range, preferably at least about 20 W / m²It has been found that the UV intensity of is sufficient to provide sufficient PASC activity for many self-cleaning applications.</p><p> To assess the PASC activity of a PASC coating, it is useful to be able to measure and compare PASC efficacy or PASC activity. A known and readily available organic contaminant is applied over the PASC coating and the PASC coating is photocatalytically activated to observe and measure the ability of the PASC coating to remove the organic contaminants. Stearic acid, CH₃(CH₂)₁₆COOH is a model of organic "contaminants" for testing the PASC activity of PASC coatings. This is because stearic acid is a carboxylic acid with long hydrocarbon chains and is therefore a good "molecular model" for those present in common contaminants such as household oils and debris. Stearic acid is applied onto the PASC coating as a thin test membrane by a convenient method including dipping, spraying and rotary coating. Generally, a stearic acid test membrane in the thickness range of about 100 Å to about 200 Å provides a suitable test membrane. Stearic acid can be applied as stearic acid in a methanol solution, about 6 x 10 per liter of solution.^-3Solutions with molar stearic acid concentrations have been found to be satisfactory.</p><p> The PASC activity of a PASC coating is such that a stearic acid film is coated on top of the PASC coating (the film generally appears as a light brown coating when applied over the PASC coating) and the stearic acid film is exposed to UV light at the desired intensity. For a reduction in the darkness of the stearic acid film compared to a portion of the stearic acid test film that was exposed for a period of time and the stearic acid test film disappeared completely or was applied on the PASC coating but not exposed to ultraviolet light. It can be estimated qualitatively by examining the stearic acid film with the naked eye.</p><p> The PASC activity of the PASC coating can also be quantitatively measured by measuring the integrated strength of the carbon / hydrogen (hereinafter referred to as CH) stretching vibration absorption band of stearic acid existing on the PASC coating. The integrated strength is commensurate with the thickness of the stearic acid film remaining on the surface of the PASC coating, and it is expected that the removal of the stearic acid film by photocatalytic activation self-cleaning will result in a decrease in CH stretching vibration zone strength. The CH bonds present in stearic acid absorb infrared light. Infrared, unlike UV, does not photocatalytically activate the PASC coating. This absorption is generally 2800-3000 cm^-1It occurs at the wave number of, and can be measured using a Fourier transform infrared spectrophotometer (hereinafter referred to as "FTIR spectrophotometer"). The FTIR may be equipped with a detector such as a triglycine deuterated sulfate detector (hereinafter referred to as "DTGS detector") or a mercury cadmium telluride detector (hereinafter referred to as "MCT detector"). .. MCT detectors are preferred because they provide a much larger signal-to-noise ratio than DTGS detectors. This is important when other coatings besides the substrate and / or PASC coating absorb the infrared radiation used by the spectrophotometer to generate an absorption spectrum. When infrared rays are absorbed by the substrate and / or other coating, the intensity of the infrared beam through the stearic acid film, the coated PASC, and the substrate to the detector is significantly reduced. The combination of this with the low concentration of stearic acid present on the surface of the PASC coating, which produces very weak infrared absorption properties, does not result in a particularly strong infrared signal. Therefore, a device with an MCT detector gives a spectrum with a signal-to-noise ratio that is about an order of magnitude larger than that with a DTGS detector. When measuring the PASC activity of a stearic acid test membrane adhering to a membrane and substrate through which the infrared beam can pass, the infrared beam was placed through the membrane and substrate on the opposite side of the sample to be tested. Point towards the detector. If the membrane or substrate does not allow infrared light to pass through, the infrared beam will be directed at an angle to the surface and will pass through the stearic acid test membrane so that it is reflected from the substrate and into the detector instead of passing through it. To do. This latter method is known as reflection IR spectroscopy.</p><p> The PASC reaction rate can be determined for the PASC coating by measuring the rate at which the PASC coating reacts and removes the stearic acid film present on it when the PASC coating is exposed to UV light. In particular, the rate of decrease in the integrated intensity (directly proportional to the surface coverage) of the CH stretch vibration characteristic in the cumulative time of irradiation with chemical rays (assumed to be ultraviolet rays in the future) gives the PASC reaction rate. For example, the initial PASC activity is measured with an FTIR spectrophotometer for the stearic acid test membrane present on the PASC coating. For this initial PASC activity measurement, the PASC coating may or may not be exposed to UV light. The stearic acid-coated PASC coating is then exposed to UV light for a period of time, after which a second PASC activity measurement is performed using an FTIR spectrophotometer. The integrated intensity of the CH stretching vibration in the second measurement is expected to be lower than that of the first one because a part of the stearic acid test film was removed by ultraviolet irradiation. From these two measurements, the curve of the integrated intensity of the CH stretching vibration with respect to time can be plotted, and the PASC reaction rate can be obtained from the slope. Although two points are sufficient to give the curve, it is preferable to make some measurements during the PASC activity measurement period to give a more accurate curve. Keep the UV exposure time between FTIR measurement points constant, or accumulate more than two PASC activity measurements (when using the cumulative UV exposure time to plot the curve) ) May vary, but the intensity and direction of the UV light (coating side or substrate side) should be kept constant for all PASC measurements taken when determining the PASC reaction rate.</p><p> PASC reaction rate is cm^-1Minutes^-1It can be reported in units of, and the larger the value, the higher the PASC activity. Whether or not a PASC coating has an acceptable level of PASC is largely determined by the purpose for which the PASC-coated article is used and the performance criteria selected in connection with that purpose, so that the PASC coating is "acceptable" or "acceptable". There is no absolute speed to make it "unacceptable". At least about 2x10 for most applications^-3, More preferably at least about 5x10^-3cm^-1Minutes^-1PASC activity is desirable.</p><p> It is also useful to measure the thickness of the PASC coating to significantly determine and compare the PASC activity of the PASC coating produced according to the present invention. This is because the thickness of the PASC coating affects the photocatalytic activity, as shown in the example below. The thickness of the PASC coating 24 and / or the SIDB layer 26, if present, is determined by angle-variable spectroscopic ellipsometry (hereinafter referred to as "VASE") or by a measured film vanishing edge profilometer. ) It can be determined by measurement or estimated from the interference color, as is known in the art.</p><p> The particle size of the PASC coating 24 and / or, if present, SIDB layer 26 can be calculated from X-ray diffraction (hereinafter referred to as "XRD") data using Scherrer relationships. This relationship is known in the art, and its essay is "X-ray Diffraction Procedures for Polycrystalline and Amorphous Materials" by Klug and Alexander. ) (1954, John Wiley &amp; Sons, Inc.), Chapter 9.</p>

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

<u style="single">Example 1</u> PASC coating with a thickness of 2100 Å formed by the CVD method The PASC activity of a titanium dioxide PASC coating with a thickness of about 2100 Å was examined as follows. PASC coating using the CVD method on a substrate 22 on the air side of a piece of soda lime silica-float glass sold under the registered brand name SOLEX glass by PPG Industries, Inc. of Pittsburgh, PA. Used to deposit. Regarding FIG. 3, the Solex glass plate has a size of about 14 cm in width × 30.5 cm in length × 0.4 cm in thickness (5.5 inches in width × 12 inches in length × 0.016 inches in thickness), as shown in FIG. , Coated with titanium dioxide PASC coating using a CVD coating machine 88. The CVD coating machine 88 generally consists of three regions separated by vertical dotted lines 90 and 92 shown in FIG. These three regions consist of a preheating region 94, a covering region 96 and an annealing region 98. The Solex glass plate, which will be shown below as the substrate 22, rides on the circulation conveyor 102 and moves in the direction of the arrow 104 through the three regions.

The substrate 22 moves into the preheating region 94 and is preheated to a temperature of about 649 ° C (about 1200 ° F) by a plurality of heaters 106 spaced above and below the conveyor 102. The substrate 22 is moved into the CVD coverage region 94 by the conveyor 102. It will be appreciated that the CVD coverage region 96 has at least one coating device 97. In order to continuously deposit more than one coating, the coating region 96 may have a plurality of coating devices 97. The covering device 97 includes a support auxiliary device and a controller, for example, a gas transfer auxiliary device, a liquid transfer auxiliary device, a temperature controller, an exhaust auxiliary device and a controller, and a temperature and pressure monitoring auxiliary device, all of which are included. Not shown. The gas transfer assist device controls the flow of carrier gas to the surface of the substrate 22. Nitrogen gas was used as the carrier gas. The introduced nitrogen flow was controlled to a temperature of 113 ° C (about 235 ° F) by a heater (not shown). 20% of the total flow rate of NH in the carrier gas₃Was contained. The exhaust flow rate corresponded to 125% of the introduced flow rate. The metal-containing precursor used to deposit the titanium dioxide PASC coating on the substrate 22 was TTIP, which was present at 0.4% by volume of the total flow rate, also at a temperature of about 113 ° C (about 235 ° F). Supplied. N passing through CVD coating machine 88₂, NH₃And the total flow rate of TTIP steam was 75 standard liters / minute (slm). The linear velocity of the conveyor 102 was about 127 cm (50 inches) / minute and the coverage gap width was about 0.48 cm (3/16 inches). The substrate 22 was maintained at a temperature of about 554 ° C (1030 ° F) while under the coating device 97, during which the coating 24 was deposited onto the substrate 22 to form the coating sample 100. A titanium dioxide PASC coating 24 of approximately 2100 Å thickness (measured by VASE) was formed on the coating sample 100.

The coated sample 100 is then advanced to the annealing region 98, where it travels from an initial temperature of about 549 ° C (1020 ° F) to a final temperature of about 121 ° C (250 ° F) for about 26 minutes. Annealed.

PASC coated sample 100 was subjected to XRD analysis. The particle size of PASC coating 24 was calculated using Scheller's relationship and determined to be approximately 309 Å. Coated sample 100 showed a strong peak corresponding to anatase titanium dioxide in the XRD image.

The PASC-coated sample 100 was then coated with a stearic acid test membrane, and its photocatalytic activity was measured. 6 x 10 per liter of solution^-3A stearic acid / methanol solution having a molar stearic acid concentration is spun on the center of the sample 100 at a rate of about 2 ml / 10 seconds while rotating the coated sample 100 at a rate of about 1000 rpm. Apply by dropping with, thereby causing stearic acid to flow centrifugally across the surface of the coated sample 100 and on the surface of the coated sample 100 a generally uniform thickness of stearic acid in the thickness range of about 100-200 Å. Giving a membrane. The thickness of the stearic acid layer is not constant along the length of the coated sample 100 and is thicker at the edges of the coated sample 100 and thinner at the center of the coated sample 100 due to the applied centrifugal force. The word "generally" is used above. It will be appreciated that the stated stearic acid solution concentration, rotation speed, sample size and pipette flow rate can be modified to obtain the desired thickness of stearic acid coating. Under the above parameters, the average thickness of the stearic acid test film was about 150 Å, as determined by the correction of IR intensity using quartz crystal microbalance.

The stearic acid test film / titanium dioxide PASC-coated sample 100 is exposed to ultraviolet rays from an ultraviolet light source perpendicular to the coating side of the coating sample 100, and is approximately 20 W / m on the surface of the PASC coating 24.²The intensity of the stearic acid test membrane was given for a cumulative period of about 30 minutes to cause photocatalytic activation self-cleaning of the stearic acid test membrane. Using an FTIR spectrophotometer equipped with an MCT detector, the FTIR spectrophotometer was measured periodically over a cumulative UV exposure time of 30 minutes, and the photocatalytic activity was quantitatively measured. In particular, the stearic acid test membrane / PASC coated sample 100 was exposed to UV light for the measurement time, and then the coated sample 100 was placed in an FTIR spectrophotometer, where the integrated region of the CH absorption band of stearic acid was measured and the PASC activity was measured. The degree was decided. The coated sample 100 was exposed to ultraviolet rays again for the next measurement time to further remove stearic acid, and then further FTIR measurement was performed. This method was repeated to plot the integrated IR absorption intensity of the CH stretching vibration with respect to the cumulative exposure time to UV light to obtain a curve, and the PASC rate for the stearic acid test film / titanium dioxide PASC coated sample 100 was given from the gradient. As mentioned above, it can be seen that all FTIR measurements were made across the same region of the coated sample 100 to minimize the effect of variations in stearic acid test membrane thickness. Photocatalytic reaction rate is 3.53 × 10^-3cm^-1Minutes^-1It was determined that it was close to the value for PASC coated substrates with little or no sodium ions (eg quartz glass substrates), and titanium dioxide PASC coatings overcome sodium ion poisoning with a thickness of 2100 Å. Showed that it is enough to do.

<u style="single">Example 2</u> A 700-800 Å thick PASC coating formed by the CVD method A titanium dioxide PASC coating 24 having a thickness of about 700-800 Å was deposited on a glass substrate by the CVD method in the same manner as in Example 1. However, the following points are excluded.

The glass composition used in Example 2 was a 3 mm (0.12 inch) thick clear (ie, low iron soda lime silica) glass. The preheating temperature in Example 2 was 593 ° C (1100 ° F). The TTIP concentration in Example 2 was 0.1% with a total flow rate of 50 slm. NH as 24% of total flow rate in carrier gas₃Was contained. The linear velocity was 76.2 cm / min (30 inches / min). The gap width was 1/16 inch (0.16 cm). The thickness of the titanium dioxide PASC coating 24 was estimated by the interference color, which is a thin film thickness measurement technique known in the art, and was determined to be in the range of about 700 to 800 Å.

A stearic acid test membrane is applied over the titanium dioxide PASC coating in the same manner as described in Example 1, exposed to UV light in the manner described in Example 1, and then periodic with an FTIR spectrophotometer for PASC activity. The measurement was performed over a cumulative time of 33 hours. Photocatalytic reaction rate is about 0.17 × 10^-3cm^-1Minutes^-1Was decided to be.

The decrease in PASC activity in Example 2 is considered to be due to the difference in the thickness of the titanium dioxide coating between Example 1 and Example 2 (about 2100 Å vs. about 700 to 800 Å, respectively). In particular, the% of the total thickness of the titanium dioxide PASC coating for the titanium dioxide PASC coating of Example 2 is greater than that of Example 1, so that the sodium ion diffusion depth into the titanium dioxide PASC coating of Example 2 is increased. Therefore, it is considered that the PASC reaction rate of Example 2 is smaller than that of Example 1. Sodium ions are believed to have migrated from the glass sample into the PASC coating of Example 2 in the annealing furnace 44. One conclusion drawn from the comparison of Examples 1 and 2 is that in the absence of the SIDB layer, a thick PASC coating is less susceptible to sodium ion poisoning and thus maintains greater PASC activity.

<u style="single">Example 3</u> PASC coating on the SIDB layer formed by the CVD method In this example, the effect of the presence of the tin dioxide SIDB layer on PASC activity is studied. In particular, a tin dioxide SIDB layer was formed on the air side of four float glasses and some physical properties of the SIDB layer were studied. After that, 16 more float glass sheets were provided with a tin dioxide SIDB layer by the CVD method, and each of the tin dioxide SIDB layers was coated with a titanium dioxide PASC coating by the CVD method this time. One sample was cut from each of the 16 PASC-coated / SIDB-layer-coated / float-glasses, and a stearic acid test film was coated on the 16 samples. Sixteen stearic acid test membrane coatings / titanium dioxide PASC coatings / tin dioxide SIDB layer coatings / samples were exposed to UV light and the PASC kinetics of those samples were determined.

<u style="single">3A.SIDB layer research</u> Soda lime silica-float method with a size of about 12.7 cm x 30.48 cm x 0.4 cm (5 inches x 12 inches x 0.16 inches thick) On the air side of four pieces of glass cut from a glass ribbon, in Example 1. The SIDB layer was deposited by the CVD method using the described CVD apparatus. In particular, the SIDB layer is a tin dioxide SIDB layer, and the effects of metal-containing precursor concentration, water vapor concentration, CVD ray velocity, preheating temperature and SIDB layer thickness on the tin dioxide SIDB layer were studied. For all four glasses, the metal-containing precursor used to form the tin oxide SIDB layer by the CVD method was MBTTCL vapor, which was mixed with the vapor in the air carrier gas.

The first of the four pieces of glass containing MBTTCL vapor with a concentration of about 1.5% and water vapor with a concentration of about 1.5% in an air carrier gas is sent toward the air side of the glass piece. Then, it was coated with the tin oxide SIDB layer by the CVD method and the apparatus of Example 1. The preheating temperature was about 648 ° C (1200 ° F) and the linear velocity was about 127 cm (50 inches) / min for this glass. The tin oxide SIDB layer formed thereby was about 3500 Å thick as determined by VASE. Measure the resistivity and particle size of the SIDB layer, each about 4.6 × 10^-3It turned out to be Ω · cm and 198 Å.

The second piece of glass was similarly coated with a tin oxide SIDB layer, but the linear velocity was reduced to about 50.8 cm (20 inches) / min, the MBTTCL vapor concentration in the air carrier gas was reduced to about 0.5%, and the water vapor. The concentration also decreased to about 0.5%. The preheating temperature was maintained at about 648 ° C (1200 ° F). The resulting tin oxide SIDB layer was approximately 4340 Å thick, as determined by VASE. The resistivity is about 3.9 x 10^-3It was found to be Ω · cm and a particle size of about 185 Å.

The third piece of glass was similarly coated with a tin oxide SIDB layer, but the preheating temperature dropped to about 480 ° C (900 ° F) and the linear velocity increased to about 127 cm (50 inches) / min. In the air carrier gas, the MBTTCL concentration was about 1.5% and the water vapor concentration was about 1.5%. The obtained tin oxide SIDB layer has a coating thickness of about 1000 Å, as determined by VASE, and is about 3.8 × 10^-2It had a resistivity of Ω cm and a particle size of about 59 Å.

The fourth piece of glass was similarly coated with a tin oxide SIDB layer, but the preheating temperature was maintained at about 480 ° C (900 ° F) and the linear velocity dropped to 50.8 cm (20 inches) / min. In the air carrier gas, the MBTTCL concentration was about 0.5% and the water concentration was about 0.5%. The tin oxide SIDB layer has a thickness of about 1010 Å, as determined by VASE, and is about 2 x 10^-2It had a resistivity of Ω cm and a particle size of about 78 Å.

From the above, all four pieces of glass had a cassiterite structure, although the resistivity or grain size varied within the temperature range, concentration, linear velocity, and SIDB layer thickness described. It was concluded that it turned out.

<u style="single">3B. Formation of titanium dioxide PASC coating formed on tin oxide SIDB layer by CVD method</u> 16 additional float method glass pieces measuring 12.7 × 30.48 cm × 0.4 cm (5 inch × 12 inch × 0.16 inch thickness), respectively, the CVD coating machine and method generally described in Example 3A. Then, it was coated with a tin oxide SIDB layer, and then further coated with a titanium dioxide PASC coating using a CVD coating device and method, as generally described in Example 1. For this coating operation, a pair of continuous coating devices (one for SIDB layer and one for PASC coating) were used by the online CVD method. The PASC coating on the SIDB layer makes separate analysis of the SIDB layer difficult, if not impossible, so the tin oxide layer coated on the PASC is coated as described in Section 3A above. Assuming to have the same properties as no tin oxide layer, both the SIDB layer and the PASC coating are listed in Table 1 below and 16 glasses under various specific coating parameters detailed below. I gave it to one piece.

Generally, 16 tin oxide SIDB layers were deposited with a metal-containing precursor of MBTTCL vapor in an air carrier gas mixed with air-carried water vapor. The MBTTCL deposition temperature was maintained at approximately 160 ° C (320 ° F). The total flow rate was 60 slm and the exhaust compatibility ratio was 115%. The gap width was 0.16 cm (1/16 inch). Specific coating parameters varied for the SIDB layer formed in this example include preheating region 94 temperature, linear velocity, MBTTCL concentration, water vapor concentration, and SIDB layer thickness. The thin tin dioxide SIDB layer coating parameters and expected SIDB layer thickness for each of the 16 pieces of glass are shown in Table 1 below. No actual thickness measurement was performed. The expected thickness is based on the results obtained in Section 3A above. The 16 pieces are divided into 4 groups consisting of 4 substrates in Table 1 based on the preheating temperature and linear velocity.

<tables num="1"><img file="JP2005095894A_D0001.tif" /></tables>

Each of the 16 pieces of SIDB-coated glass is then passed through by a second CVD coating, which is located downstream of the first SIDB, onto the SIDB layer-covered surface of the glass pieces with nitrogen (N).₂) It was coated with a titanium dioxide PASC coating deposited by sending a metal-containing precursor of the TTIP vapor carrier in carrier gas. Ammonia (NH) in 8 TTIP / carrier gas mixtures out of 16 pieces of glass₃) Was added. For all 16 pieces, the carrier gas was maintained at a temperature of about 113 ° C (235 ° F). As in Example 1, 16 pieces were annealed. The temperature of the TTIP vaporizer was maintained at approximately 104.4 ° C (220 ° F). Table 2 below shows the titanium dioxide PASC coating parameters for 16 pieces of glass. The 16 pieces of glass are divided into 4 groups consisting of 4 pieces each based on the preheating thermometer and the linear velocity in Table 2.

<tables num="2"><img file="JP2005095894A_D0002.tif" /></tables>

The preheating temperature here refers to the temperature of the preheating region 94. There is only one preheating operation, when the preheating temperatures listed here move through the CVD coating machine 88, first receiving the SIDB layer and then the PASC coating, before the glass pieces enter the annealing region 98. , It is the same temperature as the preheating temperature in which the temperature of these glass pieces is raised in the preheating region. 1/16 inch = 0.16 cm, 3/16 inch = 0.38 cm

After applying the PASC coatings listed in Table 2, the selected properties of each of the 16 pieces of glass are shown in Table 3 below. The thickness of the PASC coating has not been measured, but is expected to fluctuate within each county due to fluctuations in other deposition parameters such as linear velocity and precursor concentration. However, in order to relate the roughness and particle size to the PASC activity, the surface roughness and particle size of the PASC coating were determined. Surface roughness measurements were estimated based on Atomic Force Microscope (hereinafter referred to as "AFM") measurements performed on PASC coatings. It was found that there are large variations in surface roughness, particle size and crystal phase as a function of preheating temperature.

<tables num="3"><img file="JP2005095894A_D0003.tif" /></tables>

The peak of the anatase phase was not detected in the X-ray diffraction image (Samples 1, 2, 5, 6, 8, 9 and 14), or the peak was too wide and weak to measure (Sample). Because of 3, 4, 7 and 15), the particle size could not be calculated.

<u style="single">Explanation of PASC activity test of 3C.16 substrate</u> A 2.54 cm x 10.16 cm (1 inch x 4 inch) sample or test strip was cut from the center of each of the 16 PASC / SIDB coated glass pieces. Each of the 16 test bands was coated with a stearic acid test membrane by rotary coating as described in Example 1. 16 test bands, then 20 W / m to UV from UV light source²It was exposed for a cumulative time of 7 hours at the intensity of, and caused photocatalytic activation self-cleaning of the stearic acid test membrane.

Since the thickness of the stearic acid test membrane was found to vary along the length of the 2.54 cm x 10.16 cm (1 inch x 4 inch) test strip (ie, the rotating test strip as described above). Due to the centrifugal force that affects stearic acid when it is dropped into the center, it is visually observed by the change in interference color along the length of the test band, and the stearic acid test film is observed at each end of the test band. The stearic acid test film was thicker toward the center of each test piece), and photocatalytic activity at each end of each of the 16 test zones using an FTIR spectrophotometer equipped with an MCT detector. Was measured. Table 4 shows the PASC kinetics obtained by the FTIR spectroscopic analysis test for each pair of tests performed for each of the 16 test zones.

<tables num="4"><img file="JP2005095894A_D0004.tif" /></tables>

From Table 4, it is clear that for a test zone, there is a very large difference in activity between the two ends of the test zone. This difference is considered to be related to the non-uniform thickness of the stearic acid layer on the test band.

With respect to Table 4, there appears to be no correlation between the deposition conditions and the PASC activity of the PASC coating on the SIDB layer. As shown in Table 4, the three most active test zones are samples 13, 10 and 14 based on activity on the left side of the test zone. These bands 13, 10 and 14 correspond to high preheating temperatures of 648.8 ° C (1200 ° F). When ranked by PASC activity, the remaining 13 test zones showed a variety of preheating temperatures during the rank, similar to other coating parameters, with the presence of a sodium ion diffusion barrier layer indicating the sodium of the PASC coating. It has been shown to work to prevent ion poisoning and to provide greater tolerance for coating conditions and parameters while still achieving photocatalytic activity.

<u style="single">Example 4</u> PASC coating formed by spray pyrolysis In this example, glass pieces were coated with titanium dioxide PASC coatings of various thicknesses by spray pyrolysis, and the effect of PASC coating thickness on PASC activity was studied.

The air side of three float glass pieces each 10.16 cm × 10.16 cm × 4 mm (4 inches × 4 inches × 0.16 inches) thick was coated with a titanium dioxide PASC coating by a spray pyrolysis method.

Figure 4 shows the basic components of the spray pyrolyzer used to apply the PASC coating on a piece of glass. The spray pyrolysis apparatus has a preheating region 120 and a spray pyrolysis region 122. The glass pieces 126 are placed on a conveyor (not shown) and carried into the preheating region 120, where they are heated by multiple electric heaters 130 to temperatures in the range of about 600 to 700 ° C (1112 ° F to 1292 ° F). To do. Next, the glass piece 126 is carried by a conveyor through the vibration spray nozzle 132. The nozzle is located approximately 25.4 cm (10 inches) above the air side of the glass piece 126. The aqueous suspension 134 of the organometallic coating reaction is maintained in suspension by the stirrer 136 in the mixing chamber 138. The aqueous suspension 134 is fed through pipe 140 to the spray nozzle 132, where it is conveniently mixed with compressed air (from the compressed air source 142 sent by pipe 144 towards the spray nozzle 132). The aqueous suspension 134 / compressed air mixture was sprayed from the nozzle 132 onto the surface of the glass piece 126 to form a spray pattern 146 and pyrolyzed to form a PASC coating 24 on the glass piece 126. The PASC coated glass piece 126 was cooled in air.

In this example, the organometallic coating reactant selected is titanylacetylacetonate, and the rate of aqueous suspension delivered towards the surface of the three glass pieces 126 is the thickness of the PASC coating on each piece of glass. Controlled to give. The thickness was 400 Å, 725 Å and 1000 Å. The effect of PASC coating thickness on photocatalytic activity was determined for titanium dioxide PASC coatings deposited by spray pyrolysis on clear float glass without a SIDB barrier layer, keeping all other coating parameters constant. Table 5 shows the specific coating parameters for this example.

<tables num="5"><img file="JP2005095894A_D0005.tif" /></tables>

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

One test band from each of the three first pieces of glass, respectively, was subjected to X-ray diffraction analysis. From this analysis, it was found that all three pieces of glass in this example had strong X-ray diffraction lines compatible with anatase titanium dioxide by X-ray diffraction analysis.

In order to examine the photocatalytic activity of the three glass pieces, one test band from each of the three glass pieces was coated with a stearic acid test film by the method described in Example 1. Next, the three test bands were exposed to ultraviolet rays from an ultraviolet light source arranged perpendicular to the covering side of each test band at 20 W / m.²It was exposed over a cumulative time of 7 hours at the intensity of. The photocatalytic reaction rates of each of the three test zones were quantitatively determined by FTIR spectroscopic analysis using an MCT detector, as described above. Table 5 shows the photocatalytic reaction rates for the three pieces of glass.

From the above, it can be concluded that the PASC coating formed by the spray pyrolysis method provides a low but acceptable photocatalytic reaction rate without causing sodium ion poisoning of the PASC coating. It can also be concluded that the thicker the PASC coating, the higher the PASC activity, as shown by Sample C in Table 5.

<u style="single">Example 5</u> Study on the comparison of PASC coating formed by spray pyrolysis with and without SIDB layer, and the effect of annealing after PASC coating.

In this experimental basis, eight pieces of glass were coated with PASC by spray pyrolysis, and the effect of the presence or absence of the SIDB layer on the PASC reaction rate of the PASC coating, the effect of the PASC coating thickness, and the PASC coating during deposition. The effect of substrate temperature was examined.

In particular, on the air side of four of the eight pieces of 4mm Solex float glass, dibutyl tin difluoride, (C.₄H₉)₂SnF₂ And coated with a 500 Å thick tin dioxide SIDB layer deposited by spray pyrolysis from an aqueous suspension of wetting agent. The tin dioxide SIDB layer was applied by the spray pyrolysis apparatus and procedure described in Example 4. After coating with the SIDB layer, the glass sample was cooled to room temperature, and these four glass pieces and the remaining four glass pieces were each coated with a titanium dioxide PASC coating on the SIDB layer and cooled to room temperature. The four SIDB layer-coated glass pieces that were cooled to room temperature between the application of the SIDB layer and the PASC coating, then reheated, and then the PASC coating was applied were used in the laboratory spray pyrolysis equipment used in this experiment. Manufactured this way as it had only one spray pyrolysis position, thereby converting from dibutyltin difluoride suspension (to provide SIDB layer) to titanylacetylacetonate suspension (to provide PASC coating). It should be noted that it had to be done. Such an intermediate cooling step is eliminated in the preferred coating machine, for example, deploying two spray pyrolysis positions and applying a SIDB layer and PASC coating to a moving substrate such as a continuous float glass ribbon. The coating should be continuous without the use of intermediate cooling steps.

After cooling all eight PASC-coated glass pieces to room temperature, the glass pieces are coated with the stearic acid film described in Example 1, and then the film is coated on the stearic acid test film / PASC-coated glass piece. It is exposed to ultraviolet rays by the UVA-340 light source arranged at right angles to the PASC coating surface, and 20 W / m on the PASC coating surface.²Giving strength. The PASC reaction rate at which the stearic acid test membrane was removed was quantitatively determined using the method described in Example 1. This PASC kinetics is shown in Table 6 below with a finding of 0.00 minutes. It should be noted that the 0.00 minute parameter means that the glass pieces with the PASC coating on top have not yet been annealed after being cooled to room temperature and do not refer to the cumulative time of UV irradiation. is there.

The effect of annealing time on stearic acid removal was investigated as follows. The residual stearic acid test film was washed and removed from the PASC coating of each of the eight glass pieces by wiping the surface with a methanol-soaked wipe until no stearic acid film or fogging was observed. Each of the eight pieces of glass was then placed in a furnace, this time maintained at about 500 ° C (932 ° F) for about 3 minutes, to heat each piece of glass. The furnace heating was switched off, the furnace door was opened, and each piece of glass was cooled in the furnace to near room temperature. Annealing was given by the slow cooling rate in the furnace. Each piece of glass was then coated with a new stearic acid test membrane, exposed to UV light, and the PASC kinetics were determined in the same manner as the unannealed PASC coating described immediately above in this example. As described above, the residual stearic acid test membrane was again washed and removed from the surface of each piece of glass, and each piece of glass was subjected to another heating for 10 minutes and slowly cooled in the furnace in the same manner. Results A cumulative heating time of 13 minutes was given, where the stearic acid test membrane was applied again as described and the PASC reaction rate was determined as described above. This process was repeated several more times, giving a cumulative heating time of 73 minutes, then slowly cooling in a furnace to give annealing.

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

<tables num="6"><img file="JP2005095894A_D0006.tif" /></tables>

PASC reaction rate for removing stearic acid (× 10-3 cm-1 min-1).

The results of the photocatalytic analysis shown in Table 6 show that there is no barrier layer and the thickness of the titanium dioxide layer of about 625 Å (Sample I) is the PASC activity of the thinner 400 Å PASC coating (Sample K) above the SIDB layer. It suggests that it will be close to. In the case of sample K, the SIDB layer has undergone the described intermediate cooling and subsequent reheating operation, which reduces the effectiveness of the SIDB layer in sample K, otherwise higher PASC activity. It should be noted that you may have had it.

Sample K in Table 6 also shows the important influence that annealing time may have on PASC kinetics. After an annealing time of 3 minutes, the PASC activity of sample K was from about 4.64 to about 12.29 × 10.^-3cm^-1Minutes^-1It rose to, but then declined with additional annealing. Anatase phases were formed on the titanium dioxide PASC coating during a 3-minute annealing to measure PASC activity, without the noticeable sodium ion poisoning due to the presence of tin oxide in the SIDB layer. Conceivable. I don't want to be bound by this particular theory, but continued annealing for too long a cumulative period of time causes sodium ion poisoning despite the presence of the SIDB layer, which causes a decrease in PASC activity in sample K. It is thought that it has become.

The above examples are given to illustrate the present invention and do not limit the present invention. The methods described above for applying a PASC coating have been described in connection with the application of such coating on a continuously moving substrate, eg, a continuous float glass ribbon, during its manufacture. Can also be used downstream of the substrate manufacturing process. For example, as part of the process of curving and / or strengthening the substrate, PASC coating can be applied to the substrate, including the glass substrate, but is not limited to those glass substrates. For example, if the glass substrate is later heated to curl and / or reinforce, a PASC coating with or without a SIDB layer may be applied by the spray pyrolysis or CVD or MSVD method described above prior to curving / strengthening. can do. The CVD and spray pyrolysis methods can also be used while heating the glass substrate to a bending / strengthening temperature. A PASC coating with or without SIDB coating may be applied to the glass substrate by either CVD, spray pyrolysis, or the MSVD method after a curving / strengthening reheating operation.

95) It is considered that there is a difference between the PASC coating produced by the sol-gel method and the source produced by the above method. For example, PASC coatings made by the sol-gel process are more porous, less dense, generally thicker, generally less suitable for use as transparent materials, and more Expected to contain many OH groups. As mentioned above, excess OH groups are undesirable as they prevent the formation of suitable crystals in the PASC coating, which in turn reduces PASC activity. PASC coatings produced by CVD or spray pyrolysis are expected to have a finer particle structure than those produced by the sol-gel process.

Advantages of the present invention over the sol-gel method of forming a PASC coating include the ability to form a thin, dense PASC film on the substrate, unlike the much thicker porous coatings obtained by the sol-gel coating method. Is done. Since the PASC coatings of the present invention are thin, they are aesthetically acceptable for use as transparent coatings on glass substrates. Yet another advantage is that the method of applying PASC coating according to the invention does not require heating the substrate after application of the coating or coating precursor, as required by the currently available sol-gel process. This not only makes the present invention more cost effective and more effective, for example lower equipment costs, lower energy costs, shorter manufacturing times (but not limited to them), but also the PASC coating of the present invention. Opportunities for sodium ion transfer, and thus significantly reduce sodium ion poisoning. Moreover, the method of the present invention is readily applied to form a PASC coating on a continuously moving substrate, such as a float glass ribbon, whereas the currently available sol-gel process is so easily applied. It cannot be applied. The scope of the invention as defined by the following claims includes various modifications.

<figref num="1">FIG. 5 is an elevational view of a portion of a substrate having a dispersed PASC coating on top.</figref><figref num="2">It is the same drawing as FIG. 1 which illustrates the SIDB layer which intervenes between the substrate and the PASC coating.</figref><figref num="3">It is a schematic diagram of the selected component of a CVD coating machine.</figref><figref num="4">It is a schematic diagram of the selected part of a spray pyrolysis coating machine.</figref>