Process for the production of photocatalytic coatings on substrates

[0001] [Technical field to which the invention belongs] The present invention relates to a method for producing a photocatalytically active coated substrate, and is not particularly limited, but the present invention relates to a method for producing a photocatalytically active coated glass and the coated glass thereof. [0002] [Conventional technology] It is known that a thin film composed of one or two or more layers having various properties is deposited on a substrate including a glass substrate. One property of interest is the photocatalytic activity produced by the photoinduction of hole-electron pairs in a semiconductor when the semiconductor is irradiated with light of a particular wavelength. Hole-electron pairs can be generated by sunlight and can react in moist air to form hydroxyl and peroxy radicals on the semiconductor surface. The radical oxidizes the organic dust on the surface. This property has been applied to self-cleaning substrates, especially self-cleaning glass for windows. [0003] Titanium dioxide can be an effective photocatalyst and can be deposited on a substrate to form a transparent film with the self-cleaning properties of the photocatalyst. Titanium oxide photocatalyst coating is EP 0 901 991 A2, WO 97/07069, WO 97/10186, WO 98/41480, Summary of the 187th Electrochemical Society Meeting No.735 (Reno, NV, 95-1, It is disclosed in p.1102) and New scientist magazine (August 26, 1995, p.19). In WO 98/06675, a precursor gaseous mixture of titanium chloride and an organic compound as an oxygen source was used to form a titanium oxide film, and a titanium oxide film was deposited on the hot plate glass at a high precipitation rate. The chemical vapor deposition method for this is described. [0004] It has been considered necessary to precipitate a relatively thick titanium oxide film in order to give good photocatalytic activity. For example, in WO 98/41480, the photocatalytically active self-cleaning coating must be thick enough to provide an acceptable level of activity, preferably at least about 200 Å, preferably at least about 500 Å. It is stated to be even more preferred (all measured thicknesses of the titanium oxide coatings made in the examples are 400 Å to 2100 Å). [0005] However, the problem with the relatively thick titanium oxide film is that it has high visible light reflectance and therefore relatively low visible light transmission. This issue was acknowledged in a New Scientist Magazine paper on coated windshields, in which black, which does not reflect light into coated windshields to reduce high reflection effects. It suggests that the dashboard may have to be covered with velvet or other material. [0006] EP 0 901 above 991A2 relates to a photocatalytically activated window glass having a titanium oxide film having a unique crystal structure, which is characterized by the presence of a unique peak in the X-ray diffraction image. The specification ponders the range of coating thickness (thinner coatings have lower photocatalytic activity than thicker coatings for certain embodiments, all having thicknesses in the range of 20 nm to 135 nm). .. The specification also considers the precipitation temperature range from as low as 300 ° C to as high as 750 ° C, but prefers temperatures in the range of 400 ° C to 600 ° C, all of which are specified in the present invention. In the above examples, the titanium dioxide layer is precipitated at a temperature within or below this preferable range. [0007] [Means to solve problems] The applicant can obtain a film having improved photocatalytic activity for a predetermined thickness by precipitating the titanium oxide film at a higher temperature, especially at a temperature higher than 600 ° C. It was discovered that it is possible to obtain the photocatalytic performance of. Such thinner coatings advantageously tend to have lower visible light reflectance and, as a result of apparently higher deposition temperatures of the coating, temperature cycles, especially in friction and moist atmospheres. And, on the other hand, tend to have improved durability. [0008] The present invention comprises depositing a titanium oxide film on the surface of a substrate by bringing the surface of the substrate into contact with a fluid mixture containing a titanium source and an oxygen source when the substrate is at a temperature of at least 600 ° C. As a result, the photocatalytic activity of the coating surface of the substrate is 5 × 10.^-3cm^-1min^-1A method for producing a photocatalytically active coating substrate, which is larger and has a visible light reflectance of 35% or less measured on the coating side, is appropriately provided. [0009] Preferably, the substrate has a temperature in the range of 625 ° C to 720 ° C, and even more preferably, the substrate has a temperature in the range of 645 ° C to 720 ° C. [0010] Advantageously, the fluid mixture comprises titanium chloride as a titanium source and esters other than methyl esters. Therefore, in a preferred embodiment, the present invention comprises contacting the surface of the substrate with a fluid mixture containing titanium chloride and an ester other than the methyl ester to precipitate a titanium oxide film having a thickness of less than 40 nm. , Provide a method for manufacturing a photocatalytically active coating substrate. [0011] The manufacturing method can be carried out by contacting the surface of the substrate with the fluid mixture when the substrate has a temperature in the range of 600 ° C to 750 ° C. [0012] Preferably, the ester is an alkyl ester having an alkyl group having β hydrogen (the alkyl group of the alkyl ester is a group derived from an alcohol during ester synthesis and β hydrogen is the oxygen of the ester bond in the ester. On the other hand, it is hydrogen bonded to the carbon atom of β). Preferably, the ester is a carboxylic acid ester. [0013] Suitable esters are C₂From C₁₀It can be an alkyl ester having an alkyl group of, but preferably the ester is C.₂From<u style="single">C</u>_{<u style="single">4</u>}It is an alkyl ester having an alkyl group of. [0014] Preferably, the ester is a compound represented by the following formula. RC (O) -OC (X) (X')-C (Y) (Y')-R' Here, R and R'represent hydrogen or an alkyl group, X, X', Y, and Y'represent a monovalent substituent, preferably an alkyl group or a hydrogen atom, and at least one of Y and Y'is. Indicates hydrogen. [0015] Suitable esters that can be used in the methods of the invention are ethyl formate, ethyl acetate, ethyl propionate, ethyl butyrate, n-propyl formate, n-propyl acetate, n-propyl propionate, n-propyl butyrate, isopropyl formate, acetate. Includes isopropyl, isopropyl propionate, isopropylbutyrate, n-butyl formate, n-butyl acetate, and t-butyl acetate. [0016] Preferably, the ester comprises an ethyl ester, more preferably the ester comprises ethyl formate, ethyl acetate, or ethyl propionate. Most preferably, the ester comprises ethyl acetate. [0017] The fluid mixture can be liquid and can be dispersed as a particularly fine spray (often referred to as spray precipitation), but preferably the fluid mixture is a gaseous mixture. The precipitation method using a gaseous mixture as a precursor is often referred to as chemical vapor deposition (CVD). Laminar flow CVD is the preferred method of CVD, but turbulent CVD can also be used. [0018] The manufacturing process can be carried out on substrates of various dimensions, including on sheet substrates, especially on glass cut sheets, or preferably on glass continuous ribbons during the online float glass manufacturing process. Therefore, preferably, the manufacturing method is performed online during the float glass manufacturing process and the substrate is a glass ribbon. If the manufacturing method is performed online, it is preferable to perform the manufacturing method on the glass ribbon while the glass ribbon is in the float bath. [0019] The advantage of performing the steps online is that the coatings deposited online tend to be durable, especially with good abrasion and chemical resistance. [0020] The online precipitation step is preferably performed at substantially atmospheric pressure, and other precipitation steps can be performed at substantially atmospheric pressure. [0021] [0021] In a particularly preferred embodiment, the surface of the substrate, which has a temperature in the range of 646 ° C to 720 ° C, preferably a temperature in the range of 670 ° C to 720 ° C, is contacted with a fluid mixture containing a titanium source. Provided is a method for producing a durable photocatalytically active coated glass, which comprises depositing a photocatalytically active titanium oxide layer on the surface of a glass substrate. [0022] As described above, the applicants and others have discovered that by precipitating titanium oxide at a high temperature, a film having a photocatalytic activity relatively high relative to its thickness can be formed. Since reduced thickness coatings tend to have lower reflections, the present invention also provides novel products with a favorable combination of moderate or low light reflections and high photocatalytic activity. [0023] As described above, from another viewpoint, the present invention includes a substrate having a photocatalytically active titanium oxide film on one surface thereof, and the photocatalytic activity of the film surface of the substrate is 5 × 10.^-3cm^-1min^-1Provided is a photocatalytically active coating substrate, which is larger and has a visible light reflectance of 35% or less measured on the coating side of the coating substrate. [0024] High photocatalytic activity is advantageous because contaminants (including mud) on the coating surface of the photocatalytically active coating substrate will be removed sooner than on substrates with relatively low photocatalytic activity. is there. Moreover, low levels of UV light intensity will tend to remove surface contaminants relatively quickly. [0025] The photocatalytic activity for the purposes herein is approximately 32 W / m on the surface of the coated substrate.²The rate of decrease in the integrated absorbance of the infrared absorption peak corresponding to the CH elongation of the stearic acid thin film formed on the coating substrate under irradiation with UV light from a UVA lamp having a peak wavelength of 351 nm. Determined by measurement. The stearic acid can be formed on a coated substrate by spin-casting a stearic acid solution in methanol as described below. [0026] Preferably, the coated surface of the substrate is 1x10.^-2cm^-1min^-1Larger, more preferably 3x10^-2cm^-1min^-1Has greater photocatalytic activity. [0027] Low visible light reflectance is less scattered than high reflective ones, especially on glass substrates, where low visible light reflectance corresponds to the high visible light transmission often required when applying glass to construction and especially automobiles. Therefore, it is advantageous that there is little visible light reflection. [0028] Preferably, the visible light reflectance measured on the coating side of the coating substrate is 20% or less, more preferably 17% or less, and most preferably 15% or less. [0029] In most embodiments of the invention, the substrate is substantially transparent, and in a preferred embodiment of the invention, the substrate consists of a glass substrate. Usually the glass substrate will be a soda-lime glass substrate. [0030] When the substrate is a soda-lime glass substrate or a substrate containing alkali metal ions, the coated substrate preferably has an alkali metal ion blocking lower layer between the substrate surface and the photocatalytically activated titanium oxide coating. This is because it reduces the tendency of alkali metal ions from the substrate to move to the photocatalytically active titanium oxide film, and it is well known that alkali metal ions are harmful to the semiconductor oxide film and tend to reduce their activity. , It is advantageous to reduce the movement tendency. [0031] The alkali metal lower layer may contain a metal oxide, but preferably the alkali metal ion blocking layer is a silicon oxide layer. Silicon oxide can be silica, but it does not have to be stoichiometric, carbon (often called silicon oxycarbide, precipitated as described in GB2,199,848B), or nitrogen (silicon). It may contain impurities such as (often called oxynitride). [0032] In particular, alkali metal blocking so that the alkali metal underlayer does not significantly affect the optical properties of the coating by reducing the transparency of the transparent coating substrate or by causing interference colors in reflection or transmission. It is advantageous that the lower layer is thin. The range of suitable thickness will depend on the nature of the metal used to form the alkali metal ion blocking layer (particularly its refractive index), but usually the alkali metal ion blocking underlayer has a thickness of less than 60 nm. It preferably has a thickness of less than 40 nm. Here, the alkali metal ion blocking underlayer should always be thick enough to reduce or block the movement of alkali metal ions from the glass into the titanium oxide coating. [0033] The advantage of the present invention is that the photocatalytically active titanium oxide coating is thin (contributing to less visible reflection on the coating substrate), but the coating substrate still has excellent photocatalytic activity. Preferably, the titanium oxide film has a thickness of 30 nm or less, more preferably the titanium oxide film has a thickness of 20 nm or less, and most preferably the titanium oxide film has a thickness in the range of 2 nm to about 20 nm. Has a thickness. [0034] The present invention is advantageous because it requires less precursor to precipitate the titanium oxide film and the layers can be precipitated in a relatively short time. A thin titanium oxide coating is less likely to cause interference colors in reflection or transmission. However, the low visible light reflectance of the thin titanium oxide coating is particularly advantageous, especially when the coating substrate is coated glass. Visible light transmission, which is usually required for coated glass, will determine the thickness of the titanium oxide coating. [0035] Preferably, the coating surface of the substrate has a static water contact angle of 20 ° or less. Freshly prepared or decontaminated glass has a hydrophilic surface (static water contact angles less than 40 ° indicate hydrophilic surfaces), but organic pollutants rapidly adhere to the surface and increase the contact angle. A particular advantage of the coated substrate (and particularly coated glass) of the present invention is that even if the coated surface becomes dirty, these contaminants can be reduced or decomposed by irradiating the coated surface with UV light of the correct wavelength. And will reduce the contact angle. A further advantage is that water spreads over surfaces with small contact angles, reducing the effect of water droplets scattering on the surface (eg due to rain), and dust or other contaminants that were not destroyed by the photocatalytic activity of the surface. It will tend to be washed away. The static water contact angle is the angle of water droplets on the glass surface with respect to the meniscus, which can be determined by a known method by measuring the diameter of a known volume on the glass surface and calculated using the sequential method. [0036] Preferably, the coated substrate has a turbidity of 1% or less, which is advantageous because the visibility through the transparent coated substrate can be sharpened. [0037] In a preferred embodiment, the coating surface of the substrate is abrasion resistant, so that the coating surface retains photocatalytic activity after undergoing a 300 stroke European standard abrasion test. Preferably, the coated surface retains photocatalytic activity after undergoing a 500 stroke European standard wear test, and more preferably the coated surface retains photocatalytic activity after undergoing a 1000 stroke European standard wear test. [0038] This will often be used on coating surfaces where the self-cleaning coating substrate of the present invention is exposed to the outside (eg, coating glass having a glass coating substrate as the outer surface of a window) where the coating is susceptible to wear damage. Therefore, it is advantageous. [0039] The European standard wear test refers to the wear test described in European Standard BS EN 1096 Part 2 (1999) and consists of reciprocating the felt pad on the sample surface at a set speed and pressure. [0040] In the present specification, if the static water contact angle is reduced to 15 ° or less by irradiating with UV light (eg, peak wavelength 351 nm) after undergoing the European standard wear test, the coating substrate retains its photocatalytic activity. I think there is. To reach this contact angle after wear of the coated substrate, approximately 32 W / m on the surface of the coated substrate²With the intensity of, the irradiation time will usually take less than 48 hours. [0041] Preferably, the turbidity of the coated substrate is 2% or less after the European standard wear test. [0042] The durable coated substrate according to the present invention can also be durable to a wet cycle (which is intended to have the same effect as exposure to rain and wind). Therefore, in a preferred embodiment of the present invention, the coated surface of the substrate is resistant to wet cycles such that the coated surface retains photocatalytic activity even after the coated substrate has undergone a 200 cycle wet cycle test. .. As used herein, a wet cycle test refers to a test in which a coating is exposed to a temperature cycle of 35 ° C-75 ° C-35 ° C for 4 hours at near 100% relative humidity. If the contact angle is reduced to 15 ° or less by irradiating with UV light after the test, it is considered that the coated substrate maintains the photocatalytic activity. [0043] In a more preferred embodiment, the present invention is a durable photocatalytically active coated glass comprising a glass substrate having a coating on one side thereof, wherein the coating has an alkali metal blocking underlayer and a photocatalytically active titanium oxide layer. Provided is a durable photocatalytically active coated glass in which the coated surface of a substrate has abrasion resistance so that the coated surface retains photocatalytic activity even after undergoing a European standard abrasion test of 300 strokes. In this embodiment, the visible light reflectance measured on the coating side of the coated glass is preferably 35% or less, and the thickness of the photocatalytically active titanium oxide layer is 30 nm. It is surprising that thin coatings are abrasion resistant, as it was previously thought that only relatively thick coatings would have good durability. [0044] In a further embodiment, the present invention is a coated glass comprising a glass substrate having a photocatalytically active titanium oxide coating on one surface thereof, wherein the coated surface of the glass is 4 × 10.^-2cm^-1min^-1Larger, preferably 6x10^-2cm^-1min^-1Larger, more preferably 8x10^-2cm^-1min^-1Provided is a coated glass having a larger photocatalytic activity and having a visible light reflectance of 20% or less measured on the coated side of the coated glass. [0045] The coated substrate according to the present invention is used in many fields. For example, as a mounting glass for a window including a multi-glass mounting unit including the first mounting window glass of the coated substrate, which is opposed to the second mounting window glass at intervals, or when the coated substrate is a coated glass. As a laminated glass, including a first glass layer of the coated glass, a polymer intermediate layer (eg, polyvinyl butyral), and a second glass layer. [0046] In addition to its use in self-cleaning substrates (especially self-cleaning glass for windows), the coated substrates of the present invention may also help reduce the concentration of air pollutants. For example, coated glass under irradiation with UV wavelength light (including the presence of UV wavelengths in sunlight) destroys air pollutants adsorbed on the coated surface of the glass, such as nitrogen oxides, ozone, and organic pollutants. it can. This application may have a relatively high concentration of organic pollutants (especially in strong sunlight), but also has a relatively high usable surface area of glass, especially outdoors in urban areas (eg urban streets). It is advantageous. Alternatively, coated glass (with a coated surface on the inside) can be used to reduce the concentration of air pollutants inside buildings, especially office buildings with relatively high concentrations of air pollutants. [0047] [Example] The present invention is illustrated in the drawings below, but this is not a limitation of the present invention. [0048] In FIG. 1, the coated glass was manufactured using the online CVD method described in the following examples. The white circle 1 relates to the titanium oxide layer precipitated using titanium tetrachloride as the precursor of titanium, and the cross mark relates to the titanium oxide layer precipitated using titanium tetraethoxydo as the precursor of titanium. [0049] The coating layer can be applied online on a glass substrate using chemical vapor deposition during the glass manufacturing process. FIG. 2 illustrates an apparatus, shown as a whole at 10, useful for the online production of coated glass of the present invention, including a float section 11, a slow cooling tub 12, and a cooling section 13. The float section 11 has a bottom 14 including a molten timbus 15, a ceiling 16, a side wall (not shown), and an end wall 17, which together form a seal to form a siege zone 18 here. In the siege zone, a non-oxidizing atmosphere is maintained to prevent oxidation of Timbus 15. During the operation of the apparatus 10, the molten glass 19 is poured onto the furnace 20 and from there under the metering wall 21 and then downwards to the surface of the timbus 15 to form the float glass ribbon 37, and The float glass ribbon is removed by the lift-out roll 22, passed through the slow cooling pan 12, and then conveyed through the cooling section 13. [0050] The non-oxidizing atmosphere is created by introducing a suitable gas, such as a gas containing nitrogen and 2% by volume hydrogen, into the zone 18 through a conduit 23 operably connected to the manifold 24 to create a float section. It is kept during 11. Non-oxidizing gas is introduced from conduit 23 into zone 18 at a rate sufficient to compensate for gas loss (part of the non-oxidizing atmosphere exits zone 18 by flowing under the end wall 17). ), Keep the pressure slightly more positive than the ambient pressure. The timbus 15 and the siege zone 18 are heated by radiant heat directed downward from the heater 25. The heat zone 18 is generally maintained at a temperature of about 1330 ° F to 1400 ° F (721 ° C to 760 ° C). The atmosphere in the slow cooling tank 12 is typically air, and the cooling section 13 is not enclosed. The fan 26 blows the outside air onto the glass. [0051] The device 10 also includes coaters 27, 28, 29, and 30 located contiguously in the float zone 11 on the float glass ribbon 37. A gaseous mixture of precursors for the individual layers of the coating is fed to each coater and the gaseous mixture of precursors is directed towards the thermal surface of the float glass ribbon 37 in sequence. The temperature of the float glass ribbon 37 is highest at the position of the coater 27 closest to the furnace 20 and lowest at the position of the coater 30 closest to the slow cooling furnace 12. [0052] The present invention will be further clarified by the following examples. In the examples, the coating was applied by performing laminar chemical vapor deposition in a float bath on a moving float glass ribbon during the glass manufacturing process. In the examples, a two-layer coating was applied to the glass ribbon. [0053] All gas volumes are measured at standard temperature and standard pressure unless otherwise stated. The thickness values cited for the layers were determined by using a high resolution scanning electron microscope and by optically modeling the reflection and transmission spectra of the coated glass. The thickness of the coating was measured under an uncertainty of about 5%. The transmission and reflection characteristics of the coated glass were determined using a Hitachi U-4000 spectrophotometer. For the transmitted color and / or reflected color of glass, the a, b, and L * values described here refer to the CIE Lab color. Visible reflection and transmission of coated glass was determined based on the ISO9050 standard using a D65 light source and a standard CIE 2 ° observer (Parry Moon Airmass 2). The turbidity of the coated glass was measured using a WYK-Gardner Hazeguard + haze meter. [0054] The photocatalytic activity of the coated glass was determined from the reduction rate of the area of the infrared peak corresponding to the CH expansion and contraction of the stearic acid film on the coated surface of the glass under irradiation with UVA light. The stearic acid film is 20 μl (8.8 × 10) of a methanol solution of stearic acid.^-3mol dm^-3) Was spun on the surface of the glass substrate at 2000 rpm for 1 minute to form a 7-8 cm square on the glass sample. Infrared spectrum is measured by transmission, and CH expansion and contraction of stearic acid film (about 2700 to 3000 cm)^-1The peak height of the peak corresponding to) was measured, and the corresponding peak area was determined from the calibration curve of the peak area with respect to the peak height. On the coated side of the glass, the peak wavelength is 351 nm and the strength on the coated glass surface is about 32 W / m.²Irradiated with a UVA-351 lamp (obtained from Cleveland Q-Panel, Ohio, USA). Photocatalytic activity is referred to herein as the rate of decrease in the area of the IR peak (unit: cm).^-1min^-1) Or the UV irradiation time required to reduce the peak height (absorption) of the peak in the wavelength region to 10% of its initial value._90%(Unit is min). [0055] The static water contact angle of the coated glass is a water droplet (volume in the range of 1 to 5 μl) placed on the surface of the coated glass after irradiating the coated glass with a UVA351 lamp for about 2 hours (or another specified time). It was determined by measuring the diameter of the glass. [0056] Example 1-15 When the ribbon of 1 mm thick soda lime float glass advances on the float bath where the glass temperature is in the range of about 650 ° C to about 670 ° C, the ribbon advances at a slow cooling rate of 300 m / hr. The coating was coated. The atmosphere of the float bath consisted of a fluid gaseous mixture of nitrogen and 9% hydrogen at a bath pressure of about 0.15 mbar. [0057] Layer 1 (the first layer deposited on the glass) was a layer of silicon oxide. Layer 1 has a gaseous mixture moving path on a glass surface of about 0.15 m, see the corresponding description in UK Patent Specification 1 507 966 (particularly in Figures 2 and 3 pages 73-4 75). ), Using the coating apparatus described in), monosilane (SiH4,) parallel to the glass surface in the direction of movement of the glass. A gaseous mixture of 60 ml / min), oxygen (120 ml / min), ethylene (360 ml / min), and nitrogen (8 l / min) was brought into contact with each other and precipitated by flowing. Extraction was from about 0.9 to 1.2 mbar. The glass ribbon was coated over a width of about 10 cm at a temperature of about 670 ° C. The thickness of the silica layer was about 20 to 25 nm. [0058] [0058] Layer 2 (the second layer to be precipitated) was titanium oxide. Layer 2 contains carbon tetrachloride in the fluid nitrogen transport gas, ethyl acetate in the fluid nitrogen transport gas, and 8 Separate gas streams consisting of a total nitrogen stream of l / min (measured flow rate 20 psi (1.37895 bar)) merge as one gaseous mixture, then the gaseous mixture (through a line kept at about 250 ° C). Precipitated by supplying to a coating apparatus consisting of an oil-cooled dual flow coater. The pressure of nitrogen transport gas and bulk nitrogen gas was about 20 pounds per square inch. The gaseous mixture was allowed to flow in parallel to the glass surface in both upstream and downstream directions along the glass ribbon. With an extraction of about 0.15 mbar, the travel path of the gaseous mixture downstream was about 0.15 m and upstream was about 0.15 m. Titanium tetrachloride and ethyl acetate were transported into separate streams of fluid nitrogen transport gas by passing nitrogen through a bubbler containing titanium tetrachloride or ethyl acetate. The flow rates of the nitrogen transport gas are shown in Table 1 (flow rates were measured at 20 psi (1.37895 bar)). The titanium tetrachloride bubbler was kept at a temperature of 69 ° C and the ethyl acetate bubbler was kept at a temperature of 42 ° C. The approximate flow rates of the transported titanium tetrachloride and the transported ethyl acetate are also shown in Table 1 for each of Examples 1 to 15. [0059] The physical characteristics of the two-layer coating were measured. The thickness value of layer 2 (titanium oxide layer), the visible light reflectance value measured on the coating side, and the L * and turbidity of the coating glass are shown in Table 2 for Examples 1 to 15. .. The turbidity of the coated glass was 0.2% or less. [0060] The photocatalytic activity of the coated glass and the static water contact angle were determined. For Examples 1 to 15, the initial peak height and initial peak area of the IR peak corresponding to the CH expansion and contraction of stearic acid, the photocatalytic activity, the static water contact angle, and t._90%And are listed in Table 3. Surprisingly, the thickness of the titanium oxide layer has almost no effect on the photocatalytic activity. [0061] Example 16-19 In Examples 16-19, the bath pressure was 0.11 mbar, the extraction for precipitating the silica undercoat (layer 1) was about 0.7 mbar, the titanium tetrachloride bubbler was kept at a temperature of about 100 ° C, and the acetate The procedure was carried out under the same conditions as in Examples 1-15, except that the ethyl bubbler was kept at a temperature of 45 ° C and the supply line was kept at a temperature of about 220 ° C. [0062] The flow rates of the nitrogen transport gas and the approximate flow rates of the transport titanium chloride and the transport ethyl acetate are disclosed in Table 1 for each of Examples 16-19. [0063] The approximate thickness value of layer 2 (titanium oxide layer), the value of visible light reflectance measured on the coating side, and the L * and turbidity of the coating glass are shown for each of Examples 16 to 19. Describe in 2. [0064] For each of Examples 16 to 19, the initial peak height and initial peak area of the IR peak corresponding to the CH expansion and contraction of stearic acid, the photocatalytic activity, and t._90%And the static water contact angle are shown in Table 3. [0065] Although the titanium oxide coatings of Examples 16-19 were thicker (and thus more reflective), the photocatalytic activity was not substantially greater than the photocatalytic activity of Examples 1-15. [0066] [table 1]<img file="JP4716631B2_D0001.tif" />[0067] [Table 2]<img file="JP4716631B2_D0002.tif" />[0068] [0068] [Table 3]<img file="JP4716631B2_D0003.tif" />[0069] Examples 20-27 Examples 20-27 are from a gaseous mixture containing titanium tetrachloride transported to a nitrogen transport gas by passing layer 2 through a bubbler containing titanium tetrachloride kept at a temperature of 170 ° C. It was carried out under the same conditions as in Examples 1-15 except for the precipitated points. The flow rates of nitrogen transport gas (measured at 20 psi (1.37895 bar)) and titanium tetraethoxydo are shown in Table 4 for each of Examples 20-27. The flow rate of bulk nitrogen gas was 8.5 l / min (measured at 20 psi (1.37895 bar)). [0070] The physical characteristics of the two-layer coating were measured. The value of the thickness of the layer 2 (titanium oxide layer), the value of the visible light reflectance measured on the coating side, and the turbidity of the coating glass are shown in Table 5 for Examples 20 to 27. The turbidity of each coated glass was 0.7% or less. [0071] The photocatalytic activity of the coated glass and the static water contact angle were determined. For each of Examples 20 to 27, the initial peak height and initial peak area of the IR peak corresponding to the CH expansion and contraction of stearic acid, the photocatalytic activity, and t._90%And the static water contact angle are shown in Table 6. [0072] Examples 28 and 29 Examples 28 and 29 were carried out under the same conditions as in Examples 20-27, except that the bubbler of titanium tetraethoxydo was kept at a temperature of 168 ° C and the bath pressure was 0.11 mbar. The data for Examples 28-29, which correspond to the data for Examples 20-27, are shown in Tables 4, 5 and 6. [0073] [Table 4]<img file="JP4716631B2_D0004.tif" />[0074] [Table 5]<img file="JP4716631B2_D0005.tif" />[0075] [Table 6]<img file="JP4716631B2_D0006.tif" />[0076] Example 30-42 In Examples 30-42, the two-layer coating was applied to the float glass ribbon by online CVD over its entire width of about 132 inches (about 3.35 m) during the float glass manufacturing process in a float bath. The device used to deposit the coating is illustrated in FIG. The atmosphere of the float bath was nitrogen and 2% by weight hydrogen. The bus pressure was 0.15 mbar. [0077] The two-layer coating was composed of a silicon oxide layer first precipitated on the float glass ribbon and a titanium oxide layer precipitated on the silicon oxide layer. The chemical composition of the precursor of the gaseous mixture used to precipitate the film was the same as that used in Examples 1-15. The deposition temperature of the layer was varied using coaters 27, 28, 29, or 30 (see Figure 2). The coater 27 located closest to the furnace was the hottest, and the coater 30 located closest to the slow cooling furnace was the coldest. In Examples 30-33 and 42, two coaters (coaters 28 and 29 in Examples 30-33 and coaters 27 and 28 in Example 42) were used to precipitate the silicon oxide film. The advantage of using two coaters to deposit the silicon oxide film is that longer manufacturing run times are possible. [0078] The gaseous mixture used to precipitate the silicon oxide layer in Examples 30-41 consisted of the following gases at the following flow rates: That is, helium (250 l / min), nitrogen (285 l / min), monosilane (2.5 l / min), ethylene (15 l / min), and oxygen (10). l / min). For Example 42, the same gas and flow rate were used except for monosilane (2.3 l / min), ethylene (13.8 l / min), and oxygen (9.2 l / min). When the silicon oxide layer was precipitated using two coaters in Examples 30 to 42, the above flow rate was used for each coater. [0079] The precipitation temperatures in Examples 30-42 (ie, the float glass ribbon temperatures under the coaters corresponding to each of the coaters 27-30) are shown in Table 7. The temperatures in Table 7 have an uncertainty of about ± 50 ° F (± 28 ° C). The extraction for each coater was about 2 mbar. [0080] [0080] [Table 7]<img file="JP4716631B2_D0007.tif" />[0081] Titanium tetrachloride (TiCl)₄) And ethyl acetate were transported in separate nitrogen / helium transport gas streams. TiCl₄A thin film evaporator was used to vaporize. Liquid TiCl₄Was held in a pressurized vessel (top pressure about 5 psi). It was used to supply the liquid to a metering pump and a Coriolis force flow measurement system. The weighed precursor stream was then fed into a thin film evaporator at a temperature of 110 ° F (43 ° C). TiCl₄Was subsequently transported in transport gas (helium) and fed to the mixing point below the line kept at 250 ° F (121 ° C). Ethyl acetate was also supplied in a similar manner. Liquid ethyl acetate was held in a pressurized vessel (top pressure about 5 psi). It was used to feed the liquid to metering pumps and Coriolis force flow measurement systems. The weighed precursor stream was then fed into a thin film evaporator at a temperature of 268 ° F (131 ° C). The vaporized acetic acid gas was then taken into the transport gas (helium / nitrogen mixture) and transported to the mixing point below the line kept at 250 ° F (121 ° C). [0082] TiCl₄And a gas stream of ethyl acetate was mixed to form a gaseous mixture used to precipitate the titanium oxide layer. This mixing point was set immediately before the coater. [0083] Line velocity of float glass ribbon, precipitation temperature of silicon oxide, precipitation temperature of titanium oxide layer, He / N₂Bulk transport gas flow velocity and TiCl₄And the flow rates of ethyl acetate are shown in Table 8 for Examples 30-42. [0084] The coated float glass ribbon was cooled and cut to determine the optical properties and photocatalytic activity of the sample. Table 9 lists the turbidity of the sample, the optical properties of the sample in transmission and reflection (visible percent transmission / visible percent reflection, and color coordinates using the LAB system). The coated glass was subjected to a wear test based on BS EN 1096. In the wear test, a sample measuring 300 mm x 300 mm is firmly fixed to the testbed at four corners to ensure that the sample does not move. And standard (BS EN 1096 An unused felt pad cut to the dimensions described in Part 2 (1999) is attached to the test finger and the finger is lowered to the glass surface. Next, set the load pressure on the 4N test finger and start the test. The fingers are capable of reciprocating across the sample for 500 strokes at a speed of 60 strokes / min ± 6 strokes / min. Once this wear is complete, the sample is removed and inspected optically and in terms of photocatalytic activity. If the change in transmission does not exceed ± 5% when measured at 550 nm as a result of abrasion, and the coated substrate maintains photocatalytic activity, the sample is judged to have passed the test. Maintaining photocatalytic activity means reducing the static water contact angle to 15 ° or less after test irradiation with UV light for 2 hours. [0085] A wet cycle test was also performed on the glass, which exposed the coating to a temperature cycle of 35 ° C-75 ° C-35 ° C for 4 hours at a relative humidity close to 100%. [0086] The static water contact angle was measured at the time of manufacture, after 130 minutes of UV irradiation (about 32 W / m).²UVA 35 1nm lamp is used in), and after the European standard wear test of 300, 500, and / or 1000 strokes are shown in Table 10. The contact angle of the worn sample was determined after 2 hours of irradiation. [0087] Samples precipitated at higher temperatures from 1330 to 1250 ° F (721 ° C to 677 ° C) were photocatalytically active after 1000 European standard abrasion strokes or after 200 wetting cycles. Filmed glass t at the time of manufacture, after 300, 500, and / or 1000 stroke European standard wear tests, and after 200 wet test cycles._90%The photocatalytic activity of is shown in Table 11. The word activity in Table 11 is t_90%Was not determined, but indicates that the coated glass was photocatalytically active. [0088] [Table 8]<img file="JP4716631B2_D0008.tif" />[0089] [Table 9]<img file="JP4716631B2_D0009.tif" />[0090] [Table 10]<img file="JP4716631B2_D0010.tif" />[0091] [Table 11]<img file="JP4716631B2_D0011.tif" />[Simple explanation of drawings] FIG. 1 is a graph of photocatalytic activity of coated glass produced by the method according to the invention, as a function of the thickness of the titanium oxide layer. FIG. 2 illustrates an apparatus for chemical vapor deposition of a coating film according to the present invention online.