Process for production of photocatalytic coatings on substrates

Method for producing photocatalytic coating on substrate

The invention relates to a production of a photocatalytically active coated substrate, and particularly but not exclusively, it relates to a method for producing a photocatalytically active coated glass and the coated glass.

It is known to deposit one or more layers of coatings having various properties on substrates (including on glass substrates). A meaningful performance is photocatalytic activity. When a semiconductor is irradiated with light of a specific frequency, the photocatalytic activity is generated by the hole-electron pair generated by the light in the semiconductor. Hole-electron pairs can be generated in sunlight and can react in humid air to form hydroxyl and peroxide groups on the surface of the semiconductor. These groups oxidize organic dirt on the surface. This performance has applications in self-cleaning substrates (especially self-cleaning window glass).

Titanium dioxide can be an effective photocatalyst and can be deposited on the substrate to form a transparent coating with photocatalytic self-cleaning properties. In EP 0 901 991 A2, WO97/07069, WO97/10186, WO98/41480, Abstract 735 of the 187th Meeting of the Electrochemical Society (Reno, NV, 95-1, p.1102) and the Journal of New Scientist (1995 August On the 26th, p19) published a titanium oxide photocatalytic coating. In WO 98/06675, a chemical vapor deposition method is described for depositing a titanium oxide coating on a hot flat glass at a high deposition rate, in which a precursor gas mixture of titanium chloride and an organic compound as an oxygen source is used To form a titanium oxide coating.

It has been considered that in order to provide good photocatalytic activity, a relatively thick titanium oxide film needs to be deposited. For example, in WO 98/41480, it is stated that the photocatalytically active self-cleaning coating must be thick enough to provide an acceptable level of activity. Preferably, the coating is at least about 200 angstroms thick, and more preferably at least about 500 angstroms. Thickness (the measured thickness of the titanium oxide coating produced in the examples is in the range of 400-2100 angstroms).

However, the problem with the thicker titanium oxide coating is that the visible light reflectance is high, and therefore the visible light transmittance is low. This issue is considered in the article on coated windshield in the New Scientist Magazine. In this article, it is proposed that in order to reduce the effect of high reflection, the instrument panel must be coated with black velvet or other light that does not reflect light to the coated windshield. material.

The aforementioned EP 0 901 991A2 relates to a photocatalytic window glass with a titanium oxide coating with a specific crystal structure, and the coating is characterized by the presence of specific peaks in its X-ray diffraction spectrum. This specification considers the coating thickness range (all the specific examples have a thickness between 20 nanometers and 135 nanometers, and a thinner coating has a lower photocatalytic activity than a thicker coating). The specification also considers that the deposition temperature ranges from as low as 300°C to as high as 750°C, but the preferred temperature is between 400°C and 600°C. In all specific embodiments of the invention, it is within the preferred range or lower than the preferred range. The temperature range of deposition of titanium dioxide film.

The inventors have now discovered that by depositing a titanium oxide coating at a higher temperature, especially at a temperature higher than 600°C, for a certain thickness, a coating with enhanced photocatalytic activity can be obtained, and a thinner coating can be obtained. The same photocatalytic performance. This thinner coating is advantageous in that it tends to have lower visible light reflectivity and, apparently, due to its higher deposition temperature, it has improved durability, especially for abrasion and temperature cycling in humid gases.

Therefore, the present invention provides a method for producing a photocatalytically active coated substrate, which includes depositing a titanium oxide coating on the surface of the substrate by contacting the surface of the substrate with a fluid mixture containing a titanium source and an oxygen source, and the temperature of the substrate is at least 600 °C, so that the coated surface of the substrate has a photocatalytic activity greater than 5×10-3cm-1min-1, and the visible light reflectance measured on the coated side is 35% or lower.

Preferably, the temperature of the substrate is in the range of 625-720°C, more preferably the temperature of the substrate is in the range of 645-720°C.

Advantageously, the fluid mixture contains titanium chloride as a source of titanium and esters that are not methyl esters. Therefore, in a preferred embodiment, the present invention provides a method for producing a photocatalytically active coated substrate, which comprises contacting the surface of the substrate with a fluid mixture containing titanium chloride and an ester other than methyl esters, on the substrate A titanium oxide coating with a thickness of less than 40 nanometers is deposited.

Wherein, when the temperature of the substrate is in the range of 600-750°C, the surface of the substrate is brought into contact with the fluid mixture to perform the method.

Preferably, the ester is an alkyl ester having an alkyl group with β hydrogen (the alkyl group of an alkyl ester is a group derived from an alcohol during the synthesis of the ester, and β hydrogen is bonded to the ester relative to the The hydrogen on the β-position carbon atom of the oxygen of the ether bond). Preferably, the ester is a carboxylic acid ester.

Suitable esters may be alkyl esters with C2-C10 alkyl groups, but, preferably, the esters are alkyl esters with C2-C4 alkyl groups.

Preferably, the ester is a compound of the formula: RC(O)-OC(X)(X')-C(Y)(Y')-R', wherein R and R'represent hydrogen or alkyl The group, X, X', Y and Y'represent monovalent substituents, preferably an alkyl group or a hydrogen atom, wherein at least one of Y and Y'represents a hydrogen atom.

Suitable esters that can be used in the method of the present invention include: ethyl formate, ethyl acetate, ethyl propionate, ethyl butyrate, n-propyl formate, n-propyl acetate, n-propyl propionate, n-butyrate Propyl ester, isopropyl formate, isopropyl acetate, isopropyl propionate, isopropyl butyrate, n-butyl formate, n-butyl acetate, and tert-butyl acetate.

Preferably, the ester contains an ethyl ester, and more preferably, the ester contains ethyl formate, ethyl acetate, or ethyl propionate. It is most preferred that the ester contains ethyl acetate.

The fluid mixture may be in liquid form, especially dispersed into fine mist droplets (a method commonly referred to as spray deposition), but it is preferred that the fluid mixture is a gas mixture. The deposition method using a gas mixture as a precursor is often referred to as chemical vapor deposition (CVD), and the preferred form of CVD is laminar flow CVD, although turbulent flow CVD can also be used.

The method can be performed on substrates of various sizes, including flat substrates, especially on cut glass plates, or preferably on-line on a continuous glass ribbon during the float glass production process. Therefore, it is preferred that the method is performed online during the float glass production process, and the substrate is a glass ribbon. If the method is performed online, it is preferably performed on a glass ribbon in a float bath.

One advantage of performing this method in-line is that the coating deposited in-line tends to be durable, especially with good abrasion resistance and chemical resistance.

The in-line deposition method is preferably carried out under atmospheric pressure, and other deposition methods can also be carried out under atmospheric pressure.

In a particularly preferred embodiment, a method for producing durable photocatalytically active coated glass is provided, which includes depositing a photocatalytic activity on the surface of the glass substrate by contacting the surface of the substrate with a fluid mixture containing a titanium source For the titanium oxide layer, the substrate surface temperature is in the range of 645°C to 720°C, preferably 670°C to 720°C.

As mentioned above, the applicant has discovered that by depositing titanium oxide at high temperatures, it is possible to produce a coating with higher photocatalytic activity for its thickness. Since a coating with a reduced thickness tends to have a lower reflectivity, The present invention also provides a novel product with favorable combination of high photocatalytic activity and medium or low light reflectivity.

Therefore, in another aspect, the present invention provides a photocatalytically active coated substrate, including a substrate with a photocatalytically active titanium oxide coating on one surface thereof, characterized in that the coated surface of the substrate has a thickness greater than 5×10-3cm-1min. -1 photocatalytic activity, and the visible light reflectance measured on the coated side of the coated substrate is 35% or less.

High photocatalytic activity is advantageous because the amount of contaminants (including contaminants) on the coated surface of the photocatalytically active coated substrate decreases faster than on a substrate with lower photocatalytic activity. At the same time, faster removal of surface contaminants often occurs under low UV light intensity.

By irradiating the UV light of the UNA lamp with an intensity of about 32W/m2 and a peak wavelength of 351 nm under the surface of the coated substrate, the integrated absorption rate of the infrared absorption peak corresponding to the CH stretch of the stearic acid film formed on the coated substrate was measured To determine the photocatalytic activity used in this specification. By spin-casting a methanol solution of stearic acid, stearic acid can be formed on the coated substrate, as described below.

Preferably, the photocatalytic activity of the coating surface of the substrate is greater than 1×10-2 cm-1min-1, more preferably greater than 3×10-2 cm-1min-1.

Low visible light reflectivity is advantageous because it is less disruptive than high reflectivity, especially for glass substrates. Low visible light reflectivity corresponds to high visible light transmittance. This is used in glass construction, especially in automobiles. It is often required in aspects of the application.

Preferably, the visible light reflectance measured on the coated side of the coated substrate is 20% or less, preferably 17% or less, and most preferably 15% or less.

In the most preferred embodiment of the present invention, the substrate is substantially transparent. In a preferred embodiment of the present invention, the substrate includes a glass substrate. Generally, the glass substrate is a soda lime silica glass substrate.

When the substrate is a soda lime silica glass substrate or other substrates containing alkali metal ions, the coated substrate preferably has an alkali metal ion barrier layer between the surface of the substrate and the photocatalytically active titanium oxide coating. This reduces the tendency of alkali metal ions to migrate from the substrate into the photocatalytically active titanium oxide coating, which is advantageous because it is well known that alkali metal ions have a tendency to poison the semiconductor oxide coating and reduce its activity.

The alkali metal ion blocking underlayer may include a metal oxide, but it is preferable that the alkali metal ion blocking underlayer is a silicon oxide layer. The silicon oxide may be silicon dioxide, but does not have to be stoichiometric, and may contain impurities such as carbon (often referred to as silicon oxycarbide and deposited as described in GB 2,199,848B) or nitrogen (often referred to as silicon oxynitride).

Advantageously, the alkali metal ion barrier bottom layer is so thin that it has no significant impact on the optical properties of the coating, especially when the transparency of the transparent coated substrate is reduced or interference colors are generated in reflection or transmission. The appropriate thickness range will depend on the properties of the material used to form the alkali metal ion barrier layer (especially its refractive index). However, the thickness of the alkali metal ion barrier layer is generally less than 60 nanometers, preferably less than 40 nanometers. When the alkali metal ion barrier layer is present, it should always be thick enough to reduce or prevent the migration of alkali metal ions from the glass into the titanium oxide coating.

One advantage of the present invention is that the photocatalytically active titanium oxide coating is thin (it is beneficial to lower the visible light reflectivity of the coated substrate), but the coated substrate still has excellent photocatalytic activity. Preferably, the thickness of the titanium oxide coating is 30 nanometers or less, more preferably, the thickness of the titanium oxide coating is 20 nanometers or less, and most preferably, the thickness of the titanium oxide coating is in the range of 2 to about 20 nanometers. Inside.

The present invention is also advantageous because fewer precursors are required to deposit a thin titanium oxide coating and the coating can be deposited in a shorter time. Thin titanium oxide coatings are also unlikely to produce interference colors in reflection or transmission. However, the special advantage is the low visible light reflectivity of the thin titanium oxide coating, which is particularly important when the coated substrate is coated glass. Generally, the visible light transmittance required by the coated glass will determine the thickness of the titanium oxide coating.

Preferably, the coating surface of the substrate has a hydrostatic contact angle of 20° or less. The freshly prepared or cleaned glass surface has a hydrophilic surface (the hydrostatic contact angle is less than about 40°, indicating a hydrophilic surface), but organic contaminants quickly adhere to the surface to increase the contact angle. The special advantage of the coated substrate (especially coated glass) of the present invention is that even if the coated surface is contaminated, irradiating the coated surface with ultraviolet light of appropriate wavelength can reduce or destroy those contaminants and reduce the contact angle. Another advantage is that the water spreads on the low contact angle surface, reducing the disturbing effect of water droplets (for example from rain) on the surface, and tends to wash away any dirt or other pollutants that are not destroyed by the photocatalytic activity of the surface . The static water contact angle is the angle that the meniscus of the water droplets on the glass surface faces. It can be determined by measuring the diameter of a water droplet of a known volume on the glass surface using a known method and calculated using an iterative method.

Preferably, the haze of the coated substrate is 1% or less, which is advantageous because it can make the field of vision through the transparent coated substrate clear.

In a preferred embodiment, the coating surface of the substrate is wear-resistant, so that the coating surface maintains the photocatalytic activity after the reciprocation of the European standard abrasion test for 300 times. Preferably, the coating surface maintains photocatalytic activity after 500 reciprocations of the European standard abrasion test. More preferably, the coating surface maintains photocatalytic activity after 1,000 reciprocations of the European standard abrasion test.

This is advantageous because the self-cleaning coated substrate of the present invention is usually used when the coated surface is exposed to the outside (for example, the coated glass surface is used as the coated glass on the outer surface of the window), and the coating is easily worn out at this time.

The European standard abrasion test refers to the abrasion test described in the second part of the European standard BS EN 1096 (1999), including the felt pad reciprocating on the surface of the sample at a determined speed and pressure.

In this specification, if after the European abrasion test, ultraviolet light (for example, a peak wavelength of 351 nm) is irradiated to reduce the hydrostatic contact angle below 15°, the coated substrate is considered to maintain the photocatalytic activity. In order to obtain this contact angle, after the coated substrate is worn out, usually less than 48 hours of irradiation is required, and the intensity at the surface of the coated substrate is about 32W/m2.

Preferably, the haze of the coated substrate is 2% or lower after passing through the European standard abrasion test.

The durable coated substrate according to the present invention is also durable against moisture circulation (it is assumed that this has a similar effect to weathering). Therefore, in a preferred embodiment of the present invention, the coated surface of the substrate is durable against moisture cycling, so that the coated surface maintains photocatalytic activity after the coated substrate undergoes 200 moisture cycling tests. In this specification, the humidity cycle test refers to a temperature cycle in which the coating passes 35°C to 75°C and then to 35°C within 4 hours at a relative humidity close to 100%. If after the test, the hydrostatic contact angle is reduced below 15° by ultraviolet light irradiation, the coated substrate is considered to maintain the photocatalytic activity.

In another preferred embodiment, the present invention provides a durable photocatalytically active coated glass, comprising a glass substrate with a coating on one surface thereof, the coating including an alkali metal ion blocking bottom layer and photocatalytic activity Titanium oxide layer, wherein the coating surface of the substrate is wear-resistant, so that the coating surface maintains the photocatalytic activity after going through 300 reciprocations of the European standard test. In this embodiment, the coated glass preferably has a visible light reflectance measured on the coated side of 35% or less, and the photocatalytically active titanium oxide layer preferably has a thickness of 30 nanometers or less. Thin coatings are resistant to abrasion, which is unexpected, because it was previously thought that only thicker coatings have good durability.

In still another embodiment, the present invention provides a coated glass comprising a glass substrate with a photocatalytically active titanium oxide coating on one surface thereof, characterized in that the photocatalytic activity of the coated surface of the glass is greater than 4×10- 2cm-1min-1, preferably greater than 6×10-2cm-1min-1, more preferably greater than 8×10-2cm-1min-1, and the visible light reflectance measured on the coated side of the coated glass is less than 20% .

The coated substrate according to the present invention has applications in many fields, for example, as a window glass installation including a multi-layer window glass unit, a window glass panel including a first coating substrate in a spaced relationship with a second window glass panel, or when When the coated substrate is coated glass, the laminated glass includes a first glass plate layer (ply) of the coated glass, a polymer intermediate layer (for example, polyvinyl butyral) and a second glass plate layer.

In addition to its use in self-cleaning substrates (especially self-cleaning glass for windows), the coated substrate of the present invention can also be used to reduce the concentration of atmospheric pollutants. For example, coated glass under ultraviolet wavelengths (including ultraviolet wavelengths present in sunlight) can destroy atmospheric pollutants, such as nitrogen oxides, ozone, and organic pollutants adsorbed on the coated surface of the glass. This use is particularly advantageous in open areas in construction areas (for example, in urban streets), where the concentration of organic pollutants may be relatively high (especially under strong sunlight), but the glass surface area available in such places It is also relatively high. Alternatively, coated glass (with a coated surface on the inside) can be used to reduce the concentration of air pollutants inside buildings, especially in office buildings with high concentrations of air pollutants.

The present invention is illustrated by the following drawings but is not limited to the following drawings.

Fig. 1 is a graph showing the relationship between the photocatalytic activity of the coated glass produced by the method according to the present invention and the thickness of the titanium oxide coating.

Figure 2 shows an apparatus for on-line chemical vapor deposition of coatings according to the present invention.

In FIG. 1, the in-line CVD method described in the following examples is used to produce coated glass. Open circle 1 refers to a titanium oxide layer deposited using titanium tetrachloride as a titanium precursor, and cross number 2 represents a titanium oxide layer deposited using titanium tetraethoxide as a titanium precursor.

The coating can be applied on-line on the glass substrate by chemical vapor deposition during the glass manufacturing process. FIG. 2 shows a device for on-line production of coated glass products of the present invention, generally shown at 10, including a float part 11, a glass annealing furnace 12, and a cooling part 13. The float part 11 has a bottom 14 including a molten tin bath 15, a kiln roof 16, side walls (not shown) and end walls 17, which together form a kind of closed part, thereby providing a closed area 18 in which the non- An oxidizing atmosphere prevents oxidation of the tin bath 15. During the operation of the equipment 10, the molten glass 19 is cast on the hearth 20, and then flows under the metering wall 21, and then flows down to the surface of the tin bath 15 to form a raised roller 22 that is discharged and passed through the retreat The furnace 12 is conveyed and then passed through the float glass ribbon 37 of the cooling section 13.

A suitable gas, such as a gas containing nitrogen and 2% by volume of hydrogen, is introduced into the region 18 through a conduit 23 connected to the manifold 24, so as to maintain a non-oxidizing atmosphere in the float section 11. The non-oxidizing gas is introduced into the region 18 from the duct 23 at a speed sufficient to compensate for the gas loss (part of the non-oxidizing gas exits the region 18 due to flowing out under the end wall), and a slight positive pressure higher than the ambient pressure is maintained. The tin bath 15 and the enclosed area 18 are heated by downward radiant heat from the heater 25. The heating zone 18 is generally maintained at a temperature of about 1330°F to 1400°F (721°C to 760°C). The gas in the annealing furnace 12 is usually air, and the cooling area 13 is not sealed. The ambient air is blown on the glass by the fan 26.

The equipment 10 also includes coating machines 27, 28, 29, and 30, which are connected in series on the float glass ribbon 37 in the float area 11. The precursor gas mixture for each coating is supplied to each coating machine, and the coating machine in turn directs the precursor gas mixture onto the hot surface of the float glass ribbon 37. The temperature of the float glass ribbon 37 is highest at the coating machine 27 closest to the hearth 20 and lowest at the coating machine 30 closest to the annealing furnace 12.

The present invention is also illustrated by the following examples, in which, during the glass production process, the coating is applied to the moving float glass ribbon by laminar flow chemical vapor deposition in the float bath. In these examples, two coatings were applied to the glass ribbon.

Unless otherwise stated, all gas volumes are measured at standard temperature and pressure. A high-resolution scanning electron microscope and an optical model of the reflection and transmission spectra of the coated glass were used to determine the thickness of the coating. The measurement error of the coating thickness is about 5%. The transmission and reflection properties of the coated glass were measured using Hitachi U-4000 spectrophotometer. The a, b, and L* values of the transmission and/or reflection color of the glass mentioned herein refer to the CIE Lab color. A D65 light source and a standard CIE 2° observer according to the ISO 9050 standard (ParryMoon airmass 2) were used to determine the visible light reflection and visible light transmission of the coated glass. A WYK-Gardner Hazeguard+ haze meter was used to measure the haze of the coated glass.

The photocatalytic activity of the coated glass is determined from the reduction rate of the infrared peak area corresponding to the CH expansion and contraction of the stearic acid film on the glass coating surface under UVA light irradiation. Stearic acid is formed on the glass sample (7-8 cm square) by spin casting 20 microliters of stearic acid in methanol solution (8.8×10-3 mol/L) on the glass coating surface at a speed of 2000 rpm Film, spin casting time is 1 minute. Measure the infrared spectrum in the transmitted light, measure the peak height of the peak corresponding to the CH stretch (about 2700-3000 cm-1) of the stearic acid film, and determine the corresponding peak area from the normalized curve of the peak area to the peak height. The coated side of the glass was irradiated with a UVA-351 lamp (obtained from Q-Panel Co., Cleveland, Ohio, USA) with a peak wavelength of 351 nm, and the intensity at the surface of the coated glass was about 32W/m2. In this specification, the photocatalytic activity is either expressed as the area reduction rate of the IR peak (expressed in cm-1min-1), or expressed as t90% (in minutes). The UV exposure time required for the peak height (absorption) to decrease to 10% of its initial value.

After irradiating the coated glass with a UVA 351 lamp for about 2 hours (or according to other instructions), the static water contact angle of the coated glass is determined by measuring the diameter of the water droplets (volume in the range of 1-5 microliters) placed on the surface of the coated glass.

Layer 1 (the first layer deposited on glass) is a silicon oxide layer. Use the coating equipment described in the GB patent specification 1507 966 (specifically refer to Figure 2 and the corresponding description on page 3, line 73 to page 4, line 75), by making monosilane (SiH4, 60ml/min), oxygen (120ml/min) ), ethylene (360ml/min) and nitrogen (8L/min) gas mixture in contact and flow parallel to the glass surface in the direction of glass movement to deposit layer 1. The flow distance of the gas mixture on the glass surface is about 0.15m . The extraction pressure is about 0.9-1.2 mbar. At a position where the temperature is about 670°C, a glass ribbon is coated on a width of about 10 cm. The thickness of the silicon dioxide layer is about 20-25m.

Layer 2 (deposited second layer) is a titanium dioxide layer that contains titanium tetrachloride in a flowing nitrogen carrier gas, ethyl acetate in a flowing nitrogen carrier gas and 8l/min (measured under 20psi) The individual gas streams of the total nitrogen flow rate are mixed into a gas mixture, and then the gas mixture is sent (via a pipeline maintained at about 250° C.) to a coating equipment composed of an oil-cooled two-fluid coating machine to deposit layer 2. The pressure of the nitrogen carrier gas and total nitrogen flow is approximately 20 psig. The gas mixture flows countercurrently and downstream along the glass ribbon in contact and flow parallel to the glass surface. The downstream flow path of the gas mixture is about 0.15 meters, the countercurrent flow path is about 0.15 meters, and the extraction pressure is about 0.15 mbar. The nitrogen gas is passed through a bubbler containing titanium tetrachloride or ethyl acetate, and titanium tetrachloride and ethyl acetate are entrained in a separate flowing nitrogen carrier gas stream. The flow rate of the nitrogen carrier gas is as described in Table 1 (flow rate measured at 20 psi). The titanium tetrachloride bubbler was maintained at a temperature of 69°C, and the ethyl acetate bubbler was maintained at a temperature of 42°C. For each of Examples 1-15, the estimated flow rates of entrained titanium tetrachloride and entrained ethyl acetate are also described in Table 1.

Measure the properties of the two-layer coating. For Examples 1-15, Table 2 describes the thickness value of layer 2 (titanium oxide layer), the value of visible light reflectance measured on the coated side, the L* and the haze of the coated glass. The haze of each coated glass is less than 0.2%.

Measure the photocatalytic activity and static water contact angle of coated glass. Table 3 describes the initial peak height and initial peak area, photocatalytic activity, static water contact angle, and t90% of the IR peaks corresponding to stearic acid CH stretching of Examples 1-15. The thickness of the titanium oxide layer unexpectedly has little effect on the photocatalytic activity.

In Table 1, for each of Examples 16-19, the flow rate of nitrogen carrier gas and the estimated flow rate of entrained titanium tetrachloride and entrained ethyl acetate are published.

For Examples 16-19, the estimated thickness value of layer 2 (titanium oxide layer), the visible light reflectance value measured on the coated side, the L* and the haze of the coated glass are described in Table 2.

Table 3 describes the initial peak height and initial peak area, photocatalytic activity, t90%, and static water contact angle of the IR peak corresponding to stearic acid CH stretching for each of Examples 16-19.

The photocatalytic activity of Examples 16-19 was not significantly greater than the photocatalytic activity of Examples 1-15, although the titanium oxide coating was thicker (hence higher reflectivity).

Table 1

Table 2

a not measured table 3

Examples 20-27 were carried out under the same conditions as Examples 1-15, but the difference was that the carrier gas was passed through a bubbler containing titanium tetraethoxide maintained at 170°C in a nitrogen carrier. The layer 2 is deposited with a gas mixture of titanium tetrachloride entrained in the gas. For each of Examples 20-27, the nitrogen carrier gas (measured at 20 psi) and the flow rate of titanium tetraethoxide are described in Table 4. The flow rate of the overall nitrogen is 8.5 l/min (measured at 20 psi).

Measure the performance of the two-layer coating. For each of Examples 20-27, Table 5 describes the thickness value of layer 2 (titanium oxide layer), the visible light reflectance value measured on the coated side, and the haze of the coated glass. The haze of each coated glass is less than 0.7%.

Measure the photocatalytic activity and static water contact angle of coated glass. Table 3 describes the initial peak height and initial peak area, photocatalytic activity, t90%, and static water contact angle of the IR peak corresponding to stearic acid CH stretching for each of Examples 20-27.

Table 4

table 5

a not measured table 6

a Not measured Examples 30-42 In Examples 30-42, in the float glass production process, two layers of coating were applied on the entire width of about 132 inches (3.35 m) by in-line CVD in the float bath Coated on float glass ribbon. The equipment used to deposit the coating is illustrated in FIG. 2. The atmosphere of the float bath contains nitrogen and 2% by volume of hydrogen. The tank pressure is 0.15 mbar.

The two-layer coating consists of a silicon oxide layer first deposited on the float glass ribbon and a titanium oxide layer deposited on the silicon oxide layer. The precursor chemical composition of the gas mixture used to deposit the coating is the same as that used in Examples 1-15. The deposition temperature of the coating is changed by using different coating machines 27, 28, 29 or 30 (refer to FIG. 2). The coating machine 27 closest to the hearth is the hottest, and the coating machine 30 closest to the annealing furnace is the coolest. In Examples 30-33 and 42, two coaters (28 and 29 in Examples 30-33, and coaters 27 and 28 in Example 42) were used to deposit the silicon oxide layer. The advantage of using two coaters to deposit the silicon oxide layer is that longer production run times are possible.

For Examples 30-41, the gas mixture used to deposit the silicon oxide layer consisted of the following gases at the following flow rates: helium (250l/min), nitrogen (285l/min), monosilane (2.5l/min), ethylene ( 15l/min) and oxygen (10l/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). In the case where two coaters were used to coat the silicon oxide layer in Examples 30-42, the above-mentioned flow rate was used for each coater.

In Examples 30-42, the deposition temperature (that is, the temperature of the float glass ribbon corresponding to each coating machine 27-30 under the coating machine) is as shown in Table 7. The temperature error in Table 7 is about ±50°F (±28°C). The extraction pressure of each coater is approximately 2 mbar.

Table 7

Titanium tetrachloride (TiCl4) and ethyl acetate are entrained in a separate nitrogen/helium carrier gas stream. For the evaporation of TiCl4, a thin film evaporator is used. Liquid TiCl4 is maintained in a pressurized container (pressure head is about 5 psi). This is used to deliver liquids to metering pumps and Coriolis force flow measurement systems. The metered precursor stream is then sent to a thin film evaporator at a temperature of 110°F (43°C). Then, TiCl4 is entrained in the carrier gas (helium) and sent to the mixing point downstream line maintained at 250°F (121°C). Ethyl acetate is delivered in a similar way. The liquid ethyl acetate is kept in a pressure vessel (pressure head is about 5 psi). This is used to deliver liquids to metering pumps and Coriolis force flow measurement systems. The metered precursor stream was then sent to a thin film evaporator at a temperature of 268°F (131°C). The evaporated ethyl acetate is then entrained in the carrier gas (helium/nitrogen mixture) and sent to the mixing point downline maintained at approximately 250°F (121°C).

The TiCl4 and ethyl acetate gas streams are mixed to form a gas mixture for depositing the titanium oxide layer. The mixing point is just before the coater.

For Examples 30-42, Table 8 describes the linear velocity of the float glass ribbon, the deposition temperature of silicon oxide and the deposition temperature of the titanium oxide layer, the flow rate of the total carrier gas of He/N2 and the flow rate of TiCl4 and ethyl acetate.

The coated float glass ribbon is cooled and cut, and the optical properties and photocatalytic activity of the sample are measured. Table 9 describes the haze, optical properties in transmission and reflection of the sample (percent visible light transmittance/reflectance and color coordinates using the LAB system). The coated glass undergoes abrasion test according to BS EN 1096, in which a sample with a size of 300mm×300mm is rigidly fixed on the test bench at the four corners to ensure that the sample cannot be moved. Cut the unused felt pad to the size described in the standard (BS EN 1096 Part 2 (1999)), then install it on the test robot finger and lower the robot finger to the glass surface. Then set a load pressure of 4N on the test robot finger and start the test. Make the mechanical finger reciprocate 500 times on the sample at a speed of 60 reciprocations/min±6 reciprocations/min. When the abrasion is completed, the sample is removed, inspected optically, and inspected with photocatalytic activity. If abrasion produces a transmittance change of no more than ±5% when measured at 550 nm and the coated substrate maintains photocatalytic activity, that is, after the test, the static water contact angle can be reduced to 15° by irradiating with ultraviolet light for 2 hours, it is considered to be a test The sample passed the test.

The glass has also undergone a humidity cycle test, in which the coating passes through a temperature cycle of 35°C to 75°C and then to 35°C within 4 hours at a relative humidity close to 100%.

Table 10 describes the static water contact angle of the coated glass in the production state and after 130 minutes of ultraviolet light irradiation (UVA 351mm lamp, about 32W/m2) and after the European standard abrasion test of 300, 500 and/or 1000 reciprocations . The contact angle of the abraded sample was measured after 2 hours of irradiation.

Specimens deposited at higher temperatures of 1330-1250°F (721°C-677°C) are still photocatalytically active even after 1000 cycles of European standard abrasion or 200 moisture cycles. Table 11 describes the photocatalytic activity expressed in t90% of the coated glass in the production state after 300, 500 and/or 1000 cycles of European standard abrasion test and after 200 moisture cycle test. In Table 11, the term activity means that the coated glass is photocatalytically active, but t90% has not been determined.

Table 8

Table 9

a not measured table 10

a not measured table 11

a not measured