CN1160273C - Solar Control Coatings and Coated Workpieces - Google Patents

Abstract

A multilayer coating composite on a transparent object or glass substrate, comprising: an alternating coating of high and low refractive index coatings, mainly inorganic coatings, capable of at least UV blocking by combined thin film interference and absorption Light. The substrate of the coated multilayer workpiece comprises clear glass, tinted glass, solar control glass or colored glass that is visually transparent. A first inorganic coating mainly comprising a metal is placed over the substrate, the coating also having some visual transparency and having a refractive index selected from the group consisting of high and low refractive indices. A second inorganic coating mainly comprising a metal is overlying the first coating, the second inorganic coating has some visual transparency and has a refractive index opposite to that of the first coating. A third inorganic coating primarily comprising a metal is over the second coating, the third inorganic coating has some visual transparency and has a refractive index in the range of the first coating's refractive index. Auxiliary coatings may be placed above, below or between the above three coatings to provide different reflective and/or absorptive properties.

Description

Solar Control Coatings and Coated Workpieces

(This patent application is based on U.S. Patent Application Serial No. 60/107677, filed November 9, 1998, entitled "Solar Control Coatings and Coated Workpieces," which is hereby incorporated by reference as refer to.)

The present invention relates to solar control coatings for transparent workpieces which improve ultraviolet reflection and/or near infrared reflection and/or increase visible light transmission of the coated workpiece.

Transparent workpieces, such as glass, plastic and glass-plastic laminates used in commercial and/or residential building renovations as well as in automotive and aircraft manufacturing, require specific solar properties for specific applications. In the automotive industry, for example, designers incorporate into their designs the transparency of windows and windshields that is both functional and attractive. The heat that builds up in the passenger compartment of the car from exposure to sunlight can be dealt with by the air conditioning system. Of course, the more heat builds up, the greater the need for such a system. Reducing the heat build-up through car windows has become one of the focuses of designers. In addition, due to the effects of ultraviolet ("UV") and IR solar energy on the interior of the automobile passenger compartment, more careful consideration must be given to the quality of the interior design. Another factor to be considered at the same time is compliance with the visible light transmission requirements stipulated by the government for special transparent objects such as windshields. Therefore, transparent objects that provide lower infrared transmission and lower total solar energy transmission are desirable not only for reducing heat gain inside vehicles, but also for harmonizing the color of windshield transparent objects to some extent . Glasses with these properties are highly desirable not only for automotive applications but also for architectural applications. It would be even more desirable if the glass was also compatible with easy-to-apply flat glass manufacturing methods.

For example, in some automotive applications, glass transparent objects are required to have a UV light transmittance of less than 10% and a total solar energy transmittance ("TSET") of less than 50%. One way to meet this market requirement is to use uncoated substrates to block UV light by adding Titanium Dioxide TiO ₂ , Cesium Dioxide CeO ₂ to the glass composition. These additives generally increase the cost of the substrate. This product is only viable as green glass. Organic coatings can be used with UV and near-infrared (“NIR”) absorbing additives to achieve target specifications without the use of _CeO2 . These organic coatings generally lack durability compared to that achieved with uncoated glass substrates.

It is an object of the present invention to provide coated transparent objects or glasses with a reduced UV transmittance, especially below 10% in certain automotive applications, and with a reduced NIR transmittance, if possible using Those production processes that enable the production of solar control glass transparent objects on an industrial scale.

Multilayer coating composites on transparent objects or glass substrates comprising alternating coatings of predominantly inorganic coatings with high and low refractive indices capable of blocking at least UV light through combined thin film interference and absorption. The amount of UV light transmitted is a function of the number of layers and the nature of the substrate. For example, as few as three coatings on solar control glass can provide UV reduction. Alternating layers of titanium dioxide and silicon dioxide are possible for filtering out UV light. In this case, the thicknesses of the titanium dioxide layer and the silicon dioxide layer were about 300 Å and 550 Å, respectively.

Alternatively or additionally, the coated multilayer composite may have layers of titanium dioxide and silicon dioxide having thicknesses of about 1041 and 1725 Å, respectively, to filter out NIR. If the layer thicknesses of the multiple layers are chosen appropriately, the TSET of the coated glass can be reduced. For example, a four-layer coating on green solar control glass can have a TSET below 37%, while achieving a UV target below International Organization for Standardization ("ISO") standards. Such coatings that reduce UV and NIR light transmission are theoretically applicable to other substrates that do not have good solar control properties. Furthermore, the present invention may include a four-layer coating composite on a transparent object or a glass substrate. A four-layer coating, TiO2/SiO2/TiO2/SiO2 layer, on approximately 4.0mm thick green solar control glass achieves an ISO UV transmittance of less than 10%, while maintaining a visible light transmittance greater than 70%. Such coatings also reduce visible light reflectance to about 8.0% and total solar energy transmittance ("TSET") to less than about 45%. In addition, this four-layer transparent object can achieve an ISO UV transmittance of less than 10%, while maintaining a visible light transmittance of greater than 70% and reducing the total solar transmittance to about 36%. The multi-layer coating also reduces visible light reflectance to less than 8%. When such a four-layer coating on solar control glass is used as a windshield, the windshield installation angle can be adjusted to about 65°. This will reduce the visible light reflectance to about 13%.

Another suitable multilayer coating composition on transparent objects or glass substrates can have a coating with an auxiliary material such as tin oxide doped with fluorine or antimony. Coatings containing these materials can impart other properties such as electrical conductivity or absorption of sunlight. Properly prepared antimony-doped tin oxide absorbs green light, thereby changing the color of the transmission of green glass, such as PPG Industries Solex® ^{or Solargreen®} glass, from green to gray. By setting the deposition conditions and the specific composition of the antimony-doped tin oxide coating, and performing heat treatments such as tempering or annealing on the coated substrate, it is possible to controllably change the optical properties of the antimony-doped tin oxide coating .

Optional auxiliary features of the coated transparent object or glass are achieved through the inclusion of auxiliary materials or coatings. For example, by depositing conical titania, the multi-layer coating composite on the substrate described above can be provided with self-cleaning or easy-to-clean properties. Even the surface silica layer can have self-cleaning properties. Additionally, by replacing all or part of the titanium dioxide or high index coating with a transition metal oxide, the color of the solar coating transmission can be changed. In the above-mentioned three-layer coating composite, four-layer coating can increase the anti-reflection effect and have more appearance options. Furthermore, the thickness of these multilayer coatings can be controlled in order to maintain the reflected color within a desired range.

Fig. 1 is theoretical light reflectance and wavelength curves A and B in the spectrum, wherein, the reflectance unit is percentage (%), the wavelength unit is nanometer (nm), the light source is a white light source in the air medium, and the substrate is in the reference Clear glass at a wavelength of 380 nm and 0.0 degrees when detected with a standard detector, Curve A represents a titanium dioxide coating with a refractive index of 2.55 on clear glass and shows reflectance over the visible spectrum. Curve B is the reflectance-wavelength relationship curve of the three-layer SHLH coating on float glass, where H is the titanium dioxide layer (high refractive index), and L is silicon dioxide (low refractive index).

Figure 2 shows theoretical reflectance versus wavelength curves A and B, where curves A and B represent a SHLH coating stack and a SHLHLL coating stack, respectively, on green glass such as SOLARGREEN ^(R) glass. The light source, media detector and angle are the same as those in Fig. 1.

Figure 3 shows the theoretical reflectance-wavelength curves A and B, where Curve A and Curve B represent the SLHL coating stack on a transparent glass substrate with or without _TiO2 coating at the design wavelength of 330 nm, respectively In the case of absorption, none of them are absorbed in the _SiO2 coating. Other conditions are similar to those in Figure 1.

FIG. 4 shows theoretical correlation curves A and B for the S3H3L3H3 coating stack and the S3H3L3H3LL coating stack, respectively. The last coating in the curve B coating stack is _SiO2 , which is 1/4 wavelength in the visible and 1/8 wavelength in the NIR. Except that the design wavelength is 350nm, other conditions are similar to those in Fig. 1 .

Figure 5 shows the theoretical reflectance-wavelength relationship curves A and B, where curve A is the S3H3L3H3 coating stack in Figure 4, and curve B represents a part of the inner silica coating that is doped with fluorine The relationship curve when tin oxide is substituted. Other conditions are the same as those in FIG. 4 .

Figure 6 shows theoretical reflectance-wavelength curves A and B, where curve A is the S3H3L3H3LL coating stack in Figure 4, and curve B represents the fluorine-doped 3/3 of the inner silica coating. The relationship curve when tin oxide is substituted. Other conditions are the same as those in FIG. 4 .

Figure 7 shows theoretical reflectance-wavelength curves A and B, where curve A represents the peak NIR reflectance obtained from a SHLH stack in which _TiO2 is a high refractive index coating doped with fluorine oxide Tin is a low refractive index coating. Curve B represents the addition of the TCO coating below the SHLH coating stack to become the SMHMH coating stack. Except that the design wavelength is 1000 nm, other conditions are the same as those in FIG. 1 .

Figure 8 shows theoretical reflectance versus wavelength curves A and B comparing a coating stack without a color suppressing layer and a coating stack with an SM/2HLH stack configuration. The former is the curve A in Fig. 7, and the latter is the curve B. Other conditions are the same as those in FIG. 7 .

Fig. 9 shows and compares theoretical reflectance-wavelength curves A and B, curve A represents the coating stack without the color suppression layer, that is, curve A in Fig. 7, and curve B represents the coating stack with gradient A coating stack SGHLH with a change coat ("G") as its color suppressing layer. Other conditions are the same as those in FIG. 7 .

Fig. 10 shows and compares theoretical reflectance-wavelength curves A and B, where curve A is curve A in Fig. 7, and curve B represents the coating stack SGLHLH. Other conditions are the same as those in FIG. 7 .

Figure 11 shows and compares theoretical reflectance-wavelength curves A and B, where curve A is curve A in Figure 7, and curve B represents the coating stack SMHMHL. Other conditions are the same as in Fig. 7 .

Figure 12 shows and compares theoretical reflectivity-wavelength curves A and B, where curve A is curve A in Figure 7 and curve B represents the coating stack SHLMLMH. Other conditions are the same as those in FIG. 7 .

Figure 13 shows and compares theoretical reflectance-wavelength curves A and B, where curve A is curve A in Figure 7 and curve B represents the coating stack SHLMH. Other conditions are the same as those in FIG. 7 .

Figure 14 shows the solar absorption versus wavelength for several antimony-doped tin oxide coatings, which shows that as the antimony content increases, the electrical conductivity decreases and the coatings start to absorb solar radiation significantly.

Fig. 15 shows theoretical transmittance-wavelength relationship curves A and B and compares the two, the transmittance unit is percentage (%), and the coating stack represented by curve A is represented by curve A in Fig. 7, Curve B represents a coating stack with only a single tin antimony oxide coating. Other conditions are the same as those in FIG. 7 .

Figure 16 shows theoretical light transmittance-wavelength curves A and B, wherein the coating stack represented by curve A is the coating stack represented by curve A in Figure 7, curve B represents G and the tin oxide doped with antimony and Coating stack of fluorine-doped tin oxide. Other conditions are the same as those in FIG. 15 .

Fig. 17 shows theoretical light transmittance-wavelength curves A and B, wherein, curve A represents a coating stack similar to curve B in Fig. 16 but thicker in its antimony-doped tin oxide layer, and curve B represents the same The middle curve B is similar to the coating stack with external _TiO2 coating. Other conditions are the same as those in FIG. 15 .

Fig. 18 shows theoretical light transmittance-wavelength curves A and B, wherein the coating stack represented by curve A is the coating stack represented by curve A in Fig. 17, and curve B represents the removal of tin oxide doped with fluorine and has Gradient layers, antimony-doped tin oxide, and _TiO2 coating stacks. Other conditions are the same as those in FIG. 15 .

Figure 19 shows theoretical light transmittance-wavelength curves A and B, where curve A represents a single antimony-doped tin oxide coating on a transparent glass substrate similar to curve B in Figure 15, and curve B represents the thickness Antimony-doped tin oxide coating stack reduced to 1800 Angstroms with titania overcoat. Curve B coating stack is 1/4 wave optical thickness at 100 nm. Other conditions are the same as those in FIG. 15 .

Figure 20 shows theoretical light transmission versus wavelength curves A and B, where curve A represents a five-layer coating configured as SHLHLH, where H is _TiO2 and L is silica, and curve B represents a coating with the same configuration. Coating stack, but where L is tin oxide doped with fluorine. Other conditions are the same as those in FIG. 15 .

The transmission of light in transparent substrates can be altered by applying inorganic coatings. Inorganic coatings absorb light and can filter it out through reflection and absorption by means of thin film physics. In general, a thin film refers to a film having a thickness of 1 micron or less.

The automotive and architectural fields often require different levels of light transmission depending on the wavelength of the light. For example, in an automobile, it is important to have relatively high visible light transmission so that the driver can see out of the vehicle but at the same time filter out solar radiation outside the visible spectrum. The substrate can act as a bandpass filter, theoretically transmitting all visible light equally, but filtering out all UV and NTR parts of the solar spectrum. Passengers will feel more comfortable in the vehicle with this type of glass, and the vehicle will be more fuel efficient due to the ability to use a smaller air conditioner.

There is often a trade-off between aesthetics of the glass, solar performance, and constraints on manufacturing. A solar control glass is a glass that reflects or absorbs rather than transmits a portion of the light spectrum, for example, reflects and/or absorbs a portion of the ultraviolet and/or infrared and/or visible spectrum, thereby reducing transmission of a specific portion of the spectrum . For example, the product being tinted is solar control glass, wherein the total iron content of the finished product is generally in the range of about 0.5-2 wt.%. Typically, at least 20% by weight, preferably 30-45% by weight, of the total iron content in the finished glass comprises ferrous iron. In general, _the balance of iron present in the glass as ferrous oxide (FeO) or ferric oxide ( _Fe2O3 ) has a direct and substantial effect on the color and transmittance properties of the glass. Additionally, solar control glasses include those that reduce direct solar heat transmission (DSHT) and/or reduce ultraviolet radiation transmission while allowing some degree of desired visible light transmission. However, this type of solar control glass may also be a security window glass. Solar control glass reduces problems associated with overheating on sunny days while allowing the required amount of visible light to pass through. In addition, these glasses have the potential to maintain settings that keep the interior of the vehicle private. The glass used as the substrate of the present invention is a glass having a certain degree of visible light transmittance, or the glass has at least a certain degree of transparency so that objects on the other side can be recognized through the glass. This transparency is lower than that of security glazing. Considering solar performance and aesthetics, there are three types of solar control glass that are popular today. These are SOLARGREEN ^(R ) glass and SOLEXTRA ⁽ R) glass, green and blue respectively. SOLARGREEN glass substrate is PPG Industries' solar control glass with 71% LTA, 42.9% TSET and a performance ratio of 1.65. The dominant wavelength of this glass substrate is 512 nm, and its color is described as L ^★ =88.3, a ^★ =-8.7, b ^★ =3.5 and C ^★ =9.4 in the CIELAB color system. In addition, the substrate hue angle (hue angle) was 158°. It should be understood that although the color of this substrate is characterized as "green", it is evident from its a ^* and b ^* coordinates that this glass includes a yellowish tint. Manufacturing restrictions and federal regulations on visible light transmission have limited the commercialization of solar control glass (TSET = 50%) with other appearances. Generally speaking solar control glass has a total solar transmittance of less than 50% (TSET<50%). Examples of such glasses are those commercially available or Solargreen ^(R ) glass and Solextra ^(R) glass, and the glasses described in US Pat.

Solargreen ^(R) and Solextra ^(R) glasses aim to minimize total solar energy transmittance (TSET) and are not targeted to specific parts of the spectrum such as UV light. Recently, the Japanese automotive industry has started to trend toward gloss, ie, having a UV light transmission of less than 10% while maintaining a TSET size similar to Solargreen glass. A commercial version of this glass is Solarblock ^(R) glass from PPG Industries. Its lower UV light transmittance is obtained by adding more expensive additive _CeO2 . Coatings according to the invention can achieve UV transmissive targets and the possibility of increased features, while yielding cost advantages comparable to uncoated substrates, which are substantially free of _CeO2 .

Various thin film coatings of the present invention with certain transparency will reduce the transmission of UV light, while optionally also obtaining other properties such as anti-reflection, lower TSET, and/or self-cleaning properties and different reflected or transmitted s color. The combination of various coatings can provide several properties simultaneously in a coated glass product, which can gain both cost and performance benefits. The film structures described below have from one to five layers composed of several materials, preferably from one to four materials. These materials are selected according to different characteristics. In order to take advantage of the physical phenomena of thin films, materials with different refractive indices (RI) are used. Additionally, the material should be physically and chemically durable and, if possible, have other properties such as the ability to absorb light in different parts of the solar spectrum.

In terms of refractive index, generally a high index of refraction is simply higher than a low index of refraction, and vice versa for a low index of refraction. Preferably, the high refractive index is greater than 1.9 and the low refractive index is less than 1.6, and the medium refractive index is between 1.6-1.9. However, the boundaries of these ranges are not strict limits, and the extreme RI at the junction may cross to some extent the adjacent regions.

Examples of suitable materials for high and low index coatings include, but are not limited to, various metal oxides, nitrides, and alloys and mixtures thereof. Higher refractive index materials include: zinc oxide (refractive index = 1.90), titanium oxide (TiO ₂ ) (refractive index = 2.3-2.7), CeO ₂ (refractive index = 1.95), antimony oxide (Sb ₂ O ₅ ) ( Refractive index = 1.71), SnO ₂ , ITO (refractive index = 1.95), Y ₂ O ₃ (refractive index = 1.87), La ₂ O ₃ (refractive index = 1.95), zirconia (ZrO ₂ ) (refractive index = 2.05 ), tin oxide, and indium oxide. Also their alloys and mixtures can be used. Doped oxides have a very low refractive index in the near infrared region due to the free electrons in the material. Fluorine and/or indium doped tin oxide has a higher refractive index than antimony doped tin oxide. Non-exclusive examples of materials _for low refractive index coatings may include silicon dioxide _SiO2 (about 1.45), _Al2O3 (about 1.65), _B2O3 (about 1.60), silicon polymers, magnesium _oxide and cryolite.

The preferred coating described below consists of four different coatings. The first layer may be titanium oxide or TiO ₂ . This material has a very high index of refraction and absorbs UV light, while being chemically inert and durable, it is photocatalytic when deposited in the anatase form. The second material is silicon oxide or SiO ₂ . This material is also chemically inert and durable, and has a very low refractive index.

Most of the structures described below can be made from only these two materials, but two auxiliary materials with unique properties can also be used. The first is tin oxide doped with fluorine. This material is electrically conductive, has a high index of refraction in the UV and visible parts of the spectrum and a low index of refraction in the NIR part of the spectrum. This property allows the introduction of this unique feature into the design of various coatings. The fourth material is tin oxide doped with antimony. The material absorbs light across the entire solar spectrum, and more importantly, the relative absorption at different wavelengths can be controlled by varying the deposition process. It is thus possible to tailor the coating to absorb relatively more visible or UV light or NIR light. A very unique property of this material is its very high absorption of green light. By placing this coating on green glass, we can turn the glass into gray glass, thus producing a high performance solar control glass with a neutral appearance.

By all being treated with a durable oxide coating, the structures should be suitable for tempered automotive components.

Other materials can be used in this basic setup, which can be considered if desired. But these four materials can be used to make many kinds of coatings with widely different optical properties. The on-line float glass process, well known to those skilled in the art, can be used to make all of these products by choice of deposition materials, coating sequence and coating thickness.

All of these base coats can generally be applied in a manner similar to the conductive windshield coating described in US Patent 4,610,771, incorporated herein by reference. This in-line method utilizes similar equipment to produce these novel coatings on solar control glass substrates. Any other method known in the art for depositing any of these coatings may be used, for example radio frequency sputtering may be used. Other techniques such as cathode sputtering, in particular by CVD plasma from a suitable siliconous precursor or by gas phase pyrolysis at ambient pressure, may also be used.

Subsequent chapters describe in detail the construction of specific coatings, the results of the optical model, and the sensitivity analysis. However, when introducing more functionality into the coating, the principle of various structures can be introduced without being limited by the present invention.

UV blocking coatings are the simplest solar control coatings discussed herein, the physics of which are common to many other designs.

Regardless of whether the substrate is coated or not, the interaction between light and the substrate must obey the following formula:

A+R+T=100% Formula 1

The percentage of light absorbed (A) plus the percentage of light reflected (R) plus the percentage of light transmitted must equal 100%. If more light is reflected by the coating, less light will be absorbed and/or transmitted. For coated glass workpieces, the function of the UV reflective coating is to reflect as much UV light as possible in order to meet the transmission target of less than 10%. Some UV light will be absorbed by the coating and the glass substrate, but most of the transmission is lost due to the high reflectivity obtained by proper choice of coating material and thickness. More or fewer layers may be required depending on the UV absorbing properties of the substrate. Specific examples are discussed below.

The maximum reflection obtained by coating a single high index layer on a substrate is easily calculated, and this type of layer is called a 1/4 wave layer (ie 1/4 wavelength layer). The thickness of the 1/4 wave layer is calculated according to the following formula:

h=λ/4n ₁ Formula 2

Here: h is the layer thickness; λ is the wavelength when the maximum reflection occurs (design wavelength); n ₁ is the refractive index of the coating at the design wavelength.

If the refractive index of one or more materials of the coating is large or higher, the layer is indicated by "H"; if the refractive index is lower, it is indicated by "L"; if the refractive index is between the two or is Medium is represented by "M". Coating stacks can easily be abbreviated by this term. For example, a 1/4 wave antireflective coating with a medium index material on glass, followed by a high index half wave (two 1/4 wavelengths) on top of that, and a low index on top of that A quarter-wave layer of material, this can be denoted SMHHL, where S refers to the substrate. It should be noted that each layer is only 1/4 wavelength at the wavelength of maximum reflectance for the desired portion of the spectrum.

Use Equation 3 to calculate the intensity of the reflection.

R＝[(n ₁ ² -n ₀ n _s )/(n ₀ n _s +n ₁ ² )] ² Formula 3

Here: R is the reflectivity; n _s is the refractive index of the substrate; n ₀ is the refractive index of the incident medium; n ₁ is the refractive index of the coating. The incident medium is the environment in which the substrate or other laminated structures exist, that is, air. For a titanium dioxide coating on a transparent substrate with a refractive index of 1.51, which has a refractive index of 2.55 at a wavelength of 380 nanometers (nm), the titanium dioxide coating has a 1/4 wavelength thickness of 372 Å and a reflectivity of 26.5%. This reflectivity is only for the coated surface. For the next few examples, absorption in the coating is ignored, but it is indicated when it is included.

The reflectance in the visible spectrum is represented by curve A in FIG. 1 . As can be seen from curve A in Figure 1, the maximum reflectance occurs at the design wavelength of 380nm and the reflectance decreases at all other wavelengths of the solar spectrum.

At normal incidence, the reflectivity of the first surface of the substrate is given by:

R=[(n ₀ -n _s )/(n ₀ +n _s )] ² Formula 4

Here: n ₀ and n _s are the refractive indices of the incident medium and the substrate, respectively. Applying the 1/4 wave layer to the substrate results in a coated substrate with an equivalent refractive index _{n 1e given} by:

n _1e = n ₁ ² /n _s Formula 5

The new reflectivity of the coated substrate is then calculated by substituting the new equivalent refractive index into the substrate refractive index in Equation 4. This new formula is listed below:

R=[(n ₀ -n _1e )/(n ₀ +n _1e )] ² Formula 6

Equation 6 is equivalent to Equation 4.

The equivalent refractive index for the substrate and the coating stack expressed as SH(LH) ^m can be calculated by the following formula:

n _e ＝(n _H ² ) ^m+1 /(n _L ² ) ^m n _s Formula 7

The reflectance for any number of layers can then be calculated using Equations 6 and 7, where "m" is the number of HL or LH pairs in the coating stack.

In a three-layer SHLH coating on float glass, where H is titanium dioxide and L is silicon dioxide, the coating has an equivalent refractive index of:

n _e =(2.6 ² ) ^m+1 /(1.452) ^m 1.51=14.4, and the reflectivity is:

R=[(1-14.4)/(1+14.4)] ² =75.6%

The reflectance-wavelength curve for this coating is shown by curve B in FIG. 1 .

Table 1 summarizes the performance of exemplary and predictive examples of one, three and five layer coatings on clear glass, solar control glass SOLEX ⁽ R) and SOLARGREEN(R ⁾ , respectively.

[Table 1] example Substrate Coating of stacked substrates visible light reflectance Visible light transmittance ISO UV transmittance Total Solar Transmittance Exemplary instance A Transparent ¹ SH 28.99 69.14 43.41 69.66 Example 1 Transparent ¹ SHLH 27.51 70.51 20.24 69.49 Example 2 Transparent ¹ SHLHLH 15.59 82.2 8.39 68.71 Exemplary instance B Transparent ¹ none 7.9 89.71 64.59 82.74 Exemplary instance C Solex ^glass1 SH 28.47 62.08 20.14 45.53 Example 3 Solex ^glass1 SHLH 27.11 62.94 9.03 44.86 Example 4 ^Solex® glass ¹ SHLHLH 15.04 73.78 3.47 44.3 Exemplary instance D ^Solex® glass ¹ none 7.37 80.5 30.73 55.32 Exemplary instance E ^Solargreen® Glass ² SH 28.16 56.33 12.17 35.44 Example 5 ^Solargreen® Glass ² SHLH 26.78 57.08 5.42 34.83 Example 6 ^Solargreen® Glass ² SHLHLH 14.6 67.11 2.06 34.52 Exemplary instance F ^Solargreen® Glass ² none 6.84 73.16 19.37 43.54

S = Substrate

H=TiO ₂ , 1/4 wave layer at 380nm

L = SiO ₂ , 1/4 wave layer at 380nm

1 = Substrate thickness is 4m

2 = substrate thickness is 3.6m

The optical constants of silica and other materials with respect to wavelength are studied in a manner known in the art, taking into account the composition of the coating composition, the mode of deposition and the thickness of the coating. The reflectance curve in the figure is made by TFCalc, which is a commercial software used for thin film calculation by Software Spectrum.

Anti-reflective UV reflection

The simple SHLH configuration described above is characterized by a relatively high visible light reflectance. The high reflectivity limits the application of this approach when applied to solar control glass whose visible light transmittance approaches the 65%-70% range before being coated. High reflectivity reduces visible light transmission below the 70% limit when applied to SOLARGREEN ^(R) glass for windshields, for example.

This limitation can be alleviated by applying a half-wave layer on top of the SHLH stack. The half-wave layer is an empty layer at the design wavelength because it is optically visible at the design wavelength. Therefore, at the design wavelength, the substrate and SHLHLL coating stack play the same role as the stack SHLH, with no change in UV filtering performance. For the case of design wavelengths in UV, the top silica LL half wavelength is 1/4 wavelength in the visible spectrum. This layer acts as a reflectance reduction layer for the visible spectrum. The design wavelength and/or layer thickness can then be optimized according to the desired UV reflectance and visible light transmission requirements. SHLH and SHLHLL coatings are shown in Figure 2. These coatings have a design wavelength of 330nm. This design wavelength minimizes ISO UV while maintaining visible light transmission above 70% for 3.6 mm Solargreen( ^R) glass. Curve B represents the heap SHLHLL, and curve A the heap SHLH.

Auxiliary LH pairs can be added between the top H and LL layers to further reduce the UV light filtering properties of the coating stack. The visible light reflectance of such a stack on Solargreen ^(R) glass is shown in Table 2 for various design wavelengths. As can be seen from this table, the selection of an appropriate design wavelength has a significant effect on the properties of the resulting coating. As noted above, these predictive examples were made with TFCalc software.

[Table 2] Substrate Substrate thickness coating stack design wavelength visible light reflectance Visible light transmittance ISO UV transmittance Solargreen 3.6mm SHLHLL 220nm 4.04 75.41 18.54 Solargreen 3.6mm SHLHLL 230nm 3.79 75.58 18.35 Solargreen 3.6mm SHLHLL 240nm 3.86 75.5 17.95 Solargreen 3.6mm SHLHLL 250nm 4.2 75.21 17.26 Solargreen 3.6mm SHLHLL 260nm 4.73 74.78 16.23 Solargreen 3.6mm SHLHLL 270nm 5.37 74.26 14.93 Solargreen 3.6mm SHLHLL 280nm 6.06 73.71 13.51 Solargreen 3.6mm SHLHLL 290nm 6.72 73.19 12.12 Solargreen 3.6mm SHLHLL 300nm 7.31 72.73 10.87 Solargreen 3.6mm SHLHLL 310nm 7.82 72.33 9.81 Solargreen 3.6mm SHLHLL 320nm 8.26 72 8.96 Solargreen 3.6mm SHLHLL 330nm 8.67 71.7 8.33 Solargreen 3.6mm SHLHLL 340nm 9.12 71.35 7.87 Solargreen 3.6mm SHLHLL 350nm 9.71 70.88 7.58 Solargreen 3.6mm SHLHLL 360nm 10.55 70.21 7.43 Solargreen 3.6mm SHLHLL 370nm 11.73 69.25 7.42 Solargreen 3.6mm SHLHLL 380nm 13.35 67.93 7.54 Solargreen 3.6mm uncoated 6.84 73.16 19.37

The latter examples in Table 2 are exemplary, others are predictive.

From Figure 2, it can be seen that the reflectance of both coatings remains the same at the design wavelength (330nm), while the reflectance curve basically changes in the rest of the spectrum. Since the silica half-wave acts as an anti-reflective ("AR") layer, it maintains or increases the transmission of visible light, thereby making this UV filtering coating applicable to more substrates. If the transmission of light in the coated substrate is increased, the substrate can be tuned to absorb more solar radiation while maintaining its visible light transmission requirements. The glass composition of the solar control glass can be varied to lower the TSET to about 40% but increase the visible light transmission of the uniform nature AR coating.

The above examples readily demonstrate the effect of interference coatings on the optical properties of the glass using the optical constants of the coating without the absorption coefficient. In reality, however, the coating absorbs a portion of the light and thus has a non-zero absorption coefficient. Several of the above examples will be repeated with coatings having different optical constants to demonstrate the effect of absorption on the transmission spectrum of the coating. In practice, appropriate materials and design structures can be selected to best meet the overall desired properties of the glass being coated.

Figure 3 shows the transmission curves of SLHL stacks with or without absorption in the _TiO2 layer. Neither is absorbed in the _SiO2 layer. Curve B has no absorption while curve A has absorption.

Block UV and NIR

Increasing solar control or reducing TSET for a coated substrate can be achieved in other ways than those described above. This section describes several approaches to reduce the TSET of a coated substrate while reducing its UV transmission.

A. HLH

The previous example in Table 2 shows how to add a half-wave layer without changing its performance at the design wavelength. Thus, adding a half-wave layer to each layer of the initial SHLH stack with a design wavelength of 350 nm yields stack S3H3L3H(HHHLLLHHH). This coating works the same at the design wavelength of 350nm, but now the SHLH stack becomes closer to 1050nm. The maximum reflectance does not occur exactly at 1050 nm because the refractive index of the coating decreases at longer wavelengths. The peak thus shifts to shorter wavelengths, ie, in the near-IR ("NIR") region of the spectrum. In this way we now obtain coatings that reflect at both design wavelengths. This example uses _TiO2 with absorption and _SiO2 without absorption, and the coating is on 4.0mm clear glass. Its curve is shown in curve A in Fig. 4 .

B. HLHL/2

The reflection intensity in the visible spectrum can be changed by coating 1/4 waves in the visible spectrum. This layer may be 1/8 wave in NIR at 1050nm and 1.5 wave in UV at 350nm. Reflection strength in NIR is slightly reduced by the trade-off between low visible reflectance and high visible transmittance. The curve of this coating is shown as curve B in FIG. 4 . The reflectance of the coating on clear glass drops from about 17% to about 6%. Curve B has a _SiO2 top layer while Curve A does not.

C. Other properties

The previous two examples relate to a three-layer coating that reflects light in the UV and NIR regions of the spectrum. It was noted earlier that the reflected light intensity is a function of the number of alternating layers of high and low refractive indices. More layers means higher reflectivity. But as more layers are added to the dual-reflectance coating, the total thickness becomes an issue: costs increase and more applicators are required to produce the coating in a float line environment.

The intensity of UV reflection can be increased without increasing the overall thickness of the stack or sacrificing the intensity of NIR reflection. This can be done by replacing a third of the inner silicon dioxide layer with fluorine-doped tin oxide. But in turn, the middle layer becomes a combination of several layers. Fluorine-doped _SnO2 , like most transparent conductive oxides, has the unique property of having a high refractive index in the UV and visible spectrum and a lower refractive index in the NIR. The coating is S3HLHL3H in UV and SHLH in NIR. The coating is five coats in UV and visible and reduces to three coats in NIR. The reflectance of this coating and S3H3L3H is shown in Figure 5, and this coating with a 1/4 visible wavelength silica layer and S3H3L3HLL is shown in Figure 6. Curve "B" in these figures is the design with the addition of fluorine-doped tin oxide, while curve "A" is not.

Transparent Conductive Oxide (“TCO”)

Transparent conducting oxides ("TCO") can be used in HLH stacks with the aforementioned high refractive index materials to increase the reflection of light in the near IR due to the oxide's free electrons and their flow in the crystal lattice properties resulting in a low refractive index in the NIR region. Thus in addition to being used in the above example, TCO can also be used in the design of combined UV/NIR blocking. Curve A in Figure 7 shows the peak reflectivity obtained from a SHLH stack in which _TiO2 is the high index layer and fluorine-doped tin oxide is the low index layer.

It can be seen from curve A in FIG. 7 that the reflectance of the coating stack is about 58% at the design wavelength of 1 micron. The refractive index is also different in the visible region, and this produces interference peaks and reflected colors. This characteristic is considered unfavorable and a way of maintaining peak reflectivity while minimizing reflection can be achieved by one of two methods, coating above or below the stack. The key lies in adding layers that change the reflective properties of visible light without significantly reducing the NIR peak. One way to do this is to add coatings that are optically active in the visible region and optically inactive in the NIR region. Transparent conducting oxides ("TCOs") are suitable for this purpose. As mentioned above, compared with _TiO2 , the refractive index of TCO is low in NIR and moderate in visible spectrum. When coated underneath a SHLH stack, we obtain a stack with the following configuration: substrate, layers with medium, high, medium and high indices in visible light and SL/ 3HLH. The designation SMHMH is not used for this coating because the layers are not 1/4 wavelength optically thick in the visible region. The L/3 layer is optically inactive as shown by curve B in FIG. 7, and the curve for this stack is compared with curve A here. Curve A is a normal line, while curve B corresponding to a stack containing L/3 is a thick line. It can be seen that the NIR peak is relatively unchanged, while the visible light peak is greatly attenuated. The stack has a TSET of about 57% and a visible transmittance of about 76%. The stack also has lower radiation due to the reflection of long-wavelength light by the transparent conductive oxide. As mentioned earlier, with increasing the LH pair of the coating, the peak reflectance can be increased.

Another way to attenuate the reflected color is to add a coating that is intermediate in both the visible and NIR spectrum. It is expected that a medium index layer located between the substrate and the first high index layer would attenuate the NIR reflection because it would disrupt the normal HLH order required to enhance reflection. Surprisingly, the peak of the reflected intensity is not reduced, but only slightly shifted in the wavelength direction. By adjusting other layers in the stack, this peak can be moved back to its original position. This result allows the color of the pile to be tuned without sacrificing NIR reflective performance. FIG. 8 compares a coating stack without a color suppressing layer, represented by curve A, ie, curve A in FIG. 7 , with a coating stack having an SM/2HLH stack configuration. It can be seen that the visible light reflectance peak is reduced, while the NIR peak is slightly shifted.

Yet another way to attenuate the color is to add a gradient index layer below the coating stack. This layer generally has an increasing (or decreasing) refractive index as the film thickness of the film layer increases. Color suppression of this type is well known for suppressing the color of individual coatings (see US Pat. Nos. 5,356,718, 5,599,387, incorporated herein by reference). This type of color suppression has not been examined for whether it can be applied to the color of a suppression coating stack, and more importantly, its effect on the NIR reflection of the stack has not been examined. Gradient-index coatings can both suppress color and in some cases improve performance in HLH stacks. The graded layer used in these examples was fabricated as a ten-layer coating denoted G, where each layer was 10 nm thick and whose refractive index varied from 1.55 at the glass interface to 2.0 at the top of the graded layer. Its reflectance curve is shown in FIG. 9 and compared again with the SHLH stack shown in curve A in FIG. 7 . Now our heap is SGHLH. For curve B, which represents the graded layer, the peak reflectance drops only slightly and shifts in the wavelength direction, while the visible light reflectance drops significantly.

Since the graded layer creates a higher interface than the glass interface, the reflectivity peak can now be further increased, and the addition of another fluorine-doped tin oxide layer between the graded index layer and the first high index layer will now be Optically active and causes an increase in peak reflectivity. The heap is SGLHLH. Its color is still attenuated but performance is improved. This pile is perfect when lower radiation is required. The reflectance spectrum is shown in FIG. 10 and compared with curve A in FIG. 7 .

Fluorine-doped tin oxide coatings also absorb a portion of NIR light, making them ideal for solar control applications. They help reduce the transmission of NIR light while reflecting and absorbing it.

And unexpectedly, a high/low index layer pair that is much less than a quarter wave optical thickness can be used to attenuate the reflected color. They also do not significantly affect NIR reflections.

As mentioned earlier, adding layers on the heap results in reduced reflections, and this approach works here as well. By adding layers above and below the coating stack, the reflected color can be affected and the intensity reduced. The stack has medium index, high, medium, high and then low index (MHMHL). The resulting coating stack is shown in FIG. 11 and compared with curve A in FIG. 7 . Visible light intensity is greatly attenuated and colors are achromatic. There is some shift in the intensity of the reflectance peak, but this can be corrected by adjusting the thickness of the HLH layer.

As mentioned above, for dual NIR/UV filtering coatings, _SiO2 and TCO combinations can be used together for the low index layer. A stack (SHLMLMH) having a substrate, TiO ₂ , SiO ₂ , fluorine-doped tin oxide, SiO ₂ , fluorine-doped tin oxide, and TiO ₂ containing SiO ₂ and fluorine-doped tin oxide is shown in FIG. The integrated optical depth in NIR is 1/4 wavelength and compared with curve A in Fig. 7. From Figure 12 it can be seen that the reflectivity peak is enhanced by this multilayer low index 1/4 wave approach. It should also be noted that the peak visible reflectance is slightly lowered.

The new capability to attenuate the visible reflectance spectrum using this multi-layer low-index layer approach can be used with respect to the visible reflectance spectrum to attenuate the reflected color while maintaining the NIR reflectance peak. For example, as shown in Figure 13, a stack (SHLMH) with a substrate, _TiO2 , _SiO2 , SnO2:F, and _TiO2 has no reflected color and its reflection peak is enhanced. The reflection curve A in FIG. 7 is included in FIG. 13 for comparison. Layer combinations that are optically active in the visible and low in the NIR spectrum can be used to achieve any visible optical effect desired by the designer, rather than simply being used for color suppression only.

Addition of antimony to tin oxide at doping levels results in conductivity. As the antimony content increases, the conductivity decreases and the coating starts to absorb solar radiation significantly. Figure 14 shows the solar absorption of several antimony-doped tin oxide coatings. Table 3 lists the parameters of the chemical vapor deposition ("CVD") process used to produce these coatings. Of course other known deposition processes such as pyrolytic coating techniques and sputtering techniques such as MSVD magnetron sputtering vacuum deposition can also be used. Spray coating was made as a 5 wt% mixture.

[Table 3] (SLM is standard liter/minute) Sample No. Glass temperature in Fahrenheit (F) MBTC concentration (mol%) Water concentration (mol%) Airflow SLM Gas discharge ratio (%) Glass Thickness(MM) Line Speed (inch/min) 1 1000 0.5 0.5 55 115 4 50 2 1200 0.5 0.5 55 115 4 50 4 1200 0.5 0.0 55 115 4 50 6 1200 0.1 0.5 55 115 4 50 8 1200 0.1 0.0 55 115 4 50 9 1000 0.5 1.0 55 115 4 50 10 1000 1.0 0.5 55 115 4 50 11 1000 1.0 1.0 55 115 4 50

The mixture was antimony trichloride in monobutyltin trichloride (MBTC), and the mixture was hand sprayed onto a clear glass substrate heated to about 1150 Fahrenheit. Antimony was added in a constant amount of 20 wt% relative to MBTC for CVD trials 1-11. The applicator has a central inlet upstream and an outlet downstream. The width of the application area is 4 inches and the length of the line between outlets is 5 inches. Air was used as carrier gas.

In Table 3, coatings 4 and 8 absorb more NIR light than visible light, making these coatings well suited for solar control when high visible light transmission is required. Coatings 2 and 6 have peak absorbance at about 550 nm. These coatings are very suitable for reducing the green color of Solex ^(R) glass and Solargreen( ^R) glass. Coating 10 absorbs more visible light than NIR light, Coating 1 absorbs essentially unchanged light in the solar spectrum, and Coatings 9 and 11 absorb significant amounts of UV light.

These coatings are glazed in the annealed and tempered state, with the obvious result being colorfastness, or the inability of the color to change when the coated glass is heated. The appearance and properties of the coating are preferably the same before and after heat treatment. Whether the antimony-doped tin oxide coating used in this project changes when heated depends on its deposition parameters. The properties of the various samples and how certain properties were changed by heat treatment are listed in Table 4. The samples with an H after the number are the samples after heat treatment.

[Table 4] (Part A) average film Hall Mobility MMR H-50(cm ² /Vs) Hall carrier concentration MMRH-50 ( ^* E20 electron carrying/cm ³ ) ¹ Hall surface resistance MMRH-50(ohm/sq.) unweighted absorptivity UV-visible light 300-700nm UV-visible light 300-2500nm sample thickness average value average value average value 124810111H2H4H8H10H11H 665795310153675879 7.520.720.540.546.704.901.020.470.420.350.048.35 2.351.494.574.956.039.481.072.234.894.843.411.92 3.E+057.E+039.E+032.E+042.E+066.E+053.E+058.E+031.E+042.E+042.E+052.E+05 0.1590.3070.1730.1420.2030.254 0.1910.2980.2560.2110.2140.224

¹ = power (E) × 10 ²⁰ electrons/cm ³

[Table 4] (Part B) sample T Tx Ty R1Y R1x R1 R2Y R2x R2y 1 67.7 0.312 0.312 21.0 0.299 0.307 17.6 0.294 0.303 2 50.2 0.295 0.298 21.8 0.333 0.337 16.3 0.324 0.327 4 76.5 0.306 0.316 12.2 0.294 0.297 09.2 0.280 0.284 8 85.0 0.307 0.317 09.2 0.301 0.308 08.0 0.295 0.302 10 76.0 0.313 0.321 16.0 0.294 0.302 13.4 0.295 0.305 11 67.9 0.309 0.316 21.3 0.318 0.330 17.6 0.318 0.333 1H 70.1 0.312 0.320 19.2 0.298 0.306 16.6 0.293 0.303 2H 52.5 0.296 0.301 21.5 0.326 0.330 16.0 0.315 0.318 4H 76.7 0.306 0.316 12.2 0.294 0.297 09.2 0.280 0.284 8H 85.1 0.307 0.317 09.2 0.301 0.308 08.0 0.295 0.302 10H 72.1 0.312 0.320 18.3 0.295 0.304 16.1 0.291 0.302 11H 69.3 0.309 0.317 20.5 0.313 0.325 16.1 0.309 0.326

[Table 4] (Part C) sample ΔT ΔR1 ΔR2 Macadam T Macadam R1 Macadam R2 1 2.38 -1.78 -0.96 3.21 4.98 3.32 2 2.25 -0.32 -0.30 3.79 5.16 6.56 4 0.14 -0.02 0.01 0.26 0.10 0.19 8 0.12 -0.07 -0.02 0.18 0.31 0.15 10 -3.9 2.32 2.68 4.74 7.38 9.96 11 1.34 -0.81 0.49 1.90 4.48 6.94

R1 is the reflectance on the coated side of the glass, R2 is the reflectance on the uncoated side of the glass, and T is the transmission of light.

Sample H in Table 4 was exposed to a temperature of 1200F for about 4 minutes and then cooled to room temperature. Optical constants of Sample 8 before heat treatment are shown in Table 5 below. These optical constants are used in other examples below.

[table 5] wavelength Refractive index Virtual Refractive Index 350.0360.0370.0380.0390.0400.0410.0420.0430.0440.0450.0460.0470.0480.0490.0500.0510.0520.0530.0540.0550.0560.0570.0580.0590.0600.0610.0620.0630.0640.0650.0660.0670.0680.0690.0700.0710.0720.0730.0740.0750.0760.0770.0780.0790.0800.0 1.894501.881401.869201.858001.847501.837701.828501.819901.811801.804201.797001.790201.783701.777601.771701.766101.760701.755501.750601.745801.741201.736701.732401.728201.724201.720201.716301.712501.708801.705201.701601.698101.694701.691201.687901.684601.681301.678001.674801.671501.668301.665201.662001.658801.655701.65260 0.090500.072270.058840.049340.043010.039290.037700.037830.039380.042090.045730.050130.055140.060650.066550.072760.079220.085860.092650.099540.106500.113510.120540.127590.134630.141650.148650.155630.162560.169470.176330.183150.189930.196670.203370.210030.216650.223230.229790.236310.242800.249260.255700.262120.268520.27491

(continued) wavelength Refractive index Virtual Refractive Index 810.0820.0830.0840.0850.0860.0870.0880.0890.0900.0910.0920.0930.0940.0950.0960.0970.0980.0990.01000.01010.01020.01030.01040.01050.01060.01070.01080.01090.01100.01110.01120.01130.01140.01150.01160.01170.01180.01190.01200.01210.01220.01230.01240.01250.01260.01270.01280.01290.01300. 01310.01320.01330.01340.01350.01360.01370.01380.01390.0 1.649401.646301.643101.640001.636801.633701.630501.627301.624101.620901.617701.614501.611201.607901.604601.601301.598001.594601.591201.587801.584401.580901.577401.573901.570401.566801.563201.559501.555801.552101.548401.544601.540801.537001.533101.529201.525201.521201.517201.513101.509001.504801.500701.496401.492201.487901.483501.479101.474701. 470201.465701.461101.456501.451801.447101.442401.437601.432801.42790 0.281280.287640.293990.300330.306680.313020.319360.325710.332060.338420.344800.351180.357590.364010.370450.376910.383390.389900.396440.403010.409610.416240.422900.429600.436340.443110.449930.456790.463690.470640.477630.484670.491750.498890.506080.513320.520610.527960.535360.542820.550330.557910.565540.573240.580990.588810.596690.604630.612640. 620720.628860.637070.645340.653690.662100.670580.679140.687770.69647

(continued) wavelength Refractive index Virtual Refractive Index 1400.01410.01420.01430.01440.01450.01460.01470.01480.01490.01500.01510.01520.01530.01540.01550.01560.01570.01580.01590.01600.01610.01620.01630.01640.01650.01660.01670.01680.01690.01700.01710.01720.01730.01740.01750.01760.01770.01780.01790.01800.01810.01820.01830.01840.01850.01860.01870.01880.01890. 0 1.423001.418001.413001.407901.402801.397601.392401.387201.381901.376501.371101.365601.360101.354601.349001.343301.337601.331901.326101.320201.314301.308301.302301.296301.290201.284001.277801.271501.265201.258801.252301.245801.239301.232701.226001.219301.212601.205801.198901.191901.185001.177901.170801.163701.156501.149201.141901.134501.127001. 11950 0.705240.714080.723000.732000.741070.750220.759440.768740.778120.787580.797120.806740.816430.826210.836070.846010.856040.866140.876330.886610.896970.907410.917940.928550.939260.950040.960920.971880.982930.994071.005301.016601.028001.039501.051101.062801.074601.086401.098401.110401.122601.134801.147201.159601.172101.184701.197401.210201.223101. 23610

The NIR reflectors shown above help control the transmission of sunlight from windows. The amount of sunlight filtered is a function of the number of layers having a larger overall thickness. Many layers are required to further reduce the transmission of light through the glass. Applying a coating that selectively or preferentially absorbs NIR sunlight rather than visible light helps to make a good solar control stack. A single layer of antimony-doped tin oxide with the above optical properties has a visible light transmittance of about 69% and a TSET of 58% at a thickness of 800 Angstroms. FIG. 15 shows the transmission curve and compares it with curve A in FIG. 7 . The coating does not have as high a transmittance in the visible region but a similar TSET. When a high visible-to-TSET ratio is not required, or when the transmission of light through the window needs to be low, for example to attenuate glare, then adding an antimony layer to the stack is advantageous. Antimony-doped tin oxide layers can be used with fluorine-doped tin oxide or other TCOs for low emissivity and reduced transmission. Figure 16 shows the theoretical light transmission of a graded layer, and antimony-doped tin oxide and fluorine-doped tin oxide coatings. TSET drops to 51%, and visible light transmission is about 69%. For this design, TSET and visible light transmission can be varied by varying the thickness of the antimony-doped tin oxide layer or varying the concentration of antimony in the coating.

Government regulations are driving improvements in window performance. In the southern United States, the new performance target for windows is to have a shading factor of about 0.45. This can be achieved with a TSET of about 37%. The coating described in Figure 16 can be modified to achieve this by increasing the thickness of the antimony-doped tin oxide layer. The transmission curve of this coating is shown as curve A in FIG. 17 .

This coating has a visible light transmission of about 52% and a TSET of about 37%. A fluorine-doped tin oxide coating as the top layer will result in an emissivity of this coating below 0.35. The gradient layer had a thickness of 800 angstroms, the antimony-doped tin oxide had a thickness of 1800 angstroms, and the fluorine-doped tin oxide coating had a thickness of 1800 angstroms.

As discussed above, the TSET of this coating can be further reduced by coating a 1/4 wavelength high index layer such as _TiO2 on top of the graded antimony-doped tin oxide and fluorine-doped tin oxide. TSET drops to 32.5% but visible light transmission only drops to 51%. The transmission curves of these stacks with or without _TiO2 layer are shown in Fig. 17 by curves B and A, respectively.

If low emissivity is not required for the coating, then the fluorine doped tin oxide or other suitable transparent conductive oxide can be eliminated, leaving only the graded layer, antimony doped tin oxide and _TiO2 . The transmission curve for this coating is shown in Figure 18 and compared to a coating with fluorine doped tin oxide.

A 2100 angstrom thick antimony-doped tin oxide coating on clear glass had a visible light transmission of 49% and a TSET of about 37%. Adding a layer of _TiO2 , which is 1/4 wavelength optical thickness at 1000 nm, reduces the thickness of the antimony-doped tin oxide to 1800 Angstroms. TSET remains the same, but visible light transmission increases to 54%. Both curves are shown in FIG. 19 . The thick line is antimony-doped tin oxide with _TiO2 layer.

The position of the _TiO2 or high refractive index layer relative to the graded color suppression layer and antimony-doped tin oxide and fluorine-doped tin oxide layers was investigated. In all cases, the graded index layer was the first layer on the glass. The stack configuration is abbreviated as follows: S—substrate; G—800 Å thick color-suppressing layer with gradient refractive index change; Sn—1600 Å thick fluorine-doped tin oxide; Ti—1100 Å thick _TiO2 layer; Angstrom thick tin oxide doped with antimony. The results are listed in Table 6. Addition of _TiO2 or high-index layers improves TSET in all cases.

[Table 6] Instance# heap Visible light transmittance TSET 1 SGSbSnTi 50.6 32.4 2 SGSbTiSn 50.9 35.9 3 SGTiSbSn 52.2 35.1 4 SGTiSnSb 51.8 35.3 5 SGSnTiSb 51.5 36.0 6 SGSnSbTi 50.3 32.4 7 SGSb 51.4 36.8 8 SGSbSn 51.8 36.9

Two different five-layer coatings were made to represent the need for an absorbing layer with a low TSET at a minimum coating thickness. Curve A is a five-layer coating with a SHLHLH configuration, where _TiO2 serves as the high-index layer and silica serves as the low-index layer. Curve B has the same configuration but with F: _SnO2 as the low index layer. The design comprising _SiO2 has a total thickness of about 6747 and preferably 6747 Angstroms, has a TSET of about and preferably 60% and has a visible light transmission of about and preferably 85%. The design with fluorine-doped tin oxide has a total thickness of about and preferably 6461 Angstroms, has a TSET of about and preferably 50%, and has a visible light transmission of about and preferably 71.1%. It is obvious that adding auxiliary layers reduces NIR transmission, but this approach is too expensive to manufacture due to the many thick layers. Even adding the auxiliary fluorine-doped tin oxide and _TiO2 layer pair, increasing the coating thickness by 2700 Angstroms, only reduces TSET by 5% at the expense of a 3.5% loss in visible light transmission. Clearly, the novel antimony-doped tin oxide described herein is preferred for achieving the desired TSET with minimum coating thickness.

A. Pigment

Two specific examples are examined in detail below. The first is a coating that masks the green color of Solex ^(R) glass or Solargreen( ^R) glass and turns the glass gray. Here, a thin layer comprising tin oxide doped with antimony is applied to the glass or coated glass. As the thickness of the coating increases, the transmitted color shifts from green to gray, and if the coating is increased enough, the transmitted color shifts to deep red. For heat-treated coatings, the transmitted and reflected colors are shifted to some extent.

Solar control and anti-reflection for windshields

As the installation angle of the windshield increases, the reflectivity increases. For Solargreen ^(R) glass, the reflectance of the anti-reflection (AR) coating decreases from 18% to about 12-13% at an installation angle of about 65°. These traditional AR coatings do not get any other solar control properties, but the increased visible light transmission due to the AR properties can be used to darken the substrate and lower the TSET. Alternative pathways to AR can be used to further reduce TSET while having similar AR performance to conventional designs. This alternative approach leads to lower TSET without changing the substrate composition. The above UV/NIR coating with 1/4 wavelength silica on top was used as the basis for this application (adjusted to SHLHL/2 for NIR). As the installation angle increases, the optical thickness of the coating decreases. The physical thickness of the layer can be increased to compensate for this effect. The reflectance was reduced to 13%, and the TSET was calculated to be about 37%.

The application of these solar control coatings offers a unique opportunity to further reduce the TSET of windshields. If AR coating is not required, solar reflection can be set in the windshield interlayer. Conceivably, two coatings, one in each interlayer and tuned to reflect different wavelengths, could both reduce TSET below 37% while maintaining the targeted visible light transmission. AR coatings can also be applied to the inner interlayer of Sungate ^(R) windshields as described in the US Patent. The NIR reflector nature of this coating further enhances the performance of this product, along with anti-reflection properties.

self-cleaning properties

When titanium dioxide is deposited in the anatase form and exposed to UV light it becomes self-cleaning. Titanium dioxide can be used as the high index layer in these designs. This allows the design to achieve self-cleaning properties while enhancing solar control properties. These self-cleaning coatings may be applied in accordance with PCT Application WO 98/41480, published September 24, 1998, which is incorporated herein by reference.

NIR with colored coating

For automotive applications, transition metal oxides can be used to change the reflected and transmitted color of glass. These coatings can provide a wider color gamut, but the TSET of the glass being coated will be increased. This can be achieved by incorporating transition metal oxides in the designs described above to achieve solar control and a wider color range.

Transition metal oxides with a high refractive index can be used as the high refractive index layer in these designs. If the color is too strong using only transition metal oxides, then transition metal oxides can be used only as a high index layer, or even as part of a high index layer. As an alternative, colored transition metal oxides can be used with non-colored oxides to reduce the color of the coating. Using either of these techniques, both solar control and a wide color range can be achieved. There may even be different colored materials for different high index layers, giving the designer more options for controlling the color of the coated glass.

Claims (37)

1. A multilayer coated workpiece comprising: a) a transparent substrate selected from the group consisting of clear glass, tinted glass, solar control glass and colored glass; b) a first inorganic coating comprising a metal having visual transparency and having a refractive index selected from the group comprising high and low refractive indices; c) a second inorganic coating comprising a metal that is visually transparent and has a refractive index opposite to that of the first coating; d) A third inorganic coating comprising a metal, which coating is visually transparent and has a refractive index in the range of the refractive index of the first coating. 2. The workpiece of claim 1, wherein the coating having a high refractive index has a higher refractive index than the low refractive index of another coating; and the coating having a low refractive index has a higher refractive index than the coating having a high refractive index. The high refractive index of the layer is low. 3. The workpiece of claim 1, wherein the coating having a high refractive index has a refractive index greater than about 1.75; and the coating having a low refractive index has a refractive index less than about 1.75. 4. The workpiece of claim 1, wherein the coating having a high refractive index has a refractive index greater than 1.9; and the coating having a low refractive index has a refractive index less than 1.6. 5. The workpiece of claim 1, wherein the first coating is selected from titanium dioxide and silicon dioxide; the second coating is silicon dioxide when the first coating is titanium dioxide, and when the first coating is In the case of silica, the second coating is titanium dioxide; the third coating is the same as the first coating. 6. The workpiece of claim 5, wherein the workpiece has a transparent conductive oxide as the middle third of the inner silica coating, thereby having an intermediate layer comprising several coatings in combination , thus, transparent conductive oxides offer high refractive index in the UV and visible spectrum but low refractive index in the NIR, obtaining a five-layer coating stack with the stack configuration S3HLHL3H in the UV and a three-layer coating stack with the stack configuration SHLH in the NIR. layer coating stack; the coating effectively becomes a five-layer coating stack in UV and visible light, but reduces to a three-layer coating in the NIR, resulting in an increase in the reflected intensity of the UV without increasing the total thickness of the coating stack, And without sacrificing the reflection intensity of NIR. 7. The coated multilayer article of claim 1, wherein the coating absorbs more NIR than visible light. 8. The coated multilayer workpiece of claim 1, wherein the NIR portion and the visible portion of the spectrum absorbed by the coating are equal. 9. The coated multilayer article of claim 1, wherein the coating absorbs more visible light than NIR. 10. The coated multilayer article of claim 1 , wherein at least one coating layer has tin oxide doped with antimony, the concentration of antimony being the doping concentration, and the light-absorbing coating thickness is about 500 nanometers, determined by This changes the color of the green substrate transmission. 11. The workpiece of claim 1, wherein the material of the coating having a high refractive index has a high refractive index in the UV and visible regions of the spectrum and a low refractive index in the NIR region of the spectrum. 12. The article of claim 1 wherein the refractive index is derived from fluorine doped tin oxide. 13. The workpiece of claim 1, wherein the workpiece has a fourth coating that absorbs all light in the entire solar spectrum, the coating being tuned to absorb relatively more light from the spectrum including visible light, UV The light selected from the group of light and NIR light controls the relative absorption of the different wavelengths. 14. The workpiece of claim 13, wherein the fourth coating is antimony doped tin oxide. 15. The workpiece of claim 1, wherein the workpiece has an optically invisible at least one half-wave coating on top of the SHLH stack such that the stack SHLHLL functions the same as the stack SHLH with UV filtering properties no change. 16. The workpiece of claim 15, wherein the top half-wavelength silica LL is 1/4 wavelength in the visible spectrum for the design wavelength in the UV, the 1/4 wavelength layer being provided for blocking UV and visible light-transmitting layer thicknesses are used as visible spectrum reflectance reducing layers. 17. The workpiece of claim 1 , wherein the design wavelength is 330 nm, which minimizes ISO UV while maintaining visible light transmission greater than 70% for 3.6 mm thick green glass. 18. The workpiece according to claim 1, wherein the workpiece is inserted into an initial SHLH stack of each layer designed as a 350nm half-wave coating to obtain S3H3L3H, so that the coating stack performs the same function at a design wavelength of 350nm , but the coating stack is a SHLH stack near 1050nm, where the reflectivity is about the maximum, so that the refractive index of the coating is smaller at longer wavelengths, and its peak is toward the NIR region of the spectrum The shorter wavelengths are shifted so that the coating stack reflects at both design wavelengths. 19. The workpiece of claim 1 , wherein the workpiece has a coating to alter the intensity of reflection in the visible spectrum, the coating being 1/4 wavelength in the visible spectrum; 1/8 in the NIR at 1050 nm Wavelength; 1.5 wavelength at 350nm in UV. 20. The workpiece of claim 1, wherein the workpiece has a transparent conductive oxide coating on at least one side of the HLH coating stack. 21. The article of claim 20, wherein the transparent conductive oxide is fluorine doped tin oxide and the high refractive index coating is titanium dioxide. 22. The workpiece of claim 20, wherein the workpiece includes at least one LH index coating pair to increase reflectivity peaks. 23. The workpiece of claim 1, wherein the workpiece includes a medium refractive index coating positioned between the substrate and the first high refractive index coating to attenuate the reflected color. 24. The workpiece of claim 1, wherein the workpiece includes a medium refractive index coating on a last high refractive index coating to attenuate the reflected color. 25. The workpiece of claim 1, wherein the workpiece comprises a graded coating whose refractive index varies along the thickness of the coating and at least one HLH coating stack. 26. The workpiece of claim 1, wherein the workpiece is tempered. 27. The workpiece of claim 1, wherein the workpiece has a dual NIR/UV filter coating stack, and a silica and transparent conductive oxide coating as a low index layer. 28. The workpiece of claim 27, wherein the coating stack on the glass substrate has titanium oxide, at least one coating pair of silicon dioxide and transparent conductive oxide, and titanium dioxide, wherein the silicon dioxide and transparent conductive oxide The oxide-coated pair has a combined optical thickness of 1/4 wave in the NIR. 29. The article of claim 27, wherein the transparent conductive oxide is fluorine-doped tin oxide. 30. The workpiece of claim 27, wherein the coating stack has a graded refractive index layer, antimony doped tin oxide, and fluorine doped tin oxide. 31. The workpiece of claim 1, wherein the workpiece has a five-layer coating stack selected from the group consisting of: a coating stack configured as SHLHLH, wherein _TiO is the high index layer, two Silicon oxide is a low index layer with a total thickness of about 6747 Angstroms, a TSET of about 60%, and a visible light transmission of about 85%; the same stack configuration as the previous coating stack, but F: _SnO2 is a low index layer , and the total thickness is about 6461 Angstroms, the TSET is about 50%, and the visible light transmittance is about 71.1%. 32. The article of claim 1 wherein the glass substrate is green and has a thin coating of antimony-doped tin oxide of a thickness such that the transmitted color changes from green to deep red. 33. The workpiece of claim 1, wherein the high refractive index coating comprises a transition metal oxide having a high refractive index as the high refractive index layer, wherein the transition metal oxide is used as the An entire high-index layer or used as part of a high-index layer, with attenuated color intensity, and colored transition metal oxides can be applied with non-colored oxides to attenuate the color of the coating for both solar control and versatility. kinds of colors. 34. A multilayer coated windshield, wherein the windshield has an ultraviolet light transmission of less than 10%, a total solar energy transmission of less than 50%, and simultaneously has a visible light transmission of greater than 70%, the windshield Windshield includes: a) a transparent substrate selected from the group consisting of stained glass, solar control glass and colored glass; b) a first coating comprising a metal having a refractive index selected from the group consisting of high and low refractive indices; c) a second coating comprising a metal having a refractive index opposite to the first refractive index; d) A third inorganic coating comprising a metal having a refractive index in the range of the refractive index of the first coating. 35. The workpiece of claim 34, wherein the UV/NIR coating comprising silica at the top 1/4 wavelength has a SHLHL/2 configuration tuned for NIR as the windshield mounting angle of the automotive window increases , the optical thickness of the coating is reduced and the physical thickness of the coating is increased to compensate, further reducing the TSET of the windshield. 36. The workpiece of claim 34, wherein the coating for solar reflection is placed on different substrate surfaces so as to be placed between the substrates as an interlayer for a windshield without an anti-reflective coating. 37. The workpiece of claim 1, wherein the substrate is substantially free of _CeO2 .

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