Glass product coated by sputtering, insulating glass assembly made using this product and method of making the insulating glass assembly

The present invention relates to a sputter-coated glass product, in particular to obtain a very low emissivity value and a neutral color of the glass.

There is a great demand for layered coating systems for glass articles that provide specific solar radiation properties in many types of glass products, such as windows and doors in construction. Spray-coated glass articles are used in insulating glass units. Examples of the latter application include multi-pane windows and doors made of at least two sealing panes at their peripheral edges to form an insulating chamber therebetween.

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In order for glass products to be accepted on the market, they must have certain characteristics that relate directly to the sputter-coated layer system. These features include:

1) the desired value for visible transmittance in combination with an acceptable value for the infrared reflectance;

2) non-specular appearance (ie low visible light reflectance as defined below);

3) neutral reflected color of visible light when viewed from the glass side (ie a color ranging from colorless to slightly blue);

4) resistance to weathering or to chemicals, often referred to as chemical stability (this term is defined below); and

5) resistance to abrasion (often referred to as mechanical durability; this term is defined below) when handled, especially during the various steps necessary in the manufacture of an insulating glass window or door from two or more glass panes, at least one of which has a sputter coating .

In addition to these physical properties, the coating system used must be economical to produce. If this is not the case, the final product, such as a sputter coated glass product, may be so expensive that it will not be in demand.

It is known that these desirable properties are often contradictory and therefore often compromises become necessary when trying to achieve them. For example, achieving an acceptable value for transmittance or infrared reflectance may require a reduction in durability (chemical and / or mechanical). Another example is the inability to avoid undesirable specular colors and appearance. In other cases, production costs become an important factor. Such problems create the need for a new sputter-deposited layer system which can achieve a better balance of properties.

U.S. Patent 5,344,718 describes various suitable sputter-deposited layer systems which achieve acceptable low emissivity (E) values ​​and therefore correctly fall within the family of low emissivity systems (i.e. the family with high infrared reflectance coatings). Moreover, such coating systems as a family typically exhibit a durability that is close to or equal to that of pyrolysis coatings, and therefore are acceptable. These coatings, especially in their preferred embodiments, moreover exhibit high visible light transmission. At the same time, they show a neutral color slightly situated on the green side of the blue, which, however, is sufficiently masked by the value of the visible reflectance value, which gives the coatings a neutral appearance. Moreover, the reflectance of the visible radiation is less than 20%, thus avoiding an undesirable specular appearance when viewed from the inside or outside when used e.g. in a window or door.

The family of layer systems described in US Patent 5,344,718 uses different layers of Si₃N₄ and nickel or nichrome alternating with one or more infrared reflecting layers of metallic silver in a selected order to achieve the desired end properties.

The advantages of this known solution result from the use of a system of five or more layers, the system in an outward direction from the glass comprising:

a) Si backsheet₃N₄;

b) a layer of nickel or nichrome;

c) a layer of silver;

d) a layer of nickel or nichrome; and

e) a Si skin layer₃N₄.

When the system consists essentially of these five layers, the following thicknesses are typically used:

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Layer Range (approximately) a (Si_?N₄) 400A - 425 A b (Ni or Ni: Cr) 7 A or less c (Ag) 95 A -105 A d (Ni or Ni: Cr) 7 A or less e (Si₃N₄) 525 A - 575 A.

When more than five layers are used according to the above-mentioned patent, e.g. when two silver layers are used, then such a system in the outward outward direction comprises the following layers:

glass / Si3N4 / Ni: Cr / Ag / Ni: Cr / Ag / Ni: Cr / Si3N4, with the total thickness of the silver remaining the same (e.g. 95-100 A) so that each silver layer is approximately 50 A.

While the systems described in this patent are a significant improvement over previously known systems, especially those shown in the prior art section of the patent, the problem of improving emissivity remains. For example, in the systems compliant with the above-mentioned patent description, the normal emissivity (E_n) was usually less than or equal to about 0.12, while the hemispherical emissivity (E_h) was usually less than 0.16. However, in practice, the real lower bounds actually achieved were usually for E._nabout 0.09 and for E._h were around 0.12. The achievable sheet resistances were typically about 9-10 ohms / square.

It has hitherto been believed that if the silver thickness is increased in order to obtain greater infrared reflectance (and therefore lower emissivity values), one or more of the following four detrimental effects will occur: (1) there will be a reduction in durability; (2) the final product will be too reflective and therefore will become reflective; (3) the hue will be shifted unacceptably to deep purple or red-blue and / or (4) the visible light transmittance will be unacceptably low.

Durability, both mechanical and chemical, is an important factor in building glass, whether it is monolithic glazing or, for example, an insulating glass unit. Mechanical durability is required due to the handling, assembly and sealing of insulating glass assemblies, while chemical durability is required due to the need to edge seal the panes to form an insulating chamber therebetween, mainly due to the crevice nature that inevitably contacts the coating. For aesthetic reasons, both the mirror-like appearance and the purple color can eliminate any product with such properties from the market. Reduction in visible light transmittance, although undesirable, is not critical until the visible light transmittance is less than about 70% in the monolithic glazing and less than about 63% in the insulating glass assembly. However, in some applications, especially where low shading coefficients (ie, less than about 0.6) are desired, the transmittance may actually be too high, even if the emissivity is reasonably low. Where shading properties are desired (e.g. to reduce air conditioning costs), the visible transmittance of the monolithic glazing should be kept below 75%, preferably below 73%, while in a typical insulating glass unit the visible transmittance should be about 65-68% .

The above views are partially confirmed by the rather complicated layer system disclosed in US Patent 5,302,449 as well as its industrial realization in the form of an insulating glass unit under the name Cardinal 171 from Cardinal IG Company. The layer system of this embodiment comprises various thicknesses and types of materials in a layer system to achieve certain solar radiation properties, as well as the use of a top layer of zinc, tin, indium, bismuth or oxide alloys including zinc oxide to achieve abrasion resistance. In addition, the system includes one or two layers of gold, copper or silver.

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When two silver layers are used, the first is 100-150 Å thick, preferably about 125 Å thick, while the second, based thereon, is 125-175 Å thick. When only one silver layer is used then its thickness should be 100-175 Å. A, preferably 140 A. In this known embodiment, nickel or nichrome is used and not silicon nitride in the layering.

In actual industrial practice, the above-mentioned Cardinal insulating glass units have been found to achieve completely acceptable solar radiation properties together with acceptable color properties and relatively good non-specular visible light reflectance (comparative example is given below). However, it has been found that this otherwise acceptable system does not have chemical durability as the system fails the cooking test. Although the reason for this is not exactly known, the simple conclusion is that, as evidenced by the prior art, some compromises are needed with regard to at least one desired property to obtain desired values ​​for other properties. Moreover, due to the nature of the layer system and the components used, such a system is quite expensive to produce mainly due to the number and thickness of the layers needed to obtain the desired result.

The prior art section of US Patent 5,344,718 describes a further known building glass layered system commercially known as Super-E III, manufactured by Airco Corporation. From the glass to the outside, this system consists of the following layers: Si₃N4 / Ni: Cr / Ag / Ni: Cr / Si₃N4

In practice, it was found that in the Super-E III system, the Ni: Cr alloy contains 80/20 by weight of Ni / Cr (i.e. nichrome), respectively, where these two nichrome layers are 7 A thick, the Ag layer is only 70 A thick (with in that it is stated that the silver layer may be about 100 Å thick and the Si layers₃N₄ they are thicker, e.g. 320 Å for the backsheet and about 450 Å for the topcoat). In fact, due to their thickness (i.e. about 70 Å), the silver (Ag) layer has been found to be rather semi-continuous, as has been found in practice. However, this coating has a good durability (i.e. the coating is scratch-resistant, wear-resistant and chemically stable) and thus achieved a good value for this property compared to pyrolytic coatings, for glass with a thickness of about 3 mm (E_h) is only about 0.20-0.22, and E._n is about 0.14-0.17. Both of these emissivity values ​​are rather high. In addition, the sheet resistance (R 2) is relatively high at 15.8 ohms / square (a more acceptable value is around 10.5 or less). Although both mechanical and chemical durability proved to be acceptable and the visible transmittance of the monolithic sheet was rather high at 76 ± 1%, and although these coatings also proved to be compatible with conventional sealants used in insulating glass assemblies, the properties against infrared radiation was less than desired. Moreover, the rather high visible light transmittance of the monolithic glass of 76 ± 1% made such a system rather disadvantageous when lower shading properties are needed.

Following the Super-E III system, Airco developed the Super-E IV system. The system comprises the following layer system from the glass outwards:

Component Thickness (A)

TiO₂ about 300

NiCrN_x about 8

Ag around 105

NiCrN_x about 8

Si₃N₄ around 425

This system is quite similar in operation to the Super-E III system except that the visible transmittance is greater (e.g. greater than 80%), the emittance is lower (e.g. less than about 0.10) and the shading coefficient is much greater (e.g., about 0.80). Moreover, due to the use of TiO₂ as a back coat, this system is expensive to manufacture.

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Another layering system somewhat similar to Super-E III and IV is disclosed in US Patent 5,377,045. In the system shown here, a single silver layer is, for example, sandwiched between two nichrome layers, which in turn are sandwiched between a backing layer, e.g. TiO.₂ or Si₃N₄ doped with Zr and the outer layer with Si₃N₄ or Si₃N₄ of doped Zr. In practice, the layer systems of this embodiment are generally purple in color, are chemically stable, as determined from the boiling test described below, are heat-treatable, and are rather highly emissive. According to this solution, special sputtering techniques are needed to reduce the internal stresses in one of the dielectric layers in order to achieve the desired mechanical and chemical properties in accordance with the tests described to define these two properties.

A significant improvement in the prior art is disclosed in U.S. Patent 5,514,476, which describes a unique layer arrangement of a silver layer sandwiched between two layers of nichrome, which in turn are sandwiched between the backing layer and the Si outer layer.₃N₄. With appropriate setting of the layer thicknesses, the coating systems of this invention preferably achieved low emissivities (i.e., E_n <0.7, Ej, <0.075, ΐζ <5.5 ohm / square). Moreover, the reflectance properties (reflectance and extinction) made them acceptable (i.e., without the appearance of a mirror) when used in insulating glass units. The transmittance values ​​were also in the appropriate range and the problem of the undesirable purple color of the prior art systems was eliminated.

While these layer systems have been quite advantageous, it has been found that when trying to achieve even lower emissivity values ​​(i.e. reduced infrared radiation transmission, which is the main goal of many sandwich systems used in building and automotive glass), it was found that mainly by increasing the thickness of the silver layer (the main layer). reflecting infrared radiation), has a detrimental effect on visible light transmittance, color, and light reflectance properties. For example, increasing the thickness of the silver layer has been found to severely reduce visible transmittance to values ​​below the acceptable 70% level. Furthermore, an article (e.g., insulating glass unit) so coated with too thick a layer of silver may have a strong purple color and a mirror-like appearance on the glass side.

In addition to the layer system described above, other coatings containing silver and / or Ni: Cr are discussed in the patent and scientific literature as layers providing infrared reflection and other light properties. For example, Fabry-Perot filters and other known coatings and techniques described in US Patents 3,682,528 and 4,799,745 (and in the art discussed and / or cited therein). Also, dielectric and metal layer systems according to numerous US patents 4,179,181; 3,698,946; 3,978,273; 3,901,997 and 3,889,026.

None of the known solutions disclosed or made it possible to use the sputter coating process with high production capacity and at the same time to obtain building glass which not only is similar or equal in terms of durability to pyrolytic coatings, but also has excellent properties against solar radiation.

For the above reasons, it is evident that there is a need for a sputter-deposited layer system in which the properties of coated glass sheets described above are optimized. The object of the present invention is to fulfill these and other needs, which will become more apparent to those skilled in the art from reading the following description.

The objects of the present invention have been achieved by the unexpected finding that either by adding Si to layers₃N₄ in a layered system according to US Patent 5,514,476 of stainless steel, or by optionally placing a bottom layer of TiO underneath these doped layers₂ even further, unexpected reductions in emissivity can be obtained, as well as unexpectedly the reflectance of visible light and the color of the product viewed from the glass side giving it a non-reflective and neutral appearance

181 209 (i.e. it ranges from virtually neutral to only slightly blue), and the product remains chemically and mechanically stable despite the increase in thickness of the silver layer. In certain example embodiments, the sandwich systems are heat treatable. The sandwich system according to the invention is particularly suitable for use in insulating glass units, e.g. in windows and doors, especially when such units are manufactured using heat sealing.

According to the invention, a sputter-coated glass article comprises a glass substrate having on its flat surface facing the glass outwardly the following layer system:

a) a layer composed of Si₃N₄ and stainless steel, in which stainless steel is present in the amount of 0.5-15 wt.%. layers;

b) a layer of nickel or nichrome;

c) a layer of silver;

d) a layer of nickel or nichrome; and

e) a layer composed of Si₃N₄ and stainless steel, in which stainless steel is present in the amount of 0.5-15 wt.%. layers. For a glass substrate thickness of 2-6 mm, the coated glass substrate exhibits normal emissivity (EJ about 0.06 or less, hemispherical emissivity (E_h) about 0.07 or less, sheet resistance (R2) of about 5.0 ohms / square or less, and has a substantially neutral color of reflected visible light when viewed from the glass side.

Preferably, the coated glass substrate has a visible transmittance of at least 70% and is heat treated according to the definition of that term given below. The layer system preferably additionally comprises a back layer composed of TiO₂, and the individual layers have approximately the following thicknesses:

Layer Thickness (A)

Backsheet 100-400 a 20-120 b 7-50 c 75-225 d 7-30 e 50-600

In the glass product according to the invention with the said layer system, the glass substrate has normal emissivity (EJ about 0.05 or lower hemispherical emissivity (E_h) about 0.06 or less sheet resistance (RJ about 5.0 ohms / square or less with the product according to the invention comprising the backsheet and layers (a) - (e) having layers (a) and (e) containing 6% by weight stainless steel. Preferably the layers have approximately the following thicknesses:

Layer Thickness (A)

Bottom layer 200-250 a40-60 b7-30 c 150-180 d7-15 e 400-500

Also preferably, layers (b) and (d) are composed of chromium nitride, and the stainless steel also includes chromium nitride, the layers having approximately the following thicknesses:

Layer Thickness and A)

Backsheet 225 a50 b20 c165 d7 e450

181 209, wherein the coated glass substrate has the following characteristics:

GLASS SIDE

RqY is about 11.0 aj, it is about 2.3 b_h is about -8.8

COATING SIDE R_fY is approximately 6.0 a_h is approximately 5.4b_h is about -17.5 where R._fY is the reflectance, aa_h and b_h are color coordinates measured in Hunter units, illuminant C, 10 ° observer, furthermore, the layer system is mechanically and chemically stable and has a visible light transmittance of about 76%. A glass product with this layering is heat treated as defined below.

In another preferred embodiment, the layer system consists essentially of layers (a) - (e) and the layers have approximately the following thicknesses:

Layer Thickness (A) a 200-600 b7-50 c 115-190 d7-30 e 50-600

Preferably, the layers have approximately the following thicknesses:

Layer Thickness (A) a 400-500 b7-30 c 140-170 d7-15 e 400-600

The glass product according to the invention with this layer system is chemically and mechanically stable.

Also preferably, the layers have approximately the following thicknesses:

Layer Thickness (A) a450 b20 c155 d7 e550 where the coated glass substrate has a visible transmittance greater than 70% and the following properties:

GLASS SIDE

RqY is approximately 10.2A_h is about 0.4b_h is about -4.7

COATING SIDE

R_fY is approximately 4.6 a_h is about 6.5 b_h is about -15.8 where R._fY is the reflectance, aa_h and b_h are color coordinates measured in Hunter units, illuminant C, 10 ° observer. A glass product with this layering is heat treated as defined below. In the glass product with the above layer system, stainless steel is preferably present in layers (a) and (e)

181 209 in an amount of about 6 wt.%. layers, and layers (b) and (c) are composed of chromium nitride, and the stainless steel contains chromium nitride. In a preferred embodiment of the invention, the stainless steel is OH 17N12M2T steel (according to Al SI No. 316).

Preferably, the glass substrate coated on one of its surfaces has the following properties:

GLASS SIDE

RqY is approximately 8 to 18A_h is about -3 to +3 b_h is about 0 to -15

COATING SIDE

R_fY is approximately 4 to 15 a_h is approximately 0 to +8 b_h is about -5 to -20 where RfY is reflectance and an i are color coordinates measured in Hunter units, illuminant C, 10 ° observer.

Other favorable properties of the glass side and the coating side are as follows:

GLASS SIDE

RfjY is approximately 9 to 15A_h is about -1 to +3 b_h is about -4 to -10

COATING SIDE

R_fY is approximately 4 to 10 a_h is about +3 to +7 b_h is about -10 to -20

In an article according to the invention, preferably the visible light transmittance of the coated glass substrate is about 74-76%.

As stated above, some of the layer systems falling within the scope of the present invention have properties that enable them to be heat treated. The term heat treated as used herein means that the layer system may be subjected to at least one of the following conventional heat treatment processes without adversely affecting its desired end properties. The conventional heat treatment processes contemplated herein are glass toughening, bending, heat strengthening, or heat sealing steps used to seal two or more glass panes together to form an insulating glass assembly.

If the product of the invention has heat treatable properties, a specific coating system of the present invention can be selected for a particular application. For example, if the layer system is to be used in a curved and / or toughened automotive windshield, it would be a windshield selected to be able to undergo these processes. When used in construction windows where the same appearance of both toughened and non-toughened panes is required, the coating is selected to achieve this result due to the heat-treatable properties of the toughening process. Of course, in order to be heat treatable, it must be possible to subject the coating to at least one of the above-mentioned heat treatment operations, but not all.

Some of the coatings contemplated may or may not withstand the toughening, curing, or bending of the glass, but are still considered heat treatable if they can withstand the heat used to seal the insulating glass assembly during its single manufacture.

The subject of the invention has been shown in the following examples of the drawing, in which Fig. 1 shows a cross-section of a laminated glass product, Fig. 1A another embodiment of a laminated glass system according to the invention, Fig. 2 - a coated glass product combined into a set of two panes, fig. 3 - a house with a window, door and other elements made of coated glass products, in a perspective view,

181 209 and Figure 4 shows a coated glass product bonded into a double glazing unit during manufacture prior to pumping and sealing in cross section.

Certain terms are commonly used in the glass coating field, particularly in determining solar radiation management properties and parameters in coated glass used in construction. Such terms are used herein in accordance with their known meaning. For visible light intensity, the reflectance is defined as a percentage of that intensity and is given as R ^ Y (i.e. the Y value given below in ASTM 308-85) where X is either G on the glass side or F on the glass side shell side. The side of the glass (i.e., G) is the side visible to the side of the glass substrate opposite to that on which the coating is located, and the side of the coating (i.e., F) is the side visible to the side of the glass substrate on which the coating is located. When specifying the IG unit, the index G stands for outside and the index F stands for inside (i.e. outside or inside the apartment, as the case may be).

Color parameters are measured in a and b coordinates. These coordinates are given here with the index h to denote the conventional use of the Hunter method (or units) illuminant C, 10 ° observer, according to ASTM D-2244-93 "Standard Test Method for Calculation of Color Differences From Instrumentally Measured Color Coordinates ”, 9/15/93, as specified by ASTM E-308-85, Annual Book of ASTM Standards, vol. 06. 01“ Standard Methots for Computing the Colors of Objects by Using the CIE System ”.

The terms emissivity and transmittance are well understood in the art and are used herein in accordance with their known meaning. For example, the term transmittance here means solar light transmittance, which is made up of visible light transmittance, infrared radiation transmittance, and ultraviolet radiation transmittance. Total solar transmittance is thus usually characterized as a weighted average of these other values. With regard to transmittance, the visible transmittance as reported herein is determined by a standardized technique with an illuminant C with a wavelength of 380-720 nm. For infrared it is 800-2100 nm, and for ultraviolet it is 300-400 nm. All solar radiation is in the range of 300-2100 nm. For the purposes of emissivity, a specific infrared range (i.e., 2500-40,000 nm) is used, as discussed below.

Visible light transmittance can be measured using known, conventional methods. For example, a spectral transfer curve is obtained using a spectrophotometer such as a Beckman 5240 (Beckman Sci. Inst. Corp). Visible light transmission is then calculated using the ASTM 308 / 2244-93 methodology mentioned above. If necessary, fewer wavelength points than intended may be used. Another way to measure visible light transmittance is to use a spectrometer, such as the commercially available Spectragard spectrophotometer manufactured by Pacific Scientific Corporation. This device directly measures and reports visible light transmittance. As reported and measured, visible light transmittance (i.e., the Y value from the CIE tristimulus values, ASTM E-308-85) uses illuminant C, 10 ° observer.

The emissivity (E) is a measure or property of both the absorption and the reflection of light at a given wavelength. It is usually determined by the formula:

E = 1- Coating reflectance

For architectural purposes, the emissivity values ​​in the so-called the middle range, sometimes also called the far infrared spectrum, i.e. 2,500-40,000 nm, according to the program WINDO W 4.1, LBL-35298 (1994) from Lawrence Berkley Laboratories. The term emissivity as used here is therefore intended to refer to the emissivity values ​​measured in this infrared range, as set out in the ASTM standard proposed in 1991 for infrared energy measurements to calculate emittance as proposed by the Primary Glass Manufacturers Council under the title "Test Method for Measuring and Calculating Emittance of Architectural Fiat Glass Products Using Radiometrie Measurements ”.

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In this standard, the emissivity is given as hemispheric emissivity (E ^ and normal emissivity (E_n).

Data collection for measuring such emissivity values ​​is done conventionally and may be carried out using, for example, a Beckman Model 4260 spectrophotometer with a "VW" attachment (Beckman Scientific Inst. Corp.). This spectrophotometer measures the reflectance as a function of wavelength, and from this the emissivity is calculated using the aforementioned proposed 1991 ASTM standard.

Another term as used herein is sheet resistance. Sheet resistance (RJ is a term known in the art and is used herein in accordance with its known meaning. Generally speaking, the term refers to the resistance in ohms of any square of a layer system on a glass substrate to an electric current flowing through the layer system. Sheet resistance is an indication of how well a layer reflects infrared energy, and is therefore often used along with emissivity as a measure of this property. The sheet resistance is conveniently measured using a 4 point probe ohmmeter, such as a disposable 4 point resistivity probe with a probe head available from Magnetron Instruments Corp., Model M-800, manufactured by Signatone Corp. from Santa Ciara, California.

The terms chemical or chemically stable are used herein synonymously with terms such as chemical resistance or chemical stability. Chemical stability is determined by boiling a 2 'x 5 (approximately 5 x 13 cm) sample of the coated glass substrate to approximately 500 cm³ 5% HCl for one hour (at about 104 ° C). A sample is considered to pass this test (and therefore the layered system is chemically stable or is considered to be chemically stable) if the layered sample does not exhibit any microscopic holes greater than about 0.08 mm in diameter after this boiling for one hour.

Mechanical durability or the term mechanically stable as used herein is determined by one of two tests. The first test uses the Pacific Scientific Abrasion Tester (or equivalent), in which a nylon brush measuring 2x4x1 (approximately 5x10x2.5 cm) cyclically passes the layering system in 500 cycles with a load of 150 g on a 6x17 sample (approximately 15x3 8 cm). In another alternative test, a conventional Taber abrasive (or equivalent) is used to subject a 4x4 (approximately 10x10 cm) sample to 300 revolutions of two CS 10F diameters each with a weight of 500 g. In each test, if no significant, noticeable ones are found scratches visible to the naked eye in visible light, the test is considered positive and the product is said to be mechanically durable.

The thicknesses of the various layers in the systems in question are measured in different ways, and so the term thickness as used herein is also defined differently. One method uses known optical curves, and an alternative method uses a conventional needle ellipsometer (i.e. a profilometer). According to another and particularly preferred method, the n & k Technology Inc., Santa Clara, California analyzer is used. This method is generally described in U.S. Patent 4,905,170 along with the possibility of determining the value of the refractive index n and the extinction coefficient k of the test layer. Such procedures and methods are known to those skilled in the art and thus require no further explanation other than the note that the thicknesses are given in angstroms herein.

Figures 1 and 1A show two embodiments of the invention in partial section. As can be seen, a conventional glass substrate 1 used in building is used. Such glass is preferably produced by the conventional float process and is therefore referred to as float glass. Its normal thickness is 2-6 mm. The composition of the glass is not critical and can vary widely. The glass typically used is one of the family of soda-lime-silica glasses known to the glass art.

The production of the various layers on the glass substrate 1 can be accomplished by a conventional multi-chamber (multi-plate) sputtering system such as

181 209 production system by Airco Inc. In this regard, the preferred method of sputtering the coating to be used is the same as that disclosed in U.S. Patent 5,344,718. It should be noted that the unique results of the present invention are obtained by using conventional sputtering techniques without the need for special internal stress relief processes, as reported in above in U.S. Patent 5,377,045.

Five layers (a) - (e) are used in the layer system shown in Fig. 1. In this specific embodiment the arrangement of the layers and the preferred range of their thicknesses as measured by the n & k technique mentioned above from the glass towards the outside is as follows:

<td>Abcde layer</td><td>Component Thickness (A) Si₃N₄/ SS * around 200-600 Ni or nichrome ** around 7-50 Silver around 115-190 Ni or nichrome ** around 7-30 Si₃N₄/ SS around 50-600</td>

In particularly preferred embodiments, the layer thicknesses are:

Layer Thickness (A) a approx. 400-500 b approx. 7-30 c approx. 140-170 d approx. 7-15 e approx. 400-600

In the five-layer embodiments shown in FIG. 1, particularly preferred layer thicknesses are approximately:

Layer Thickness (A) a450 b20 c155 d7 e550

In the sputtering of layers (a) and (e), it is preferable to use silicon (Si) targets doped with silicon of the desired amount of stainless steel (OH17N12M2T) to obtain the desired final amount in a thin layer. When sputtering is carried out in nitrogen, Si is formed₃N₄and at least some of the chromium contained in the stainless steel forms chromium nitride. Optionally, aluminum may also be used as a dopant in minor amounts (e.g., 6 wt.%) To keep the target conductive. However, stainless steel also serves this purpose, so aluminum is not required to achieve the desired level of conductivity.

Accordingly, it has been found that generally the amount of stainless steel to be used in such a layer is about 0.5-15 wt%. this thin layer. As the sputtering process typically involves sputtering silicon and stainless steel (and aluminum if optionally used) at approximately the same rate, the amount of each component used (if evenly distributed) in the target itself can be taken with reasonable accuracy for the purposes of the present invention on the basis of the resulting amounts in the layer after spraying (according to analytical confirmations). Thus, when it is said to contain a certain weight percentage of stainless steel, it usually means that approximately that amount was used up in the wheel.

* SS = stainless steel, preferably OH17N12M2T (according to AISI No. 316) ** preferably nichrome (e.g. 80/20 Ni / Cr by weight)

181 209

Fig. 1A shows a six-layer embodiment of the invention. The top five layers (a ') - (e') are made of the same components as the corresponding layers (a) - (e) in Fig. 1. However, they have been added to a bottom uc layer of TiO₂ such that the thicknesses of these layers are preferably approximately:

<td>Uc layer a 'b' c 'd' e '</td><td>Thickness (A) 100-400 20-120 7-50 75-225 7-30 50-600</td>

In some preferred embodiments, the layers are approximately the following thicknesses:

<td>Uc layer a 'b' c 'd' e '</td><td>Thickness (A) 200-250 40-60 7-30 150-180 7-15 400-500</td>

In the six-layer embodiments of Fig. 1A, particularly preferred thicknesses are approximately:

<td>Uc layer a 'b' ć d 'e'</td><td>Thickness (A) 225 50 20 165 7 450</td>

Unique use of stainless steel in Si layers₃N₄ resulted in a layered system (shown as examples of Figures 1 and 1A) which, when applied to a flat surface of a monolithic glass sheet (e.g. float glass) about 2-6 mm thick, gives a glass product with normal emissivity ( EJ about 0.06 or less, hemispherical emissivity (E._h) about 0.07 or less, sheet resistance (RJ about 5.0 ohms / square or less, and shows a neutral color for visible reflected light (i.e., neutral to slightly blue) when viewed from the glass side. visible is at least about 70% and the monolithic sheet may be heat treatable as noted above.

A typical range of reflectance and reflectance and color coordinates for the embodiments of the present invention when using the thickness of the monolithic glass sheet and layers as set forth above is:

GLASS SIDE

RqY is approximately 8 to 18A_h is about -3 to +3 b_h is around Odo-15

COATING SIDE

R_fY is approximately 4 to 15 a_h is approximately 0 to +8 b_h is approximately -5 to -20

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In preferred embodiments, the features are as follows:

GLASS SIDE

The hand is approximately 9 to 15 a_h is about -1 to +3 b_h is about -4 to -10

COATING SIDE

R_fY is about 4 to 10 aj, it is about +3 to +7 b_h is about -10 to -20

In the embodiment of Fig. 1, when using the preferred thicknesses above given for this five-layer embodiment, the reflectance and color coordinates are:

GLASS SIDE

R ^ Y is approximately 10.2 Å_h is about 0.4b_h is about -4.7

COATING SIDE

R_fY is approximately 4.6 a_h is about 6.5 b_h is around -15.8

In the embodiments of Fig. 1A, when preferred thicknesses greater than those given for this six-layer embodiment are used, the reflectance and color coordinates are as follows:

GLASS SIDE

R ^ Y around 11 a_h about 2.3 b_h about -8.8

COATING SIDE

R_fY about 6.0 a_h about 5.4 b_h about -17.5

Such a monolithic glass sheet made of clear float glass has actually been found to have a visible transmittance of about 76%, while a visible transmittance of the above-described particularly preferred five-layer system is about 71%. In both cases, it was found that the layer system was heat treatable, mechanically and chemically stable.

While the amount of stainless steel may be varied to suit particular requirements, it is preferable to sputter the five layers or six layers of Fig. 1-1A using a silicon (Si) target containing about 6 wt.% Of stainless steel, thus assuming the above-described assumption. a layer containing about 6% by weight of stainless steel. It is also advantageous in the practice of the present invention when sputtering the two conjugated crystal layers b, d, or b ', d' for the silver layer c or c ', to perform the sputtering under a nitrogen atmosphere if nichrome is used (e.g. 80 / 20, Ni / Cr by weight), so as to achieve the conversion of at least part of the chromium contained in the nichrome into nitride. Likewise, at least some of the chromium contained in the stainless steel will form nitride when sputtering the Si / SS target under a nitrogen atmosphere to form Si₃N₄ (i.e. silicon nitride).

Figure 2 is a schematic representation of a coated glass product combined in a unit of two panes. To distinguish the inside of the insulating unit from the outside, Sun 9 is schematically drawn. Such an insulating glass unit is made of an outer pane 11 and an inner pane 13. The two panes (e.g., 2-6 mm thick) are sealed at their peripheral edges by conventional sealant 15 and desiccant tape 17. These panes are then attached to a conventional window or door frame 19 (shown schematically).

181 209

By sealing the peripheral edges of the panes and replacing the air in the chamber 20 with a gas such as argon, a highly insulating glazing unit is typically obtained. The chamber 20 is typically about 13 mm wide.

By using the sandwich systems of the present invention described above as a sandwich system 22 on the inner surface 24 of the outer pane 11 inside the chamber 20 or alternatively on the inner surface 26 of the inner pane 13 inside the chamber 20 (not shown), a particularly unique, non-mirror insulating glass unit is obtained. with a neutral color when viewed both from inside and outside the apartment, in which the insulating glass unit is mounted. Fig. 2 shows only one example of an insulating glass unit in which the unique sandwich systems of the present invention may be used. In fact, the layering of the coated glass articles of the present invention may be used generally in a wide variety of insulating glass units, including units that have more than two panes. Insulating glass assemblies with coated glass articles according to the present invention, when the laminate is positioned on any pane within the insulating chamber of the assembly, will typically have the following range of properties:

Table 1

<td rowspan="2">Properties</td><td colspan="2">Page 24</td><td colspan="2">Page 26</td>

<td>Range</td><td>Favorable</td><td>Range</td><td>Favorable</td>

<td>Visible light transmittance (%)</td><td> &gt;61</td><td> 70</td><td> &gt;61</td><td> 70</td>

<td>Reflection (%, visible light, outer side)</td><td> 14-20</td><td> 16</td><td> 11-18</td><td> 13</td>

<td>Reflection (%, visible light, inner side)</td><td> 11-18</td><td> 13</td><td> 14-20</td><td> 16</td>

<td>Shading factor (SC)</td><td> 0,45-0,60</td><td> 0,53</td><td> 0,55-0,69</td><td> 0,63</td>

<td>Solar radiation energy gain factor</td><td> 0,38-0,58</td><td> 0,45</td><td> 0,47-0,60</td><td> 0,55</td>

<td>U (winter) [kJ / m²/ h / ° C]</td><td> 4,83-5,88</td><td> 5,25</td><td> 4,83-5,88</td><td> 5,25</td>

<td>U (summer) [kJ / m²/ h / ° C]</td><td> 4,83-5,88</td><td> 5,25</td><td> 4,83-5,88</td><td> 5,25</td>

<td>7 Relative heat gain [kJ / m / h / ° C]</td><td> 1890-2520</td><td> 2310</td><td> 2310-3150</td><td> 2730</td>

In some embodiments, typical reflectance and color coordinates will fall within the following range when viewed from outside and inside:

FROM THE OUTSIDE

RgY, about 14 to 20 a ^ about -2 to +2 b_h, around Odo-10

FROM INSIDE RfY, approximately 11 to 18 a ,,, approximately 0 to +4 b_h, about 0 to -10 and the visible transmittance is at least 61%, preferably at least 63%.

In addition to the above features, certain preferred embodiments where the particularly preferred five-layer system shown in Fig. 1 (with the particularly preferred thicknesses given above), the following properties are obtained when such an arrangement is used in an insulating glass assembly with an approximately 13 mm wide chamber 20 filled with argon, these properties calculated according to the WINDO W 4.1 program by Lawrence Berkley Laboratories of Berkeley, California, and in addition using a Hitachi spectrophotometer providing input for: (1) visible light and sunlight transmittance; (2) sunlight reflectance

181 209 on the shell side and the glass side; and (3) a Beckman infrared spectrophotometer for measuring the emittance.

Table 2

<td>Property</td><td>Page 24</td><td>Page</td>

<td>T. ¹ wid</td><td> 66</td><td> 66</td>

<td>Rwid, outside</td><td> 15</td><td> 12</td>

<td>Property</td><td>Page 24</td><td>Page</td>

<td>Rwid. , inside</td><td> 12</td><td> 15</td>

<td>T._words.</td><td> 41</td><td> 41</td>

<td>Rsl</td><td> 34</td><td> 15</td>

<td>Shading coefficient</td><td> 0,51</td><td> 0,63</td>

<td>Thermal energy amplification factor</td><td></td><td></td>

<td>solar radiation</td><td> 0,44</td><td> 0,54</td>

<td>AT_withjma</td><td> 0,26</td><td> 0,26</td>

<td>Ulato</td><td> 0,25</td><td> 0,25</td>

<td>E._n</td><td> 0,06</td><td> 0,06</td>

<td>E._h</td><td> 0,07</td><td> 0,07</td>

<td>Relative heat gain</td><td> 105</td><td> 129</td>

<td>R ^ ohm / square)</td><td> 4,7</td><td> 4,7</td>

Color (monolithic sheet, Hunter C illuminant, 10 ° observer).

<td>You</td><td> 70,9</td>

<td>^andh</td><td> -2,4</td>

<td>K.</td><td> 6,4</td>

<td>RqY (outside)</td><td> 10,2</td>

<td>^andh</td><td> 0,4</td>

<td>b_h</td><td> -4,7</td>

<td>R_fY (inside)</td><td> 4,6</td>

<td>^andh</td><td> 6,5</td>

<td>bh</td><td> -15,8</td>

In a similar manner, using the same measurement technique, the following performance characteristics are obtained in the above system, when the particularly preferred six-layer system shown in Fig. 1A (using the particularly preferred thicknesses given above) is a layer system either on page 24 or on page 26 (fig. 2) as given below:

Table 3

<td>Property</td><td>Page 24</td><td>Page 26</td>

<td>T. ^x wid.</td><td> 70</td><td> 70</td>

<td>Rwid., Outside</td><td> 16</td><td> 13</td>

<td>Rwid., Inside</td><td> 13</td><td> 16</td>

<td>T._SI.</td><td> 42</td><td> 42</td>

<td>Rsl.</td><td> 31</td><td> 33</td>

<td>Shading coefficient</td><td> 0,53</td><td> 0,63</td>

<td>Thermal energy amplification factor</td><td></td><td></td>

<td>solar radiation</td><td> 0,45</td><td> 0,55</td>

<td>Uzima</td><td> 0,25</td><td> 0,25</td>

<td>E) ato</td><td> 0,24</td><td> 0,24</td>

<td>E._n</td><td> 0,05</td><td> 0,05</td>

<td>Eh</td><td> 0,06</td><td> 0,06</td>

<td>Relative heat gain</td><td> 110</td><td> 130</td>

<td>R ^ ohm / square)</td><td> 4,8</td><td> 4,8</td>

181 209

Color (monolithic sheet, Hunter C illuminant, 10 ° observer).

<td>You</td><td> 76,2</td>

<td>^andh</td><td> -2,7</td>

<td>bh</td><td> 3,1</td>

<td>RqY (outside)</td><td> 11,0</td>

<td>^andh</td><td> 2,3</td>

<td>b_h</td><td> -8,8</td>

<td>R_fY (inside)</td><td> 6,0</td>

<td>^andh</td><td> 5,4</td>

<td>b_h</td><td> -17,5</td>

In both of these embodiments, the monolithic glass sheet may be subjected both to a boil test to determine chemical durability and to an abrasion test to determine mechanical durability. Both embodiments passed these tests with positive results.

An Airco ILS-1600 lab coater was used to make the sandwich systems of Fig. 1 and Fig. 1A. This coater is suitable for the use of three or four targets (in this case four targets, at least two of which must be c-mag, e.g. Si and Ti). In this case, for the embodiment of Fig. 1A, cathode # 1 is titanium, cathode # 2 is silicon with 5% Al and 6% stainless steel OH17N12M2T as dopants, cathode # 3 is silver and cathode # 4 is nichrome (80/20 Ni / Cr by weight ). As noted, cathode # 1 and # 2 may be c-mag. For the embodiment of Fig. 1, the titanium cathode has been eliminated and the other three are the same.

The two-layer systems are manufactured on a monolithic sheet of clear soda-lime-silica titanium float glass 0.2 cm thick. The following coating device settings were used:

(Five-layer system - fig. 1)

<td>Layer</td><td>Material</td><td>n₂%</td><td>Ar%</td><td>Pressure (Tr)</td><td>Cathode power</td><td>Cathode voltage</td><td>Cathode current</td><td>% linear speed</td><td>Number of passes</td>

<td> 1</td><td>Silicon</td><td> 50</td><td> 50</td><td>4.0x10</td><td>4.9 kW</td><td>483 V</td><td>10.5 A.</td><td> 42,5</td><td> 9</td>

<td> 2</td><td>Nichrome</td><td> 50</td><td> 50</td><td>3.1x10</td><td>0.7 kW</td><td>387 V</td><td>2.0 A</td><td> 100</td><td> 1</td>

<td> 3</td><td>Silver</td><td> 0</td><td> 100</td><td>5.7x10</td><td>5.0 kW</td><td>498 V</td><td>5.0 A.</td><td> 100</td><td> 1</td>

<td> 4</td><td>Nichrome</td><td> 50</td><td> 50</td><td>3.1x10</td><td>0.3 kW</td><td>344 V</td><td>1.0 A</td><td> 100</td><td> 1</td>

<td> 5</td><td>Silicon</td><td> 50</td><td> 50</td><td>4.0x10</td><td>4.9 kW</td><td>483 V</td><td>10.5 A.</td><td> 45</td><td> 11</td>

(Six-layer system - fig. La)

<td>Layer</td><td>Material</td><td>N₂ cm³</td><td>Arem³</td><td>ABOUT₂ cm³</td><td>Pressure (Tr)</td><td>Cathode power</td><td>Cathode voltage</td><td>Cathode current</td><td>% linear speed</td><td>Number of passes</td>

<td> 1</td><td>Titanium</td><td> 0</td><td> 45</td><td> 15</td><td>2.0x10 '³</td><td>5 kW</td><td>580 V</td><td>8.8 amps</td><td> 45</td><td> 13</td>

<td> 2</td><td>Silicon</td><td> 80</td><td> 20</td><td> 0</td><td>2.0x10 '³</td><td>3.5 kW</td><td>550 V.</td><td>6.4 amps</td><td> 45</td><td> 1</td>

<td> 3</td><td>Nichrome</td><td> 80</td><td> 20</td><td> 0</td><td>2.0xl0 '³</td><td>0.9 kW</td><td>391 V</td><td>2.2 A</td><td> 100</td><td> 1</td>

<td> 4</td><td>Silver</td><td> 0</td><td> 100</td><td> 0</td><td>2.0x10 '³</td><td>4.4 kW</td><td>479 V</td><td>9.4A</td><td> 100</td><td> 1</td>

<td> 5</td><td>Nichrome</td><td> 80</td><td> 20</td><td> 0</td><td>2.0xl0 '³</td><td>0.3 kW</td><td>332 V</td><td>1.0 A</td><td> 100</td><td> 1</td>

<td> 6</td><td>Silicon</td><td> 80</td><td> 20</td><td> 0</td><td>2.0xl0 '³</td><td>3.5 kW</td><td>550 V.</td><td>6.4 amps</td><td> 45</td><td> 5</td>

181 209

The thickness measured by the technique n &amp; k described above is:

<td colspan="2">(Five-layer system - fig, 1)</td><td colspan="2">Six-layer system - fig. 1 A)</td>

<td>Layer</td><td>£ AI</td><td>Layer</td><td>(AND)</td>

<td></td><td></td><td>UC</td><td> 225</td>

<td>and</td><td> 450</td><td>and'</td><td> 50</td>

<td>b</td><td> 21</td><td>b '</td><td> 21</td>

<td>c</td><td> 155</td><td>c '</td><td> 166</td>

<td>d</td><td> 7</td><td>d '</td><td> 7</td>

<td>e</td><td> 550</td><td>e '</td><td> 450</td>

The optical and electrical properties of each system are as follows:

(Five-layer system - fig, 1)

<td>Glass side</td><td>Shell side</td>

<td>RgY, 1θ&gt; 2</td><td>RfY, 4.6</td>

<td>and_h, 0,4</td><td>ah, 6.5</td>

<td>b_h, -4,7</td><td>b_h, -15,8</td>

Visible light transmittance 70.9A_h, -2.4 b_h, 6,4

Electrical properties

Rs, 4.7

E._n, 0,06

E ^, 0.07 (Six-layer system - fig, 2)

<td>Glass side</td><td>Shell side</td>

<td>RgY 11</td><td>RfY, 6.0</td>

<td> 2,3</td><td>and_h, 5,4</td>

<td>K, -8.8</td><td>b_h, -17,5</td>

Visible light transmittance, 76.2A_h, -2.7 b_h, 3,1

Electrical properties

Rs, 4.8

E._n, 0,05

E._h, 0,06

The two sandwich systems, as described above, are each formed in an insulating glass unit of the type shown in Fig. 2 (coating on page 24, insulating chamber approximately 13 mm wide, argon filled or deflated). Its optical, thermal and electrical properties (using the WINDOW 4.1 technique described above) are as follows:

<td colspan="2">Six layers</td><td>Five Layers 15.0</td>

<td>RfYout.,</td><td> 15,5</td><td> 15,0</td>

<td>^andh</td><td> -0,2</td><td> -1,9</td>

<td>b_h</td><td> -2,6</td><td> -1,0</td>

<td>η γ¹ internal,</td><td> 12,6</td><td> 11,5</td>

<td>an</td><td> 0,9</td><td> 2,0</td>

<td>b_h</td><td> -5,6</td><td> -4,9</td>

<td>Light transmittance</td><td></td><td></td>

<td>visible</td><td> 70</td><td> 66</td>

<td>^andh</td><td> -2,4</td><td> -2,1</td>

<td>b_h</td><td> 1,5</td><td> 4,8</td>

<td>U value in winter</td><td>0.25 (argon chamber)</td><td> 0,26</td>

<td></td><td>0.05 (vacuum chamber)</td><td> —</td>

181 209

<td>The value of R.</td><td>4 (argon chamber) 20 (vacuum chamber)</td><td> 3,85</td>

<td>Shading coefficient</td><td> 0,53</td><td> 0,51</td>

<td>Rs</td><td> 4,8</td><td> 4,7</td>

<td>E._n</td><td> 0,05</td><td> 0,06</td>

<td>E._h</td><td> 0,06</td><td> 0,07</td>

The effect of stainless steel on optical and electrical properties is demonstrated by comparing the properties of the above five-layer (with 6 wt.% OH 17N12M2T stainless steel) with a double five-layer configuration of substantially the same thicknesses using the same three targets, except that in this in a double system, a silicon shield doped with 5% Al is used without any admixture of stainless steel. The coating equipment settings for this double sandwich system without stainless steel are as follows:

<td>Layer</td><td>Mate rial</td><td>N₂ %</td><td>Ar%</td><td>Pressure (Tr)</td><td>MoC cathode</td><td>Cathode voltage</td><td>Cathode current</td><td>% linear speed</td><td>Number of passes</td>

<td> 1</td><td>Silicon</td><td> 80</td><td> 20</td><td>2.0xl0 '³</td><td>244 kW</td><td>429 V</td><td>569 A.</td><td> 175</td><td> 1</td>

<td> 2</td><td>Nichrome</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>1.16 kW</td><td>312V</td><td>3.7 amps</td><td> 175</td><td> 1</td>

<td> 3</td><td>Silver</td><td> 0</td><td> 100</td><td>2.0xl0 '³</td><td>8.6 kW</td><td>382 V</td><td>22.5 A.</td><td> 175</td><td> 1</td>

<td> 4</td><td>Nichrome</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>0.4 kW</td><td>350 V.</td><td>1.1 A</td><td> 175</td><td> 1</td>

<td> 5</td><td>Silicon</td><td> 80</td><td> 20</td><td>2.0x10 '³</td><td>322 kW</td><td>394 V</td><td>817 A.</td><td> 175</td><td> 1</td>

The optical and electrical properties of this double monolithic five layer system (on the same glass substrate) without stainless steel are as follows:

Glass side The side of the shell

<td>RgY,</td><td>about</td><td> 13,9</td><td>RfY,</td><td>about</td><td> 7,9</td>

<td>^andh&gt;</td><td>about</td><td> 0,2</td><td>and_h,</td><td>about</td><td> 5,3</td>

<td>bh,</td><td>about</td><td> -8,8</td><td>b_h,</td><td>about</td><td> -16,4</td>

Visible light transmittance, 70.7A_h, -2.7 bh, 4.7

Electrical properties

Rs, 5.2

E._n, 0,07

E._h, 0,08

The use of stainless steel apparently results in a significant improvement in the properties of the glass product, in particular by reducing the emissivity values, which are even lower in the case of a six-layer system. For further comparison, the following properties differ from the properties of the above two embodiments of the invention by using the above-described WINDOW 4.1 technique (approximately 13 mm wide argon-filled chamber) compared to the above-mentioned known commercial Cardinal-171 insulating glass product.

Tabe 1 a 4

Properties Page 24 Page 26

<td>T. ¹ wid.</td><td> 73</td><td> 73</td>

<td>Rwid., Outside</td><td> 11</td><td> 12</td>

<td>Rwid., Inside</td><td> 12</td><td> 11</td>

<td>T._words.</td><td> 41</td><td> 41</td>

181 209

<td>Rst</td><td> 33</td><td> 36</td>

<td>Shading coefficient</td><td> 0,52</td><td> 0,62</td>

<td>Thermal energy amplification factor</td><td></td><td></td>

<td>solar radiation</td><td> 0,443</td><td> 0,531</td>

<td>Uzima</td><td> 0,25</td><td> 0,25</td>

<td>AT]_andthis</td><td> 0,24</td><td> 0,24</td>

<td>E._n</td><td> 0,051</td><td> 0,051</td>

<td>Eh</td><td> 0,060</td><td> 0,060</td>

<td>Relative heat gain</td><td> 106</td><td> 127</td>

<td>Rsiom / square)</td><td> 3,27</td><td> 3,27</td>

Color (h) Hunter illuminant C. 10 ° observer (monolithic sheet)

You, 80.7 a_h, -1.26 b_h,+2,62

RqY, 5.98 a_h, + 2.37 b_h,-5,68

RfY, 4.90 a_h, -2.01 b_h,0,60

It should therefore be underlined that this product of Cardinal-171 insulating glass has been very well received on the market. Its only drawback is its lack of chemical stability.

The exact arrangement of the layers is unknown. However, it is believed to be in accordance with U.S. Patent No. 5,302,449, cited above.

By comparing the results of the present invention with those of a commercially accepted product, it appears that the present invention has achieved a high level of competitiveness using a markedly different and less costly layering system. For example, although the Cardinal product achieves higher visible light transmission than the embodiment of the present invention (73% versus 70%), however, this 70% not only is well within the acceptable range, but when lower shading coefficients are desired as explained above (eg to reduce air conditioning costs in high outdoor temperatures), this 70% is more commercially desirable than 73%. However, it is particularly important to achieve greater chemical stability with the present invention. Both products have very low emissivities and essentially equal and excellent U-values.

Regarding the insulating glass performance mentioned above, not previously defined such as U value_winter, R value, etc., these terms are understood in the art and are used herein according to their accepted meaning. For example, the U value is a measure of the insulation performance of an insulating glass system. U values_winter and U_summer are determined according to NFRC 100-91 (1991), a standard covered by the WINDO W 4.1 software. The shading factor (SC) is determined according to NFRC 200-93 (1993) by first determining the solar thermal energy gain factor and dividing by 0.87. The relative heat gain is determined by the same procedure NFRC 200-93. T._words is the total solar energy transmittance, which is known to be the combination of ultraviolet, visible and infrared transmittance. Likewise, Ιζ] denotes total solar reflectance, which is known to be the combination of ultraviolet, visible and infrared reflectance.

Figure 3 shows a typical family home 28 with various openings in which the present invention is applied. For example, window 30 may use either a monolithic glass pane with the layered glass of the invention on the pane, or may use

181 209 as a storm window a coated glass pane according to the present invention bonded to a double glazing unit as shown in Fig. 2. Likewise, sliding wall 32 or fixed wall 34, as well as front door 36 may be constructed using the present invention or as a monolithic glass pane. or as an insulating glass unit.

Figure 4 is a schematic diagram of a coated glass article bonded into a conventional two-pane unit during manufacture prior to sealing. In certain example embodiments of this invention, as already stated above, the layered systems are heat treatable. In Fig. 4, the pre-assembly uses two conventional clear float panes 31 and 33 positioned at a selected distance from each other (e.g. 0.1 mm) that is held by glass spheres 35. The lower pane 33, with dimensions slightly larger than the upper pane 31, has a laminate 37 according to the present invention sputtered on its inner flat surface (optionally the inner flat surface of the pane 31 can be used for the layering). Then, conventional sealant 39 (e.g., low melting point ceramics) is placed in the circumferential region 41 defined by centering the smaller pane 31 on the larger pane 33.

Sufficient heat is applied conventionally (e.g., a temperature of approximately 500 ° C) to melt the sealant 39 and thereby form an insulating chamber 43. During this process, as much air and water vapor as is economically possible is removed by vacuum in this process and either a vacuum is left or the air and water vapor are replaced with an inert gas such as argon. The edges of the glass can also be flame fused instead of using sealant. In either case, heat must be applied to seal and remove the water vapor. The heat treatable embodiments of the present invention thus find a unique possibility of being used in insulating glass assemblies of the type shown in Fig. 4 where the sandwich system must be resistant to the applied temperature during sealing without adversely affecting its desired properties.

In another alternative, no pumping is used, and a gap of about 13 mm for the chamber is caused by various known, conventional methods. In such a process, the isolation chamber is usually filled with argon to displace air and water vapor.

181 209

<img file="PL181209B1_D0001.tif" />

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