Low-e glass coated with double silver and thermally insulating units made thereof

The present invention relates to a coated glass article and a low emissivity glass insulating unit.

Background of the invention

The importance of sputter-coated glass systems for the controlled supply of solar energy through windows and doors in architecture is now well established commercially. Moreover, the importance of using such sandwich systems in insulating glass units (known in the art as "IG" units) is also well received. Examples of the latter application include double and triple glazed windows and doors made of at least two glass panes sealed at their edges to form an insulated chamber between them. Such chambers, in this regard, are often filled with a gas other than air, such as argon.

Relevant to accepting such units in the drawing are the following properties which are directly related to the sputter coated layer system and include:

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1) a desired amount of visible transmittance coupled with an acceptable level of infrared reflectance;

2) non-mirror appearance;

3) an appearance in a color that is either neutral or within the range of acceptable shades of undisputed color;

4) resistance to weathering or other chemical attack, often referred to as "chemical stability"; and

5) resistance to abrasion (often referred to as "mechanical durability") during handling, in particular during the various steps necessary to manufacture an IG window or door from two or more glass panes, at least one of which has been sputter coated with the above layer system.

In addition to these physical properties, the coating system used must be economically viable to produce. If it is not, the end product, such as an IG unit, may become too expensive which will hold back demand.

It is well known in the art that when desirable properties are desired they are often difficult to reconcile and therefore compromises often become necessary. For example, achieving acceptable levels of transmittance or IR (infrared) reflectance may come at the expense of durability (either chemical or mechanical, or both). Other compromises, unwanted staining and mirrored windows (or doors) are unavoidable. In still further calculations, the manufacturing cost becomes a significant factor. Such problems create the need for new sputter-coated layer systems that can provide a better balance between these properties.

U.S. Patent No. 5,344,718 discloses various excellent sputter-coated layer systems that achieved acceptably low emissivity (E) values ​​and thus correctly classified as the "low-E" family of systems (e.g., the family of high reflectance coatings). IR as defined below). Moreover, such coating systems, as a family, generally exhibit durability properties that are close to or equal to pyrolysis coatings, and therefore entirely acceptable. Still further, these coatings, especially in their preferred embodiments, exhibit high visible transmission. At the same time, they show a suitably neutral color, in the range slightly shifting to the green side of the blue, which is suitably masked by the reflection level achieved and thus appear essentially neutral. Moreover, their visible reflection characteristics are below 20%, thus avoiding the undesirable mirror-like appearance both when viewed from outside and inside; when used for example as windows or doors.

Different layers of Si are used in the family of layer systems disclosed in US Patent No. 5,344,718₃N₄ and nickel or nichrome for depositing one or more silver metallic IR reflecting layers therebetween, in a selected order, thereby obtaining the desired final properties. The entire disclosure of this patent, including its prior art, is provided herein by reference.

Generally speaking, the solution of this specification (5,344,718) achieves unique results by using an array of five or more layers, and from the glass towards the outside, the array comprises:

a) Si backing layer₃N₄;

b) a layer of nickel or nichrome;

c) a layer of silver;

d) a layer of nickel or nichrome; and

e) a Si surface layer₃N₄.

When the system consists essentially of five (5) layers, the thicknesses generally used are as follows:

Layer Scope (approximate)

a) (Si₃N₄) 400 A - 425 A.

b) (Ni or Ni: Cr) 7 A or less

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c) (Ag) 95A -105 A

d) (Ni or NirCr) 7 A or less

e) (Si₃N₄) 525 A - 575 A.

When more than five layers are used in the system of this description (5,344,718), for example when two silver layers are used, the glass outward system typically comprises layers:

glass / Si₃Ń₄/ Ni: Cr / Ag / Ni: Cr / Ag / Ni: Cr / Si₃N₄, while maintaining the same total thickness (e.g. 95-105A) so that each layer of silver alone is only about 50A to maintain the given total amount, while the thickness of the Ni: Cr and Si layers₃N₄ it is the same as in a five-layer system.

Although systems such as those disclosed in the prior art (Patent 5,344,718) represent a significant improvement over existing known systems, particularly those described in the prior art section of this specification; however, there remains the issue of improving the emissivity. For example, in the systems of Patent 5,344,718, the normal emissivity (E_n) was generally less than or equal to about 0.12, while the hemispherical emissivity (E_h) was generally less than about 0.16. However, in practice, the lower limits actually achieved were generally for E._n about 0.09 and for E._h about 0.12. The obtained resistances of the sheet (R.) in this regard were generally from about 9-10 ohms /_sq.

Regarding the inhibition of achieving better IR reflection (i.e. The lower "E" value), it was generally held that if the silver thickness was increased to achieve higher IR reflectance (and therefore lower "E" values), one or more of the following four effects should occur: (1) a loss of durability could occur; (2) the final product could be too reflective and become mirrored; (3) the color could go unacceptably to highly purple or red / blue; and / or (4) visible transmission could become unacceptably low.

Durability, both mechanical and chemical, is generally an important factor for obtaining architectural glass either as monolithic panes or, for example, in the form of IG units. As stated above, the handling, assembly and sealing of IG units comes first in terms of mechanical durability, while the need to seal the panes at the edges to form an insulating chamber between them creates the need for chemical durability, mainly due to the nature of the sealant that will come into contact with the shell is inevitable.

Aesthetically, both the mirror-like appearance and the purple color can reduce the demand for a product with such features. Loss of visible transmittance, although undesirable, in fact does not become unacceptable until it drops below about 70% in monolithic glazing and in IG units until it drops below about 63%. However, in some applications, especially where low shading coefficients (i.e. less than about 0.6), the transmittance may currently be too high, even though the emissivity is reasonably low. Generally speaking, where shading is desired (e.g. to reduce air-conditioning costs), the visible transmission of monolithic glazing should be kept below 75% and preferably below 73%, whereas in a typical IG unit the transmission should be about 65% to 68%.

In part, this belief is supported by the rather complex sandwich system disclosed in U.S. Patent No. 5,302,449 as well as its putative commercial counterpart IG unit known as Cardinal 171 sold by Cardinal IG Company. The layer system described in this patent differs in the thicknesses and types of materials in the overlapping layers to achieve a certain controlled supply of solar energy, as well as the use of an outer coating of zinc, tin, indium, bismuth or oxides and their alloys including zinc oxide. for resistance to abrasion. In addition, this system uses one or two layers of gold, copper or silver to achieve the end result. When two silver layers are used, the thickness of the first is said to be between 100 Å-150 Å and preferably

179 946 approximately 125A, while the thickness of the second one based thereon is between 125A-175A. When using only one silver layer, its thickness is stated to be about 100 Å -175 Å, preferably 140 Å, nowhere in this patent discloses the use of nickel or nichrome or the use of silicon nitride as component (s) in overlapping layers.

In current industrial practice, it has been found that the above-mentioned Cardinal IG units achieve satisfactory controlled solar input characteristics, including acceptable color characteristics and relatively good non-specular visible light reflectance (a comparative example is given below). However, this otherwise quite acceptable system has been found to have chemical resistance, and according to the definition given herein, it can be said to lack chemical resistance because it fails in the cooking test performed. Although the exact cause is not known, the simple conclusion is that, as indicated in the art, at least one desired property must be sacrificed to obtain the desired levels of others. Moreover, due to the nature of the layers applied and the elements used, the system is expensive to produce mainly because of the number and thickness of the layers required to obtain the desired result.

In the prior art section, US Patent No. 5,344,718 discloses a further layered system of architectural glass, which is commercially known as Super-E III, from Airco Corporation. This arrangement, starting with the glass towards the outside, consists of the following layers superimposed on top of each other:

Si₃N₄/ Ni: Cr / Ag / Ni: Cr / Si₃N₄

In practice, it was found in this Super-E III system that the Ni: Cr alloy is degreeNi / Cr, correspondingly 80/20 by weight (i.e. nichrome), it is stated that the two layers of nichrome are 1k thick, the Ag layer as stated is only about 70 A thick. (unless indicated that the silver may be 100 Å thick) and the layers of Si₃N₄ they are relatively thicker (e.g., 320 Å substrate and about 450 Å topcoat). In fact, due to its thinness (e.g., around 70 Å), it has been found in practice that the silver (Ag) layer is rather semi-continuous in nature.

While this coating achieved a good "durability" (e.g. the coating was scratch-resistant, wear-resistant and chemically stable), it thus achieved an important dimension of this property compared to pyrolytic coatings, for about 3 mm thick glass, E_h was only about 0.20-0.22 a E_h was about 0.14-0.17. Both of these emissivity values ​​are rather high. Moreover, the measured sheet resistance (R ^) was relatively high 15.8 ohms /_hv(a more acceptable value is around 10.5 or less). Thus, while both the mechanical and chemical durability are acceptable and the visible transmittance of the monolithic pane is rather high 76 ± 1% and while the coatings have been proven to be compatible with traditional sealants used in IG units, their ability to cope with infrared radiation is less than satisfactory. Moreover, their rather high monolithic visible transmission of 76 ± 1% makes such an arrangement rather undesirable when less shading properties are required.

Following the Super-E III layout, Airco designed the Super-E IV layout. This arrangement includes as layers superimposed on the glass towards the outside:

Element Thickness (A)

TiO₂ about 300

NiCrN_x around 8

Ag around 105

NiCrN_x around 8

Si₃N₄ about 425

This system is very similar in behavior to the Super-E III system, except that visible transmittance is greater (e.g., greater than 80%), emittance is lower (e.g., less than about 0.10), and the shading coefficient is much greater (e.g., about 0.8). Moreover, due to the use of TiO₂ as a substrate layer, the system is expensive to manufacture.

In addition to this Super-E III layer system, other coatings containing silver and / or Ni: Cr as layers for reflecting infrared radiation have been described in the patent and scientific literature.

179 946 heating and for other thermal management purposes. See, for example, Fabry-Perot filters and other known coatings and techniques disclosed in U.S. Patent Nos. 3,682,528 and 4,799,745 (and the prior art discussed and / or cited therein). See also dielectric metal layering systems described in numerous patents, including, for example, U.S. Patent Nos. 4,179,181, 3,698,946, 3,978,273, 3,901,997 and 3,889,026 to name a few. Although such other coatings have been known or reported in the art for the present invention, none of the disclosures teaches or achieves the possibility of using highly productive sputter coating methods while simultaneously producing architectural glass that not only would be close to or equal to pyrolytic coatings, but which would also achieve perfect regulation of the solar energy input.

Briefly, the above factors in the prior art would directly dissuade one skilled in the art from any rational suggestion that substantial silver thickening in a system such as the family of chips in US Patent No. 5,344,718 coupled with appropriate Si thickness adjustment₃N₄ will achieve the full range of desired properties, especially the combination of properties: (1) acceptable, non-purple / blue or non-red / blue color; (2) non-mirror appearance on both sides, inside and out; (3) reasonably high transmission values; (4) good mechanical durability; (5) excellent chemical stability; and (6) extremely low emissivity values.

In our parallel application lot 08 / 356,515, filed December 15, 1994 and entitled "Low-E Glass Coating System and Glass Insulating Units Made Thereof," we disclose a family of layer systems that meets the needs of the art with respect to the above-described problems and drawbacks. . The layer system disclosed therein generally comprises from the glass to the outside:

a) Si layer₃N₄ about 450 A - 600 A thick;

b. a nickel or nichrome layer about 7A or less thick;

c) a silver layer approximately 115A-190A thick;

d) a nickel or chromium layer about 7A or less thick;

e) Si layer₃N₄ about 580 A to 800 A thick;

and wherein, when the glass substrate is about 2mm-6mm thick, the coated glass substrate has a visible transmission of at least about 70%, the normal emissivity (E_n) less than about 0.07, the hemispheric emissivity (E_h) less than about 0.075, sheet resistance (R5) less than about 5.5 ohms /_sq and has the following reflectance and color coordinates where the characteristics on the glass side are as follows:

R_gY about 12 to 19 a_h about -3 to +3 b_h approximately -5 to -20 and wherein the film side characteristics are as follows:

R_fY about 8 to 12 a_h about 0 to 6 b_h about -5 to -30 wherein RY is reflectance a, a ^ b_h are color coordinates as measured in Hunter II1 .C units. 10 ° observer.

In some embodiments of this parallel invention, a glass sheet provided on one of its sides with the layered system described above is used with at least one other glass sheet in such a way that each is substantially parallel to the other but is spaced a distance therefrom. , is sealed at the edges forming an insulating chamber between them and thus forming an insulating glass unit (IG) suitable for windows, doors or walls, the layer system is located on surface 24 as shown in Fig. 2 such that the reflectance and color coordinates have the following characteristics when viewed from outside:

RqY about 16 to 18 a * about -3 to +3

179 946 b * around Odo-15 when viewed from the inside:

R_fY about 14 to 16 a * about 0 to +5 b * about 0 to -20 and the visible transmission is at least about 63% and preferably about 65% - 68%. When the coating system is located on surface 26 (Fig. 2), the reflectance and color coordinates are opposite to those given above, but the transmittance remains the same. The asterisk (*) here refers to the color coordinates as described below as measured by conventional technique III. C, 2 ° observer.

The term "outside" as used herein means that an observer is looking from outside the dwelling in which a coated glass sheet (eg, IG unit) is used. As used herein, the term "inside" means that the side is viewed by an observer from inside the apartment in which the unit is located (eg, from a room of a house or office building) looking towards "outside".

The layer system disclosed in this parallel invention is highly effective. These systems not only achieve the excellent characteristics of a regulated solar input but are also tangibly non-reflective (e.g. below an undesirable 20% level) and both (chemically and mechanically) durable. However, it has now surprisingly been found and it is part of the invention that: (1) by using a double silver layer system with an even more combined thickness than in this known parallel invention, (2) by using a correspondingly thick middle Si layer₃N₄, in addition to the Si backing and top layer₃N₄, and (3) by separating each layer with a nucleating layer of nickel or nichrome, a further reduction in reflectance is achieved without unduly affecting the other desirable characteristics given above.

Summary of the invention

Generally speaking, the invention achieves its unique results by providing a sputter coated glass article comprising a glass substrate having a layered array thereon sequentially from the glass substrate outwardly:

a) Si layers₃N₄ about 300 A - 550 A;

b. nickel or nichrome layers about 7A or less thick;

c) about 70 Å thick silver layers - 130 Å thick;

d. nickel or nichrome layers about 7A or less thick; and

e) Si layers₃N₄ about 700 Å to 1100 Å thick;

f. Nickel or nichrome layers about 7 Å thick or less;

g) about 70 Å thick silver layers - 190 Å thick;

h. Nickel or nichrome layers about 7 Å thick or less; and

i) Si layers₃N₄ about 350 A - 700 A.

In some preferred embodiments, the thicknesses of the above layers are as follows: layer thickness (A) a about 350-450 b about <7 c about 100 -125 d about <7 e about 900 -1,000 f about <7 g about 140 -170 h about <7 and about 400 -500

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In some particularly preferred embodiments, the thicknesses of the individual layers are as follows:

layer thickness (A) a about 400 b about 7 c about 110 d about 7 e about 950 f about 7 g about 155 h about 7 and about 450

In such articles as contemplated by the present invention, when said glass substrate is about 2mm - 6mm thick, the coated glass substrate has a visible transmission of at least about 70%, preferably about 72% - 76%; normal emissivity (E_n) about 0.02-0.09, preferably about 0.03-0.06; hemispheric emissivity (E_h)) about 0.03-0.12, preferably about 0.04 to 0.07; sheet resistivity (RJ of about 2-10, preferably 3-5, and has the following reflectance and glass-side color coordinates:

RgY, less than about 10, preferably about 4-7;

and_h about -3 to +5, preferably about +2.5 to +4.5; and b_h about 0 to -10, preferably about -4.0 to -8.0;

and in which the characteristics from the film side are as follows

R_fY, less than about 10, preferably about 3-7;

and_h about -3 to +5, preferably about 0.0 to 2.0; and b_h about 0 to -10, preferably about 0.0 to -2.0;

where RY is the reflectance and a_h, b_h are the color coordinates as measured in Hunter units, IIL, C., 10 ° observer.

In some embodiments of the present invention, a glass pane provided on one side with a layer system as described above is used with at least one other glass pane such that each is substantially parallel to the other but spaced apart and sealed to it at its extremities. edges so that they form an insulating chamber between themselves, thus creating a glass insulating unit, useful as a window, door or wall, wherein the layer system is located on the surface 24 as shown in Fig. 2 wherein the reflectance and the color coordinates have the following characteristics:

when viewed from the outside

R 5 Y is less than about 16 and is preferably 9-12;

a is about -3.0 to +3.0, and preferably about 0.0 to +2.0;

b * is about 0.0 to -8.0 and preferably about -4.5 to -6.5 when viewed from the inside

R_fY is less than about 15 and is preferably about 9-12;

a * is about -3.0 to +3.0, and preferably about 0.0 to +2.0;

b * is about 0.0 to -8.0, and preferably about 0.0 to -2.0;

and visible transmission is at least about 63% and preferably about 65% 68%. When the coating system is located on surface 26 (Fig. 2) the reflectance and color coordinates are the reciprocal of the above, but the transmittance remains the same. As noted above and described below, the asterisk (*) indicates III.C, 2 ° observer.

The invention will now be described with reference to some embodiments thereof, with reference to the accompanying drawings in which:

Figure 1 shows a partial side section view of a layer system according to the invention.

Figure 2 is a partial cross-sectional view of an IG unit contemplated in this invention; and

Figure 3 is a partial schematic perspective view of a house using the window, door and walls of the IG units shown in Figure 2.

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Detailed Description of Embodiments of the Invention

Certain terms are commonly used in the field of glass coating, particularly in determining the properties and control characteristics of the solar energy delivery through coated glass, in the architectural field. These terms are used herein in accordance with their well-known meanings. For example, they are used here:

The light intensity of the visible wavelength "reflectance" (reflectance) is defined as its percentage and is given as ItyY, where X is either "G" on the glass side or "F" on the film side. By the side of the glass (i.e., "G") it is meant that the side of the glass (i.e., "G") is viewed from the side of the glass substrate, opposite to that on which the coating is provided, while the film side (i.e. "F") means you are looking at the glass pane from the side on which the coating is located on the glass substrate. Alternatively, it is referred to as "R ^ knitted from the outside" or "R ^ taken from the inside" P¹^ ^party^m "G" is equivalent to "outside" and "F" is equivalent to "inside".

Color characteristics are measured at the "a" and "b" coordinates. Sometimes these coordinates are marked with the index "h" to denote the use of the traditional Hunter method (or units) III.C, 10 ° observer, according to ASTM E 308-85, Annual Book ASTM Standards, vol. 06.01 "Standard Method for Computing the Colors of Objects by Using the CIE Systems ”. Other times they are marked with an asterisk (*) to indicate the alternative traditional standard, ie III. C, 2 ° observer also published in the above-mentioned ASTM E 308-85.

The terms "emissivity" and "transmittance" are well known in the art and are used herein with their well-known meanings. Thus, the term "transmittance" as used herein means solar energy transmittance, which includes visible light transmittance, infrared energy transmittance, and ultraviolet light transmittance. Total solar energy transmittance is typically characterized as a weighted average of these other values. With regard to these transmittances, visible transmittance as reported herein is characterized by the standard technique of Illuminant C at 380-720 nm; infrared 800 - 2100 nm; ultraviolet 300 - 400 nm; and the total solar energy is 300 - 2100 nm. However, for the purposes of emissivity, a specific infrared range (ie, 2500 - 40,000 nm) was used as discussed below.

Visible transmittance can be measured by known traditional methods. For example, by using a spectrophotometer such as a Beckman 5240 (Beckman Sci. Inst. Corp.) spectral transmission curves are obtained. Visible transmittance is then calculated using the above-mentioned ASTM-308 "Method for Computing the Colors of Objects by Using the CIE Systems" (Annual Book of ASTM Standards vol 14.02). Optionally, fewer wavelength points than prescribed may be used. Another technique for measuring visible transmission uses a spectrometer, such as the commercially available Spectragard spectrophotometer from Pacific Scientific Corporation. This device measures and reports visible transmittance directly. As stated and measured herein, visible transmission is measured by a Hunter III.C. technique, 10 ° observer (unless otherwise stated).

"Emissivity" (E) is a measure or characteristic of both the absorption and reflectivity of light at a given wavelength. It is usually represented by the formula:

E = 1 - reflectance f_llm

For architectural purposes, the emissivity values ​​become quite important in the so-called "mid-range", sometimes also called "far-range" of the infrared spectrum, i.e. around 2,500 - 40,000 nm, for example as specified by WINDOW 4.1, LBL-35298 (1994 ) by Lawrence Berkley Laboratories as described below. The term "emissivity" given herein is therefore used to give an emissivity value measured in this infrared range as specified by the 1991 Proposed ASTM Standard to measure infrared energy for the calculation of emittance as proposed by the Primary Glass Manufacturersf Council and entitled "Test Method for Measuring and Calculating Emittance of Architectural Fiat Glass Products Using Radiometrie Measurements ”. This standard and its clauses

179 946 is hereby incorporated by reference. In this standard, the emissivity is reported as hemispherical emissivity (E._h) and normal emissivity (E_n).

The actual data collection for measuring such emissivity values ​​is known and can be performed by 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 above-mentioned 1991 Proposed ASTM Standard which is hereby incorporated by reference.

Another term as used herein is "sheet resistance". Pane resistance (R._s) is a well-known term in the art and is used herein according to its well-known meaning. Generally speaking, the term refers to the resistance in ohms of any square (kw) of a layer system on a glass substrate to an electric current passing through the layer system. Pane resistance is an indication of whether a layer is good at reflecting infrared energy and is therefore often used together with emissivity as a measure of this property, so important in many architectural glasses. The "pane resistance" is conveniently measured using a 4 point ohmmeter probe such as the 4 point redundant resistivity probe from Magnetron Instruments Corp. warhead, Model M-800 by Signatone Corp., From Santa Clara, California.

The term "chemical stability" is used synonymously herein with the prior art terms "chemical resistance" or "chemical stability". Chemical stability is determined by boiling a 2 "x 5" sample of the coated glass substrate to approximately 500 cm³ 5% HCl for 1 hour (i.e. at about 100 ° C). A sample is considered to have passed this test (and thus the layer system is considered to be "chemically stable") if the layer system of the sample shows no pitting greater than about 0.0762 mm in diameter after one hour of cooking.

The term "mechanical durability" as used herein is defined by one of two tests. The first test uses the Pacific Scientific Abrasion Tester (or its equivalent) in which a 2 ”x 4” χ 1 ”(5 cm χ 10 cm x 2.5 cm) nylon brush is cycled over the layering for 500 cycles with a load of 150 g applied to a 6 "x 17" (15 cm x 42 cm) sample. In the second alternative test, a conventional Taber grinder (or equivalent) is used by subjecting a 4 "x 4" (10 cm χ 10 cm) sample to 300 revolutions of two CS 10F grinding wheels, each loaded with a weight of 500 g. the sample has passed the test and the product is mechanically stable if, in each of the two tests, no significant, noticeable scratches appear when viewed with the unaided eye in visible light.

The thickness of the various layers in the given systems is measured by, and thus as used herein, the term "thickness" is defined by the use of known optical curves or alternatively by the use of a conventional needle ellipsometer. These procedures and techniques are well known to those skilled in the art and thus need not be further elucidated except that the optical thicknesses are given in angstroms.

Returning now to Fig. 1, a partial sectional sketch of a typical embodiment of the invention is shown. As can be seen, a typical glass substrate 1 traditionally used in architecture is used. Such glass is preferably produced by the traditional "floaf" process and is therefore referred to as "flotation glass". The usual thickness is from about 2mm - 6mm. The composition of the glass is not critical and can vary widely. The commonly used glass is glass from the family of well-known soda-lime-silica glasses.

The method and apparatus used to form layers 2a-e, 3a-d and 4a, b on the glass substrate 1 may be a conventional multi-chamber (multi-target) sputtering system, may be such as manufactured by Airco, Inc. In this regard, the preferred sputter coating process herein is the same as that disclosed in US Patent No. 5,344,718, the entire disclosure of which is discussed above.

Layers 2a, 2b and 2c are layers consisting of Si₃N₄, optionally with a small amount of the dopant material and / or other Si-sputtering target material and used with it, for example in an anti-cathode, for example to keep the anode conductive. This concept is contained in co-pending United States Patent Application Serial No. 08 / 102,585 filed August 15, 1993, now Patent No. 5,403,458. Such

179 946, the selection of the target dopant and / or conductive materials is usually kept to a minimum so as to achieve their purpose and not to interfere with the purpose of Si₃N₄ in the system.

The thickness of the backing layer 2a is about 300 Å - 550 Å. This thickness has been found to be important in achieving the objectives of this invention.

Preferably, the thickness of layer 2a is above 350A-450A and most preferably about 400 Å. The thickness of the face layer 2c is around 350 Å-700 Å. Preferably, the thickness of layer 2c is around 400 Å -500 Å and the most preferred thickness is around 450 Å. Such thickness has been found to be important in order to achieve the object of the invention.

The four layers 3a, b, c and d are sandwich layers, nucleation for the two silver layers 4a and 4b. These seed layers 3a, 3b, 3c and 3d consist essentially of metallic nickel or metallic nichrome (e.g. 80/20 Ni: Cr by weight). When nichrome is used, it is preferred that at least some of the chromium is sputtering converted to nitride as set forth and for the reasons given in US Patent 5,344,718. The thickness used for these four seed layers is preferably the same as in description 5,344,718, i.e. less than 7 Å, and preferably about 8 Å or less.

A significant feature of this invention is its uniqueness in relation to the above-described prior art, which consists in the use of double, suitably thick metallic silver layers 4a, 4b in combination with the middle layer 2b, which is a significantly thick layer of Si₃N₄. Layer 2b is combined with layers 4a and 4b which are two of the four seed layers 3b and 3c described above.

The metallic silver layer 4a is the underside of silver and its thickness should be about 70 Å -130 Å, preferably around 100 Å -125 Å and most preferably around 110 Å. The silver metal layer 4b is an overlay silver and should be about 70 Å thick. 190A, preferably 140A-170A and most preferably about 155A. Together, these two layers are essential reasons why the invention achieves its low emissivity discussed above. In this regard, it is preferable that the top silver layer 4b is thicker than the bottom silver layer 4a. The emissivity is thus generally governed by the different thickness of the top silver layer, while the bottom silver layer has little effect on the emissivity. However, both layers greatly contribute to achieving the desired visible transmission, reflection and color characteristics. In this regard, to achieve the emissivity level as above-mentioned, without adversely affecting other desirable characteristics, the total thickness of the layers 4a, 4b should be about 200 A - 300 A, preferably about 225 A - 275 A and most preferably 265 A.

Middle layer of Si₃N₄ marked with 2b is important to this invention. It is constructed to be substantially thicker than the other two Si layers₃N₄, 2a and 2c, and in its preferred embodiment, it is substantially thicker than the layers 2a and 2c. While the reasons why this is not fully understood, it is believed that such a thick layer 2b allows the use of a rather thicker bonded silver layer giving a low emissivity value while still providing the desired levels of resistance (chemical and mechanical), low non-mirror reflectance (e.g._G. Y and RfY less than about 10 for monolith and less than about 16 in IG units), visible transmission, and significantly neutral and non-purple color characteristics, both for monolithic glass and IG units. Thus, in order to achieve these goals, the middle Si layer₃N₄, 2b should have a thickness of about 700 Å -1,1000 Å, preferably 900 Å, 000 Å and most preferably about 950 Å.

The sandwich system of the invention described with reference to Fig. 1 achieves a unique combination of regulated solar energy management which becomes particularly desirable when coated glass is used in an IG unit as schematically illustrated in Fig. 2 (discussed below). Generally speaking, the glass substrate is about 2mm-6mm thick; a monolithic coated glass sheet (using clear glass of course) has a visible transmission of at least about 70% and preferably about 72% - 76%. The latter range obviously gives excellent visibility, but the given nature of the layer stack according to the invention still achieves excellent shading properties. Moreover, the coated glass sheet has a normal emissivity (E_n)

179 946 of less than about 0.02-0.09, preferably about 0.03-0.06; hemispheric emissivity (E_h) less than about 0.03-0.12, preferably about 0.03-0.08, and a pane resistance (RJ less than about 2-10 ohms /_sq. hereinafter still such monolithic coated glass sheet will have the following reflectance and color coordinates:

<td>A wide range</td><td>beneficial</td><td>most preferably</td>

<td>RqY less than about 10</td><td>about 4-7</td><td>about 5</td>

<td>and_h around -3 to +5</td><td>about +2.5 to 4.5</td><td>around +4</td>

<td>b_h about 0 to -10</td><td>about -4.0 to -8.0</td><td>about -7 to -8</td>

<td>R_fY less than about 10</td><td>about 3 to 7</td><td>about 3 to 4</td>

<td>and_h around -3 to +5</td><td>about 0.0 to +2.0</td><td>about +1 to +2</td>

<td>b_h about 0 to -10</td><td>about 0.0 to -2.0</td><td>around -1</td>

As can be seen, the reflectance characteristics of the inventive product distinguish it from the significantly different reflectance characteristics of the parallel embodiments of the present invention that do not use a Si middle layer.₃N₄ and a single layer of silver. In this regard, it should be understood that in our parallel invention, the reflectance characteristics have achieved satisfactory results in some important part of the consumers by achieving higher reflectance, e.g. R ^ Y around 12 -19 and R_fY about 8-12 for monolithic forms. Whilst "non-mirrored", the final product has achieved basic aesthetic values, which in some important part of the market for a specific population are demanding architectural glass windows. In the subject matter of the invention, on the other hand, other important parts of the market have been satisfied by achieving substantially low reflectance ratios of less than about 10 for R ^ Y and R_fY, preferably about 4-7 and 3-7 for R 1, Y and R_fY respectively, for monolithic forms. At the same time, as can be seen from the color coordinates, substantially neutral color values ​​are achievable without the masking effect that was needed to achieve the neutral color in practicing the above parallel invention. In addition, excellent values ​​for low-E, strength (chemical and mechanical) and permeability have been achieved; both for a single glass pane and in IG units (discussed later).

As stated above, figure 2 only schematically illustrates a typical IG unit according to the present invention. In order to distinguish "inside" the IG unit is labeled "inside" and "outside" is labeled "outside", the sun 9 is schematically shown. As can be seen, such IG unit is made of an "outer" glass sheet 11 and an "inner" glass sheet 13. These two glass panes (eg. 2mm - 6mm thick) are sealed at their extreme edges by a conventional sealant 15 and a drying strip 17. The panes are then seated within 19 of a conventional window or door (shown in part in schematic form). By sealing the edges of the glass sheets and replacing the air in the chamber 20 with a gas such as argon, a typical high value IG unit is created. Chamber 20 is typically about 1/2 "(1.27 cm) wide.

By using the stack of layers described above as a layer 22 on the wall 24 of the outer glass sheet 11 in the chamber 20 as illustrated, or alternatively on the wall 26 of the inner glass sheet 13 in the chamber 20 (not shown) a particularly unique, non-mirror, non-purple red / red color is created. blue IG unit. In this regard, it should be understood that Fig. 2 illustrates only one embodiment of an IG unit in which the unique layered systems of the invention are used. In fact, the sandwich systems of the invention generally are available for use with a wide variety of IG units, including those of more than two panes. Generally speaking, however, the IG units of the invention, when having a layering positioned on the wall of one of the two glass panes in the chamber of an insulating IG unit, will typically have the following characteristics:

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Table 1

<td rowspan="2">Performance characteristics</td><td colspan="2">Wall 24</td><td colspan="2">Wall 26</td>

<td>Range</td><td>Recommended</td><td>Range</td><td>Recommended</td>

<td>Perceptible transmittance (%)</td><td> &gt;63</td><td> 65-68</td><td>same</td><td>same</td>

<td>Reflection (%, visible from the outside)</td><td> &gt;16</td><td> 9- 12</td><td> &lt;15</td><td> 8- 11</td>

<td>Reflections (% visible, inside)</td><td> &lt;15</td><td> 8-11</td><td> &lt;16</td><td> 9- 12</td>

<td>Shading coefficient (SC)</td><td> &lt;15</td><td> 8-11</td><td> &lt;16</td><td> 9-12</td>

<td>Solar Heat Gain Coefficient (SC x 0.87)</td><td></td><td></td><td></td><td></td>

<td>U (Winter) [BTU / ft²/ hr / ° F]</td><td> 0,20 - 0,30</td><td> 0,25</td><td>same</td><td>same</td>

<td>U (Summer) [BTU / ft²/ hr / ° F]</td><td> 0,24 - 0,26</td><td> 0,24</td><td>same</td><td>same</td>

<td>Relative heat gain [BTU / ft / hr ° F]</td><td> 90 - 100</td><td> 92 - 102</td><td> 100 - 140</td><td> 120-130</td>

<td>Color Characteristics</td><td></td><td></td><td></td><td></td>

<td>You</td><td> 63-70</td><td> 65-68</td><td></td><td></td>

<td>and</td><td>-5 to +5</td><td>Odo -4</td><td>same</td><td>same</td>

<td>b '</td><td>-10 to +10</td><td>0 to +4</td><td>same</td><td>same</td>

<td>Ry outside (R approximately, outside visible range, above)</td><td></td><td></td><td></td><td></td>

<td>and'</td><td>+3 to -3</td><td>0 to -2.0</td><td>+3 to -3</td><td>0 to +2</td>

<td>b '</td><td>Odo-8</td><td>-4.5 to -6.5</td><td>Odo-8</td><td>Odo-2</td>

<td>Ry inside (roughly R, visible range inside, above)</td><td></td><td></td><td></td><td></td>

<td>and</td><td>+3 to -3</td><td>0 to +2</td><td>+3 to -3</td><td>0 to -2.0</td>

<td>b '</td><td>Odo -8</td><td>0 to -2.0</td><td>Odo-8</td><td>-4.5 to -6.5</td>

An asterisk () indicates the measurement with the mentioned technique ΙΠ. C. 2 ° ASTM observer.

In addition to the above characteristics, in some recommended applications, the following performance characteristics have been obtained when such a system is used on an IG unit with a 1/2 "wide argon-filled chamber when this characteristic was processed by a computer program known as" Window 4.1 "with Lawrence Berkeley Laboratories in Berkeley, California, and additionally using a Hitachi spectrophotometer, the following input data was obtained for: (1) perceived and visible transmittance; (2) solar reflection on the layer and glass side; and (3) measuring the emittance with a Beckman infrared spectrophotometer.

WINDOW 4.1, 1988-1994, is the copyright of the University of California Authority and is entitled "Fenestration Production Thermal Analysis Program".

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Table 2

<td>Performance characteristics</td><td>Wall 24</td><td>Wall 26</td><td>Monolithic tile</td>

<td>Twidzial</td><td> 66</td><td> 66</td><td></td>

<td>R-visible, from the outside</td><td> 9</td><td> 11</td><td></td>

<td>^ visible, inside</td><td> 11</td><td> 9</td><td></td>

<td>Solar</td><td> 36</td><td> 36</td><td></td>

<td>^ - solar</td><td> 32</td><td> 36</td><td></td>

<td>Shading coefficient</td><td> 0,46</td><td> 0,61</td><td></td>

<td>Heat gain coefficient</td><td> 0,392</td><td> 0,522</td><td></td>

<td>solar</td><td> 0,25</td><td> 0,25</td><td></td>

<td>Uzima</td><td> 0,24</td><td> 0,24</td><td></td>

<td>Ubato</td><td> 0,054</td><td> 0,054</td><td></td>

<td>En</td><td> 0,060</td><td> 0,060</td><td></td>

<td>Eh</td><td> 94</td><td> 125</td><td></td>

<td>Relative heat gain R._s(ohms / kw.)</td><td> 3,39</td><td> 3,39</td><td></td>

<td>Color (ULC.2 ° observer)</td><td></td><td></td><td>(h) Kutner, Observer III.</td>

<td></td><td></td><td></td><td>C. 10 °</td>

<td>You</td><td> 65,7</td><td> 65,7</td><td> 72,4</td>

<td>and</td><td> -3,2</td><td> -3,2</td><td>-2.59 a_h</td>

<td>b *</td><td> 2,76</td><td> 2,76</td><td>-2.57 b_h</td>

<td>RgY (from outside)</td><td> 8,8</td><td> 10,8</td><td> 4,91</td>

<td>and</td><td> +1,81</td><td> +0,46</td><td>+4.13 a_h</td>

<td>b *</td><td> -6,4</td><td> -1,1</td><td>-7.62 b_h</td>

<td>R_fY</td><td> 10,8</td><td> 8,8</td><td> 3,48</td>

<td>and</td><td> +0,46</td><td> +1,81</td><td> +1,64 3,,</td>

<td>b '</td><td> -1,1</td><td> -6,4</td><td>-0.69 b_h</td>

In this application, the monolithic sheet was subjected to both a boil test to determine its chemical resistance and the aforementioned abrasion test (Pacific Scientific Abrasion tester) to determine its mechanical strength. The pane successfully passed both tests.

An Airco ILS-1600 laboratory coating machine was used to shape the layer system in this application. It contains 3 cathodes containing: cathode # 1 - silicon with 5% aluminum admixture; cathode # 2 - silver; cathode # 3 - Ni: Cr, nichrome, 80/20 weight ratio. The layer arrangement shown in Fig. 1 is as follows:

<td>Material</td><td>Coating No.</td><td>Thickness (approx.)</td>

<td>Si₃N₄*</td><td>2a</td><td>450 A.</td>

<td>Ni: Cr</td><td>3a</td><td>7 A.</td>

<td>Ag</td><td>4a</td><td>155 A.</td>

<td>Ni: Cr</td><td>3b</td><td>7 A.</td>

<td>Si₃N₄*</td><td>2b</td><td>950 A.</td>

<td>Ni: Cr</td><td>3c</td><td>7 A.</td>

<td>Ag</td><td>4b</td><td>lio A</td>

<td>Ni: Cr</td><td>3d</td><td>7 A.</td>

<td>Si₃N₄*</td><td>2c</td><td>400 A.</td>

* In these layers there is a smaller amount of Al impurity by about 5%.

A monolithic sheet of clear soda lime silica smooth glass was used, 0.087 inch thick. The following parameters of the coating machine were used:

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Table 6

<td>Layer</td><td>Material</td><td>* n₂%</td><td>Ar%</td><td>Pressure (Torr)</td><td>Cathode power</td><td>Cathode voltage</td><td>Cathode intensity</td><td>Line speed%</td><td>Number of strokes</td>

<td> 1</td><td>Silicon</td><td> 50</td><td> 50</td><td>4.0 χ 10⁴</td><td>4.9 kW</td><td>483 V</td><td>10.5 A.</td><td> 42,5</td><td> 8</td>

<td> 2</td><td>Nichrome</td><td> 50</td><td> 50</td><td>3.1 x 10 "</td><td>0.7 kW</td><td>387 V</td><td>2A</td><td> 100</td><td> 1</td>

<td> 3</td><td>Silver</td><td> 0</td><td> 100</td><td>5.7 χ 10^-4</td><td>2.8 kW</td><td>454 V</td><td>6.4 amps</td><td> 100</td><td> 1</td>

<td> 4</td><td>Nichrome</td><td> 50</td><td> 50</td><td>3.1 χ 10⁴</td><td>0.3 kW</td><td>344 V</td><td>1 A.</td><td> 100</td><td> 1</td>

<td> 1</td><td>Silicon</td><td> 50</td><td> 50</td><td>4.0 χ 10</td><td>4.9 kW</td><td>483 V</td><td>10.5 A.</td><td> 42,5</td><td> 19</td>

<td> 2</td><td>Nichrome</td><td> 50</td><td> 50</td><td>3.1 χ 10⁴</td><td>0.7 kW</td><td>387 V</td><td>2A</td><td> 100</td><td> 1</td>

<td> 3</td><td>Silver</td><td> 0</td><td> 100</td><td>5.7 x W.⁴</td><td>5.0 kW</td><td>498 V</td><td>10.5 A.</td><td> 100</td><td> 1</td>

<td> 4</td><td>Nichrome</td><td> 50</td><td> 50</td><td>3.1 χ 10^-4</td><td>0.3 kW</td><td>344 V</td><td> 1</td><td> 100</td><td> 1</td>

<td> 1</td><td>Silicon</td><td> 50</td><td> 50</td><td>4.0 x W.⁴</td><td>4.9 kW</td><td>483 V</td><td>10.5 A.</td><td> 42,5</td><td> 8</td>

Alternatively, the nichrome layers can be sputtering in an atmosphere with 100% Ar, thereby preventing the formation of chromium nitride. Additionally, the silver layers can be sputtering in an atmosphere partially containing Ni because the silver does not combine to nitride.

Contrary to or compared to the characteristics of the above embodiment of this invention, reference can be made to the following characteristics obtained by applying the above-described WINDO W 4.1 (1/2 inch Argon Chamber) technique to the aforementioned prior art commercial IG "Cardinal -171" type product.

Table 4

<td>Performance characteristics</td><td>Wall 24</td><td>Wall 26</td><td>Monolithic sheet</td>

<td>Twidzial</td><td> 73</td><td> 73</td><td></td>

<td>^ visible from the outside</td><td> 11</td><td> 12</td><td></td>

<td>^ -visible, inside</td><td> 12</td><td> 11</td><td></td>

<td>^ sunny</td><td> 41</td><td> 41</td><td></td>

<td>R-solar</td><td> 33</td><td> 36</td><td></td>

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

<td>Solar heat gain coefficient</td><td> 0,443</td><td> 0,531</td><td></td>

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

<td>ULato</td><td> 0,24</td><td> 0,24</td><td></td>

<td>En</td><td> 0,051</td><td> 0,051</td><td></td>

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

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

<td>R_s (ohm / sq.)</td><td> 3,27</td><td> 3,27</td><td></td>

<td colspan="3">Color (Observer ΙΠ. C. 2 °)</td><td>(h) Hunter, Observer III. C. 10 °</td>

<td>You</td><td> 73,5</td><td> 73,5</td><td> 80,7</td>

<td>and</td><td> -1,8</td><td> -1,8</td><td>-1.26 a_h</td>

<td>b *</td><td> +2,74</td><td> +2,74</td><td>+2.62 b_h</td>

<td>RgY (outside)</td><td> 11,1</td><td> 12,0</td><td> +5,98</td>

<td>and</td><td> +2,14</td><td> -3,4</td><td>+2.37 a ,,</td>

<td>b</td><td> -5,5</td><td> +0,49</td><td>-5.68 b_h</td>

<td>RpY (inside)</td><td> 12,0</td><td> 11,1</td><td> 4,90</td>

<td>and</td><td> -3,4</td><td> +2,14</td><td>-2.01 a_h</td>

<td>b '</td><td> +0,4</td><td> -5,5</td><td>+0.60 b_h</td>

179 946

In view of the above, it should be emphasized that the product IG "Cardinal-171" has gained considerable market acceptance. Its only real drawback is its lack of chemical purity. The exact layering of this product is unknown. However, it should be considered to conform to the arrangement disclosed in said US Patent No. 5,302,449.

As can be seen from comparing the results of this invention with a commercially accepted product, the present invention achieved a high level of competition using a significantly different layering system, for example, while the Cardinal product achieves slightly better permeability than the use of the present invention (73% vs. 66%), nevertheless the achieved 66% is not only within the acceptable limits, but on the other hand, if a lower shading coefficient, as already explained, is highly desirable (e.g. due to lower air conditioning costs in hot weather), this 66% achieved is even more commercially important. Of particular importance, however, is the much higher chemical purity achieved with the present invention. Both products have very low, in fact equal discharge and equally excellent U-values.

Due to the previously mentioned performance characteristics of the IG, previously undefined terms such as U_winter, U_summer, etc., are known in the art and are used herein according to their accepted meanings. For example, the value "U" is a measure of the insulating properties of an IG system. AT_winter and U_lat0 are determined according to NFRC100-91 (1991), the standard established in the WINDO W 4.1 program. The "shading coefficient" ("SC") was determined using the NFRC 200-93 (1993) procedure, by first determining the "solar heat gain coefficient" and dividing it by 0.87. "Relative heat gain" (rhg) was determined using the same procedure NFRC 200-93. "T._sunny"Stands for total solar energy transmittance, the known combination of UV, visible and IR transmittance. "R._S.Solar "similarly means the total reflection of solar energy, known as the combination of UV, visible and IR reflection.

Figure 3 is a partial, schematic representation of a typical family home 28 having various openings in which the present invention may be used. For example, in the window 30, a monolithic pane of glass sputtered with a layer system according to the present invention may be used, or as a "storm window" an IG unit according to the invention as shown in Fig. 2. Likewise, the sliding wall pane 32, the non-sliding wall pane 34 as well as the front door pane 36 can also be produced using the invention, both as a monolithic glass pane as well as an IG unit.

Upon introduction to this disclosure, many other features, modifications, and improvements will become apparent to the skilled artisan. Such features, changes and improvements are therefore considered part of this invention, the scope of which will be defined by the following claims.

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