FI72613C - Non-iridescent glass structures, process for making them and using them. - Google Patents

Description

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LBJ (11) UTLÄGGNINGSSKRIFT flO \ Ö * J * f $ * & (45) Γ 'i 1, 1' 1 - rjf> rf »1 '' .'Af (51) Kv.lk.7lnt.CI. * G 02 B 1/10, C 03 C 17/22 FINLAND —FINLAND (21) Patent application - Patentaruökning 783196 (22) Filing date - Ansökningsdag 20 1 0 78 '· (23) Starting date - Glltighetsdag 20.10.78 (41) Published to the public - Blivit offentlig 2j ggg

National Board of Patents and Registration Date of publication and hearing publication__

Patent and registration authorities '' Ansökan utlagd och uti.skriften pubiieerad 27.Ο2.87 (86) Kv. application - Int. trap (32) (33) (31) Claim claimed privilege - Begärd priority (71) (72) Roy Gerald Gordon, 22 Highland Street, Cambridge, Massachusetts, USA (7 ^) Oy Koister Ab (5 * 0 Non-iridescent glass structures , method of preparation and use - Icke-iriserande g 1asstrukturer, förfarande för fram-ställning av dessa och användning av dessa

The invention relates to glass articles or glass structures provided with a thin, functional, inorganic coating (for example a tin oxide coating, which is a substance which improves reflectivity with respect to infrared radiation). These articles have improved appearance due to the reduced iridescence previously associated with such thin coatings. The invention also relates to a method for manufacturing these articles and to their use.

Glass and other transparent materials can be coated with transparent semiconducting films, for example, tin oxide, indium oxide, or cadmium stannate, to reflect infrared radiation. Such materials are useful in the manufacture of windows with improved insulation values (lower heat transfer) in furnaces, building windows, etc. Coatings formed from these materials are also conductive and are used as resistance heating means to heat windows in vehicles to remove steam or ice.

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One less desirable feature of these coated windows is that the light reflected from them shows interfering side effects (iridescence) and the transmitted light shows a smaller number of them. This iridescence has been a serious obstacle to the wider use of these coated windows (see, e.g., American Institute of Physics Conference Proceeding No. 25, New York 1975, page 288).

In certain cases, i.e., when the glass has a very dark hue (e.g., when its light transmittance is less than about 25%), this iridescence is obscured and acceptable. For most applications, the walls and windows in buildings have an iridescence normally associated with coatings less than n thick.

0.75 / am, an often undesirable property for aesthetic reasons (see, e.g., U.S. Patent 3,710,074). Very little or no success has been achieved in trying to substantially reduce or eliminate unwanted and visible iridescence in clear, teal, and poorly tinted glasses.

Iridescent dyes are a very common phenomenon in transparent films with a thickness ranging from about 0.1 to 1 μm, especially below n.

At thicknesses of 0.85 μm. Unfortunately, it is precisely this thickness range that is of practical importance for most commercial applications.

Semiconductor coatings thinner than about 0.1 microns do not provide interference colors, but such thin coatings have significantly poorer reflectivity to infrared light and significantly reduced electrical conductivity.

Coatings with a thickness greater than about 1 / am also do not provide visible iridescence in daylight, but coatings with a large thickness are much more expensive to manufacture due to the need for larger amounts of coating material and the corresponding amount of time required to deposit the coating. longer. Furthermore, films with a thickness greater than 1 μm tend to be turbid due to light scattering due to surface irregularities that become larger with such a film. Such films also have a greater tendency to crack under thermal stresses due to thermal expansion differences.

Due to these technical and economic limitations, almost all commercial production of coated glassware is concentrated on films with a thickness between about 0.1-0.3 μm and 3,76613 with clear iridescent colors. To date, hardly any use has been found for such glass for construction purposes, despite the fact that its use would reduce costs due to energy savings. Thus, for example, heat losses due to infrared radiation in a building heated through glass surfaces can be about half of the heat losses through uncoated windows. The presence of iridescent dyes in these coated glass products is the main reason why such coatings are not used.

The present invention relates to a product comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflective material, the material consisting of a transparent semiconductor capable of exhibiting iridescent colors in daylight. The product is characterized in that a second coating is arranged between the glass sheet and the first coating, this second coating acting as a means of substantially reducing iridescent colors of the first coating by forming at least two interfaces which, together with the second coating mass, reflect and refract light. the refractive index of the second coating is approximately the square root of the product of the refractive indices of the glass and the first coating, wherein the thickness of the second coating is about 1/4 of the wavelength of light having a vacuum wavelength of about 500 nm, or the total refractive index of the second coating is approximately : the square root of the product of the refractive indices of the coating, the second coating: comprising two layers, each having a thickness of about 1/4 of the wavelength of light having a vacuum wavelength of about 500 nm, or with a second coating o n is a refractive index gradient that gradually varies between the glass and the infrared reflecting material from a refractive index close to the refractive index of the glass to a refractive index close to the refractive index of the infrared reflecting material.

The invention also relates to a process for the preparation of the product described above. The method is characterized by applying a second coating having a refractive index of approximately the square root of the product of the refractive indices of the glass and the first coating, wherein the second coating has a thickness of about 1/4 of the wavelength of light having a vacuum wavelength of about 500 nm. , or having a total refractive index of approximately the square root of the product of the refractive indices of the glass and the first coating, the second coating comprising two layers each about 1/4 of the wavelength of light having an empty wavelength of about 500 nm or a refractive index varying, between the glass and the infrared reflecting material from a refractive index close to the refractive index of the glass to a refractive index close to the refractive index of the infrared reflecting material before the application of the first inorganic coating.

The invention further relates to the use of a product to provide an iridescent-free appearance of glass surfaces in a building and to prevent heat loss from the building by reflecting infrared radiation from the building through these glass surfaces back to the thin surface

The invention provides a means of removing visible iridescence from semiconducting thin film coatings on glass while maintaining their desired properties in terms of transparency to visible light, reflection of infrared radiation and electrical conductivity. This is achieved without substantially increasing the manufacturing cost compared to the cost of using ordinary iridescent films.

The process according to the invention is continuous and can be fully integrated with modern manufacturing processes used in the glass industry.

The product has high strength and is resistant to light, chemicals and mechanical wear.

The substances used in the invention are sufficiently available and thus enable the product to be used on a large scale.

To allow a proper quantitative evaluation of the conceivable different structures that eliminate iridescent dyes, the intensity of these dyes was calculated using optical values and 5,72613 color detection data. In this review, it is assumed that the film layers have planes with similar thickness and similar refractive index in each layer. Changes in refractive indices are assumed to be steep at planar interfaces between adjacent film layers. Actual values of refractive indices are used, which corresponds to negligible absorption losses in the layers. The reflection coefficients are normally given for incoming planar waves of unpolarized light.

Using these assumptions, the amplitudes for reflection and transmission at each interface are calculated from Fresnel’s formula.

These amplitudes are then added together, taking into account the phase differences obtained as the through the layers. These results have been shown to be equivalent to the Airy formula (see, e.g., Optics of Thin Films, F. Knittl, Wiley and Sons, New York, 1976) for multiple reflection and interference in thin films when these formulas are applied to the same cases treated in accordance with the invention.

The calculated intensity of the reflected light has been observed to vary with the wavelength and is thus amplified more in certain colors than in others. To calculate the reflected color seen by the observer, it is desirable to first determine the book distribution of incoming light. For this purpose, the "International Commission on Illumination Standard Illuminant C" can be used, which defines approximately normal daylight lighting. The book distribution of reflected light is the product of the calculated reflection coefficient and the spectrum of the illuminant "Illuminant C". The hue and saturation that the perceiving person sees as a reflection is then calculated from this reflective book using approximate color scales known to those skilled in the art. One useful scale is provided by Hunter in Food Technology, Volume 21, pages 100-105, 1967. This scale has been used to calculate the relationship, which is set forth in the following description.

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The results of the calculations for each combination of refractive index and thickness in the layers are a couple of numbers, i.e., "a" and "b". "a" represents a red (if the value is positive) or green (if the value is negative) hue, while "b" represents a yellow (if the value is positive) or blue (if the value is negative) hue. These hue results are useful for comparison calculations. A single number, "c", represents the "color saturation-2 2 1/2 reason": c = (a + b) .This saturation factor, "c", is directly attributable to the color observed in the samples according to the invention. proportional to the eye's ability to detect difficult iridescent hues.When the saturation factor falls below a certain value, no color can be seen in the reflected light. The Measurement of Appearance, Wiley and Sons, New York, 1975, which is an overview of numerical color scales).

To determine the basis for comparing structures, a first set of calculations is performed to mimic a simple semiconductor layer on glass. The refractive index for the semiconductor layer was set to 2.0, which is an approximate value for tin oxide, indium oxide or cadmium stannate films. A value of 1.52 was used for the glass substrate and this is a value typical of commercial window glass. The calculated color saturation values are given in Figure 1 as a function of the thickness of the semiconductor film. The color saturation proves to be high for reflections from films ranging in thickness from 0.1 to 0.5 μm. For films thicker than 0.5, the color saturation decreases with increasing thickness. These results are consistent with qualitative observations on real films. The clear fluctuations are due to the varying sensitivity of the eye to different wavelengths of the spectrum. Each of the peaks corresponds to a specific color, as indicated by the curve (R = red, Y = yellow, G = green, B = blue).

Using these results, the lowest detectable value for color saturation was found in the following experiment: tin oxide films with a continuously varying thickness up to about 1.5 μm were precipitated on glass plates by oxidizing tetramethyltin vapor. The thickness profile was obtained by varying the temperature from about 450 to 500 ° C across the glass surface. The thickness profile was then measured by observing the interference lashes in monochromatic light. When observed in indirect daylight, the films gave interference colors in the right places, as shown in Figure 1. Those parts of the films with a thickness exceeding 0.85 μm did not give detectable interference colors in indirect daylight. A green peak calculated to be 0.88 μm thick could not be seen. The threshold for perceptibility is therefore assumed to exceed 8 for these color units. Similarly, no calculated blue peak at 0.03 μm could be seen, which is why the threshold was more than 11 color units, which is the calculated value for this peak. However, a faint red peak at 0.81 μm could be seen under good observation conditions, for example, using black velvet as a background and no reflective colored objects in the field of view, for which reason the threshold is less than 13 color units calculated for this color. From these studies, it can be concluded that the threshold for detecting reflected light is between 11 and 13 color units on this scale, therefore 12 units are assumed to represent the threshold for detecting reflected light under conditions where detection occurs in daylight. This means that a color saturation of more than 12 units occurs as a visible color iridescence, while a color saturation of less than 12 units appears neutral.

It can be assumed that there is little resistance to the commercial use of products with color saturation values of 13 or lower. However, it is very suitable for a value of 12 or less and, as will be seen in more detail below, there does not appear to be any practical reason why the most advantageous products of the invention, for example those with completely color-free surfaces, i.e. less than 8, should not be manufacture economically.

A value of 12 or lower indicates a reflection that does not interfere with or distort the color as detectable in the reflected image. This 12-unit threshold is assumed to be a quantitative standard against which the usability or lack of usability of various multilayer structures can be assessed in terms of attenuation of iridescent colors.

Coatings with a thickness of 0.85 μm or more give color saturation values lower than this threshold 12, as shown in Figure 1. The experiments shown in Example 15 confirm that these thicker coatings do not give disturbing iridescent colors in daylight.

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In the following, a simple layer is used between the glass and the semiconductor.

One embodiment of the invention involves the use of a simple undercoat to avoid reflected color saturation.

This requires the use of a carefully selected simple layer whose refractive index (n ^ is the refractive index of glass (n ^ or n.

1.52) and the refractive index of the semiconductor (nh or approx. 2.0). It follows from the intermediate refractive index, which is the geometric mean n. = 1/2 1 (n ^ n ^) ', i.e. about 1.744, that the reflections from both surfaces of the intermediate layer have the same amplitude. By selecting about 1/4 of the wavelength as the thickness of the interlayer, these two reflected waves extinguish each other and do not contribute to the iridescent colors. This quenching is accurate with only a single wavelength value and the wavelength must be carefully selected. A study was then performed to find values that reduce the color saturation coefficient for semiconductor films, especially in the thickness range of 0.15 to 0.4 μm, which are the semiconductors that are most interesting for thermal reflection and have particular problems with iridescence. The optimal intermediate film thickness for the substrate coating (i.e., the coating between the glass and the semiconductor) was found to be about 0.072 μm (72 nm), which corresponds to 1/4 of the wavelength for the 500 nm (vacuum) wavelength. The color saturation remains below the threshold of 12 units for semiconductor films at all thicknesses, as shown in the curve of Figure 1. Ordinary strong iridescent dyes from a heat radiating film having a thickness of, for example, 0.3 μm can also be attenuated by this simple intermediate undercoat film.

The sensitivity of this anti-iridescent undercoat layer to variations in refractive index and thickness was investigated. Changes in refractive index - 0.02 and changes in thickness - by 10% are sufficient to increase the color saturation to detectable values. Precise control of these parameters can be achieved by known glass coating methods. For example, U.S. Patent 9,726 3,350,679 describes a device capable of coating with a thickness uniformity of -2%.

Double interlayers give even better results.

An effective product can also be prepared using two layers with an intermediate refractive index on glass under a semiconductor film. With semiconductor films with a thickness between 0.1 and 0.4 μm, it proved possible to achieve only about one unit or less color saturation. This interval is much lower than the threshold for perceptibility. Both intermediate refractive index values (n1 and n2) for such a structure can be represented as nl = (nh) (rig 1) i.e. about 1.63 n2 = 8Nh) 0.74 (ng] _) 0.26 i.e. about 1 , 86.

The optimal thickness is about 1/4 wavelength (vacuum) for a wavelength of 500 nm, i.e. approx.

d 2 = δ 6.7 nm d 2 = 67.2 nm.

The layer with the lower refractive index (n2) is mainly glass, while the layer with the higher coefficient (n2) is closest to the semiconductor film.

This structure with a double substrate is even more tolerant in terms of parameter deviations from the optimal values than the embodiment with a simple substrate.

- Variations of 25% of the optimal thickness further attenuate the iridescence values below the detectable limit, i.e. below the color saturation 10. Very efficient structures can thus be based on or coefficients between n. = (N.) 0.26 ± 0.03 0.74 ± 0.03 1 h gl „_, 0.74 i 0.03,, 0.26 - 0.03 n2 = (nh> "gl corresponding to a range of 1,62 to 1,65 and for n2 a range of 1,88 to 10 7261 3 1,84. The degree of precision required for the coating package with the tolerance of 25%, can easily be obtained by methods known in the art, and the accuracy required for refractive indices can be easily achieved, although mixed substances are required to obtain the required values.

It has also been found that a film having a progressively varying composition, for example, gradually varying from a silica film to a tin oxide film, can be constructed between the glass substrate and the semiconductor layer. Such a film can best be illustrated as a film comprising a very large number of intermediate layers.

A wide variety of transparent materials can be used to make products that meet the above criteria by forming one or more anti-iridescent coating layers. Various metal oxides and nitrides, as well as mixtures thereof, have the desired optical properties in terms of transparency and refractive index. Table A shows certain alloys with the correct refractive index values for a simple layer coating between a glass and a tin oxide or indium oxide film. The required weight percentages are obtained from measured curves in which the refractive index is plotted as a function of composition, or calculated by standard Lorentz-Lorenz law for mixtures or coefficients of mixtures (Z. Knittl, Optics of Thin Films, Wiley and Sons, New York, 1976, page 473 ) using measured refractive index values for clean films. This law of mixing generally gives sufficiently accurate interpolations for optical work, although the calculated refractive index values in some cases are somewhat smaller than the measured values. The refractive index values of the films also vary somewhat depending on the coating method used and the conditions used.

Routine inspection can be readily performed prior to manufacture and, if required, the composition can be set to optimal values if this effect is actually required.

For example, alumina films provide a degree of variation in refractive index between about 1.64 and 1.75 due to coating conditions. In Tables A, B, and C, Al2-03 ~ h means films with a high refractive index (n = 1.7 5), while A ^ O ^ -1 represents a low refractive index (n = 1.64). Films with a medium refractive index require intermediate compositions to give the desired refractive index values.

Tables B and C give certain blends with the correct refractive index values (about 1.63 and 1.86) for use in the bilayer between the glass substrate and the primary semiconductor coating.

In addition to these optical properties, suitable vessel coating layers are selected so that they are chemically resistant and resistant to air, moisture, cleaning solutions, etc. Such a requirement eliminates in most cases those types of germanium dioxide films that are easily hydrolyzed by water. Films made of about half GeO 2 and half SnO 2 appear to be insoluble and resistant to water.

Table A

Dielectric films with a refractive index of about 1.73 to 1.77 Mixture Component A Weight% Component B Weight% 1 SI3N4 67-4 SiO2 33 - 4 2 Al2O3-h 100 3 ZnO 78-3 SiO2 22 - 3 4 Al203-1 55-8 ZnO 45-8 5 MgO 76-11 ZnO 24 - 11 6 SnO2 81-3 SiO2 19 - 3 7 SnO2 50 - 7 Sl ^ -l 50-7 8 MgO 73 - 11 SnO2 27 - 11 9 In2 ° 3 81-3 SiO2 19 - 3 10 ln203 50-7 Al2 ° 3-1 50-7 11 MgO 73 - 12 ln203 27 - 12 12 Ge02 55-7 ZnO 45 - 7 13 Ge02 52-7 Sn02 48-7 14 Ge02 51-7 In2 ° 3 49 - 7 15 Ga2 ° 3 91-3 SiO2 9-3 16 Ga2 ° 3 71 ”10 Λ12 ° 3" 1 29 “10 IV MgO 53 - 20 Ga2 ° 3 47“ 20 18 Ga2 ° 3 70 “10 Ge02 30“ 10 7261 3 12

Table B

Dielectric films with a refractive index of about 1.62 to 1.65 Mixture Component A Weight% Component B (residue) 1 SiO 2 53 i 4 Si3N4 2 Al203-1 100 3 Al203-1 97-3 SiO2 4 Al2O3-h 74 ± 5 SiO 2 2 ZnO 59-4 SiO 2 6 MgO 79-5 SiO 2 7 SnO 2 62-3 SiO 8 8 In2 ° 3 63-3 SiO2 9 Ge02 100 10 Ga2 ° 3 71-3 SiO

Table C

Dielectric films with a refractive index of about 1.86 ^ 0.02 Mixture Component A Weight% Component B (residue) 1 si3N4 84-3 SiO2 2 ZnO 91-2 SiO-4- 3 ZnO 76-5 Al2O3-1 4 ZnO 59-9 Al 2 O 3 ~ h

5 Zno 68 - 7 MgO

6 SnO 2 91-2 SiO 2 7 SnO 2 78 - 5 Al 2 -1 8 SnO 2 60-8 Al 2 O 3 ~ h

9 SnO2 70 - 6 MgO

10 In2 ° 3 91-2 SiO2 11 In2 ° 3 78-5 Al203-1 12 In2 ° 3 61-8 Al203-h

13 In 2 ° 3 71-6 MgO

14 ZnO 75 - 7 Ge02 15 Sn02 76-7 Ge02 16 In2 ° 3 76 - 4 Ge02 17 Ga2 ° 3 80 ~ 14 Zn0 18 Ga2 ° 3 79 “14 Sn02 19 Ga2 ° 3 78“ 15 In2 ° 3

Note:

Al 2 O 3 ~ h = high density alumina film with n of about 1.75 Al 2 O 3-1 = low density alumina film with n of about 1.64.

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All of these films can be prepared by simultaneously evaporating the appropriate materials in a suitable mixture. For coating large surfaces such as window panes, chemical vapor deposition (CVD) at normal atmospheric pressure is simpler and cheaper. However, chemical vapor deposition requires suitable volatile compounds to form each substance. The most suitable sources for chemical vapor deposition are gases at room temperature.

Silicon and germanium can be precipitated by chemical vapor deposition from gases such as silane, SiH 2, dimethylsilane (CH 2 Cl 2) and germanium (GeH 2) .Liquids that are sufficiently volatile at room temperature are almost as suitable as gases. such a source for the chemical vapor deposition of tin compounds, while (C2H, -) 2SiH2 and SiCl2 are volatile liquids which are suitable sources of silicon. Continuously useful sources for chemical vapor deposition are solids or liquids that are volatile at temperatures above room temperature but below the temperature at which they react to form coating films. -liasetonaa tit (also called 2,4-pentanedioneates), aluminum alkoxides such as aluminum isopropoxide and Aluminum ethylate, and zinc propionate. Magnesium does not find suitable known compounds that are volatile at coating temperatures, therefore chemical vapor deposition is not expected to be useful for the manufacture of magnesium oxide films.

Typical conditions in which metal oxide films have been prepared by chemical vapor deposition with good results are shown in Table D. Typically, organometallic compound vapor is present in the air at a concentration of about 1% by volume. Films prepared in this way have good adhesion to both the glass substrate and the tin oxide or indium oxide coating layer applied thereafter. Mixed oxide layers have been prepared from all of these metal lipars using chemical vapor deposition methods (except for magnesium for which no suitable volatile compound was available% 14 72 61 3). The refractive indices for the mixed films were suitably measured by taking the visible reflection spectrum as a function of wavelength. The locations and heights of the maxima and minima with respect to the reflected intensity can be related to the refractive index of the precipitated film. The concentrations of the reactants are then set so as to obtain the desired refractive index.

Using these methods, a series of borosilicate glass (Pyrex) samples have been prepared using (SiO 2 - Si 3 N 4)> (SiO 2 - SnO 2), (GeO 2 - SnCl 2), (Al 2 O 3 - SnO 2), (Al 2 O 3 - Ga 2 O 3) or * Al2 ° 3 ”

AnO) as mixed layers under a SnO 2 semiconductor layer with a thickness of 0.3 μm. If the refractive indices and thickness values are adjusted correctly, the reflected daylight will be neutral and colorless to the eye. The coatings are clear and transparent and free of visible mist (scattered light).

Table D

A range of volatile oxidizable organometallic compounds suitable for precipitating metal oxide layers and mixed metal oxide layers with oxidizing gases such as O 2 or N 2 O

Compound Evaporation temperature Coating temperature (6C) (° C) 1 SiH 2 gas in 20 300-500 2 (CH 3) 2 SiH 2 gas in 20 400-600 3 (C 2 H 5) 2 SiH 2 20 400-600 4 GeH 2 gas in 20 300-600 450 5 (CH3) 3Al 20 400-650 6 Al (OC2H5) 3 200-300 400-650 7 Al (OC3H7) 3 200-220 400-600 8 A1 (C5H702) 3 200-220 500-650 9 Ga (C5H502 ) 3 200-220 350-650 10 In (C5H702) 3 200-220 300-600 11 (CH3) 2Zn 20 100-600 12 Zn (C3H502) 2 200-250 450-650 13 (CH3) 4Sn 20 450-650 14 Ta (OC4Hg) 5 150-250 400-600 15 Ti (OC3H7) 4 100-150 400-600 16 Zr (OC4Hg) 4 200-250 400-600 17 Hf (OC4Hg) 4 200-250 400-600 is 7261 3

When the same coatings were tested with ordinary window glass (soda-lime glass or soft glass), many of the coatings obtained showed considerable turbidity, i.e. light scattering. When the layer first applied to the soft glass is amorphous and consists of Pigs, Si 3 N 4 or GeCl 2 or mixtures of these substances, the coating is free of turbidity regardless of the subsequent layer. Al 2 O 3 gives even brighter coatings, provided that this material is precipitated in amorphous form, preferably below about 550 ° C. If the first layer contains large amounts of Ga2C> 3, ZnO, ln2 ° 3 or SnC> 2, turbidity is likely.

The first anti-iridescent layer deposited on the window glass surface is preferably amorphous instead of crystalline. Silicon nitride is preferred. The applied layers can then be polycrystalline without causing light scattering.

Sodium and other alkali ions have a detrimental effect on infrared reflection and electrical conductivity in tin oxide and indium oxide films.

The amorphous films described above, and in particular the silica-nitride films, are good barrier layers against the diffusion of sodium ions from the glass to the semiconductor layer. By changing the oxygen / nitrogen ratio in the films, the entire refractive index range can be from a refractive index of about 1.5 to a refractive index of tin oxide or indium oxide, which is approx.

2, cover. The same starting reagents can thus be used to prepare anti-iridescent structures with an arbitrary number of refractive index cycles. Thus, films can also be prepared in which the ratio of the reaction components is constantly changing. Only readily available and inexpensive materials are needed to make silicon oxide.

Numerous volatile reagents are available for the preparation of silica nitride dia films. Table E shows some of the most suitable volatiles for the chemical vapor deposition of silicon oxynitride. The reaction SiH 2 + N 2 H 4 is preferred because this reaction appears to give higher precipitation rates in the temperature range of interest for window glass, i.e. 500-600 ° C. However, numerous other reagent combinations can also provide valuable silicon oxynitride films.

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Table E

Source areas for chemical vapor deposition of silicon oxynitride films

Silicon sources: Nitrogen sources:

SiH4 N2H4 CH3NHNH2 (CH3) 2SiH2 NH3 (CH3) 2NNH2 (C2H2) 2SiH2 Sources for both oxygen and nitrogen

(CH3) 4Si NO

SiCl4 NH2OH

SiBr4 N2H4H2O

Oxygen sources: ° 2 h20 n20

Interference colors, i.e., iridescence, can be reduced by using reflections from two thin coatings of the functional inorganic coating on separate but parallel glass surfaces. If the coating thicknesses, for example the thicknesses of the tin oxide coatings, are chosen so that they deviate by about 1/4 at a wavelength (about 0.07 μm = 0.50 μm and n = 2.0), the interference colors practically disappear. Interference colors are reduced to a state where colors no longer become an aesthetic problem for the manufacturer and the customer. For example, the additional shading of a red reflection in one coating and the green reflection of a nearby interference sequence in another coating combine to form a virtually white (neutral) reflection. Similarly, light transmission through such a combination of complement coatings is also neutral in color.

This color compensation is used in double glazing to reduce the intensity of interference colors from heat reflective semiconducting coatings. For example, if SnO 2 coatings are used on two interior surfaces of a double-glazed window, they can be selected to have a thickness difference of 0.07 μm. For extended light sources, the reflective colors go out well if the glass surfaces are more than parallel. For small light sources or well-defined light sources, the compensation for reflection will not be perfect unless the coated surfaces are very parallel. With regard to penetration observations, the requirements for parallel surfaces are not nearly as stringent.

It should also be noted that films in which interference colors have been reduced in intensity with a substrate having an intermediate or progressively varying refractive index can also be paired to provide additional color compensation.

The following is a review of the attached figures.

Figure 1 is a graph illustrating the variation of the calculated color intensity for different colors with the thickness of the semiconductor film.

Figure 2 schematically shows a cross-section of a non-iridescent coated glass structure according to the invention with a simple anti-iridescent interlayer.

Figure 3 schematically shows a cross-section of non-iridescent coated glass provided in accordance with the invention with a plurality of anti-iridescent interlayers.

Figure 4 schematically shows a cross-section of a double-glazed window structure with a substantially improved appearance as a result of coatings on the glass which reduce or eliminate disturbing iridescence.

Figure 2 shows a transparent plate 20 comprising a glass substrate 22 overlying a SiO 2 / SiO 2 (or other material according to Table A) interlayer 24 having a thickness of 1.072 μm and a refractive index of 1.744. On top of the film 24 is a coating 26 having a thickness of 0.4 μm, which is a semiconductor reflecting infrared radiation, tin oxide.

Figure 3 shows a window 36 made of the same half of the conductive film 26 and the same glass 22 and two intermediate coatings as follows: a coating 30 having a thickness of 0.077 / am and a refractive index of about 183. Coating 32 having a thickness of about 0.067 μm and a refractive index of about 1.86. Coating 30 is made of one of the materials shown in Table B. Coating 32 is made of one of the materials shown in Table C.

Figure 4 shows a double glazed window structure 40 comprising an insulating air space 42 between an inner transparent plate 44 and an outer transparent plate 46. Both plates 44 and 46 are made of glass 45 with a semiconductor coating 43a and 48b on the inner surface of the glass.

The thickness of the semiconductor coating 48a is about 0.2 μm, but the thickness of the coating 48b is about 0.27 μm. Thus, there is a difference in wavelength of about 1/4 between the thickness of the two coatings.

Example 1

Glass with a simple anti-iridescent undercoat layer was prepared by heating a clear window pane with a diameter of 15 cm to about 580 ° C. A gas mixture containing about 0.4% silane (SiH 2), 0.1% nitric oxide (NO), 2% hydrazine and the remaining nitrogen (N 2) was passed over the glass surface n.

for one minute at 1 1 / min. In this case, the glass surface was coated: with a flat, transparent silicon oxynitride film. The surface was then further coated with a fluorine-saturated tin oxide layer by passing a gas mixture of 1% tetramethyltin (CH 2 Cl 2, 3% bromotrifluoromethane CF 2 Br, 20% oxygen O 2 and the remainder N 2> over the surface of silicon nitride at 560 ° C for one. After this, the coated glass was allowed to slowly cool in air to room temperature over a period of about one hour.

The glass coated in this way had no visible interference colors in reflected or transmitted daylight. The surface reflected about 90% of the infrared radiation at a wavelength of 10 μm and transmitted about 90% of the visible light. The electrical layer resistance was measured to be about 3 ohms / square.

To measure the properties of the silicon nitride film, the coated surface of the tin oxide film was removed by rubbing with a mixture of zinc dust and dilute hydrochloric acid. This etchant does not affect the silicon oxynitride undercoat. The refractive index of the silicon nitride film was measured to be 1.7 4 CH 2> 12 liquid, as described below. The visible reflectance of the silicon nitride film was measured and the maximum was found at 5,000 Å and at a thickness of 0.072 μm, which corresponded to the desired 1/4 wavelength thickness for 5,000 Å light.

The refractive index for these silicon oxynitride films depends on the nitrogen / oxygen ratio in the films. This composition can be easily adjusted by changing the H 2 / NO ratio in the gas. Increasing the N / O ratio also increases the refractive index. The exact refractive index value also depends on the degree of purity of the starting materials and in particular on the amount of water present as an impurity in the hydrazine. Commercial hydrazine always contains at least a few percent water. By drying the hydrazine by distillation from a desiccant such as sodium hydroxide, potassium hydroxide or barium oxide, the refractive index of the film can be increased. Conversely, the refractive index can be reduced by adding water to the hydrazine. The refractive index of the film also depends on the exact conditions for further growth of the film, in addition to the precipitation temperature, gas flow (amount per unit time): etc. Therefore, the above conditions cannot be expected to give a film with exactly n = 1.74 refractive index. precipitation conditions. However, small compositional adjustments should be sufficient to provide films with the desired refractive indices.

Semiconductor films may also have refractive index values that differ from the value measured for the tin oxide films described. The corresponding optimal value or values for a single or (double) underlayer layer can then be adjusted in the context described above. Corresponding gas phase compositions which provide films with the desired refractive index for anti-iridescent coatings can then be routinely determined to suit the requirements of any manufacturer or researcher skilled in chemical vapor deposition techniques.

The thickness of the film having the measured refractive index is easily determined by measuring the reflection spectrum in visible and infrared light. This spectrum can be easily calculated as a function of film thickness using 20 7 2 6 1 3

Fresnel and Airy standard optical formulas. In most of the above practical structures, it is desired to provide a film having a thickness of 1/4 of a wavelength at a wavelength of about 5,000 Å (in air). In this case, the spectrum of reflection gives a simple such film on glass a wide maximum centered at a wavelength of 5,000 A.

Example 2

Aluminum 2,4-pentanedione, AlfCl (H 2 Cl 2) 2 (also called aluminum acetylacetonate) is a white solid that melts at 189 ° C to a clear liquid that boils at 315 ° C. This material was placed in a pulper flask heated to about 250 ° C through which nitrogen was passed as a carrier gas. When this gas mixture was mixed with dry oxygen at 250 ° C, no reaction was obtained. However, when moisture was added to the oxygen, strong white smoke formation was obtained in the gas mixture. This smoke is a sign of hydrolysis. To prevent this premature hydrolysis reaction, the gas streams must be kept as dry as possible.

A mixture of aluminum 2,4-pentanedionate vapor, nitrogen carrier gas and 20% oxygen was passed over heated glass surfaces. At 500 ° C, a thin coating with a thickness of less than 0.1 μm was obtained, which could only be detected by the increased reflectivity. At 525 ° C, a film thickness of 0.3 μm was obtained in about three minutes. This film showed faint interference colors in white light and clear interference bands in monochrome. in terrestrial lighting. At 550 ° C, the alumina film grew even faster and a small amount of powder formed due to homogeneous core formation and precipitated on the surfaces of the device.

The fluorine-saturated tin oxide film was then allowed to grow on the alumina films at temperatures between 500 and 540 ° C. Thicknesses ranging from 0.3 to 0.5 μm were carefully examined because these thickness values gave the strongest interference colors. The color intensity was substantially reduced compared to tin oxide films of the same thickness without the alumina undercoat.

In films with an alumina film thickness of 1/4 of the wavelength (wavelength 500 nm, which is very close to the peak value for ocular spectrum sensitivity under daylight), the largest decrease in iridescent color was observed. At these thickness values (about 0.072 μm for 21 7261 3 1/4 wavelength) the reflections from the glass-Al 2 O 3 - and Al 2 O 3 -SnO 2 ~ interfaces most effectively quench each other. However, a considerable reduction in color intensity is also obtained when the thickness of A ^ O ^ is not optimal.

Both Pyrex-type borosilicate glass and soda-lime glass (window glass) are used as glass substrates. Good results were obtained on both of these platforms.

The alumina layer was also effective in preventing surface crystallization of the soda-lime glass surface when tin oxide was applied at 500-540 ° C. Alumina is assumed to protect the soda-lime-glass surface against crystallization around the cores produced by the tin oxide crystals and thus contribute to preventing the glass from becoming light-scattering in the coating process.

Example 3

The double-glazed window is made of clear soda-lime type glass. The glass has been treated with a silica-type coating to remove light scattering by the conventional method disclosed in U.S. Patent 2,617,745.

The structure of this double-glazed window is in line with that shown in Figure 4. The inner surface A has a tin oxide coating with a thickness of 0.26 μm. The inner surface B has a tin oxide combination coating having a thickness of 0.33 to 0.02 μm. Each of these coatings has, when viewed both as such, very visible: a brightly colored iridescent dye that was predominantly red or green in the view of most observers. When combined substantially parallel to each other, as in the structure shown in Fig. 4, the iridescent color was largely covered both when viewed from the side of the double-glazed structure facing the sun and from the other side of the same structure.

Example 4

Experiments were performed to prepare layers with a gradually varying refractive index between the refractive index of glass (n = about 1.5) and the refractive index of tin oxide coatings (n = about 2.0). Gradually changing Si Sn was used. 0 „layer, where" x "gradually decreased from one to zero when the layer was built on the glass surface. The thickness of the SnO 2 layer was about 0.3 μm and the thickness of the 22 7261 3 progressively variable region below it was about 0.3 μm. The resulting structures gave a significantly reduced interference color compared to SnO 2 layers of the same thickness but with no progressively varying interlayer area between the glass and SnO 2.

The oxidizable silicon sources are in one case SiH 2 (from a 1% mixture in which N 2 is the carrier gas) and in the other case (CH 3) 2 SiH 2 (from a cylinder with pure gas). Precipitation was performed at a surface temperature of 480 ° C. The gas concentrations were initially about 0.4% silane (or alkyl-substituted silane), 10% oxygen, and the remainder nitrogen. Tetramethyltin (CH 2 Cl 2) was then gradually introduced to a concentration of 1% over about three minutes, while the silane content was gradually reduced to zero over the same time period. The carrier gas to the tetramethyltin was then sealed and the apparatus purged with air over about 5 minutes. A gas stream of 1% (CH 3) 4 Sn, 3% CF 2 Br, 20% Cl 2 and the remainder nitrogen was then passed below the surface for three minutes to precipitate a fluorine-saturated tin oxide layer of thickness n. 0.4 μm.

Interference dyes were substantially less mobile with these coatings having a base coat with a gradually changing refractive index.

Example 5

A similar process was carried out using GeH 2 SiH 4 instead. The progressively changing layer is formed by GexSn ^ _x02, where the "x" gradually decreases from one to zero as the layer is built on the glass. Since the refractive index of pure GeO 2 is about 1.65, the gradually changing layer has a continuously refractive index opening from the refractive index of the glass (about 1.5). However, the uniformity of the coating was somewhat better than that obtained with SiH 2. A reduction in the visibility of iridescent was observed in the seam to the same extent as in Example 4.

Examples 6-9

Example 1 was repeated using the following materials selected from Table A as an intermediate layer between glass and tin oxide:

Example 6: 82% Tn 2 O 3/18% SiO 2

Example 7: 58% GeO 2/42? ZnO

23

Example 8: 70% Ga 2 O 2/30% AJ 2 O 2 -1

Example 9: 60% Al 2 O 2 -1 / 40% ZnO

In all these cases, low iridescence was obtained.

Examples 10-14

The following materials, all selected from Tables B and C, were used as two intermediate layers to replace the simple intermediate layer shown in Examples 1 and 6-9: n = about 1.63 n = about 1.86

Example 10: 97% Al 2 O 3 ~ 1/3% SiO 2> 84% Si 3 N 4/16% SiO 2

Example 11: 60% ZnO / 40% SiO 2 90% ZnO / 10% SiO 2

Example 12: 63% lN 2 O 3/37% SiO 2> 60% SnCl 2/40% Al 2 O 3 ~ h

Example 13: 70% Ga 2 O 3/29% SiO 2 2 76% SnO / 24% GeO 2

Example 14: 62% SnO 2/38% SiO 2> 61% In 2 O 3/39% Al 2 O-h

Example 15

The tin oxide coating is applied to the glass substrate in various thicknesses. (The glass substrate is first coated with an ultra-thin film of silicon oxide to obtain an amorphous, light-scattering surface.)

Tin oxide thickness Irisibility visibility 0.3 strong 0.6 clear but weaker 0.9 barely visible, not only in fluorescent light 1.3 weak but also in fluorescent light

The latter two substances are not aesthetically disturbing when used for construction purposes.

The following is a method for determining the quality of a coating.

A simple method for rapidly checking the refractive index of thin films has been developed to find the deposition conditions for films with the desired refractive index. For example, it can be assumed that a film with a refractive index n = 1.74 is desired for the undercoating layer. Select a liquid with this refractive index. For example, diiodomethane, n = 1.74 can be used. A film having a thickness of about 0.2 to 2 is deposited on the glass surface. Coated 24 7261 3 glass is observed with reflected light from a monochromatic light source, for example a filtered mercury lamp with a wavelength λ = 5 461 A. Coated glass gives an interference pattern with dark and light bands if the film thickness varies across the glass surface. A drop of liquid with a known refractive index is introduced into the film. If the refractive index of the film exactly matches the refractive index of the liquid, the interference pattern disappears under the drop.

If the refractive indices of the membrane and the droplet do not exactly match, the interference pattern is continuously visible under the droplet, but at a lower intensity. If this weak interference pattern under the droplet is a direct extension to the tape mal on the rest of the film, the refractive index of the film is higher than that of the reference solution. On the other hand, if the strip pattern under the droplet is the opposite (light and dark areas have changed location) compared to the pattern occurring outside the liquid droplet, the refractive index of the film is lower than that of the reference liquid.

Using this simple but accurate measurement of the refractive index of the film, the conditions for making the film can be easily adjusted by a series of experiments to achieve consistency with the desired value. By selecting other reference fluids, the membranes can be adjusted to various other values. The refractive index n = 1.63 used in the two-layer undercoat can be set using 1,1,2,2-tetrabromoethane as the reference liquid. The refractive index n = 1.86 for the second layer in the two-layer substrate coating can be set for a solution of sulfur and phosphorus in diiodomethane, as described by West in American Mineral, Vol. 21, page 245 (1936). From the above, it is clear to a person skilled in the art that this general method can be used for quality control in manufacturing. Liquids with known refractive indices are also commercially produced by Cargille Laboratories, New Jersey, A. f. S.

It is obvious that the method according to the invention makes it possible to improve heat savings in buildings with considerable glass surfaces and also to be applied to electric window heating, for example in cars and airplanes, by using the resistance properties of the coatings according to the invention. These coatings generally have an ohmic resistance, usually of the semiconductor type.

Claims (17)

25 72 61 3 An article comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflective material, the material consisting of a transparent semiconductor capable of exhibiting iridescent colors in daylight, characterized in that the second coating is applied to the first glass sheet and , said second coating acting as a means for substantially reducing the iridescent colors of the first coating by forming at least two interfaces which, together with the mass of the second coating, reflect and refract light so as to substantially reduce the visibility of iridescent colors under daylight. the thickness of the second coating is about 1/4 of the wavelength of light with a vacuum wavelength of about 500 nm, or the total refractive index of the second coating is the square root of the product of the refractive indices of approximately the glass and the first coating, the second coating comprising two layers each having a thickness of about 1/4 of the wavelength of light having a vacuum wavelength of about 500 nm, or the second coating having a refractive index gradient varying a refractive index close to the refractive index of the glass, or a refractive index close to the refractive index of the infrared reflecting material:. Product according to Claim 1, characterized in that the thickness of the first layer of semiconducting material is less than 0.4 μm. Product according to Claim 1 or 2, characterized in that the product comprises only glass sheets consisting of clear glass or glass with a light color and without metallic luster, bronze luster gray or other dark shades which can dampen the visibility of iridescence. and preferably reduces the permeability of the product to less than about 25%. 26 7261 3 Product according to one of Claims 1 to 3, characterized in that the thickness of the common or all inorganic coatings of the first and second coatings is 0.1 to 1 μm. Product according to one of the preceding claims, characterized in that it has a color saturation value of less than 5, preferably less than 8 and in particular less than 13. Product according to one of the preceding claims, characterized in that the first coating is stannous oxide. Product according to one of the preceding claims, characterized in that the second coating is an amorphous substance and forms a means for avoiding clouding of the glass when the first coating is applied. Product according to any one of the preceding claims, characterized in that the second coating has a refractive index of about 1.7 to 1.8 and a thickness of about 64 to 80 nm, the first coating having a refractive index of about 2 and a glass having a refractive index of about 1.5. Product according to one of the preceding claims, characterized in that the second coating is mainly a metal oxide, in particular alumina, metal nitride or a mixture thereof, in particular mixtures 1-18 described in Table A of the description. Product according to one of the preceding claims, characterized in that the amorphous film is silicon oxynitride. Product according to any one of claims 1 to 9, characterized in that the second coating consists of two layers comprising a) a layer closer to glass, the composition of which is described in the description table B, and b) a layer closer to the first coating, the composition of which is described in the description table C. Product according to one of the preceding claims, characterized in that the second coating consists of two layers comprising a) a layer closer to glass, the refractive index of which is approximately given by the formula 27 7261 3 n = „° '26n ° '74 a se gl and b) closer a second layer of the first coating having a refractive index of approximately 0.74 0.26 n. = nn, b se gl where ngc is the refractive index of the first coating and n ^ is the refractive index of the glass. A product according to claim 12, characterized in that the second coating consists of two layers comprising a) a layer closer to glass with a refractive index of about 1.6-1.7, b) a layer closer to the first coating with a refractive index of about 1, 8-1.9, wherein the refractive index of the first coating is about 2 and the refractive index of the glass is about 1.5. Product according to one of the preceding claims, characterized in that the second coating consists of a silicon oxynitride mixture of the formula xSiO 2 (1-x) Si 2 O 2, or Si Sn 2 O 2 or Ge Sn,. of mixtures, wherein X 'varies from almost one surface of the glass X «la JL to zero or almost zero at the interface of the first coating. Product according to one of the preceding claims, characterized in that the gradient changes gradually with a plurality of sublayers with gradually different refractive indices. A method of manufacturing a product according to any one of the preceding claims, comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflective material, the material consisting of a transparent semiconductor capable of indicating iridescent colors in daylight, and a second coating - 28 7 2 6 1 3 la at least two interfaces which, together with the mass of the second coating, reflect and refract light so as to substantially reduce the visibility of the iridescent colors in daylight; , characterized in that a second coating is applied, the refractive index of which is approximately the square root of the product of the refractive actions of the glass and the first coating, the thickness of the second coating being about 1/4 of a wavelength of light having a vacuum wavelength of about 500 nm or having a total refractive index of approximately the square root of the product of the refractive indices of the glass and the first coating, the second coating comprising two layers each having a thickness of about 1/4 of the wavelength of the light or having a refractive index gradient that gradually varies between the glass and the infrared reflective material from a refractive index close to the refractive index of the glass to a refractive index close to the refractive index of the infrared reflective material before the first inorganic coating is applied. Use of a product comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflective material, the material consisting of a transparent semiconductor capable of exhibiting iridescent colors in fluorescent lighting, and a second coating coated on the first glass sheet. wherein this second coating serves as a means for substantially reducing the iridescent colors of the first coating by forming at least two interfaces which, together with the mass of the second coating, reflect and refract light so as to substantially reduce iridescent color perception under daylight the thickness of the coating is about 1/4 of the wavelength of light with a vacuum wavelength of about 500 nm, or the total refractive index of the second coating in is approximately the square root of the product of the refractive indices of the glass and the first coating, the second coating comprising two layers each having a thickness of about 1/4 of the wavelength of light having a vacuum wavelength of about 500 nm, or the second coating having a refractive index gradient of 29 and an infrared refractive index close to the refractive index of the glass to a refractive index close to the refractive index of the infrared reflective material, characterized in that the product is used to infiltrate the glass a thin coating of reflective semiconductor film on the surface of the glass and / or to electrically heat these glass surfaces by subjecting the thin coating of the semiconductor to a voltage. 30 7261 3