SE434634B - Article comprising at least a transparent, non-iridescent glass plate, procedure for its production and application of the same in a building - Google Patents

Abstract

The invention concerns transparent glass plate constructions and glass window constructions 20, 36, 40 of the type which carry a first coating 26 of infrared reflecting material, which preferably has a thickness below ca. 0.85μm, whereby the visibility of iridescence (interference) arising from the first coating is markedly reduced by application of a second coating 24, 30, 32, 48a, 48b next to the first coating, by which the second coating gives at least two interfaces, which together with the mass of the second coating provide a means for reflection and splitting of light so that the visibility of iridescence is counteracted or prevented. The invention concerns also a procedure for the production of such windows. A special advantage of the invention is that it is practical with clear or lightly coloured glass, where the problem of iridescent colours has its largest commercial significance. <IMAGE>

Description

"10 3,710,074). 7810974- 1 2 In some cases, ie when the glass has a very_dark hue (for example, with a light transmission capacity of less than about 25%), this iridescence is hidden and can be tolerated. For most wall applications and windows for buildings, the iridescence normally associated with coatings having a thickness of less than about 0.75 microns is aesthetically unacceptable to many viewers (see, for example, U.S. Pat.) Little or no success has been achieved in substantially reducing or eliminating the unwanted and visible iris in clear, blue-green and lightly colored glasses.

Iridescent dyes are a very common phenomenon in single film thicknesses ranging from about 0.1 to 1 micron, especially at thicknesses below about 0.85 microns. Unfortunately, it is especially this thickness range that is of practical importance for most commercial applications. Semiconductor coatings thinner than about 0.1 do not show inter-. ferrous colors, but such thin coatings have a markedly poorer reflectivity for infrared light and a markedly reduced electrical conductivity. Coatings with a thickness greater than about 1; 1 do not show any visible irritation in daylight lighting, but coatings with such a thickness are much more expensive to manufacture, because larger amounts of coating material are required and because the time required to deposit the coating is correspondingly longer.d Furthermore, films with a thickness exceeding l; ¿m have a tendency to show turbidity, which is due to light scattering from surface irregularities, which becomes larger on such a film. Such films also show a greater tendency for cracking under thermal stresses, due to differences in thermal expansion.

Due to these technical and economic limitations, virtually all previous commercial production of such coated glassware includes films having a thickness in the range of about 0.1 to 0.3 .mu.m, which exhibit pronounced iridescent colors; To date, there has been virtually no use of such 1a1o9v4-1 3 coated glass for building purposes, although it would be cost effective to save energy. Thus, for example, the heat losses through infrared radiation through glass areas in a heated building can amount to about half of the heat losses through uncoated windows.

The presence of iridescent paints on these coated glass products is a major reason for not using such coatings.

It is an object of the present invention to provide means for eliminating the visible iridescence from semiconductor thin film coatings on glass while maintaining their desirable properties in terms of transparency to visible light, reflection of infrared radiation and electrical conductivity.

Another object of the invention is to achieve the above-mentioned results without substantially increasing the cost of production compared to the cost of using ordinary iridescent films.

Another object of the invention is to provide the foregoing results by a process which is continuous and fully compatible with modern manufacturing processes used in the glass industry.

A further object of the invention is to achieve all the above-mentioned results with products which have high durability and are stable to light, chemicals and mechanical abrasion.

Another object is to achieve all the results set forth above using materials which are readily available to allow for widespread use.

A further object of the invention is to provide a new double-glazed construction comprising an ultra-thin, infrared: L 1810974-1 4. red-reflecting substance, this structure being free from disturbing iridescence.

Another object of the invention is to provide a glass structure comprising a compound coating, an outer coating being formed of an infrared reflecting surface having a thickness of about 0.7 .mu.m or less, an inner coating being a means for (a) reduce the haze on the coated glass and at the same time and independently thereof (b) reduce the iridescence of the glass structure by means of a coherent addition of reflected light.

A further object of the invention is to provide a glass structure with the above-mentioned non-iridescent properties, this structure being characterized by a stepwise or gradual change of the composition of the coating between the glass and the air.

A further object of the invention will become apparent to those skilled in the art from the information set forth in the specification.

One aspect of the invention utilizes the formation of one or more layers of transparent material between the glass and the semiconducting film. These layers have refractive index values that lie between the value of glass and the value of the semiconductor film. With appropriate choices of thickness and refractive index values, it has been found that the iridescent paints can be made too weak to be observed by most people, and certainly too weak to interfere with extensive commercial use even for building purposes. Suitable materials for these intermediate layers are also specified, as is a procedure for producing these layers.

Another new method described is the joining of two glass surfaces with coatings arranged at a mutual distance of 0.25 times a visible wavelength in terms of thickness (for example about 0.07 .mu.m when tennoride coatings are used) and arranged parallel to each other, so that light which would form iridescent colors is added incoherently and any undesired iridescent effects are effectively reduced below the threshold for aesthetic remarks.

Examples of the invention include a double glazed window with a coating on each glass sheet or on a single one of the glass sheets with a coating on each glass surface.

A coordinating aspect of these various embodiments is that they all utilize a thin semiconductor coating arranged congruently with a second coating, which is a means of substantially reducing the iridescence by offering at least two additional interfacing agents, together with the mass of the second coating, for reflection. and refraction of light in such a way that it markedly counteracts the observation of iridescent colors.

In view of the subjective nature of color perception, it is desirable to discuss methods and assumptions used to evaluate the present invention. It should be noted that the application of a large part of the theoretical discussions in the following is of a retrospective nature, since this discussion is inevitably based on knowledge of the present invention.

To enable an appropriate quantitative evaluation of the various conceivable constructions that counteract iridescence colors, the intensity of these colors was calculated using optical data and color perception data. In this discussion, film layers are assumed to be planar with uniform thickness and uniform refractive index in each layer. The changes in refractive index are assumed to be abrupt at the planar interfaces between adjacent film layers. Actual refractive index values were used corresponding to negligible absorption losses in the layers. The reflection coefficients are given for normally incident flat waves of unpolarized light. Using these assumptions, the amplitudes of reflection and transmission from each interface are calculated using the Fresnelsy formula. These amplitudes are then summed taking into account the phase differences obtained by propagation through the layers in question. These results have been shown to be equivalent to the Airy formula (see, e.g., Optics of Thin Films by 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 being treated. according to the invention.

The calculated intensity of reflected light has been observed to vary with the wavelength and is thus amplified for some colors more than for others. To calculate the reflected color seen by an observer, it is desirable to first specify the spectral distribution of the incident light. For this purpose, you can use the "International Commission on * Illumination Standard Illuminant C", which approximates normal daylight lighting. The spectral distribution of the reflected light is the product of the calculated reflection coefficient and spectrum of Illuminant C. The hue and saturation seen on reflection by a human observer are then calculated from this reflected spectrum using the uniform color scales known to those skilled in the art. A useful scale is the one specified by Hunter i_Food Technology, Volume 21, p. 100-105, l967. This scale has been used to calculate the relationship given in the present description.

The results of the calculations for each combination of refractive index and thickness of the layers are a couple of numbers, ie. "a" 'and "b". * "a" represents red (if the value is positive) or green (if the value is negative) hue, while "b" describes a yellow (if the value is positive) or blue ( if the value 'is negative) hue. These hue results are useful for checking the calculations against the observable colors of samples, including those of the invention. A single 2) l / 2. This color saturation index, "c", is directly related to the eye's ability number, "c", represents the color saturationfz c = (a2 + b to observe the troublesome iridescent color tones. When the saturation index is below a certain value, no 7810974- The numerical value of this threshold saturation for observability depends on the particular uniform color scale used and on the observation conditions as well as the illumination level (see, for example, RS Hunter, The Measurement of Appearance, Wiley and Sons, New York, 1975). , for a late overview of numerical color scales) .- To establish a basis for comparing structures, a first series of calculations is performed to mimic a single semiconductor layer on glass.The refractive index of the semiconductor layer was set to 2.0, which is a value that approximates tin oxide, indium oxide or cadmium stannate films The value 1.52 is used for the glass substrate and this is a value typical of commercial windows erglas. The calculated color saturation values are given in Figure 1 as a function of the thickness of the semiconducting film. The color saturation is found to be high for reflections from films with a thickness ranging from 0.1 to 0.5 .mu.m. For films thicker than 0.5 μm, the color saturation decreases with increasing thickness. These results are consistent with qualitative observations of real films.

The clear oscillations are due to the eye's varying sensitivity to different spectral wavelengths. Each of the peaks corresponds to a certain color, as indicated on the curve (R = red, Y = yellow, G = green, B = blue).

Using these results, the minimum observable value for color saturation was determined by the following experiments: Tin oxide films of continuously varying thickness, up to about 1.5 microns, were deposited on glass sheets by oxidation of tetramethyltin vapor. The thickness profile is achieved by a temperature variation from about 450 to 500 ° C across the glass surface.

The thickness profile was then measured by observing the interference fringes under monochromatic light. When viewed in diffuse daylight, the films showed interference colors at the correct positions shown in Figure 1. The parts of the films having a thickness exceeding 0.85, fl m did not show any observable interference colors in diffused daylight.

The green peak calculated to be at a thickness of 0.88 could not be seen. The threshold for observability is therefore assumed to exceed 8 for these color units. Similarly, the calculated blue peak value at 0.03 fan could not be seen, so 1 threshold is above 11 color units, the calculated value for this peak. However, a faint red peak at 0.81 microns could be seen under good observation conditions, e.g. using a background of black velvet and without colored objects in the field of view that was reflected, so the threshold is below 13 color units calculated for this color. From these studies it can be concluded that the threshold for observation of reflected color is between ll and 13 color units on this scale, so the value of 12 units is assumed to represent the threshold for observability of reflected color under conditions of observation in daylight. means that a color saturation of more than l2 units appears as a visible colored iris, while a color saturation of less than 12 units appears neutral.

It can be assumed that there is little resistance to commercial use of products with color saturation values 13 or lower.

However, it is highly suitable that the value is 12 or lower, and as will be seen in more detail below, there seems to be no practical reason why the most advantageous products according to the invention, for example those characterized by completely colorless surfaces, i.e. under 8, could not be manufactured economically. A value of 12 or less indicates a reflection that does not interfere with or distort the color of a reflected image. This threshold value of 12 units is assumed to constitute a quantitative standard, with which one can evaluate the usability or lack of usability of different multilayer constructions with regard to the suppression of iridescent paints.

Coatings with a thickness of 0.85; 1m or more exhibit color saturation values lower than this threshold 12, as shown in Figure 1. Experiments given in Example 15 confirm that these _ .. ...__ ...___ -.-___ _ __... ... l? aio974-1 9 thicker coatings do not show disturbing iridescent colors in daylight lighting.

The following is the use of a simple layer between glass and semiconductor.

An 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 with a refractive index (ni), which lies between the refractive index for glass (ngl or approx. 1.52) and the refractive index for semiconductors (nh or approx. 2.0). An intermediate refractive index which is the geometric mean ni = (nhngl) 1/2 or about 1.744 means that reflections from the two surfaces of the intermediate layer have the same amplitude. By choosing the thickness of the intermediate layer to about 1/4 wavelengths, these two reflected waves cancel each other out and do not contribute to the iridescent colors. This extinction is accurate only at a single wavelength value and the wavelength must be carefully selected. A study was then conducted to find the values that reduce the color saturation index for semiconductor films, especially in the thickness range 0.15 - 0.4; 1m, which are the semiconductors that are of greatest interest for heat reflection and show special problems. as far as iris is concerned. The optimum intermediate film thickness for an undercoat (ie a coating between glass and semiconductor) was found to be about 0.072_pm (72 nm) which corresponds to 1/4 wavelength for a (vacuum) wavelength of 500 nm. The color saturation remains below the threshold value 12 units for semiconductor films of all thicknesses, as shown by the curve in Figure 1. The usual strong iridescence colors from a heat-reflecting film with a thickness of, for example, 0.3 m can be suppressed even with this simple intermediate undercoating film.

The sensitivity of this simple anti-irradiation undercoating layer to variations in refractive index and thickness was investigated. Changes in the refractive index by 00.02 and by the thickness by 310% are sufficient to increase the color saturation to observable values. Accurate regulation of these parameters can be achieved with known glass coating methods. For example, U.S. Pat. No. 3,850,679 discloses a device which can provide a coating with a thickness uniformity of: 2%.

Double intermediate layers give even better results.

An effective product can also be produced using two layers with an intermediate refractive index on the glass during the semiconductor film. For semiconductor films with a thickness in the range 0} 1 - 0.4 pm, it was found possible to achieve a color saturation of only about one unit or less. This' interval is much lower than the threshold value for observability.

The two intermediate refractive index values (nl and nz) for such a construction can be given with o'74 or about 1.63_ nl: O'74 (n O'26 or about 1.86 n2 = lnh) gl) The optimum thickness is approx. 1/4 wavelengths for (vacuum) wavelength 500 nm or approx. Dl = 76.7 nm d2 = 67.2 nm The layer with a lower refractive index (nl) is closest to the glass, while the layer with a higher index (n2) is closest to the semiconductor film.

This construction with double sublayers is even more tolerant of deviations in the parameters from the optimum values than the embodiment with simple undercoating.

Variations of: 25% from optimum thickness still suppress the irisation values below the observable limit, i.e. under a color saturation of 10; Highly efficient constructions can thus be based on the refractive index within the ranges in "l" í ° s1dèl? L {ïd1dldl 'du 11 + + nl:, nh) o, 2e-o, o3 ¿ngl) o, 74-o, o3 + + nz: (mh) o, 74-o, o3 (ngl) o, 26-0.03 which corresponds to a range for nl from 1.62 to 1.65 and a range for n2 from 1.88 to 1.84 The degree of manufacturing accuracy required to maintain coating thicknesses with a tolerance of 125% can be easily achieved by prior art methods, as can the accuracy required for refractive indexes, even if blended materials are required to provide the required values. .

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

Useful materials.

A large amount of transparent materials can be used for the production of products that meet the criteria set out above by forming one or more anti-irradiation undercoating layers. Various kinds of metal oxides and nitrides and mixtures thereof have the desired optical properties with respect to transparency and refractive index. Table A lists certain mixtures which have the correct refractive index values for a single-layer coating between glass and a tin oxide or indium oxide film. The required weight percentages have been obtained from measured curves or refractive indices as a function of composition or are calculated by the standard Lorentz-Lorenz refractive index law for blends (Z. Knittl, Optics of Thin Films, Wiley and Sons, New York, 1976, p. 473). ) using measured refractive index values for the pure films. ? 81097ls4-1- 12 This type of mixture generally provides sufficiently accurate interpolations for optical work, even if the calculated refractive index values are in some cases slightly lower than the measured values. The refractive index values of the films also vary somewhat with the coating method and conditions used.

A routine inspection before production can easily be carried out and if necessary, the composition can be adjusted to optimal values, if this effect is really required.

Alumina films, for example, show a certain variability in refractive index from about 1.64 to 1.75, depending on the coating conditions. In Tables A, B and C, Al2O3-h denotes high refractive index films (n = 1.75), while Al2O3-1 denotes low refractive index (n = 1.64) .V Medium refractive index films require intermediate compositions to give the desired refractive index values of Tables B and C indicate certain mixtures which have correct refractive index values (about 1.63 and 1.86, respectively) for use in a bilayer between a glass substrate and a primary semiconductor coating. In addition to these optical properties, suitable undercoat layers are selected so that they are chemically resistant and resistant to air, moisture, cleaning solutions, etc. Such a requirement eliminates in most cases germanium dioxide films of the type which easily undergo hydrolysis of water. Films made with about half GeO2 and half SnO2 appear to be insoluble and resistant to water attack.

Mixture Component A Weight percent Component B Weight percent l P * O \ O G) \ l O! U! than u) NF * F * F 'N) P * LU P4 fi> P' UI FJ O \ P4 ~ J FJ G) Mixture Component A Weight percent _Component B (residue) 1 P4 CD KO CD ~ J Ch LH then Lu BJ Dielectric films with refractive index approx. 1.73 - 1.77 Si3N4 Al2O3-h ZnO A1203-1 MgO Sn02 SnO2 MgO In2O3 In2O3 MgO Ge02 GeO2 GeO2 Ga2O3 Ga2O3 MgO Ga2O3 Dielectric films with refractive index Si0-1.2 - 1.62 l Al2O3-l Al2O3-h ZnO MgO SnO2 In2O3 Ge02 Ga2O3 67 100 78 55 76 81 50 73 81 50 73 55 52 51 91 71 53 70 13 Table A. + | + l + l + l + | + | + l + | + l + l + | + | + I + l + l + l + 4 ll ll 12 10 20 10 SiO SiO ZnO ZnO SiO 2 2 2 Al2O3-1 Sn0 Si0 2 2 Al2O3-1 In2O ZnO SnO2 _In2O SiO2 A12O3-1 Gezo Ge02 Table B. + 53 - 4 100 97 74 59 79 62 63 100 71 l + l + | + | + | + | + l + LO Lu LH d> LH U) _SiO Si3N SiO2 Si02 SiO2 2 2 2 SiO SiO SiO2 3 3 3 4 fza1o9v4- “17 i 33 22 45 24 19 50 21 19 so 27 45 48 _49 9 29 47 30 | + | + | + | + | + | + | + | + | + | + + l + I + I + I + l + I + 4 ll ll 12 10 20 10 7a1o974 +1 14 Table C.

Dielectric films with refractive index approx. 1.86 ï 0.02 Mixture Component A Weight percent Component B (residue) 1 s13N4 84 ï 3 sioz 2 zno 91 1 2 sioz 3 zno 76 i 5 A12o3-1 4 zno 59 i 9 A12o3-h s zno 68 i 7 Mgø 6 snoz 91 i 2 s1o¿ 7 snoz '78 I 5 A12o3-1 8 snoz so I 8 A12o3-h 9 snoz 7o f 6 Mgo 1o 1n2o3 91 i 2 sioz '11 In2o3_ 78 ï 5 A12o3-1 12 1n2o3 861 3 8 A12o3-h 13 In2o3 '71 1 6 Mgo 14 - zno' 75 ii? Geoz 15 snoz "78 i 7 Geoz 16 In2o3 76 i 4 ceo2 '. 17 Ga2o3 so i 14 zno 18 Ga2o3 79 i 14 dsnoz 19 Ga2o3 78 i 15 1n¿o3 Note: Al2O3-h = high density alumina film with n approx. 1, 75 Al2O3-1 = low density alumina film with n about 1.64 'Process for the production of films.

All of these films can be prepared by simultaneous vacuum evaporation of the appropriate materials in a suitable mixture.

For coating large surfaces, such as window glass, chemical vapor coating (CVD) at normal atmospheric pressure is simpler and less expensive. However, chemical vapor coating requires suitable volatile compounds to form each material. The most suitable sources of chemical vapor deposition are gases at room temperature. Silicon and germanium can be deposited by chemical vapor deposition from such gases as silane, SiH4, dimethylsilane (CH3) 2SiH2 and german (GeH4). Liquids that are sufficiently volatile at room temperature are almost as suitable as gases. Tetramethyltin is one such source of chemical vapor coating of tin compounds; while (C2H5) 2SiH2 and SiCl4 are volatile liquids, which are suitable sources of silicon.

Similarly, trimethylaluminum and dimethylzinc and their higher alkyl homologues are volatile sources of these metals.

Unsuitable but still useful sources of chemical vapor coating are solids or liquids which are volatile at temperatures above room temperature but below the temperature at which they react to form coating films. Examples of the latter category are acetylacetonates of aluminum, gallium, indium and zinc (also called 2,4-pentanedionates), aluminum alkoxides, for example aluminum isopropoxide and aluminum ethylate, and zinc propionate. For magnesium, there are no suitable known compounds which are volatile below the coating temperature, so chemical vapor coating is not believed to be useful for the production of magnesium oxide films. Z Z Typical conditions under which metal oxide films have been successfully produced by chemical vapor deposition are given in Table D. Typically, the organometallic compound vapor is present in a content of about 1% by volume in air. The films prepared in this way show good adhesion to both the glass substrate and subsequently applied coating layers of tin oxide or indium oxide. Mixed oxide layers have been prepared between all these metal pairs using chemical vapor coating methods (except magnesium, for which a suitable volatile compound not available). The refractive index of the mixed films is conveniently measured by taking the visible reflection spectrum as a function of the wavelength.

The positions and heights of maxima and minima in terms of reflected intensity can be related to the refractive index of the deposited film. The concentrations of reactants are then adjusted to obtain the desired refractive index.

Using these methods, a number of samples have been prepared on borosilicate glass (Pyrex) using (S102 - si3N4), (S102 - snoz), (Geoz - »sno2), (Al2o3 - snoz), _..-. ._, _ .. f ._ _., v-. . - ...__-__ .........-... r ......._ .. n "-m- f ... _ s .. .ma -... M 1810974-15 16 ¶Al203 - Ga203) or (Al203 - ZnO) as mixed layers under a semiconductor layer with a thickness of 0.3Aßm.of Sn02.r If the refractive index and thickness values are adjusted correctly, the reflected daylight becomes neutral and colorless to the eye. fThe coatings are clear and transparent and free from visible haze (scattered light).

'Table 0.

Selection of volatile oxidizable organometallic compounds suitable for the deposition of metal oxide layers, as well as mixed metal oxide layers with oxidizing gases, such as O 2 or N 2 O Evaporative Coating Temperature (OC) Temperature (OC) Temperature (OC) -1 SiH4 gas at 300 - 500 2 (CH3) 2SiH2 gas at 20 .400 - 600 3 (C2H5) 2siH2 20 400, - 600 4 GeH4 'gas at 20' 300: 450 5 (cH3) 3A1 _20 400 _- 650 6 A1 (Oc2H5) 3 200 - 300 _ 400 - 650 -7 Al (0C3H7) 3 200 - 220 _ _40O - 600 8 Al (C5H702) 3, '200 - 220 i 500 - 650 9 Ga (C5H502) 3 200 - 220 350 - 650 10 In (C5H702) 35 200 - 220 _ 300 - 600 ll (CH3) 2Zn _- 20 100 - 600 12 Zn (C3H5O2) 2 200 ~ 250 450 - 650 132 (CH3) 4Sn 20. 450 - 650 14 Ta (0c4H9) 5 _ 150 2- 250 '400 -5600 15 Ti (OC3H7) 4 100 - 150 400 - 600 16 zr (0c4H9) 4 200 - 250. 400 '- 600 17 Hf (0C4H9) 4 200 - 250 400 - 600 Problems with haze or light scattering (haze).

When the same coatings were tested on ordinary window glass (soda-lime glass or soft glass), many of the coatings obtained showed considerable turbidity or light scattering.

When the layer first applied reaches soft glass is amorphous and consists of SiO 2, Si 3 N 4 or GeO 2 or mixtures of these Iivàñoàvášiw 17 substances, the coating is free from turbidity regardless of the nature of subsequent layers. Al 2 O 3 also gives clear coatings, provided that this substance is deposited in amorphous form, preferably under a temperature of about 550 ° C. If the first layer contains large amounts of Ga2O3, ZnO, In2O3 or SnO2, turbidity is likely.

The first anti-irradiation layer deposited on a window glass surface is preferably amorphous instead of crystalline. Silicon oxynitride is preferred. Subsequently applied layers can be polycrystalline without causing any light scattering.

Sodium and other alkali ions exert a detrimental effect on the infrared reflection and electrical conductivity of tin oxide and indium oxide films.

The amorphous films mentioned above, and in particular silicon oxynitride films, are good barrier layers against the diffusion of sodium ions from the glass into the semiconductor layer. By changing the oxygen / nitrogen ratio in the films, the entire refractive index range from refractive index for glass with refractive index about 1.5 to refractive index of tin oxide or indium oxide with a value of about 2 can be covered. With the same starting reagents, anti-iris structures with any number of refractive index steps can thus be prepared. Thus, films with continuously varying proportions of reactants can also be produced. Only readily available and inexpensive materials are required for the production of silicon nitride.

A number of volatile reagents are available for the production of silicon oxynitride films. Table E lists some of the more suitable volatile materials for chemical vapor deposition of silicon oxynitride. The reaction SiH4 + NO> + NZH4 is preferred, since this reaction appears to give higher deposition rates in the temperature range of interest for window glass, i.e. 500-600 ° C. However, a number of other combinations of reagents can also provide valuable silicon oxynitride films. 7810974-1 1s_ Table E.g Source material for chemical vapor deposition of silicon oxynitride films.

Silicon sources: SiH4 (CH3) 2SiH2 (Czïf fi zsi fi z (CH3) 4Si SiCl SiBr 4 4 Oxygen sourcesš 02 H20 N20 Nitrogen sources: NZH4 CH3NHNH2 NH3 (CH3) 2NNH2 HN3 Sources for both NOH2 and N Interference colors, ie iridescence, can be reduced by using reflections from two thin coatings of a functional inorganic coating on separate but parallel glass surfaces.If the coating thicknesses, for example the thicknesses of tin oxide coatings, are chosen so as to differ by approx. l / 4 of a wavelength (approx. 0.07 / Lm for> / \ = 0.50 / lm and n = 2.0), the interference colors disappear in practice.The interference colors are reduced to a state where the colors no longer become an aesthetic problem for the manufacturer and the customer. The additive coloring of, for example, a red reflection in a coating and a green reflection of a nearby interference order in a second coating are combined to form a practical? a1ó9 š4? å 19 taken white (neutral) reflection. Similarly, the transmission of light through such a combination of complementary coatings is also neutral in color.

This color compensation is used in double glazing to reduce the strength of the interference colors from the heat-reflecting semiconductor coatings. For example, if coatings of SnO 2 are used on the two inner surfaces of a double glazed window, they can be selected to have a thickness difference of 0.07 .mu.m. For extended light sources, the reflection colors become well extinguished if the glass surfaces are somewhat parallel. For small light sources or light sources with sharp boundaries, the compensation in terms of reflection will not be complete, unless the coated surfaces are highly parallel. For observations during transmission, the requirements for parallel surfaces are not nearly as strict.

It should also be noted that films in which the interference colors have been reduced in intensity with an undercoat with an intermediate or gradually varying refractive index can also be combined in pairs to provide additional color compensation.

Embodiments of the invention.

The description and the accompanying drawing figures show and describe a preferred embodiment of the invention and state various alternatives and modifications thereof, but it is given that these are not intended to be exhaustive and that other changes and modifications may be made within the scope of the invention. These embodiments are selected and incorporated to illustrate the invention so as to be apparent to those skilled in the art as well as the principles thereof so that those skilled in the art may modify and apply the invention in a variety of forms depending on what is best suited to the conditions in a particular case. . Figure 1 shows a diagram illustrating the variation of the calculated color intensity for different colors with the thickness of the half-film.

Figure 2 schematically shows a section through a non-iridescent coated glass construction according to the invention with a single anti-irisation intermediate layer.

Figure 3 schematically shows a section through a non-iridescent coated glass, which is made according to the invention with a plurality of anti-irradiation intermediate layers. Figure 4 shows schematically and in section a double-glazed window construction, which shows a significantly improved appearance due to coatings supported by the glass and which reduces or eliminates disturbing iridescence.

Figure 2 shows a transparent sheet 20 comprising a glass substrate 22, which supports an intermediate film 24 with a thickness of 0.072 μm of Si3 N4 / SiO2 (or any other material according to Table A) with a refractive index of 1.744. On top of the film 24 there is a coating 26 with the thickness 0, 4; nn of an infrared-reflecting semiconductor, tin oxide. I I I Figure 3 shows a window 36 made with the same semiconductor film 26 and the same glass 22 as well as two intermediate coatings as follows: The coating 30 having a thickness of 0.077, μm and refractive index about 1.63. The coating 32 with a thickness of about 0.67 Åum.and refractive index about 1.86. The coating 30 is made of any of the materials listed in Table B. The coating 32 is made of any of the materials listed in Table C.

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

The semiconductor coating 48a has a thickness of about 0.2 .mu.m, but the coating 48b has a thickness of about 0.27 .mu.m. Thus there is a difference of about 1/4 wavelengths between the two coatings.

Example 1.

A glass with a simple anti-iris undercoating layer was prepared by heating a clear window glass pane with a diameter of 15 cm to about 580 ° C. A gas mixture containing about 0.4% silane (SiH4), 0.1% nitric oxide (NO), 2% hydrazine (NZH4) and the remaining nitrogen (N2) was passed over the glass surface for about 1 minute in an amount of 1 liter / minute . In this way, the glass surface was coated with a uniform, transparent film of silicon oxynitride. The surface was then further coated with a fluorine-doped tin oxide layer by passing a gas mixture of 1% tetramethyltin (CH 3) 4 Sn, 3% bromotrifluoromethane CF 3 Br, 20% oxygen O 2 and the remainder NZ past the silicon oxynitride surface at 56,000 for about 1 minute. The coated glass was then allowed to cool slowly in air to room temperature over a period of about 1 hour.

The glass coated in this way showed invisible interference colors in reflected or transmitted daylight.

The surface reflected about 90% of the infrared radiation at the road length høfun and transmitted about 90% of the visible light.

The electrical layer resistance was measured at about 3 ohms / square.

To measure the properties of the silica nitride layer, the tin oxide film was removed from a portion of the coated surface 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 oxynitride film was measured to be 1.74 with the CH 2 I 2 liquid test described below.

The visible reflectivity of the silicon oxynitride film was measured and a maximum was found at SOOOÅ and a thickness of 0.072 μm corresponding to the desired 1/4 wavelength thickness of SOOOÅ light.

The refractive index of these silicon oxynitride films depends on the ratio of nitrogen oxygen in the films. This composition can be easily adjusted by varying the NZH4 / NO ratio in the gas.

An increase in the ratio N / 0 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 hydrazine. Commercial hydrazine always contains at least a few percent water. By drying hydrazine by distillation from a drying agent, for example sodium hydroxide, potassium hydroxide or barium oxide, the refractive index of the film can be increased. Conversely, the refractive index can be lowered by adding water to hydrazine. The refractive index of the film also depends on the exact conditions for the film growth, including the deposition temperature, the gas flow (amount per unit time), etc. The conditions stated above can therefore not be expected to give a film with a refractive index exactly n = 1.74, if other reagents or deposition conditions were used. However, small adjustments to the composition should be sufficient to produce films with the desired refractive index values. The semiconductor films may also exhibit refractive index values which differ from the value 2.0 measured for the tin oxide films described. The corresponding optimum value or values for a single (or double) undercoat layer can be adjusted with the relationships stated above.

Corresponding gas phase compositions that provide films with the desired refractive index for anti-irradiation undercoatings can then be determined by routine experimentation to suit the exact conditions of each manufacturer or examiner with expertise in chemical vapor deposition techniques.

The thickness of a film with measured refractive index is easily determined by measuring the reflection spectrum within visible and infrared light. This spectrum can be easily calculated as a function of film thickness using standard optical formulas according to Fresnel and Airy. In most of the practical constructions given above, it is desired to provide a film having a thickness of 1/4 wavelengths for a wavelength of about 5000 Å (in air). In this case, the reflection spectrum of a simple film on glass has a wide maximum centered at a wavelength of SOOOÅ.

Example 2.

Aluminum-2,4-pentanedionate, Al (C5H702) 3 (also called aluminum acetylacetonate) is a white solid that melts via 19 ° C to a clear liquid, boiling at 315%. matte material was introduced into a bubble bottle heated to about 250 ° C, through which nitrogen was passed as the 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, intense white smoke was obtained in the gas mixture. This smoke indicates hydrolysis. To prevent this premature hydrolysis reaction, the gas streams must be kept as dry as possible.

The 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 was obtained, thickness less than 0.1 .mu.m, which could be observed only by increased reflectivity. At 525 ° C, a film thickness of 0.3 nn was obtained within cag3 minutes. This film showed faint interference colors under white light and clear interference bands under monochromatic lighting. At 550 ° C, the alumina film grew even faster and a small amount of powder was formed by homogeneous nucleation and deposited on the surfaces of the apparatus.

Thereafter, fluorine-doped tin oxide film was allowed to grow on top of the alumina films at temperatures in the range of 500 - 54000. Thicknesses in the range of 0.3 - 0.5 μm were carefully examined, as these thickness values showed the strongest interference colors. The intensity of the paints was significantly reduced when compared to tin oxide films of the same thickness without the alumina undercoat.

Films in which the alumina film had a thickness of 1/4 wavelength (wavelength 500 nm, which is close to the peak value for spectral sensitivity of the eye to daylight illumination) show the greatest reduction in iridescence color. For these thickness values Ica 0.072, pm for 1/4 wavelength), the reflections from the 7 glass-A103 and Al2O3-SnO2 interfaces effectively cancel each other out. 2 However, a considerable reduction in color intensity is also obtained, even when the thickness of Al 2 O 3 is not optimal.

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

The alumina layer was also effective in preventing superficial devitrification of the soda-lime glass surface when tin oxide was applied at 500-54000. in coating pro- CGSSGII.

Example 3. A double-glazed window is made of clear soda-lime-type glass. The glass is treated with a silica-type coating to eliminate light scattering by the conventional method disclosed in U.S. Pat. No. 2,617,745.

The construction of the double-glazed window corresponds to those shown in Figure 4. The inner surface A bears a coating of tin oxide with a thickness of 0.26 .mu.m. The inner surface B carries a coating of a tin oxide composition with a thickness of 0.33 in 0.02 μm. Each of these coatings exhibits, viewed separately, a highly visible, strongly colored iridescent color, which was predominantly red or green to most observers. When joined together substantially parallel to each other as in the construction shown in Figure 4, the iris color was largely hidden both when viewed from the side of the double-glazed construction facing the sun and from the other side of the same construction.

I va fl wfzrf) 25 Example 4.

Experiments were performed to produce layers with gradually varying refractive indices between refractive indices for glass (n = about 1.5) and tin oxide coatings (n = about 2.0). A gradually varying layer of SixSnl_xO2 was used, in which "x" gradually decreased from 1 to zero as the layer was built up on the glass surface. The SnO 2 layer had a thickness of about 0.3; and the underlying gradually varying area had a thickness of about 0.3 .mu.m. The obtained constructions showed markedly reduced interference color compared to layers of SnO 2 of the same thickness but without the gradually varying intermediate layer area. between the glass and Sn02.

The volatile sources of silicon are, in one case, SiH4 (from a 1% mixture in N2 as carrier gas) and in the other case (CH3) 2SiH2 (from a cylinder with pure gas). The deposition was carried out at a surface temperature of 48,000. The gas concentrations were initially about 0.4% silane (or alkyl-substituted silane), 10% oxygen and the remainder nitrogen. Thereafter, tetramethyltin (CH 3) 4 Sn was gradually introduced up to a concentration of 1% over a period of about 3 minutes, while the silane concentration was gradually reduced to zero within the same period. Thereafter, the carrier gas for tetramethyltin was turned off and the device was purged for about 5 minutes with air to remove the last traces of silane. Then a gas stream of 1% (CH3) 4Sn, 3% CF3Br, 20% O2 and the remaining nitrogen was passed under the surface for 3 minutes to deposit a layer of fluorinated doped tin oxide with a thickness of about 0.4 .mu.m.

The interference colors were significantly less vivid on these undercoatings with gradually varying refractive indices.

Example 5.

A similar process is performed using GeH4 instead of SiH4. The gradually varying layer consists of GeXSn1_xO2, whereby "x" gradually decreases from one to zero when the layer is built up on the glass. Since the refractive index of pure GeO2 is about 1.65, the gradually varying layer still has a refractive index discontinuity from the refractive index of the glass (about 1.5). However, the uniformity of the coating was slightly better than that obtained with SiH 4. The reduction in the visibility of the iris was determined to a degree similar to that obtained according to Example 4.

Examples 6 - 9.

Example 1 was repeated using as an intermediate layer between glass and tin oxide the following materials selected from Table A: Example 6: sz% 1n2o3 / 18% sioz Example 7: 58% GeO2 / 42% ZnO Example 8: 70 Ga2O3 / 30% Example 9: 60 Al 2 O 3 -1 / 40% ZnO 'ww' Low iridescence was obtained in all these cases.

Examples 10 - 14.

The following materials, all of which are selected from Tables B and C, were used as two interlayers as a replacement for the single interlayers listed in Examples 1 and 6 - 9: n about 1.63 - n about 1.86 Example 10; 97% A12o3-1 / 3% sioz à4e% esi3N4 / 16% sioz Example ll: 60 ZnO / 40% SiO2 90% ZnO / 10% SiO2%% dP o \ ° Example 12: 63 In203 / 37% SiO2 60 SnO2 / 40% Al 2 O 3 -h Example 13: 70 Ga 2 O 3/29% SiO 2 76 SnO / 24% GeO 2 Example 14: 62 snoz / ss% sioz 61% In 2 O 3/39% Al 2 O 3 -h 6069 Example 15.

A tin oxide coating is applied to a glass substrate having different thickness values (the glass substrate is first coated with an ultra-thin film of silica nitride to give an amorphous, light scattering inhibiting surface). d 27 Thickness of tin oxide Visibility of the iris 0.3 strong 0.6 distinct but weaker 0.9 barely visible with the exception of fluorescence light 1.3 faint even in fluorescence light The latter two materials are not aesthetically disturbing when used for building purposes.

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

A simple method for rapidly controlling the refractive index of thin films has been developed to be able 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 an undercoating layer. A liquid with this refractive index is selected.

A film whose thickness is about 0.2 - The coated glass is observed For example, diiodomethane, n = 1.74, can be used. 2 μm is deposited on a glass surface. with reflected light from a monochromatic light source, example- The coated glass shows an interference pattern with dark and light bands, shows a filtered mercury lamp at Å == 5461Å. if the thickness of the film varies over the glass surface. A drop of the liquid with known refractive index is applied to the film. If the refractive index of the film exactly corresponds to the index of the liquid, the interference pattern disappears during the drop.

If the refractive index of the film and drop does not exactly match, the interference pattern is still visible during the drop. If this weak interference pattern below the drop is a direct continuation of the band but with weaker intensity. pattern on the rest of the film, the refractive index of the film is higher than that of the reference liquid. On the other hand, if the strip pattern below the drop is reversed (light and dark areas reversed) compared to the pattern present outside the liquid drop, the refractive index of the film is lower than that of the reference liquid. va1osv4-1 28 Using this simple but accurate measurement of the refractive index of the film, the conditions for producing a film can be easily adjusted with a series of attempts to correspond to the desired value. By selecting other reference liquids, you can adjust the films to various other values. Refractive index n = 1.63, which is used in a two-layer undercoat, can be adjusted using 1,2,2,2-tetrabromethane as the reference liquid. Refractive index n = 1.86 for the second layer in a two-layer undercoat can be adjusted to a solution of sulfur and phosphorus in diiodomethane, as described by West in American Mineral, Volume Z1, p. 245 (1936). From the above, it is also obvious to those skilled in the art that this general method can be used for quality control in manufacturing. Liquids with known refractive indices are also marketed by Cargille Laboratories, New Jersev, A.f.s.

It is obvious that the method according to the invention makes it possible to improve the heat saving in buildings with substantial glazing and to also apply electric heating of windows, for example in automobiles and aircraft, using the resistance properties of coatings according to the invention.

These coatings usually exhibit ohmic resistance, usually of the semiconductor type.

Claims (17)

'? 81 @ 97'lß- 1 93 PATENTKRAV An article comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflecting material consisting of a transparent semiconductor tending to exhibit iridescent colors in daylight illumination, characterized in that a second coating is applied between the glass sheet and the first coating, said second coating acting as a means of 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 in such a manner that the visibility of the iridescent colors in daylight illumination is substantially reduced, the second coating having a refractive index which is essentially the square root of the product of the refractive index of the glass and the first coating, the second coating having a thickness of about 1/4 of the wavelength of light with a vacuum wavelength of about 500 nm, or the a the second coating has a composite refractive index amounting to substantially the square root of the product of the refractive index 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 with a vacuum wavelength of about 500 nm, or the second coating has a refractive index gradient, which gradually varies between the glass and the infrared reflective material from a refractive index near the refractive index of the glass to a refractive index near the refractive index of the infrared-reflecting material. 2. An article according to claim 1, characterized in that the first layer of semiconductor material has a thickness of less than 0.4 .mu.m. 3. An article according to claim 1 or 2, characterized in that the article comprises only glass sheets of clear glass or light colored glass and is free of metallic luster, bronze luster, gray tones and other dark tones. with the ability to suppress the visibility of iridescence and preferably reduce the object's transmittance to less than about 25%. 4. An article according to any one of claims 1-3, characterized in that the first and the second coating together or all inorganic coatings on the article have a thickness of from 0.1 to light. 5. An article according to any 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. I An article according to any one of the preceding claims, characterized in that the first coating consists of stannous dioxide. 7. An article according to any one of the preceding claims, characterized in that the second coating consists of an amber material and forms means for avoiding haze formation on the glass during the application of the first coating. ' An article according to any one of the preceding claims, characterized in that the second coating has a refractive index value of from about 1.7 to 1.8 and has a thickness of about 64 to 80 nm, the first coating has a refractive index value of about 2 and the glass has a refractive index value of about 1.5. 9. An article according to any one of the preceding claims, characterized in that the second coating consists mainly of metal oxide, in particular alumina, metal nitride or a mixture thereof, in particular mixtures 1-18 according to Table A in the description. . 76 '1 09-71: -.- 1 '31 10. An article according to any one of the preceding claims, characterized in that the amorphous film is silicon oxynitride. 11. ll. An article according to any one of claims 1-9, characterized in that the second coating comprises two layers comprising (a) a first layer closer to the glass with a composition according to Table B in the description and (b) a second layer closer to the first the coating with a composition according to Table C in the description. An article according to any one of the preceding claims, characterized in that the second coating comprises two layers, of which (a) a layer closer to the glass with a refractive index, which is mainly determined by the formula na = nsc gl and (b ) a second layer closer to the first coating with a refractive index substantially according to the formula O, 74n 0.26 nb = n gl SC wherein nsc is the refractive index of the first coating and ngl is the refractive index of the glass. An article according to claim 12, characterized in that the second coating comprises two layers, which comprise (a) a first layer closer to the glass with a refractive index of about 1.6-1.7, (b) a second layer closer the first coating having a refractive index of about 1.8-1.9, the first coating having a refractive index of about 2 and the glass having a refractive index of about 1.5. An article according to any one of the preceding claims, characterized in that the second coating comprises silicon oxynitride mixture of the formula XSiO 2 (1X) Si 3 N 4 or mixtures of SixSn1_xO2 or GexSn1_x02, wherein x varies from near one at the glass surface to zero or near zero at the interface to the first coating. Object according to one of the preceding claims, characterized in that the gradient is changed stepwise with a plurality of sublayers with stepwise different refractive indices. A method of manufacturing an object comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflecting material, which consists of a transparent semiconductor with a tendency to exhibit iridescent colors in daylight lighting according to any one of the preceding claims. in a second coating applied between the glass sheet and the first coating, this second coating acting as a means of substantially reducing the iridescent colors of the first coating by forming at least two interfaces which, together with the mass of the the second coating, reflects and refracts light in such a way that the visibility of the iridescent colors in daylight illumination is substantially reduced, characterized in that a second coating is applied, which has a refractive index which is essentially the square root of the product of refractive index of the glass and the first coating, the second coating n has a thickness of about 1/4 of the wavelength of light with a vacuum wavelength of about 500 nm, or I has a composite refractive index, which amounts to substantially the square root of the product of the refractive index of the glass and the first coating, the second the coating comprises two layers, each of which has a thickness of about 1/4 of the wavelength of light with a vacuum wavelength of about 500 nm, or I has a refractive index gradient which gradually varies between the glass and the infrared reflecting material. -1 '53 rial from a refractive index near the refractive index of the glass to a refractive index close to the refractive index of the infrared reflective material before the application of the first inorganic coating. 17. l7. Use of an object comprising at least one transparent glass sheet provided with a first inorganic coating of an infrared reflective material, which consists of a transparent semiconductor with a tendency to exhibit iridescent colors in daylight illumination, which is characterized in that a second coating is applied between the glass sheet and the first coating, said second coating acting as a means of 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 refracts light in such a way that the visibility of the iridescent colors in daylight illumination is substantially reduced, the second coating having a refractive index which is essentially the square root of the product of the refractive index of the glass and the first coating, the second coating having a thickness of about 1 / 4 of the wavelength of light with a vacuum wavelength gd of about 500 nm, or the second coating has a composite refractive index, which amounts to substantially the square root of the product of the refractive index 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 with a vacuum wavelength of about 500 nm, or the second coating has a refractive index gradient, which gradually varies between the glass and the infrared reflective material from a refractive index near the refractive index of the glass to a refractive index near the refractive index of the infrared reflective material to achieve an iridescent appearance of glass surfaces in a building and counteract loss of heat from the building through these glass surfaces by reflecting infrared radiation into the building from the thin coating of the infrared reflecting semiconductor film on the surface of the glass and / or for electric heating of these glass surfaces geno m that a voltage is applied across the thin coating of semiconductors.