MXPA01002712A - Alkali metal diffusion barrier layer - Google Patents

Abstract

Amorphous metal oxide barrier layers of titanium oxide, zirconium oxide and zinc/tin oxide are effective as alkali metal ion barrier layers at thicknesses below 180 Angstroms. The amorphous metal oxide barrier layers are most effective when the density of the layer is equal to or greater than 75%of the crystalline density. The barrier layers prevent migration of alkali metal ions such as sodium ions from glass substrates into a medium e.g. electrolyte of a photochromic cell, liquid material of a liquid crystal display device contacting the glass surface and a photocatalytic coating. The properties of the medium, particularly electroconductive metal oxide coatings, are susceptible to deterioration by the presence of sodium ions migrating from the glass.

Description

LAYER OF BARRIER AGAINST THE DIFFUSION OF ALKALINE METAL INFORMATION ON THE CONTINUATION OF THE APPLICATION This application is a continuation, in part, of United States Patent Application No. 08 / 597,543 filed on February 1, 1996, in the name of James J. Finley and F. Howard Gillery. , which is a continuation application, in part, of United States Patent Application Serial No. 08 / 330,148 filed October 4, 1994, now abandoned, in the name of James J. Finley and F. Howard Gillery .

FIELD OF THE INVENTION This invention relates to a barrier layer and, more particularly, to a barrier layer for preventing the diffusion of alkali metal ions, such as sodium ions, from a glass substrate in a medium, by example, a coating, such as an electroconductive coating or a photocatalytic coating.

DESCRIPTION OF THE PROBLEM OF THE TECHNIQUE The alkali metal ions, for example, the sodium ions in glass, particularly at elevated temperatures, migrate from the surface of the crystal to the interior of the medium covering the glass. For example, in liquid crystal display ("LCD") devices, similar to the type described in U.S. Patent No. 5,165,972, sodium ions on the surface of the glass substrate migrate into the interior of the liquid crystal, which causes deterioration of the liquid crystal material. Additionally, in the electrochromic screens, the sodium ions migrate within the coatings that cover the surface of the glass substrate and / or within the electrolyte, which causes the deterioration of the coating and / or the electrolyte. During the manufacture of LCD devices and / or electrochromic devices, the glass substrate is heated to temperatures as high as 1100 ° F (593 ° C) to seal the devices; during such heating, the migration of sodium ions is accelerated. Unless prevented, the sodium ions migrate to the interior of the medium, for example, the electroconductive coating, the electrolyte and / or the liquid crystal material that coats the surface of the glass substrate that deteriorates the medium.

It is also believed that the migration of alkali metal ions, for example, the migration of ions ^^^ Sodium, also causes the deterioration of photocatalytic compositions of the type described in International Application Publication No. WO 95/11751, in coatings. of photocatalytic self-cleaning of the type described in United States Patent Application Serial No. 08 / 899,257, filed July 23, 1997, in the name of Charles B. Greenberg et al., for "PHOTOCATALYTICALLY- ACTIVATED SELF -CLEANING ARTICLE AND METHOD OF MAKING SAME "and in the photoelectrically reducing coating of the type described in United States Patent Application Serial No. 08 / 927,130 filed on September 2, 1997, in the name of James P. Thiel for "PHOTOELECTROLYTICALLY- DESICCATING MULTIPLE-GLAZED WINDOW UNITS". In general, the compositions include particles of titanium dioxide or zinc oxide held together and to a glass substrate by a silicone binder or coatings of titanium oxides, iron oxides, silver oxides, copper oxides, oxides of tungsten, to name a few. The surface of the composition and the film can act as a biocidal agent under the application of light.

A technique for preventing or minimizing the migration of alkali metal ions is to provide a barrier coating between the medium and the glass substrate. U.S. Patent No. 5,165,972 to Porter discloses barrier coatings to prevent the migration of alkali metal ions from a glass surface. The barrier coating is deposited by pyrolysis of a silane gas on the glass surface above 600 ° C in the presence of a gaseous electron donor compound. The oxygen from the glass is incorporated with silicon to form a transparent barrier coating up to 50 nanometers thick on the glass surface to prevent the migration of alkali metal ions into superposed layers sensitive to alkali metal ions. Although the technique of the Porter v972 document is acceptable, there are drawbacks. For example, oxygenation by pyrolysis requires high energy inputs especially if the sheets that must be heated before coating make the process expensive. U.S. Patent No. 4,238,276 in the name of Kinugawa discloses a barrier layer which includes silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and nickel oxide. Kinugawa describes a barrier coating of silicon oxide having a thickness of 1000 Angstroms. Although the barrier coating described by Kinugawa is acceptable, it has drawbacks. More particularly, the deposition of a layer of 100 Angstroms thick silicon oxide by any technique is more expensive than the deposition of a layer of silicon oxide less than 1000 Angstroms thick by the same process. Additionally, a thin silicon oxide layer of the type described in Kinugawa can not act as an effective barrier. The Publication of the Descriptive Report of European Patent No. 0 071 865 B in the name of Mizuhashi et al. Discloses a glass body having a glass substrate containing alkali and a layer of silicon oxide formed on its surface to prevent the diffusion of alkali metal ions from the glass substrate. The silicon oxide layer has from 0.01 to 25 mole percent of hydrogen adhered to silicon. Although the technique described by Mizuhashi et al. It seems that prevents the migration of alkaline metal ions, there are drawbacks. More particularly, the barrier coating can trap hydrogen gas that ^ ^ "Kf. it can escape during the manufacture / use of the product, for example, LCD devices. Copo may find it preferable not to have a coating that can randomly gas hydrogen in a medium that can cause deterioration of the medium. In addition, the hydrogen that is chemically adhered to the coating can affect the optical and mechanical properties of the coating. As can be appreciated, it would be advantageous to provide a thin barrier layer that can be economically applied, and does not have the drawbacks / limitations of currently available technology.

SUMMARY OF THE INVENTION The present invention recognizes the desire to use a fine material as a diffusion barrier for alkali metal ions, such as sodium ions. Although the prior art suggests that the refractive index of such a diffusion barrier should match the refractive index of the substrate as closely as possible, thus selecting silica for the glass substrates, in accordance with the present invention, very thin layers of metal oxide are produced, such as zirconium oxide, titanium oxide and zinc / tin oxide, ^^^^ aA * ^ ^^^^^^^ gg as effective barriers against the diffusion of sodium ions without compromising the optical properties of the coated glass. In general, the present invention relates to a article having a medium, eg, photocatalytic coating, water-reducing coating, electroconductive coating, electrolyte of a photochromic device and / or liquid liquid crystal display material on top of it. distance from the surface of the substrate crystal. A barrier layer, for example, zirconium oxide, titanium oxide or zirconium oxide / tin is deposited by magnetron sputtering onto the glass substrate to provide a barrier layer between the medium and the glass substrate. The barrier layer or film is a thin amorphous film and has a density equal to or greater than about 75% of the crystalline density of the metal oxide of the film in the practice of the invention, and the barrier films are in the range of 30 to 180 Angstroms depending on the selected barrier film.

Although zirconium oxide, titanium oxide and / or zinc oxide / tin have refractive indices significantly larger than the refractive index of typical glass substrates, since they are very thin, there is no g ^^ a Sj ^ * ^^^^^ M ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ effect detrimental to the optical properties of the coated glass substrate. The glass substrate, which has the barrier layer, can be used as a component of a liquid crystal display cell, and / or a photochromic device and / or may have a photocatalytic film deposited thereon. BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING Figure 1 is a cross section of a liquid screen device ("LCD") that incorporates the features of the invention. Figure 2 is a cross section of a glass sheet having the barrier layer of the invention between a photocatalytic composition and a glass substrate. Figure 3 is a side view of a sputtering apparatus having the walls of the chamber removed to show the path of the cathode housing with respect to a glass substrate to be sputter coated. Figure 4 is a view similar to the view of Figure 3 showing the protections on the cathode housing according to the invention. Figure 5 illustrates the effectiveness in reducing the migration of alkali metals from a barrier layer of X2MX titanium oxide at thicknesses of 45, 90, 135 and 180 Angstroms (Examples 1 to 4), compared to uncoated glass. Figure 6 illustrates the effectiveness of a zirconium oxide barrier layer at thicknesses of 30, 60, 90 and 120 Angstroms (Examples 5 to 8), compared with uncoated glass. Figure 7 illustrates the comparative performance of a barrier layer at thicknesses of 30, 60, 90 and 120 Angstroms of zinc oxide / tin (Comparative Examples 9 to 12), compared to crystal not coated. Figure 8 compares the effectiveness of barrier layers of titanium oxide, zirconium oxide and zinc / tin oxide at thicknesses of 45, 30 and 90 Angstroms, respectively (Examples 1, 5 and 9). Figure 9 compares the effectiveness of barrier layers of titanium oxide, zirconium oxide and zinc / tin oxide at thicknesses of 90, 60 and 60 Angstroms, respectively (Examples 2, 6 and 10). Figure 10 shows the effectiveness of the layers of titanium oxide, zirconium oxide and zinc oxide / tin barrier as a function of the thickness of the barrier layer (information of Figures 5-9).

Figure 11 is a replication to the transmission electron microscope ("TEM") of the deposited coating that puts the invention into practice. Figure 12 is a TEM replica of the coating 5 deposited without practicing the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An effective barrier layer against alkali metal ions is preferably stable and remains waterproof diffusion of alkali metal ions even at elevated temperatures, for example, as high as 1100 ° F (593 ° C). Optically, the barrier layer preferably has a high transmittance in the visible wavelength range so as not to affect the properties optics of the overlay. In applications where the overlay is electroconductive, the barrier layer is preferably non-electrically conductive. If the overlay is subjected to partial pickling, for example, to produce a circuit, it is recommended that the layer barrier is not soluble in the stripper, often hydrochloric acid. If the refractive index of the barrier layer matches the refractive index of the substrate as closely as possible, as with the use of a Silica barrier layer, for a silica-lime-sodium bicarbonate, a thicker barrier layer may be applied, for example, as described in U.S. Patent No. 4,238,276 for greater effectiveness without great loss of transmission of visible light or other undesirable optical effects. However, when the refractive index of the barrier layer does not match the refractive index of the substrate, a thinner barrier layer is preferable to prevent the loss of visible light. As will be appreciated, the barrier layers or films of the invention are fine and stable. An advantage of the present invention is the elimination of the requirement of the barrier film for the same or substantially the same refractive index as the substrate. Since the films are thin, they have a minimal effect, if any, on the transmission of the coated article. In other words, the film and the thickness of the film should be selected to be optically acceptable, for example, the film does not decrease the transmission of the substrate, when the film is directly coated on the substrate, by more than 10% of the transmission measured at 550 nanometers and preferably not greater than 5% Additionally, the selected ones are not soluble in most paint strippers. ***** "Conventional sodium silica-carbonate bicarbonate glass substrates formed by a floating process are preferred in the practice of the invention, however, as will be appreciated, the barrier layers of the invention do not They are limited to this and can be used with any type of substrate from which alkaline metal ions can migrate.

Preferred in the practice of the invention prevent or minimize to the minimum the migration of the alkali metal ions, for example, sodium ions from the substrate into the superposed medium. In addition, the barrier layers of the invention can be used to prevent or minimize the The migration of alkali metal ions from glass into media even when the crystal is subjected to high temperatures, for example, a temperature as high as 1100 ° F (593 ° C). With reference to Figure 1, the LCD device 10 is similar to the type described in U.S. Patent No. 5,165,972 and includes opposite glass sheets 12 and 14 separated by the peripheral seal 16 to define a chamber 18 containing liquid crystal material 20. Each of the sheets 12 and 14 carry a transparent barrier layer or "M-tfc" film 22 of the invention sputtered onto the glass sheets or substrates according to the invention. An electroconductive coating 24 is on the barrier layer 22. An alignment layer 26 is on the electroconductive coating 24 in contact with the liquid crystal material 20. The light transmitting properties of the liquid crystal material 20 can be controlled by the application of a potential difference between the electroconductive layer 10 on the glass sheets 12 and 14. The barrier layer of the present invention can also be used to prevent deterioration of catalytic compositions, for example, of the type described in the Publication International Application No. WO 95/11751, 15 of photocatalytic films and water reduction films. With reference to Figure 2, there is shown an article 30 having a barrier layer 32 of the invention between the glass substrate 34 and a composition or film 36. The composition may be titanium dioxide particles in a silicone binder. and the film can be a photocatalytic self-cleaning film of the type described in United States Patent Application Serial No. 08 / 899,257 filed July 23, 1997, or a film ? * * á * ~. -fif ^ f -ífrWif íl 'I • Tftff ~~ ^ - »» - **** - "* - - .. ^^^ x ^^^ .z. * ^ ..A **. ^. . of photoelectric reduction of the type disclosed in U.S. Patent Application Serial No. 08 / 927,130 filed September 2, 1997, and include, but are not limited to, titanium oxides, iron oxides, copper oxides, tungsten oxides. The disclosure of U.S. Patent Applications Serial Nos. 08 / 899,257 and 08 / 927,130 is incorporated herein by reference. As can be seen, the LCD 10 and the article 30 described above do not limit the invention and are presented to illustrate two means in which the barrier layer of the present invention can be used. The invention contemplates the use of amorphous, fine metal oxide barrier layers having a density equal to or at least about 75% of the crystalline density of the metal oxide of the film (described in more detail below). Examples of metal oxides which can be used in the practice of the invention are zirconium oxide, titanium oxide and zinc / tin oxide films. Preferred metal oxides in the practice of the invention include, but are not limited to, zirconium oxide and titanium oxide, since they are found to be more effective at thicknesses as low as 20 to 100 Angstroms, are optimally effective at espe'ggjires in the range of 301 60 Angstroms and less soluble in paint strippers than zinc / tin oxide. The metal oxide barrier layers of the present invention are preferably deposited, but not limited to, magnetron sputtering of a metal target in an oxidizing atmosphere in the manner described below. The morphology of metal oxide films, such as titanium oxide, zirconium oxide and zinc oxide / tin usually when measured by X-ray diffraction is amorphous when deposited as thin films, for example, films having a thickness less than approximately 180 Angstroms. Amorphous films have no grain boundaries and, therefore, they are expected to be acceptable as barrier layers to prevent the migration of alkali metal ions, for example, from sodium ions. However, it is believed for the reasons described below that amorphous films are more effective as barrier layers as their density increases. For example, titanium oxide films having a thickness in the range of about 45 to about 180 Angstroms are effective as barrier layers when the amorphous titanium oxide films have densities equal to or greater than about 75% of its crystalline density, that is, densities equal to or greater than about 3.20 grams per cubic centimeter; they are more effective as barrier layers when amorphous titanium dioxide films have densities equal to or greater than about 80% of their crystalline density, ie densities equal to or greater than about 3.41 grams per cubic centimeter, and are even more effective as the density of the amorphous titanium oxide film approaches its crystalline density, i.e., approaches a density of about 4.26 grams per cubic centimeter, which is the density of rutile titanium dioxide. As appreciated by those skilled in the art, zirconium oxide has different crystalline forms. Of particular interest is the cubic zirconium oxide which has a density of 5.6 grams per cubic centimeter and the badeliite which has a density of 5.89 grams per cubic centimeter. Zirconium oxide films having a thickness in the range of about 30 to about 120 Angstroms are effective barrier layers when the amorphous zirconium oxide films have densities equal to or greater than about 75% of their crystalline density, for example, densities equal to or greater than about 4.2 grams per cubic centimeter using the density of cubic zirconium oxide and 4.42 grams per cubic centimeter using the zirconium oxide density of badeliite; are more effective as barrier layers when the amorphous zirconium oxide films have densities equal to or greater than about 80% of their crystalline density, ie densities equal to or greater than about 4.48 grams per cubic centimeter using the density of the oxide cubic zirconia and 4.71 grams per cubic centimeters using badeliite zirconium oxide density, and are even more effective as the density of amorphous zirconium oxide film approaches its crystalline density; that is, it approximates a density of approximately 5.6 grams per cubic centimeter using the density of cubic zirconium oxide and approximately 5.89 grams per cubic centimeter using the density of zirconium oxide of badeliite. Zinc oxide / tin films having a thickness in the range of about 60 to about 120 Angstroms are effective barrier layers when the zinc oxide / tinned amorphous films have densities equal to or greater than about 75% of their crystalline density , for example, equal densities greater than about 4.8 grams per cubic centimeter; are more effective as barrier layers when the amorphous zinc oxide / tin films have densities equal to or greater than about 80% of their crystalline density, ie, densities equal to or greater than about 5.1 grams per cubic centimeter, and are even more effective as the densities of the amorphous zinc oxide / tin film approach their crystalline density, For example, they approximate a density of approximately 6.38 grams per cubic centimeter. In the foregoing description, reference was made to the specific metal oxide, for example, titanium oxide, zirconium oxide and zinc / tin oxide. How can In order to appreciate, the metal oxide can be metal oxide or sub-oxide. Therefore, when the terms titanium oxide, zirconium oxide or zinc oxide / tin are used, reference is made to the titanium, zirconium or zinc / tin oxides present in a titanium oxide film, Zirconium oxide or zinc oxide / tin film sprayed cathodically, respectively. Although there are several techniques for determining the density of a thin film coating, the following technique is preferred. The thickness of the film was determined using a profilometer of * style. The X-ray fluorescence technique is used to determine the weight per unit area of the film. The thickness of the film measured using the Angstroms style profilometer is converted into centimeters and divided into the weight per unit area determined using the X-ray fluorescence technique in micrograms per square centimeter and converted to give the film density in grams per cubic centimeter. The description will next be directed to the coating of a glass substrate to provide a metal oxide barrier layer of the present invention., that is, an amorphous film having a density of at least 75% of its crystalline density. With reference to Figure 3, the vacuum magnetic spray device 40 had a cathode housing 42 mounted within the chamber (not shown) to move along an alternate motion path designated by number 44. A glass substrate 46 was mounted on a stationary support 48. The crystal was heated by the heater 49 to a temperature of approximately 200 ° F (93.3 ° C). As the material sputtered cathodically moves out of the casing directions; however, for this description and to simplify it, it is considered to move to the left as shown by the displacement path 52, downward as shown by the travel path 53 and to the right as shown by the displacement path 54 outside the housing 42 as seen in Figure 3. In the practice of the invention, the cathode was a metal cathode of zirconium sputtered cathodically in an argon / oxygen atmosphere of 50/50 percent. The zirconium oxide moving along the displacement paths 52, 53 and 54 was deposited on the surface 50 of the glass substrate. As seen in the figure 3, as the housing 42 moves to the left, the material moving along the path 52 drives the housing, and as the housing moves to the right, the material moves as it moves. along the path 54 drives the housing. The material that is moves along the path 53 does not drive or follow the housing. The material that travels along paths 52 and 54 has a low angle of incidence shown in Figure 3, as the angle a delimited by the plane of the carousel and paths 52 or 54. It is believed that the device shown in Figure 3 ~ r deposited a thin zirconium film having a density less than 75% of its crystalline density, i.e. less than about 4.2 grams per cubic-meter cubic. With reference to Figure 4, the apparatus 40 modified according to the invention is shown. More particularly, the aluminum covers 56 were provided on the front and rear sides of the housing. The aluminum covers extended downward towards the surface of the glass substrate 46, but did not come into contact with the surface 50. It is expected that the thin layers of the metal oxide films coated using the device shown in Figure 4 are effective barriers against migration. from Sodium ions, since the amorphous films deposited using the device shown in Figure 4 have a density greater than about 75% of their crystalline density, for example, greater than about 4.2 grams per cubic centimeter. In the practice of the invention, glass substrates of 12 inches (0.30 meters) by 12 inches (0.30 meters) were coated in an apparatus of the type shown in Figure 4. The heater 49 heated the substrates of crystal -a &? - a ^ = - ^^ - ^ - ^ a .-- ^ A, ^ - ^ i - a-te ^ - »> ,. ^ - .. A¿ ^ jatfe., -.-. ^ - ^ -. ^ -.- ^^^^ | »- - rtH ^ -ta-tta-to ^ up to approximately 200 ° F (93.7 ° C) The glass substrates were cleaned by first polishing the surface to be coated with cerium oxide and then rinsed to The glass substrate was then rinsed in a 50/50 mixture by volume of deionized water and 2 (iso) -propanol.The effectiveness of the zirconium oxide barrier layer was determined by exchanging silver ions of the barrier layer by sodium ions that penetrated the barrier layer, and then measuring the ion concentration silver using X-ray fluorescence. The concentration of silver ions (which is proportional to the sodium concentration) was determined by calculating the net intensity (NI) of the silver emission line, Ag (NI). The silver counts per second (Ag (CPS)) were determined counting the Ag (NI) for a period of 40 seconds. Indicated otherwise, the Ag (CPC) are Ag (NI) counts for 40 seconds. To provide a reference of the sodium concentration, the Ag (NI) for coated glass was compared with the Ag (NI) of uncoated glass. The background level of the X-ray spectrometer gave an Ag (NI) of approximately 16,000, which indicates a zero silver concentration and, therefore, a zero sodium concentration. Barrier layers j ----- S-E ---.

Thus, optimum values should preferably have Ag (NI) close to its value, that is, an Ag (NI) of 16,000 or 400 counts per second (CPS). Each coated substrate was cut into three 5-square pieces of 1-3 / 8 inches (4.5 centimeters). One piece of the substrate was not heated, one piece was heated to 700 ° F (371, 1 ° C) for one hour, and one piece was heated to 900 ° F (482 ° C) for one hour. The hot pieces were cooled to room temperature, and the barrier layer of Each piece was prepared for ion exchange which included applying a potassium nitrate of 62% mole eutectic and a silver nitrate solution of 38% mole to the coated surface of the pieces, and heating the pieces for 1 hour to approximately 150 ° C. Before applying the eutectic solution, the pieces were preheated at 150 ° C for 15 minutes, and the eutectic solution was applied to the heated pieces. The solution was captured on the surface by providing a boundary around the edge of the pieces with tape sold under the Teflon brand. The Teflon tape is applied before the pieces were preheated. The solution was uniformly applied by covering the exposed coated surface to a thickness of approximately 0.100 inches (0.254 cm). After heating the pieces that had the eutectic solution, the pieces give, glass was baked and the solution was left to cool and harden. The hardened solution was then rinsed thoroughly with water. The pieces were then immersed in nitric acid to remove the residual silver film on the glass surface and rinsed to remove the silver nitrate residues resulting from the reaction of silver with nitric acid. The X-ray fluorescence analysis of the pieces exchanged with silver ions was then carried out to determine the migration of sodium. The following table provides details for the coated and exchanged parts A-L with ions in the above manner and the effectiveness of the zirconium oxide barrier. The column (1) of the TABLE indicates the part number; the column (2) indicates the number of passes made by the zirconium oxide cathode, one pass is the movement in one direction along the reciprocal path 44 (see figures 3 and 4); column (3) indicates the current in amps applied to the cathode during sputtering; column (4) indicates the voltage in volts applied to the cathode during sputtering; column (5) indicates the material of the coated substrate; the column (6) is the percentage transmission of the pieces ^^. ^. ^^ i ^ ....., ^ ..., ^^ ^ A fc¿--. ^ .. ^., ^^^ £ & £ ^^ ,. ! coated in the visible range - (note: the transmission was not measured for parts F and it for reasons not known now); column (7) indicates the thickness of the films in Angstroms measured using the net intensity of the zirconium emission from the X-ray fluorescence calibrated against the thickness of the zirconium oxide film measured using an angstrometer; columns (8), (9) and (10) indicate the Ag (NI) readings for the heated and unheated parts. The notes * and ** in the TABLE identify the process for the manufacture of the glass substrate and its thickness and the note *** indicates the% transmission for the uncoated parts. The transmission values given in the TABLE were measured at 550 nanometers. As described above, the optimal barriers have an Ag (NI) reading of approximately 16,000 (400 CPS); however, as can be seen, depending on the degree of penetration of the alkali metal ions that may have existed without deterioration of the medium, it is the desired level, and therefore, the Ag (NI) number does not limit the invention.

-•Y TABLE * Flt - 0.125"float glass - ** S- 0.050" Flachglas sheet glass *** The transmission for uncoated float glass is 90% The transmission for uncoated sheet glass is 91.3%. - ^ - - * - 3 - M ^ j ^^ AC¿ "-MAI ~ T f ^ aá .ja-- .. ^ -. ^^ LJ ^ A ^^^^^.-..-- -fa-Ai-at ^. * 'r "^ r ~' z The Ag (NI) for the unheated part F has the highest reading It is believed that the film was not as dense as expected, perhaps due to the preparation of the substrate for the coating The Ag (NI) for parts E, F, G, J and K in columns (9) and (10) seems high.It should be noted that the corresponding unheated parts F, G, J and K in the column (8). ) are also high, indicating that the film was not affected, perhaps for the reason indicated above.10 It should be noted that, although the zirconium oxide had a higher refractive index than the glass substrate, the zirconium oxide was sufficiently fine , since the transmission of the coated piece decreased less than 2% (see column (6)). A glass substrate was prepared as described above and coated using the coating device shown in Figure 3 (without the sleeve 56 shown in figure 4). Zirconium oxide had a thickness of 233 Angstroms. The coated substrate was cut into square pieces of 1-3 / 8 inches (4.5 centimeters). A piece was heated at 300 ° F (149 ° C) for 1 hour and then ions were exchanged as described above; the piece had an Ag (NI) reading of 60,000. ^? ¡^ Í ^^? B ^ ü ^^? ^^? J ^^ fe. ^^ fe ^ ^^, ^^^,,., ^ ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ ^^^ ¡a ^ - Another piece was heated to 500 ° F -dj'C) for 1 h and then ions were exchanged, as described above, the piece had an Ag (NI) reading of 145,000. piece at 750 ° F (399 ° C) for 1 hour and then ions were exchanged, as described above, the piece had an Ag (NI) reading of 155,000. A fourth piece was heated to 900 ° F (482 ° C) ) for 1 hour and then ions were exchanged, the piece had an Ag (NI) reading of 180,000.The performance of the oxide barrier layer Zirconium deposited without the use of the sleeves (see Figure 4) was significantly better than the zirconium oxide barrier layer deposited without the sleeves (see Figure 3). It is believed that the improved performance of zirconium oxide as a barrier layer was due to the oxide film of zirconium deposited using the apparatus in Figure 4 which was an amorphous zirconium oxide film having a density equal to or greater than 75% of its crystalline density. The following Examples 1-12 were coated using an Aireo ILS 1600 coating device. The coating device had a stationary housing having the metal cathode and a conveyor for moving a glass substrate under the housing. The glass substrate was moved through a coating area adhered by fcfl & ^ - * A * --- ^ - ^ .. ^^ - MfeMM-tr • | - * ífrpftÍMÍ ---- MM- r - ^^ * ^ * "- * ^^^^ The walls walls 56 shown in 4, but were not as restrictive in reducing the units of absorbed doses as shown in Figure 3. Example 13 was coated using the device shown in Figure 4 described above. measure the effectiveness of the barrier layer deposited on the samples in the prevention of alkali metal diffusion, the glass samples coated with The barrier layer was heated at about 575 ° C for 10 and 20 minutes to promote the migration of alkali metals from the glass substrate. Afterwards, the samples were cooled to room temperature. After this, the ion exchange procedure was used described above, except that the samples having the eutectic solution were heated for 2 hours at 150 ° C. The coated surfaces were then analyzed by X-ray fluorescence to measure the amount of silver present, which is proportional to the amount of sodium that is diffused into the coating from the glass. The concentration of silver ions was measured as Ag (CPS). For comparison, the unheated coated samples were exchanged with ions and the silver was measured for a previous count, same as the samples of criscln: not coated not heated and heated. When the barrier layer is zirconium oxide, the thickness is preferably in the? range from 20 to 120 Angstroms, more preferably j ^ 3e 20 to 90 Angstroms, particularly 30 to 60 Angstroms, and more particularly 50 to 60 Angstroms, and the film had a density equal to or greater than 4.48 grams per cubic centimeter using the value of density of cubic zirconium oxide. When the The barrier layer is titanium oxide, the thickness is preferably in the range of 20 to 90 Angstroms, preferably 30 to 90 Angstroms, particularly 45 to 90 Angstroms, and more particularly 50 to 60 Angstroms, and the film had a density equal to or greater than 3.4 grams per cubic centimeter. When the barrier layer is zinc oxide / tin, the thickness is preferably in the range of 60 to 120 Angstroms, and preferably 60 to 90 Angstroms, and the film has a density equal to or greater than 4.8 grams per cubic centimeter. . As you can see, it's Preferably a thin barrier layer so as not to reduce the optical transmission. In a particularly preferred embodiment of the present invention, the barrier layer is coated with an electroconductive metallic oxide coating pair fflcl!% ***. on a liquid crystal screen. Preferred electroconductive metal oxide coatings include indium oxide, tin oxide, indium tin oxide and zinc / aluminum oxide. A particularly preferred electroconductive coating is indium / tin oxide, commonly referred to as ITO. The indium / tin oxide coating preferably used in a liquid crystal display device typically has an electrical resistance 10 of about 300 ohms per square. The indium / tin oxide coating is preferably deposited on the barrier layer by magnetron sputtering. The electroconductive metal oxide films may be deposited by sputtering a metal cathode lens 15 in an oxidizing atmosphere, or by sputtering ceramic metal oxide targets. The present invention will be further understood from the descriptions of the specific examples that follow below.

EXAMPLES 1 TO 4 Floating crystal samples of I -.-- * v * _-.-! * Were coated. lime-sodium bicarbonate, which contained a glass substrate thickness of 2.3 millimeters and a visible light transmission (measured at 550 nanometers) of 91.3 percent, with layers of 5 titanium oxide barrier j | § g¡ | ÍÍa next way. A flat titanium target was sputtered with magnetrons at 85 kilowatts, 520 volts in an atmosphere of 50 percent argon and 50 percent oxygen. The glass substrates were transported past a stationary cathode at a rate of 53 inches (1.35 meters) per minute. The titanium oxide barrier layers having thicknesses of 45, 90, 135 and 180 Angstroms were deposited by passing the glass substrates under the objective 1, 2, 3 and 4 times, respectively, (examples 1 to 4 respectively) . The visible light transmittances (measured at 550 nanometers) of the glass substrates coated with titanium oxide were 90.8 percent at 45 Angstroms, 89.4 percent at 90 Angstroms, 87.3 percent at 135 Angstroms and 84 , 8 percent at 180 Angstroms (Examples 1 to 4, 20 respectively). The glass substrates coated with titanium oxide were heated at 575 ° C or for 10 or 20 minutes, then subjected to exchange of silver ions to replace any sodium diffused with silver. The . ^ aa-Jh- ^ i ^ ^ - * "^ * - • • a ^ ~ *« ~ ~ * ¡i * m * £?. < * 3 ».. eteñ ito? t«, ^^ ^ ^^^^ Máti ^.

Silver was then measured by fluo escence of x-rays. 'He- shows in Figure 5 a comparison of the effectiveness of the barrier layer of titanium oxide at thicknesses up to 180 Angstroms.

EXAMPLES 5 TO 8 Silica-lime-sodium bicarbonate floating glass samples, having a thickness of 2.3 millimeters and a visible light transmission of 91.3, were coated. percent, with zirconium oxide barrier layers as follows. A zirconium target was sputtered with magnetrons at 6.5 kilowatts, 374 volts in an atmosphere of 50 percent oxygen and 50 percent argon. Since zirconium is sputtered faster than titanium, the glass substrates were transported beyond the stationary cathode at a rate of 190 inches (4.8 meters) per minute to deposit the zirconium oxide barrier layers having thicknesses of 30, 60, 90 and 120 Angstroms, respectively, from 1, 2, 3 or 4 passes (examples 5 to 8, respectively). The visible light transmittance of the glass substrate with the thicker zirconium oxide barrier layer (example 8 to 120 Angstroms) was 90.2%. hundred. The glass substrates coated with zirconium oxide were heated and subjected to silver ion exchange, as in the previous examples. Figure 6 shows the effectiveness of the zirconium oxide barrier layers at 5 thicknesses of 30 to 120 Angstroms.

COMPARATIVE EXAMPLES 9 TO 12 For comparison, samples of floating silica-lime-sodium bicarbonate glass, which had a thickness of 2.3 millimeters with zinc oxide / tin. A lens comprising 52.4 weight percent zinc and 47.6 weight percent tin was sputtered with magnetrons at 0.78 kilowatts, 386 volts in an atmosphere of 50 percent argon and 50 percent from oxygen. The glass substrates were transported at a rate of 190 inches (4.8 meters) per minute to deposit zinc oxide / tin coatings of 30, 60, 90 and 120 Angstroms in thickness from 1, 2, 3 and 4 passed, respectively (examples 9 to 12, respectively).

The transmittance of the glass substrate with the thicker zinc / tin oxide coating (example 12 to 120 Angstroms) was 90.7 percent. The glass substrates coated with zinc oxide / tin were heated, they underwent exchange of silver ions and measured X-ray fluorescence, as in the previous examples. Figure 7 shows that a zinc / fine tin oxide layer, for example, less than 30 Angstroms is not an effective barrier against sodium diffusion. More particularly, the effectiveness of the zinc / tin oxide as a barrier against the diffusion of sodium is achieved at a thickness greater than the thicknesses for titanium oxide and zirconium oxide, as well as a percentage of the density of the crystals formed of the same. zinc / tin films, as described above.

EXAMPLE 13 A zirconium oxide barrier layer was deposited on a 0.048 inch glass sheet (1.2 millimeters thick) by sputtering a zirconium cathode in an argon / oxygen atmosphere at a deposition rate of 7.8 Angstroms per second of zirconium oxide. In the three passes of the cathode at a rate of 2 inches per second (3.05 meters per minute), deposited a zirconium oxide barrier layer of 55 ± 5 Angstroms in thickness, decreasing the transmission of the glass substrate by approximately 0.5 to 1 percent. On the barrier layer of zirconium oxide was deposited indium / tin oxide layer the same crystal. Three passes of a cathode target, comprising 90 weight percent of indium and 10 weight percent of tin, produced a glass substrate coated with indium / tin oxide with a surface resistance of about 300 ohms per square and one transmittance of approximately 83.6 percent. Figures 8-10 show a further comparison of the thickness examples selected to show the effectiveness of the barriers of the invention. The foregoing examples are offered to illustrate the barrier layers of the present invention. Other metal oxides that effectively prevent alkali metal migration to similarly low thicknesses are within the scope of the invention, together with deposition methods other than magnetron sputtering. The overlay may be a single layer or multiple layers of various metals, metal oxides and / or other metal compounds, including silicon-containing coating layers. The heating time and temperature cycles described herein illustrate only one assay procedure useful for determining the effectiveness of the relative barrier layer.

Figure 11 is a replica, under the transmission electron microscope ("TEM"), of a coating, i.e., the barrier film deposited by practicing the invention, for example, using the coating apparatus shown in the figure 4. Figure 12 is a TEM replica of a deposited coating film without applying the invention, for example, using the coating apparatus shown in Figure 3. Each of the films shown in Figures 11 and 12 have a greater thickness than the thickness described for the invention and indicated again in the claims. Thicker films were made because the morphology of the film is easier to observe. As can be seen from Figures 11 and 12, the film shown in Figure 11 appears to be denser than the film shown in Figure 12. The scope of the present invention is defined by the following claims.

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Claims (21)

Claims

1. An article comprising: a glass substrate having alkali metal ions on a surface! a medium on the surface of the substrate and spacing thereof, the medium characterized in that predetermined concentrations of alkali metal ions deteriorate the function of the medium, and between the surface and the medium, a cathodically sputtered amorphous layer of a zirconium oxide having a thickness in the range of 30 to 120 Angstroms and having a density in the range equal to or greater than 75% and less than 90% of its crystalline density to provide a barrier layer against alkali metal ions between the glass substrate and the medium .

2. The article according to claim 1, wherein the density of the amorphous zirconium oxide is equal to or greater than 4.2 grams per cubic centimeter using cubic zirconium oxide, and 4.42 grams per cubic centimeter using badeliite. iÉ * ~~ jí j &UB utaun

3. The coated article according to claim 2, wherein the zirconium oxide barrier layer has a thickness in the range of 30 to 60 Angstroms.

4. The article according to claim 1, wherein the medium is an electroconductive coating selected from the group consisting of indium oxide, tin oxide, indium tin oxide and zinc / aluminum oxide.

5. The article according to claim 1, wherein the medium is a photocatalytic composition.

6. The article according to claim 5, wherein the composition includes titanium oxide particles in a silicone binder.

7. The article according to claim 1, wherein the medium is a liquid electrolyte.

8. An article comprising: a glass substrate having alkali metal ions on a surface; a medium on the surface of the substrate and spain thereof, characterized the medium because predetermined concentrations of alkali metal ions deteriorate the function of the medium, and between the surface and the medium, an amorphous layer sputtered from a titanium oxide having a thickness in the range of 45 to 180 Angstroms and having a density in the range equal to or greater than 75% and less than 90% of its crystalline density to provide a barrier layer of alkali metal ions between the glass substrate and the medium .

9. The article according to claim 8, wherein the density of the titanium oxide layer is equal to or greater than 3.2 grams per cubic centimeter.

10. The article according to claim 9, wherein the titanium oxide barrier layer has a thickness in the range of about 90 to 180 Angstroms.

11. An article according to claim 8, wherein the medium is an electroconductive coating - * - "- - - - '**? * ~ ^ ~ - á > ° *»? »?? * k6 ^ A ^« fc > adÍ Jbx. selected from the group consisting of indium oxide, tin, indium tin oxide and zinc / aluminum oxide.

12. The article according to claim 8, wherein the medium is a photocatalytic composition.

13. The article according to claim 2, wherein the composition includes titanium oxide particles in a silicone binder.

14. The article according to claim 8, wherein the medium is a liquid electrolyte.

15. An article comprising: a glass substrate having alkali metal ions on a surface; a medium on the surface of the substrate and spacing thereof, characterized the medium because predetermined concentrations of alkali metal ions deteriorate the function of the medium, and between the surface and the medium, an amorphous layer sprayed with a zinc / tin oxide it has a thickness in the range of 60 to 120 Angstroms and that has a density in the range equal to or greater than 75 9 - > less than 90% of its crystalline density to provide a barrier layer of alkali metal ions between the glass substrate and the medium.

16. The article according to claim 15, wherein the zinc / tin oxide layer has a density of 4.8 grams per cubic centimeter.

17. The article according to claim 16, wherein the thickness of the zinc oxide / tin layer is from 90 to 120 Angstroms.

18. The article according to claim 15, wherein the medium is an electroconductive coating selected from the group consisting of indium oxide, tin oxide, indium tin oxide and zinc / aluminum oxide.

19. The article according to claim 15, wherein the medium is a photocatalytic composition.

20. The article according to claim Kf wherein the composition includes particles of titanium oxide in a silicone binder.

21. The article according to claim 15, wherein the medium is a liquid electrolyte. 10