MXPA97005147A - Vid coatings - Google Patents

Abstract

The invention relates to a method for producing mirrors and coated glass substrates, which incorporate highly reflective "mirror" coatings.

Description

REVESTIMIEMTOS IS GLASS The invention relates to a method for producing mirrors and coated glass substrates, which incorporate highly reflective "mirror" coatings. The mirror reflective properties of mirrors are generally provided by a layer of highly reflective material, especially silver, aluminum or chromium, which is applied to a glass or plastic substrate; Sometimes copper layers are used as an alternative, but in general they are less acceptable due to the strong red tint of the reflected light. Silver coatings are generally applied to cold-formed glass plates by wet chemistry methods, where a silver salt solution is applied to the glass surface and reacts with a reducing agent that reduces silver ions present in silver metal that It is deposited on the surface of the glass. The silver used is not very durable in use and in practice requires protection by other layers, and these methods are generally not suitable for application to glass in the production line in which it is formed in such a way that a line of "plated" separated to produce the silvered glass. Aluminum coatings are difficult to apply by chemical methods due to the strongly reducing nature of aluminum metal, and aluminum mirrors are generally produced by deposition methods that are carried out at low pressure, for example by electrodeposition. These low pressure methods are essentially batch processes and like the wet chemical methods used for deposition of silver mirrors, they are generally inconvenient for online applications in the production line where the glass is made. The patents of the U.S.A. Nos. 3,656,926 and 3,681,042 each propose a process for the production of mirror coatings by condensing a metallic vapor on the hot glass surface in the production line in which the glass is made. According to the patent of the U.S.A. No. 3,656,926 A body of molten metal, for example silver, copper or gold aluminum, is located adjacent to the upper surface of the glass by a beam of refractory material that extends transversely across the width of the glass, and an electric current is passed through. through the beam of the refractory material extending transversely across the width of the glass, and an electric current is drawn through the beam to heat it, for example at a temperature of 2,000 ° C, and evaporate the metal for condensation in the adjacent glass. According to the patent of the U.S.A. No. 3681042 A body of molten metal, for example silver, aluminum, copper, gold, or tin, is contained in a channel in a pipeline held on the glass ribbon and heated at a high temperature eg 2,000 ° C, and a gas carrier is passed over the molten metal body in the channel to trap metallic vapor that is released from there. The carrier gas containing the metallic vapor is directed to the glass surface where the metal vapor condenses in the glass. In order to improve the alloy of the reflecting metal to the glass, it is also proposed first to deposit, in a similar way, a palladium tungsten, nickel or palladium nickel alloy layer in the glass, before deposition in the reflecting layer. In addition to these techniques require use of extremely high temperatures and none have found commercial application. Silicon has been deposited in hot glass during the glass production process to produce reflective layers (which like the silver and aluminum layers are substantially neutral in reflection color) to be used in architectural glazing for solar and aesthetic control purposes. GB-A-1507465, GB-A-15007996 and GB-A-1573154 relate to a continuous chemical vapor deposition method for producing float glass having this silicon layer and GB-A-4661381 describes a development of that method. Nevertheless, these layers of silicon do not provide the high reflections commonly required in a mirror. In this way, REFLECTAFLOAT glass (registered trademark) commercially available from Pilkington Glass Limited of St Helens, England, has a reflection of approximately 50% and MIRROPANE (Trademark) commercially available from Libbey-Owens-Ford Co. has a reflection of approximately 60% GB-A-0583871 discloses mirrors and their production in which a mirror coating comprises a stack of layers. The mirrors can be produced in-line during glassmaking, for example during the float glass production process. The layers comprise materials that can be deposited in line, for example non-metallic materials such as silicon, silicon dioxide, titanium dioxide, etc. It is disclosed that reflective metals, for example aluminum, chromium, cobalt or titanium can be used as an alternative to silicon and that a metal can be deposited by condensation of metallic vapor or by deposition of chemical vapor using a suitable organometallic vapor. However, specific conditions for deposition of metal on the glass substrate are not described. GB-A-2248853 discloses a pyrolytic glass material coated with aluminum to form a mirror. A solution of an alano amine adduct is formed and the liquid is deposited on the heated glass. The adduct decomposes to form an aluminum coating. It is anticipated that the invention may be employed in conjunction with float glass production, and it is suggested that aluminum deposition may be carried out on hot glass, typically at 180 ° C, emerging from the float glass process. Unfortunately, it has been found that coatings produced in the manner described are insufficiently durable for commercial application as mirrors. There is a need in the art for a method to reliably deposit a reflective metal on a glass substrate during the glass production process, to give a reflective coating having good optical and mechanical properties, to allow the coated glass substrate be used as a mirror. According to the present invention, there is provided a method of producing mirrors during the glass production process, the method comprising pre-treating the surface of a hot glass ribbon with an activating agent and depositing pyrolytically on the pretreated surface with a layer of reflecting metal. The term "mirror" as used in the present specification and claims to refer to a coated glass substrate having a visible light reflection (when viewed from a coated side or the glass side, whichever of the highest reflection (at least 70%) The term "visible light reflection" refers to the percentage of light reflected under the Illuminant D-65 source, 1961 Observer conditions.The term "pyrolysis" is intended to refer to a process for decomposing precursor material with or without the participation of an additional reagent, for example oxygen or water under the effect of heat The surface pre-treatment has been to improve nucleation of the metal forming the reflective metal layer and therefore improved its structural refinement It leads to better adhesion and a denser layer with consequently improved durability.The improved structure can also lead to a beneficial increase in the reflection of light of the metal layer. The surface pre-treatment can be carried out on the glass surface directly or in a barrier layer which is previously applied to the glass surface, for example by a pyrolytic deposition process. The barrier layer acts to reduce or prevent ions in the glass more particularly alkali metal ions, eg sodium, from interfering with the nucleation and growth of the reflective metal layer. the inventors have found that it reduces the turbidity of subsequently deposited aluminum coatings. The barrier may include SiCx0y, ie a silicon oxide with a significant proportion, typically around 25 to 30% carbon; silicon oxide or aluminum oxide.

Surprisingly, improved results can be obtained by using a surface pre-treatment that simply "passivates" the glass surface, presumably because the glass surface contains sites that are energetically unfavorable for metal nucleation. A primer layer of silicon oxide or silicon nitride can be used and is considered to work in this manner. However, it is preferred to use a metal oxide layer that currently provides favorable nucleation sites; the metal oxide layer itself should show good adhesion to the glass, be easily deposited and if the mirror is to be used as a rear surface mirror, preferably it should be substantially transparent to visible light. Preferred metal oxide layers for use as primer layers are tin oxide and titanium oxide. In general, it is unnecessary for the primer layer to be more than a few monolayers of thickness, although thicker layers can be used if desired. In order to provide nucleation sites in the glass, the primer layer can be discontinuous. The primer layer can be deposited by pyrolysis on the hot glass ribbon. For example, a layer of silicon oxide can be deposited in a known manner (see for example European patent specifications EP-A-0275662 and EP-A-0348185) by applying a gaseous mixture of a silane, an unsaturated hydrocarbon and carbon dioxide or another gas containing oxygen to the hot glass surface at a temperature in the range of 600 ° C to 750 ° C; the term silicon oxide is used herein to encompass silicon oxides containing other elements, for example carbon or nitrogen, which are typically found in silicon oxide layers prepared in the manner indicated. A layer of metal oxide can be deposited by pyrolysis (ie decomposition with or without participation of an additional reagent, for example oxygen or water, under the effect of heat) of a metal halide, for example tin tetrachloride or titanium tetrachloride; if only a very thin metal oxide primer layer is required in general, sufficient oxygen will be available on the glass surface to form the metal oxide primer, but if an additional source of oxygen, for example water, is required, it can be used . According to a particularly preferred aspect of the present invention, the surface pre-treatment of the glass or a barrier layer superimposing the glass comprises surface activation of the surface to be coated by the reflecting metal layer by the use of a metal halide, more preferably titanium tetrachloride, which is introduced into the atmosphere on the surface to be coated. The inventors have found that the use of this surface activation with titanium tetrachloride greatly increases the degree of reflectivity of the metal coating and also the uniformity of the metal coating obtained. The precise mechanism by which the surface is activated by titanium tetrachloride before metal deposition is not fully understood. Without being bound by theory, titanium tetrachloride is considered to react with the underlying surface to form a titanium compound, which may include a Ti-0 bond and which acts as a low energy site for nucleation of the metal layer. The present inventors have carried out Auger profiling of deposited aluminum reflective coatings using a pretreatment of titanium tetrachloride during in-line manufacture of the glass. The inventors found titanium present only in a very small amount from .5 to 1% under the reflecting aluminum layer. This suggests that titanium tetrachloride can act primarily as a catalyst that activates the nucleation of aluminum metal on the surface of the barrier layer or glass. The inventors have found during on-line testing that it is possible to use low temperature pyrolysis of certain metallic precursors such as Alans, if there is no pre-treatment of the surface layer or barrier or glass, then no reflective aluminum layer is deposited and that moreover, if the pretreatment is carried out for too long to deposit a coarse layer of titanium dioxide on a substrate, no very thin semitransparent aluminum coatings V are formed or formed.

If a layer of titanium dioxide is formed during the pretreatment, it is considered that this layer preferably should be discontinuous and up to about 400 angstroms in thickness. The use of a primer layer in accordance with the present invention is most beneficial when the reflective metal layer is applied to the glass ribbon at a site where the glass temperature is below 400 ° C, and becomes more beneficial as that application temperature is reduced. Thus, in preferred aspects of the invention, the reflective metal layer is applied to the glass ribbon in places where the glass temperature is below 300 ° C or even below 200 ° C. It is preferred, for reasons of convenience and operational control, depositing the reflective metal layer by pyrolysis of a metal precursor supplied in the vapor phase, and the ability to achieve a durable product at a low deposition temperature facilitates the use of metal precursors that They are volatile at low temperatures and / or tend to decompose in the gas phase at higher temperatures.The reflective metal is conveniently aluminum that has both a high reflection of light and a neutral color in reflection, although other metals with sufficiently high light reflection For example, copper, silver, gold, palladium, rhodium or platinum can be used whenever suitable precursor materials are available. for example, a metal alloy can be used if desired. It is not essential that the metal layer be made of pure metal, and small amounts of other elements, for example up to about 20%, preferably up to about 10%, for example 2 atomic percent of oxygen or carbon may be present, provided that the required high reflection is achieved. Suitable precursor materials include metal hydrides and organometallic compounds, for example metal alkyls and metal acetyl acetonates, which may be employed in solution or in the vapor phase. Preferred materials include an Al-H bond. The vapor may be produced by evaporation in a conventional manner or by "nebulization" that is, forming a solution of the metal precursor (or liquid metal precursor) in very fine droplets (commonly described as an aerosol) in a heated carrier gas, so such that the metal precursor evaporates in the carrier gas. Typically, vapor is formed by bubbling nitrogen gas through the precursor in liquid form. When aluminum is deposited as the reflective metal, it prefers to use Alanis, especially the Alano products of GB-A-2248853, the description of which is incorporated herein by reference. In particular, it is preferred to use alane adducts of the formula A1H3. [NR ^^ R111], where n is in the range of 1 to 10 and Rx, R ", and Rllx each are alkyl groups containing 1 to 4, especially 1 to 2 carbon atoms for example A1H3. N (CH3) 2C2Hs] n where n is in the range of 1 to 10. It is important that for any precursor material that was used, ensure that the precursor material is supplied to the glass at the correct temperature in order to ensure that the Aluminum deposition is achieved by decomposition or reaction of the precursor and it is also important that the glass substrate is at the proper temperature for successful deposition.For example, for successful deposition of aluminum from alane dimethyl ethyl amine, the glass substrate typically is around 170"c. In addition, the alano dimethyl ethyl amine precursor should preferably be supplied from the sparger and supply lines that are maintained at approximately 50 ° C and once they are at this temperature, preferably the precursor should be used to coat as soon as possible. possible in order to avoid-degradation of the coating. If the precursor is supplied at lower temperatures, then decomposition of the precursor can not be reliably achieved. if the precursor is supplied at higher temperatures, then it is possible for the precursor to decompose on surfaces other than the glass substrate, for example parts of the coating apparatus that can reduce or even prevent successful deposition of the aluminum on the glass substrate. The.

The temperature of the coating apparatus may be increased as compared to the temperature of the sparger in order to obtain reliable deposition of the aluminum from the alano adduct. Typically, the coating apparatus can be maintained at a temperature of about 100 ° C on the glass substrate. Modes of the present invention will now be described by way of example only with reference to the accompanying drawings wherein: Figure 1 is a section (not to scale) through a mirror produced in accordance with an embodiment of the present invention; Figure 2 is a section (not to scale) through a mirror produced according to a second embodiment of the present invention; Figure 3 is a scanning electron microphotograph of an edge of a mirror having a structure illustrated in Figure 2; and Figure 4 is a diagrammatic representation of an assembly of coating stations in a float glass production line for production of mirrors, according to the method of the present invention. With reference to Figure 1, a mirror, illustrated as a front surface mirror, comprises a glass substrate 1, which carries a primer layer 2, and a reflective metal layer 3. The primer layer is preferably a very thin layer of tin oxide or titanium oxide, while the reflective metal layer is preferably an aluminum layer. With reference to Figure 2, a mirror designated generally as 10 and acting as a rear surface mirror, comprises a glass substrate 11 carrying, a barrier layer 12 and a reflecting metal layer 13. The barrier layer comprises a silicon oxycarbide, that is SiC-.0y, which contains approximately 25-30% carbon. The barrier layer typically has a thickness of typically 300 to 700 angstroms. The reflecting metal layer 13 comprises an aluminum layer with a thickness of at least about 200 angstroms, typically a thickness of about 500 to 700 angstroms. The barrier layer may alternatively comprise silicon oxide or aluminum oxide. In this embodiment, the surface of the remote barrier layer 12 of the glass substrate 11 has been subjected prior to deposition of the reflective aluminum layer 13, to a surface pre-treatment comprising activation in an atmosphere of titanium tetrachloride. Figure 13 is a scanning electron microphotograph of a mechanically broken edge of the mirror illustrated in Figure 2 showing the glass substrate 11, the barrier layer SiC * 0y, having a thickness d «4J00A and the overlapping aluminum layer 13 that has thickness of 600A. The microphotograph shows that the priming layer formed of any significant thickness can not be seen separately. In the scale at the bottom of the same photograph, each graduation represents 600 angstroms. In the practical application of the invention, the primer layer and the reflective metal layer will be applied to the hot glass ribbon, in general but not necessarily a float glass ribbon, of the coating sections located at appropriate locations to provide the temperatures of glass required (in the glass production line). Figure 4 illustrates diagrammatically a float glass production line comprising a glass melting section 21, a floating float section 22 for forming the molten glass in a continuous belt, an annealing tunnel section 23 for annealing the belt of glass and a storage section 24 for cutting glass from the tape for storage and / or distribution and use. A first coating station for applying the priming layer or performing the surface pretreatment according to the invention will normally be located in or between the section of the flotation lot 22 and the annealing tunnel section 23, in a position where the glass ribbon sub-substantially has reached its fineness thickness (usually at a glass temperature of about 750 ° C) so that it is not subjected to further stretching which can crack any applied coating, but where its temperature remains high enough for formation of an additional pyrolytic layer or for pre-treatment. That temperature depends on the nature of the pre-treatment and the barrier layer formed. The first coating station additionally or in alternate fornix can be used to deposit a barrier layer on the glass surface. In the illustrated embodiment, this first coating station 25 is illustrated located towards the downstream (colder) end of the float bath section 22. The coating station for applying the reflective metal layer is located downstream of the first coating station and usually but not in forrae. necessary will be in the annealing tunnel section 23, where the glass temperature has bridged below 400 * C and preferably below 300 ° C or even below 200 ° C.; in the drawing, the coating station 26 is illustrated located towards the downstream (colder) end of the annealing tunnel section 23. An important advantage of applying the reflective metal layer at low temperatures is that in this way none of the The annealing problems that could result from the presence of a reflecting metal layer in the glass is overcome.

In the particularly preferred embodiment of the invention, the reflective metal layer is deposited at a temperature of approximately 200"or less, using as the aluminum precursor an alane adduct which is suitable for use in a low temperature supply system. A particularly preferred alkane adduct has the formula [NCH] CHazCaHslí.β in dimethylethylamine in an oxygen-free nitrogen carrier gas In this low temperature delivery system, the use of surface activation using titanium tetrachloride is particularly preferred. Titanium tetrachloride is supplied in vapor form in oxygen-free nitrogen gas, which is passed over the heated glass surface.A more preferred temperature range for glass is from about 170 ° C to about 250 ° C, more preferably from approximately 170 ° C to approximately 180 ° C. The hot glass tape, which contains the primer and / or layer The reflective metal layer is cut into sections in a generally known manner to provide large mirror sheets for cutting to the required size. The reflective metal layers will generally have a sufficiently low light transmission to use already. either as front or rear surface mirrors, without the need for an opacifying layer. However, it may be convenient to apply a protective layer on the reflective metal layer to improve the durability of the mirror to a more, although if the mirror is to be used as a front surface mirror, this protective layer will obviously be selected to have a high light transmission. It was found by the inventors that the reflective metal films formed in accordance with the invention have improved durability as compared to conventional silver metal mirrors and mirrors having reflective layers of evaporated aluminum. The tests performed by the inventors resulted in qualitative results. Reflecting aluminum films formed in accordance with the invention were tested for bonding by rubbing or adhering and removing pressure sensitive adhesive tape. It was found that reflective metal films formed in accordance with the invention exhibited improved durability compared to conventional silver metal layers and evaporated aluminum layers, with the reflective aluminum layer remaining firmly adhered to the underlying glass substrate. The "manageability" of the reflective metal layers formed in accordance with the invention was acceptable because the films survived physical and mechanical handling during the manufacturing and testing processes. The chemical durability of the reflective metal films was tested by application of solffffbjes and weak alkaline solutions. The chemical durability is improved compared to the known evaporated aluminum and metal silver mirrors. It is considered by the inventors that this improved chemical durability may possibly result from metallic films containing carbon and oxygen contamination. The thermal durability of the reflective metal films is also tested by heat impregnation of the coated substrates at elevated temperatures. Reflective metallic films appear to be more stable to a thermal impregnation test than evaporated aluminum. The invention is still further illustrated by the following non-limiting examples. Example 1 In an experiment designed to simulate production of a mirror by in-line application of a reflecting metal layer to a hot glass surface, a 4 mm transparent float glass substrate was placed on an electrically heated support in a tubular reactor. The glass is heated to 125 ° C and the reactor is evacuated alternately and filled with dry nitrogen until the dew point in the reactor filled with the nitrogen was below -30 ° C. Steam of titanium tetrachloride in dry nitrogen is then passed over the heated glass surface for approximately 30 seconds to deposit a primer layer containing titanium and thin oxygen on the glass. Then the reactor is evacuated, llerai with hydrogen and a solution of the alano adduct of formula A1H3. [N (CH3) 2C2H5] 4.6 in dimethyl ethylamine as a solvent, is nebulized by directing a fine spray of the solution to the hydrogen atmosphere in the reactor to deposit a layer of reflecting aluminum on the hot glass surface. The resulting aluminum layer having a thickness of approximately 500A was durable and the mirror formed had a visible light reflection (seen from the side of the glass) of up to 85%. COMMON EXAMPLE I An aluminum layer applied to a shape similar to a second glass subst, but without the primer layer is found to have poor adhesion to the glass surface and a maximum visible light reflection of 60%, indicating a less refined structure. EXAMPLE 2 In this example, a reflective metal layer is deposited on a glass subst in a dynamic laminar coating appas that is capable of depositing multilayer coatings on moving glass substs in a controllable atmosphere. The appas for dynamic laminar coating simulates the deposition of coatings on glass during the production of glass line, for example in the float glass process. For example, an aluminum coating is deposited using a precursor of alane dimethylethylamine. A subst pretreatment employing titanium tetrachloride is employed in order to produce a smooth reflective aluminum coating. A float glass subst coated with SiCO with a thickness of 4 mm is placed on a substm subst which in turn is placed inside a preheated controlled atmosphere oven. The glass is heated to a tempere of approximately 170 ° C within a nitrogen atmosphere. The glass is transported below a coating head that is maintained at 25 ° C at a speed of 388 mm / min. during which vapor of titanium tetrachloride in oxygen-free nitrogen gas is passed over the heated glass surface. In this way the SiCO barrier layer is "printed" or activated by titanium tetrachloride. The deposition time for titanium tetrachloride was approximately 15.5 seconds. The glass, at a tempere of about 70 ° C, is then transported below a second coating head which is maintained at 50 ° C, &; a velocity of 240 mra / min during which the vapor of an alane adduct solution of the formula A1H3. [NICHlCaHgjí.β in dimethylethylamine in an oxygen-free nitrogen carrier gas is passed over the surface of the substrate. This vapor is achieved by bubbling nitrogen through the liquid solution of the alano adduct. A layer of reflective aluminum is deposited on the glass surface.

The resulting adherent aluminum layer had a thickness of approximately 600 gAngstroms. The mirror had a visible light reflection (seen from the glass side) of up to 88%, and 0 transmission. The glass had a brightness of 95% and the color coordinates were approximately neutral. In this specification, the color standard was CIELAB (L * a * b *) with conditions D65 standard illuminant and conditions 1931 observe, as implemented by ASTM E 308-90. The parameter L * denotes the brightness and the parameters a * and b * denote the color coordinates. As it is known by people with skill in the specialty, when a * b * = +/- 3, the color is considered approximately neutral. Comparative Example 2 In contrast, when Example 2 is repeated by the intended application of an aluminum layer to a second substrate using similar conditions, but without the use of surface pretreatment with titanium tetrachloride, no aluminum was deposited on the substrate. In additional tests when additional glass substrates were subjected to similar deposition conditions, but with a longer pre-treatment with titanium tetrachloride being entrained, which the inventors consider deposited a relatively thick layer of titanium oxide in the SiCO barrier layer , no aluminum was deposited or a semi-transparent aluminum coating was placed (under reflector). Example 3 essentially repeats Example 2 when passing a float glass substrate coated with SiCO d & 4 mm through the dynamic laminar coating device. The glass temperature however was about 180 ° C the glass was subjected to a pretreatment with titanium tetrachloride at a carrier speed of 388 mm / min. and during deposition of the aluminum from the same alano adduct, the carrier speed was 240 mm / min. The coating formed was a reflective aluminum coating on the entire substrate. When measured on the glass side, the minimum transmission was 0.3%, the maximum transmission was 3.0%, the reflectance was 67.69%, the brightness L * was 85.85 and the color coordinates were a * and b * -2.17 and 1.15, respectively. These parameters can be compared with a standard silver mirror that has 89.42 as a percentage reflectance, brightness L * 95.76, and color coordinates a * and b "-2.18 and 1.95, respectively." When measured from the coated side, the coated aluminum mirror had the following properties: reflectance 86.9%, brightness L * 94.7 and color coordinates a * and b * 0.17 and 0.17, respectively.

Example 4 Example 4 was similar to Example 3 except that the substrate consisted of a float glass substrate having no barrier layer deposited thereon. The glass temperature was 180"c and the coating conditions were the same as in Example 3. A reflective aluminum coating was deposited on the entire substrate, on the glass side, the minimum and maximum percentage transcendence were 0.2% and 13.6%. The reflectance was 69.88%, the brightness L * was 86.94% and the color coordinates a * and b * -2.18 and 0.83 respectively.On the coated side, the reflectance was 74.52%, the brightness L * 89.17 and the coordinates of color a * and b * -2.92 and 0.68 respectively Example 5 In this example, aluminum was deposited in line on a float glass ribbon Float glass had a thickness of 1.1 mm and traveled at a linear speed of 365 m / hour The pretreatment with titanium tetrachloride and the deposition of the aluminum reflective layer were initially attempted in a position where the glass temperature was 130 ° C. It was found that at a glass temperature of 130 ° C, the temperature of vi drio was too low to achieve deposition of aluminum in the glass substrate. When the glass temperature was increased 170 ° C, reflective aluminum coatings were observed. The inventors found that the supply temperature of the aluminum precursor, ie the alano dimethyl ethyl amine adduct, affected the coating achieved. The precursor was supplied in a nitrogen carrier gas from a bubbler which is maintained at a temperature of about 60 * C. At a coating head temperature of about 60 ° C, only coatings in aluminum patches were obtained and this is considered to be because sufficient heat was not provided to the alane adduct, to achieve precursor decomposition. When the temperature of the coating head is increased to 100 ° C, at this higher temperature an upper decomposition temperature was achieved allowing more uniform aluminum coatings to be obtained. When the coating head temperature was further increased to 180 ° C, the coating thickness was reduced and it is considered by the inventors that the reason for this is that the precursor was controlled to provide a sufficient precursor to develop the required coating thickness of metal in the coating station. During the example, the concentration of titanium tetrachlo was varied and it was found that an increased flow expense gave a more uniform coating. A sample of the coated glass product obtained in the example is measured using atomic force microscopy and Auger XPS depth profiling against a reference standard. The aluminum coating had a thickness of about 225 to 250 angstroms and had an average reflectivity of about 38.5%. The thickness of reflective aluminum layer was lower than that which is produced using the ionic laminar coating apparatus, but by varying the deposition time, the thickness of the reflective aluminum coating will increase correspondingly increasing the reflectivity to an acceptable value for a mirror, for example at least 70% in visible light. Example 5 In this example, which is similar to Example 1 since the glass substrate is kept stationary during the deposition process, the aluminum precursor comprises dimethyl aluminum hyd. A glass substrate is kept stationary in a carbon susceptor heated to 230 ° C. The glass substrate was initially pre-treated with titanium tetrachlo in a manner similar to that described in Example 1. Subsequently, dimethyl aluminum hyd was supplied on the glass substrate. An opaque aluminum layer is deposited which exhibits reflective metallic properties.

Claims (15)

1. CLAIMS 1.- A method for producing mirrors during the glass production process, the method is characterized in that it comprises pre-treating the surface of a hot glass ribbon with an activating agent and pyrolytically depositing on the pre-treated surface a layer of reflecting metal.
2. 2. - A method according to claim 1, characterized in that in the pre-treatment step, the glass surface is activated by an activating agent comprising a metal halide.
3. 3. A method according to claim 2, characterized in that the metal halide comprises titanium tetrachloride in a non-oxidizing carrier gas.
4. 4. A method according to any of claims 1 to 3, characterized in that in the pre-treatment step, the glass has a temperature of at least about 170 ° C.
5. 5. A method according to any of claims 1 to 4, characterized in that the pre-treatment step is carried out for a period of up to 20 seconds.
6. 6. A method of soundness with any of claims 1 to 5, characterized in that the aluminum is deposited from a selected precursor of an alkane adduct or an aluminum alkyl hydride.
7. 7. - A method according to claim 6, characterized in that in the step of deposition of aluminum, the glass had a temperature of at least about 170 ° C.
8. 8. - A method according to any of claims 6 or 7, characterized in that the precursor is supplied to the glass surface in a nitrogen gas carrier.
9. 9. A method according to any of claims 6 to 8, sarasterized in that the pressurizer is an aluminum anode adduct, the precursor is supplied to the glass surface by a coating head at a temperature of approximately 100 ° C.
10. 10. A method of conformity is any of claims 6 to 8, sarasterized because the pressurizer is an aluminum alkyl hydride, the pressurizer is supplied to the glass surface by a coating head at a temperature of about 230 ° C.
11. 11. A method according to any of claims 1 to 10, sarasterized because in addition to the pre-treatment step, the step of forming a barrier layer on the glass substrate is also formed.
12. 12. A method of sonification is the claim 11, characterized in that the barrier layer comprises Si0x0y, Si02 or A1203.
13. 13. - A method of soundness is any of the claims 11 or 12, sarasterized because the barrier sapa is 300 to 700 angstroms thick.
14. 14. A sonicity method is any of the claims 1 or 13, sarasterized because the reflecting metal sapa is 500 to 700 angstroms thick.
15. 15.- Mirror produced by a method in accordance with any of the presedent claims. INVBTCIQK The invention is relased to a method to produce mirrors and coated glass substrates, which insorporates highly reflective "mirror" coatings. RS / BO / < 20) / PCTOlß 30