Coating glass involving coating with an incompletely oxidized undercoat
13 claims: 5 independent, 8 dependent
- 1Patentkrav 1. Sätt att bilda en beläggning omfattande ett pyrolytiskt bildat oxidskikt på ett sig rörande varmt glassubstrat genom att kontakta substratet med förbeläggningsmaterial i närvaro av syre, kännetecknat av att ett underskikt av 5 oxid (underbeläggningen”) bildas pyrolytiskt i ett ofullständigt oxiderat tillstånd genom att kontakta substratet i en underbeläggningskammare med förmaterial till underbeläggning i närvaro av molekylärt syre i otillräcklig mängd för full oxidation av underbeläggningsmaterialet på substratet 10 och av att sådan underbeläggning täckes med ett övre beläggningsskikt då det fortfarande befinner sig i ett ofullständigt oxiderat tillstånd och då substratet ännu är varmt, för att därvid bevara sådan underbeläggning i ett ofullständigt oxiderat tillstånd.
- 2Sätt enligt krav 1, kännetecknat av att förmaterialet för underbeläggningen bringas i kontakt med en övre yta på ett varmt glassubstrat, bestående av just bildat plant glas.
- 3Sätt enligt krav 1 eller 2, kännetecknat av att underbeläggningskammaren är omgiven av en reducerande atmosfär. 25
- 4Sätt enligt krav 2 och 3, kännetecknat av att förbeläggningsmaterialet för underbeläggning bringas i kontakt med en övre yta på ett varmt floatglassubstrat i underbeläggningskammaren belägen inom en floatkammare i vilken floatglaset tillverkas.
- 5Sätt enligt krav 4, kännetecknat av att förmaterialet för underbeläggningen kontaktar glaset vid ett läge utmed floatkammaren, så att glaset har en temperatur som är åtminstone 50°C och företrädesvis åtminstone 100°C högre 35 än den temperatur vid vilken glaset skulle utträda från floatkammaren om ingen beläggning bildades på glaset däri. 501 632
- 6Sätt enligt något av föregående krav, kännetecknat av att substratet når underbeläggningskammaren med en temperatur av åtminstone 400°C.
- 7Sätt enligt krav 6, kännetecknat av att förmaterialet för underbeläggningen först kontaktar glaset då glaset har en temperatur av åtminstone 650°C.
- 8Sätt enligt krav 1, kännetecknat av att luft tillföres underbeläggningskammaren för att införa syre däri.
- 9Sätt enligt något av föregående krav, kännetecknat av att förmaterialet för underbeläggningen väljes till att innehålla kisel, företrädesvis en silan, för bildningen av en kiseloxidunderbeläggning på glaset.
- 10Sätt enligt krav 9, kännetecknat av att förmaterialet för underbeläggningen innehållande silan intimt blandas med syre innan det får komma i kontakt med glaset.
- 11Sätt enligt krav 9 eller 10, kännetecknat av att silan som förmaterial till underbeläggningen ledes mot underbeläggningskammaren i ångfas i en i huvudsak inert bärgasström, som företrädesvis utgöres av kväve och syre införes i den silanhaltiga bärgasströmmen innan den inträder i underbeläggningskammaren .
- 12Sätt enligt krav 11, kännetecknat av att turbulens framkallas i bärgasströmmen efter det att syre införts däri för att säkerställa intim blandning av den silanhaltiga bärgasen och syret.
- 13Sätt enligt något av föregående krav, kännetecknat av att silan som förmaterial till underbeläggning införes i underbeläggningskammaren med ett partialtryck av mellan 0,1% och 1,5%, företrädesvis mellan 0,1% och 0,4%. 501 632
Independent claims13
104 paragraphs in 11 sections, as filed
(54) (56) (57)
INVENTOR INVENTOR
Glaverbel, Brussels BE
Robert Terneu, Thim ^ on BE, Michel Hannotiau, Jodoigne (Piétrain) BE
H Albihns patent agency AB
Methods of forming a coating comprising a pyrolytically formed oxide layer on a hot glass substrate
CALLED PUBLICATIONS:
REPRESENTATIVE TITLE
EP Al 0 114 282 (C03C 17/27), EP Al 0 348 185 (C03C 17/245), DE C2 233 594 (G03C 17/25), DE Bl 2 646 513 (C03C 17/34) SUMMARY:
By way of forming a coating comprising a pyrolytically formed oxide layer on a hot glass substrate, the substrate is contacted with pre-coating material in the presence of oxygen.
In order to prevent the interaction between the pre-coating material used to apply an upper coating layer and / or to facilitate modification of the optical or other properties of the coating as a whole, an oxidic sub-layer is formed in the coating (the undercoating) pyrolytically in an incompletely oxidized contacted oxide. the substrate in a subcoating chamber with precoating material in the presence of insufficient oxygen for full oxidation of the undercoating material on the substrate and of such undercoating being covered with an upper coating layer, while still in an incompletely oxidized state and while the substrate is still hot, thereby preserving the undercoating in an incompletely oxidized state.
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The numbers in brackets indicate international identification code, INID code. Letters in clamps indicate international document code.
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The present invention relates to a method of forming a coating comprising a pyrolytically formed oxide layer on a hot glass substrate, by contacting the substrate with a coating precursor in the presence of oxygen.
It is well known to coat glass for various different purposes. Conductive coatings of varying types can be applied to form part of an electrical circuit or to reduce the emissivity of the coated surface with respect to infrared radiation.
Reflective coatings, for example of a metal, can be applied to shield solar radiation as well as absorbent coatings.
The invention relates in particular to multilayer coatings in which there is an undercoat of an oxide having one or more layers applied thereon, which may be of oxide or of other material.
It is also well known to manufacture multi-layer coatings comprising an undercoat of oxide and one or more coating layers applied thereon. There are various different reasons for applying a multi-layer pyrolytic coating, the main purpose of which is to modify the manner in which the upper layer or layers are deposited; or to reduce the interaction between the upper coating material and the glass in the substrate and / or to modify the properties of the entire coating or to reduce the interaction between a lower layer of the coating such as oxide during coating and the atmosphere to protect the lower layer from contamination or especially from abrasion and so as to preserve the properties that the lower layer imparts to the panel.
It may be useful to prevent the interaction between the glass in the substrate and the material in an upper coating 501 632 layer. As an example, silica coatings can be used as undercoating layers, which are covered with other coating layers, which may be of one or more oxides or other materials such as metals. The presence of a silica undercoat on soda lime glass has the particular advantage of inhibiting the migration of sodium ions from the glass either by diffusion or otherwise into an upper coating layer either during formation of the upper layer or under subsequent high temperature treatment. As an example, it has been found that in the pyrolytic formation of a tin oxide coating from tin chloride on a soda lime glass substrate, sodium chloride tends to be included in the coating as a result of the reaction of the glass with the precoating material or its reaction products and this leads to haze in the coating.
Alternatively, it may be desirable to modify the optical properties of a coating applied for radiation shielding purposes. The radiation shielding coatings specifically referred to here tend to be thin and thus affect their appearance, whether viewed through or reflected light by interference effects and minor variations in coating thickness can have an important impact by modifying the visible color of the coating. In order to reduce the effect of thickness variations on the visible color of the coating, it has been proposed to provide an oxide undercoat and this may have a highly beneficial effect in reducing undesirable interference effects due to variations in the thickness of the total coating provided that the optical thickness is below that of the coating. in itself is well chosen.
Alternatively, it may again be desirable to provide an oxide undercoat which imparts certain special properties to the panel as a whole and to protect that undercoat with a coating resistant to abrasion, which also serves to protect the undercoat from chemical attack from the surrounding atmosphere.
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It is a principal object of the present invention to provide a method of forming a multi-layer pyrolytic coating on glass where a coating sub-layer itself has certain special properties or which acts in combination with at least one other coating layer to impart the coated glass. certain special features.
According to the present invention, there is contemplated a method of forming a coating comprising a pyrolytically formed oxide layer on a hot glass substrate, by contacting the substrate with pre-coating material in the presence of oxygen and characterized by forming a sub-layer of oxide (the undercoating) in an incompletely oxidized state. by contacting the substrate in an undercoating chamber with pre-coating material in the presence of molecular oxygen in insufficient amount for the full oxidation of the undercoating material on the substrate and for such undercoating to be covered with an upper coating layer when still in an incompletely oxidized state and when the substrate is still hot, thereby preserving such undercoating in an incompletely oxidized state.
The invention thus relates to a method of forming an incompletely oxidized undercoat layer followed by an upper coating layer which will retain the properties of the undercoat with incompletely oxidized material and thus preserve the properties as it is given. The term incompletely oxidized material is used herein to denote a true suboxide, i.e., an oxide in a lower valence state of a polyvalent element (e.g., VO<sub>2</sub> or
TiO) and also to denote an oxide material containing oxygen lids in its structure: an example of the latter is δίθ<sub>χ</sub> where x is less than 2, which may have the general structure of SiO<sub>2</sub> but has a proportion of gaps that would be filled with oxygen in the dioxide.
The exact nature of the particular properties that can be imparted to the undercoat of incompletely oxidized material will depend, at least in part, on the nature of that material.
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For example, the undercoat may be designed as a semiconductor layer. Semiconductor layers may be formed of zinc or cadmium oxides, of titanium oxide or of vanadium oxide and such layers may be formed by a method of the present invention to a given degree of oxidation and may be retained in a state of incomplete oxidation of the overlay layer. The overlay layer (s) can be readily selected to protect the undercoat against further oxidation due to atmospheric oxygen, against other chemical attack due to ambient atmosphere, and against abrasion.
However, it is currently envisaged that the present invention will find an important industrial application in forming undercoatings of incompletely oxidized silica. As indicated, the presence of a silica oxide coating on soda lime glass has a beneficial effect by reducing or eliminating sodium poisoning in an overlying coating layer. Further, and this is also very important, the refractive index of silica varies according to its oxidation state and in relation to the gaps present in its structure. Thus, the incorporation of the present invention provides an additional control parameter for forming the underlying layer, for example, of silica, which facilitates control of the optical coating thickness. Of course, it is the optical thicknesses of different coating layers that determine many of the optical and radiation transmitting properties of the coating as a whole and the optical thickness of a coating layer is the product of the actual thickness and refractive index of the material to which the coating layer is made ( the important factor may be the double product of the current thickness and refractive index). Different oxides of varying elements exhibit different refractive indices and the present invention thus permits not only control of the actual thickness to which a subcoating is deposited but also a measure of independent control of its optical thickness by appropriate selection of the degree of oxidation permitted in the subcoating.
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It may be a much easier matter to regulate the degree of oxidation of the material in an undercoat than it is to regulate the exact thickness to which the undercoat and the overcoat are deposited, especially during the course of large-scale series of coated glass. The coating device can be set to provide a uniform coating of approximately the required current thickness, taking into account the nature of the coating material and adjustment can be made to achieve the required optical thickness of the undercoat simply by controlling the amount of oxygen allowed to enter undercoating.
If the undercoating glass substrate is exposed to an oxidizing atmosphere for a sufficient period of time, it can be expected that the undercoating will tend to be fully oxidized so that its desired properties are lost. Therefore, such undercoating is covered in accordance with the invention with an upper covering layer while still in an incompletely oxidized state and while the substrate is still warm, thereby preserving such undercoating in an incompletely oxidized state. The time during which the just undercoated glass substrate can be exposed to an oxidizing atmosphere such as air and before the undercoat is covered, without damaging the properties of the undercoat, will depend on the temperature of the glass during such exposure and the nature of the undercoat. Generally, however, for silica, an exposure time of 15 seconds and possibly up to a minute can be tolerated. Such time periods may be insufficient to complete the oxidation of the undercoating and the resulting increase in oxidation may be predictable and thus be adjusted by changing the degree of oxidation allowed in the undercoating step itself.
The undercoating chamber is advantageously surrounded by a reducing atmosphere. The use of this feature helps prevent ambient oxygen from entering the undercoat.
501 632 chamber, thereby allowing better control of the oxidizing conditions within the undercoating chamber.
The invention could be used to form a sub-oxide coating on pre-cut and reheated glass sheets if required. However, when it is desired to make pyrolytically coated flat glass, it is best to do so when the glass is newly formed. To do so has economic benefits in that there is no need to re-heat the glass for the pyrolytic reactions to take place and it also has advantages in the quality of the coating, as it is ensured that the glass surface is in a pristine state. The undercoating material for the undercoating is therefore preferably contacted with an upper surface of a hot glass substrate consisting of just formed flat glass.
For example, the undercoating chamber could be located in or near the upstream end of a cooling gallery through which the belt is advanced and the belt could be formed either in a tractor or in a float chamber.
However, we have found that some problems arise when converting a channel previously used for cooling uncoated glass to form a cooling channel and two or more coating stations for producing glass coated with a multi-layer coating. such problems arise as a result of the possibly different temperature conditions for forming the coating on the one hand and for proper cooling of the glass on the other, and as a result of limitations in the available space for placing the different coating stations. Furthermore, the coating reactions have a cooling effect on the glass, not only in that the glass is cooled everywhere but also that the coated surface tends to be cooled more than the uncoated surface: thus, a different temperature relationship often has to be established within a cooling channel equipped with two or more coating stations. when changing the production from coated glass to uncoated glass and back again and sometimes even when a significant change is made in the thickness of the coating applied to the glass.
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To overcome these problems, it is most preferred that the undercoating material for the undercoating be contacted with an upper surface of a hot float glass substrate in a subcoating chamber located within a float chamber where the float glass is manufactured.
By operating according to this preferred embodiment of the invention and forming the undercoating within the float chamber, any need to find space for the undercoating station at or near the upstream end of a cooling duct is avoided. Furthermore, we have found it possible to ensure that the temperature of the glass band leaving the float chamber is substantially unaffected whether the band is coated with undercoating or not and thus there is no need to modify the temperature conditions in a cooling channel when switching between having the undercoating chamber in operation. or take it out of service.
It is quite surprising to suggest forming an undercoat of oxide within a float chamber. Float chamber contains a molten metal bath, wholly or partially of tin, which is quite easily oxidizable at the temperatures required for the glass band to spread and become fire-polished, and thus it is common practice to maintain a reducing atmosphere within the float chamber, since any surface slag such as being absorbed by the glass band from the metal bath surface would become a source of defects in the glass being produced. Representatively, such atmosphere contains about 92-95% nitrogen and about 8-5% hydrogen, and it is kept at a slight overpressure to prevent oxygen from leaking into the float chamber from the surrounding atmosphere. Much research has also been done to remove surface slag that is almost always formed on the metal bath surface despite all the precautions taken to avoid oxygen entry into the float chamber. It is therefore against the tide of the doctrine of the manufacture of float glass to deliberately maintain oxidizing conditions in the float chamber. However, we have found that it is possible to create oxidative conditions within a float chamber without giving rise to
501 632 the expected problems. We assume that this is at least partly due to the fact that the undercoating pre-material is brought into contact with the surface of an undercoating chamber. The use of an undercoating chamber facilitates the limitation of the oxidizing conditions, of the undercoating precursor, and of the reaction products of the undercoating so that their effect on the metal bath in the float chamber can be minimized or neglected.
Placing the undercoating chamber within a float chamber is also a very simple way of ensuring that the undercoating chamber is surrounded by a reducing atmosphere and it does not require the provision of any additional equipment to maintain that atmosphere.
The undercoat can be formed in any position along the float chamber downstream of the position where the strip has reached its final width and the currently selected location depends on the desired temperature to begin coating the glass. The glass is withdrawn from the float chamber to pass to the cooling duct at a temperature usually in the range 570-650 ° C. Band temperatures above 570 ° C are inherently suitable for the pyrolytic coating reactions to take place, so that the coating station could actually be located quite close to the exit from the float chamber. However, the coating material preferably contacts the glass at a position along the float chamber so that the glass has a temperature at least 50 ° C and preferably at least 100 ° C higher than the temperature the glass would exit from the float chamber if no coating was formed therein. The application of this preferred feature of the invention offers the advantage that there is plenty of time for the tape to recover heat released during the coating reactions, so that when it leaves the float chamber its temperature is substantially unaffected by the undercoating operation.
Although the glass is not undercoated within a float chamber, it is preferred that the substrate reach the undercoat chamber with a
501 632 temperature of at least 400 ° C. such temperatures are very suitable for the rapid formation of, for example, a silica coating from a pre-coating material containing a silane. It should also be noted that, as a general rule, the higher the temperature of the glass during the coating formation, the faster the coating reaction, so that the coating yield, i.e. the proportion of coating material converted into useful coating oxide, is increased and for a given tape advancement rate it is possible to thicker coating if desired. Also, for this reason, it is preferred that the precoating material first touch the glass when the glass has a temperature of at least 650 ° C. For many purposes, the glass may have a temperature of between 700 ° C and 750 ° C when first contacted by the undercoat pre-coating material.
The oxygen required for the undercoating reactions is preferably present in the form of molecular oxygen. It can be supplied as pure oxygen, but this unnecessarily increases costs and it is therefore preferred that air be supplied to the undercoating chamber to introduce oxygen therein.
Advantageously, the precoating material is selected so that it contains silicon to form a silica oxide coating on the glass. Silicon oxide coatings are valuable as undercoats for various purposes. It is particularly advisable to use a precoating material comprising a silane.
The use of a silane, especially SiH<sub>4</sub> is well known in and of itself for the formation of pyrolytic coatings on glass. The silane decomposes at temperatures above 400 ° C and silicon deposits can be formed. However, it is difficult to oxidize such a silica coating in situ to form a silica coating. For this reason, it is preferred to react the silane directly with oxygen. For this reaction to take place to deposit silica on the glass substrate instead of on any part of the coating device wherein all previously published proposals for using a silane-containing coating material
501 632 when forming a silica coating insisted that the precoating material should only be allowed to mix with oxygen within a coating chamber which is open to the substrate to be coated at a site where these materials are free to contact the substrate directly. However, we have found that this is not favorable for the production of high quality silica coatings.
In the most preferred embodiments of this invention, the silane-containing precoating material is intimately mixed with oxygen before being allowed to contact the glass. We have found that this prior blend of the undercoating reagents offers great advantages in achieving a uniform undercoat across the width of the substrate. Surprisingly, the prior blend does not lead to such premature reaction in the coating material as might be expected from what has been learned by the prior art and is in fact favorable for the production of high quality silica coatings.
In preferred embodiments of the invention, the strainer is guided as a precoat material to the vapor phase coating chamber in a substantially inert carrier stream and oxygen is introduced into the silane-containing carrier stream prior to entering the coating chamber. While it is desirable to have the oxygen and the precoat silane intimately mixed prior to entering the coating chamber, it is also advantageous to be able to control the length of time during which these reagents are mixed prior to delivery to the coating chamber. Conducting the silane toward the coating chamber in a substantially inert carrier stream and then introducing oxygen into that carrier stream allows selection of the point at which oxygen should be introduced to achieve that regulation.
Advantageously, nitrogen is used as a substantially inert carrier gas. Nitrogen is sufficiently inert for the intended purpose and it is inexpensive compared to the noble gases.
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The pre-coating and / or oxygen may conveniently be introduced into the carrier gas stream by means of a venturi device.
In preferred embodiments, turbulence is induced in the carrier gas stream to ensure intimate mixing of the substantially inert carrier gas and the silane. A certain degree of turbulence will be induced if a venturi device is used as previously stated, but this can be augmented, for example, by the use of a supply conduit which has a constriction downstream of the insertion point of the precoating material. Such a narrowing can be symmetrical. Intimate mixing of the pre-material into the carrier gas is ensured by inducing turbulence.
For similar reasons, it is advantageous for turbulence to be induced in the carrier gas stream after oxygen is introduced therein to ensure intimate mixing of the silane-containing carrier gas and oxygen.
The rate at which the coating reagents are to be applied is to some extent dependent on the desired thickness of the undercoat to be formed and on the rate at which the substrate passes the coating chamber. The silane as a subcoating preform is preferably introduced into the subcoat in a chamber with a partial pressure of between 0.1% and 1.5%. A concentration in that range is suitable for forming subcoatings from about 30 nm to about 240 nm on a substrate moving at a rate of up to 20 meters per minute.
For the preparation of coated glass moving at a rate of less than 10 m per minute, the silage is advantageously introduced as the undercoating material into the undercoating in the undercoating chamber with a partial pressure of between 0.1% and 0.4%.
Preferably, steps are taken to limit the transfer of thermal energy to the undercoating pre-material as it moves toward the glass. This maintains the temperature of the laying reagents at a lower level than the surrounding conditions would otherwise dictate and further helps to reduce any tendency for premature reaction.
Advantageous pre-coating materials are provided to contact the glass via at least one gap extending or extending transversely across at least the majority of the width of the undercoating to be formed on the glass. This facilitates the formation of a uniform coating of uniform and uniform thickness across the width of the glass substrate.
Advantageously, the pre-coating material contacts the glass within the undercoating chamber, which chamber is restricted by the substrate path and a downwardly opening hood and the undercoating chamber are under vacuum around their entire periphery. This helps prevent the entry of unused pre-coating pre-coating and coating reaction products from the under-coating chamber into the surrounding space.
Such "ventilation" preferably generates an inward flow of ambient atmosphere about substantially the entire circumference of the undercoating chamber. This creates a pneumatic seal between the oxidizing conditions within the coating chamber and the surrounding atmosphere, which is particularly valuable for preventing the exit of the oxidizing atmosphere from the undercoating chamber when that chamber is located within a float chamber.
The invention will now be described in more detail with reference to the accompanying drawings, by way of example only
Fig. 1 shows a transverse cross-section of an undercoating device placed in a float chamber,
Fig. 2 is a longitudinal cross-section of the undercoating device of Fig. 1, <sub>13</sub> 501 632
Fig. 3 is a schematic plan view of the undercoating device and
Fig. 4 finally shows the supply of undercoating reagents to a supply line supplying the undercoating station.
In the drawings, a strip 1 of glass is conveyed along a road also designated 1, while being supported by a bath of molten metal 2, in a float chamber 3. An undercoating station is surrounded by a wall and roof structure generally designated by 4.
The undercoating station 4 comprises a hood 5 which limits a subcoating chamber 6 which opens downwardly towards the band path 1, a supply conduit 7 for supplying subcoating reagents to the subcoating chamber 6 and a chimney 8 for peripherally sucking the subcoating chamber.
The feed conduit 7 is fed with a substantially inert gas such as nitrogen from a source not shown and the pre-coating material such as the silane is introduced into the carrier gas stream at a first venturi device 9. The shown supply conduit 7 is specially designed to feed the strainer to the undercoating chamber. The carrier gas with dispersed precoating material for the undercoating flows along the supply line 7 to a first constriction 10, which is arranged to impart turbulence to the carrier gas and ensure intimate mixing of the carrier gas and the entrained precoating material. Further downstream is a second venturi device 11 for introducing oxygen, for example as a constituent of air. A further turbulence-induced constriction 12 ensures intimate mixing between the oxygen and the entrained precoating material in the carrier gas stream. The undercoating reagents are fed through the feed conduit 7 to a flow control block 13, which is provided with an exit slit 14 which extends across most of the width of the hood 5.
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It is convenient to feed pre-coating and oxygen pre-materials to the supply conduit 7 outside of the float chamber 3. At all parts of the float chamber 3, the supply conduit is surrounded by a cooling jacket 15 which is equipped with cooling water inlet 16 and outlet 17 as shown in Fig. 1. If desired For example, the cooling jacket may be extended within the flow control cap 13 as shown at 18 with dotted lines in FIG. 2 and 4, so that the undercoating reagents are protected from overheating until they exit from the slot 14 for contact with the strip 1 in the undercoating chamber 6.
As shown in Fig. 2, the cap 5 and the flow control block 13 are conveniently suspended from the ceiling of the float chamber 3 by means of strands 19. It is desirable to use strings 19 provided with threads so that the height of the base of the cap 5 can be adjusted for small play, e.g. cm or less from the band path 1.
The hood 5, the undercoating chamber 6 and the flow control block 13 are surrounded by a peripheral passage 20, through which reaction products from the undercoating and unused subcoating preamble together with, if desired, inwardly aspirated ambient atmospheric material from the float chamber can be sucked up and through the chimney 8. and the undercoating station wall structure 4 is shown provided with optional peripherally extending skirts 21 at the base of the peripheral passage 20. These skirts are preferably made of flexible refractory curtains, for example manufactured by Refrasil (registered trademark).
After the glass strip has left the float chamber 3, it is taken to an overcoating station (not shown) located near the exit end of the float chamber. The overcoating chamber itself may be of a type known per se and located at or before the upstream end of a horizontal cooling duct through which the strip is passed before cutting into slices. It is desirable that there be a closed passage between the exit end of the float chamber and entry into the overcrowding chamber, especially if that passage is more than a few meters
501 632 long and also that the passage is filled with non-oxidizing or reducing atmosphere. This can be easily accomplished by blowing nitrogen into contact with and along the newly formed undercoat and can be supplemented by leakage from the atmosphere of the float chamber along that passage.
EXAMPLE 1
In a particularly practical embodiment for coating float glass moving at a speed of 7 m per minute along a float chamber, the coating station is placed in a position along the float chamber where the glass is at a temperature of about 700 ° C. The supply line is fed with nitrogen and the silane is introduced therein with a partial pressure of 0.2% and oxygen is introduced with a partial pressure of 0.36% (ratio 0.55). A coating of silica SiO<sub>x</sub>, where x is approximately equal to 1.8 is obtained with a refractive index of about 1.69. The coating formed has a thickness of 75 nm. The pre-coating material in its carrier gas is fed along the supply conduit 7 to exit at a gap about 4 mm wide at such a rate that the supplied material flows along the glass and the cap 5, which is 15 mm above the path of the glass at a speed of about 2 mm. 3 m / sec in both directions parallel to the direction of movement of the belt. The hood 5 has a length in that direction of about 40 cm. Atmospheric material is sucked through the chimney 8 at such a rate that an upward flow of gases is generated in the peripheral passage 20 at a rate of about 7-8 m / sec and this causes a continuous inward flow of gas from the float chamber into the base of the passage 20 about the entire circumference of the coating chamber 6, whereby entry into the float chamber of coating reagents and their reaction products occurs. Of course, such extraction also removes coating reaction products and unused coating reagents.
In a subsequent coating step, performed in a manner known per se in a coating station located near the exit from the float chamber and prior to the upstream end of a horizontal cooling channel, an upper coating layer of doped SnO is formed.<sub>2</sub> to
501 632 a thickness of 225 nm by pyrolysis of SnCl<sub>2</sub> in aqueous solution. A tolerance of +45 nm in the thickness of SnO<sub>2</sub>The overcoat and +4 nm in the undercoat can be accepted without giving rise to undesirable color variations due to interference effects.
In the absence of an undercoat, such a tin oxide layer upon reflection exhibits a greenish dominant wavelength and it may appear greenish yellow or greenish blue depending on the exact thickness from place to place. A quantitative estimate of the light-modifying ability of the coating can be expressed in the well-known Hunter coordinates. In the absence of the undercoat, such a tin oxide coating has a Hunter a<sup>M</sup>coordinate of -6 to -7 and a Hunter b "coordinate of -7 to +5. However, in the case of the two-layer coating of this example with the silica undercoating of about 75 nm with a refractive index of 1.69-1.7, the Hunter a and b coordinates were both between +2 and -2, thereby obtaining a much more evenly neutral product.
EXAMPLE 2
It is desired to produce glass coated with a layer of doped tin oxide about 500 nm thick to shield long-wavelength infrared radiation. Such a coating can easily be formed by a technique known per se. Variations in thickness may show variations in tone over the coated panel from greenish (Hunter α-coordinate-15) to reddish (Hunter α-coordinate +7) which is considered commercially unacceptable. Therefore, the glass is first provided with an undercoat of incompletely oxidized silica with a thickness of 80 nm and a refractive index of 1.75 + 0.01. This is easily accomplished by adjusting the flow rates of the silane and oxygen entering the undercoating chamber in the manner described in Example 1. This undercoat has the effect of mitigating color variations due to interference effects so that for thickness variations in the overcoating of up to + 30 nm, both Hunter a and b17 were
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the coordinates both between +2 and -2 thus giving one much more evenly neutral product. This remains valid for variations of up to + 5 nm in the thickness of the undercoat.
EXAMPLE 3
A low emissivity doped zinc oxide coating should be formed to a thickness of 310 nm by pyrolysis of zinc acetate dissolved in aqueous isopropanol as a topcoat material for coating. Indium chloride is added to the upper coating precursor to provide the required doping ions.
In accordance with the invention, the glass is first provided with a sub-coating, in this example, incompletely oxidized silica having a thickness of 73 nm and a refractive index of 1.79 and the upper coating is applied to maintain this incomplete oxidation state. This is easily accomplished by adjusting the flow rates of the silane and oxygen into the undercoating chamber in the manner described in Example 1. This also has the effect of significantly mitigating color variations due to variations in the thickness of the upper layer. The Hunter a and b coordinates were both +2 and -2.
Variations in the thickness of the upper coating up to + 10 nm and variations in the thickness of the lower coating up to + 3 nm could be tolerated without giving rise to observable variations in the color of the coated glass when viewed in reflected light.
EXAMPLE 4
A low emissivity coating of doped zinc oxide should be formed to a thickness of 505 nm, again by pyrolysis of zinc acetate dissolved in aqueous isopropanol as a precursor to the upper coating. Indium chloride is added to the overcoating precursor to provide the required doping ions.
501 632
In accordance with the invention, the glass is first provided with a subcoating, in this example, of incompletely oxidized silica, having a thickness of 78 nm and a refractive index of 1.8 and the upper coating applied to maintain this incomplete oxidation state. This is easily accomplished by adjusting the flow rates of the silane and oxygen in the undercoating chamber in the manner described in Example 1. This also has the effect of significantly mitigating color variations due to variations in the thickness of the upper layer. Hunter "a" - and b<sup>M</sup>the coordinates were both between +2 and -2.
Variations in the thickness of the upper coating up to ± 5 nm and variations in the thickness of the lower coating of up to ± 2 nm could be tolerated without giving rise to noticeable variations in the color of the coated glass when viewed in reflected light.
EXAMPLE 5
A low emissivity indium tin oxide coating is to be formed to a thickness of 300 nm by pyrolysis of indium chloride and tin chloride dissolved in dimethylformamide as the topcoating precursor by a coating technique known per se.
In accordance with the invention, the glass is first provided with a subcoating, in this example of incompletely oxidized silica, having a thickness of 74 nm and a refractive index of 1.77, and the upper coating is applied to maintain this incomplete oxidation state. This is easily accomplished by adjusting the flow rates of the silane and oxygen in the undercoating chamber in the manner described in Example 1. This also has the effect of significantly mitigating color variations due to variations in the thickness of the upper layer. The Hunter "a" and "b" coordinates were both +2 and -2.
501 632
Variations in the thickness of the upper coating up to + 10 nm and variations in the thickness of the under coating up to + 2 nm could be tolerated without giving rise to noticeable variations in the color of the coated glass when viewed in reflected light.
EXAMPLE 6
A low emissivity indium tin oxide coating should be formed to a thickness of 500 nm.
In accordance with the invention, the glass is first provided with a subcoating, in this example, incompletely oxidized silica with a thickness of 85 nm and a refractive index of 1.8, and the upper coating is applied to maintain this incomplete oxidation state. This is easily accomplished by adjusting the flow rates of the silane and oxygen into the undercoating chamber in the manner described in Example 1. This also has the effect of significantly mitigating color variations due to variations in the thickness of the upper layer. Hunter a<sup>M</sup>- and the b coordinates were both between +2 and -2.
Variations in the thickness of the overcoat up to + 5 nm and variations in the thickness of the undercoat up to + 1 nm could be tolerated without giving rise to noticeable variations in the color of the coated glass when viewed in reflected light.
EXAMPLE 7
A semiconducting undercoat is formed by incompletely oxidized zinc by contacting a glass band in a subcoating chamber within a metallic zinc vapor float chamber in the presence of oxygen in insufficient amount to fully oxidize the zinc coating thus formed on the glass.
The semiconductor ZnO<sub>x</sub>~ The undercoat is then covered by a conductive coating, 500 nm thick, formed by doped tin501 632 oxide, which serves to preserve ZnO<sub>x</sub>~ the layer in an incompletely oxidized state, so that it can function as a semiconductor and at the same time serve as an electrode for the final product.
EXAMPLE 8
A glass band within a float chamber is first provided with a silica dioxide layer, 90 nm thick. This can be done by modifying the method described in Example 1 so that enough oxygen is used to fully oxidize the silicon. To do this, the silane is introduced into the coating layer of the sub-layer at a partial pressure of 0.25% and oxygen is introduced at a partial pressure of 0.5% (ratio 0.5).
That sub-layer serves to prevent sodium poisoning of a post-applied undercoat of a vanadium suboxide. An undercoat of vanadium dioxide is formed in an undercoat station also located in the float chamber, downstream of the undercoat coating station, by contacting the underside of the glass with vanadium trichloride in vapor phase in the presence of insufficient oxygen to complete oxidation of the vanadium undercoat during the undercoat of the vanadium. .
In accordance with the invention, the vanadium dioxide is covered while still in a state of incomplete oxidation. A 500 nm thick tin oxide coating layer is applied to the undercoat outside the float chamber prior to cooling the strip.
501 632
Contents11
3 sheets
Sheet 1 Sheet 2 Sheet 3
31 members in 15 offices
Priority claims4
| Document | Office | Kind | Date |
|---|---|---|---|
| 9019069 | United Kingdom | A | |
| 9019069 | United Kingdom | A | |
| 9019069 | – | – | – |
| GB19900019069 | – | – | – |
Members31
| Document | Office | Kind | |
|---|---|---|---|
| GB9019069D0 | United Kingdom | D0 | |
| NO912905D0 | Norway | D0 | |
| ITTO910651A0 | Italy | A0 | |
| ITTO910651D0 | Italy | D0 | |
| SE9102490D0 | Sweden | D0 | |
| CA2049441A1 | Canada | A1 | |
| SE9102490L | Sweden | L | |
| NO912905L | Norway | L | |
| LU87997A1 | Luxembourg | A1 | |
| DE4128600A1 | Germany | A1 | |
| FR2666325A1 | France | A1 | |
| GB2247691A | United Kingdom | A | |
| NL9101446A | Netherlands (Kingdom of the) | A | |
| JPH04270144A | Japan | A | |
| ITTO910651A1 | Italy | A1 | |
| US5203903A | United States of America | A | |
| BE1005317A5 | Belgium | A5 | |
| CH682745A5 | Switzerland | A5 | |
| FR2666325B1 | France | B1 | |
| ES2049135A1 | Spain | A1 | |
| ES2049135B1 | Spain | B1 | |
| GB2247691B | United Kingdom | B | |
| IT1249989B | Italy | B | |
| SE501632C2This record | Sweden | C2 | |
| NO303280B1 | Norway | B1 | |
| ATA167891A | Austria | A | |
| AT404935B | Austria | B | |
| JP3214713B2 | Japan | B2 | |
| CA2049441C | Canada | C | |
| NL194963B | Netherlands (Kingdom of the) | B | |
| NL194963C | Netherlands (Kingdom of the) | C |
1 legal event, as the office reported them to INPADOC
Events
| Event | Code | |
|---|---|---|
| Patent has lapsedLapsedNUG | NUG |
Numbers
- Publication, DOCDB
- 501632
- Publication, EPODOC
- SE501632
- Application
- 9102490
- Application, DOCDB
- 9102490
- Application, EPODOC
- SE19910002490
Titles2
- Swedish
- Sätt att bilda en beläggning omfattande ett pyrolytiskt bildat oxidskikt på ett sig rörande varmt glassubstrat
- English
- Methods of forming a coating comprising a pyrolytically formed oxide layer on a hot glass substrate
Classification
- CPC, 4
- C03C17/3423
- C03C17/002
- C23C16/407
- C23C16/453
- IPC, 4
- C03C17 00
- C03C17 34
- C23C16 40
- C23C16 453
