CA1291680C

CA1291680C - Method for the manufacture of a tempered and/or bent glass pane with platinum coating or the like

Info

Publication number: CA1291680C
Application number: CA000530847A
Authority: CA
Inventors: Rolf Groth; Franz-Josef Schmitte
Original assignee: Flachglas Wernberg GmbH
Current assignee: Flachglas Wernberg GmbH
Priority date: 1986-02-28
Filing date: 1987-02-27
Publication date: 1991-11-05
Anticipated expiration: 2008-11-05
Also published as: BR8700960A; ES2023371B3; EP0239750A1; KR930009324B1; AU587894B2; DE3771245D1; DE3611844C2; KR870007862A; GR3002292T3; EP0239750B1; AU6956287A; DE3611844A1

Abstract

Method for the manufacture of a tempered and/or bent glass pane of soda-lime-silica glass with reduced transmission for solar radiation, in which to at least one side of the transparent glass carrier is applied a metal coating of platinum, iridium or optionally rhodium, alloys of these metals or metal alloys with a preponderant proportion of at least one of these metals in a thickness such that the light permeability of the laminate formed from the glass carrier and the metal coating is between 10 and 90%, particularly between 30 and 90% of that of the glass carrier alone and a tempering and/or bending process is performed in air at a temperature of 580 to 680.degree.c, preferably 600 to 650.degree.C, characterized in that the metal coating is applied to the substantially flat glass carrier before the tempering and/or bending process and on the side of the metal coating remote from the glass carrier an oxide stabilizing coating from or with a preponderant content of at least one metal oxide or mixed metal oxide, preferably from the group Bi, In, Ni, Sb, Sn, Ta, Ti and Zn is applied with a thickness of 2 to 20 nm before the tempering and/or bending process. (Fig. 1)

Description

~9~

ME~IIOD FOR THE MANUFACTURE OF A TEMPERED AND/OR BENT GLASS PANE
WITH PLATINUM COATING OR THE LIKE

The invention relates to a method for the manufacture of 8 tempered and/or bent glass pane of soda-lime-silica glass with reduced transmission for solar radiation, in which to at least one side of the transparent glass carrier is applied a metal coating of platinum, iridium or optionally rhodium, alloys of these metals or metal alloys with a preponderant proportion of at least one of these metals in a thickness ~uch that the light permeability of the laminate for~ed from the glass carrier and the metal coating is between 10 and 90%, particularly between 30 and 90~ of that of the glass carrier alone and a tempering and/or bending process is performed in air at a temperature of 580 to 680 C, preferably 600 to 650C.

Glass panes having a surface coating of a metal or metal alloy are used in the building ~ector and in vehicle glazing for reducing the transmission of the uncoated glass carrier in certain spectral ranges. This is done e.g. in order to subdue the light and/or pre~ent glare. Metals or metal alloys from elements with atomic numbers 22 to 28 of the periodic table are preferably used for the metal coating, if it is wished to obtain glass panes in which there is no colour change to the coating in direction vision and in reflection. Generally standard soda-lime-silica glass is used as the glass carrier and can be additionally dyed in th~ mass, as is the case with bronze, grey and green glass. This dying in the mass already leads to a basic glare pre~enting action, which is reinforced by the coating. Particularl~-1~9~680 in the case of glazing systems for motor vehicles, frequent useis made of green glass dyed in the mass, which has a ~ood glare preventing action, in conjunction with high light permeability.
In such cases, particular interest is attached to mixed glazing systems, some of the panes being additionally coated. Thus, for example, the windscreen and furthest forward side windows, which are subject to legal requirements regarding the minimum light transmittance, are made from green glass which has been dyed in the mass. For the rear part of the vehicle, where lower light transmittance values are accepted, use is made of panes which are dyed in the mass and additionally coated in order to increase the protection against the sun. It is particularly important in such mixed glazing systems to use a coating without any colour distortion in reflection and direct ~ision, so that direct vision from the interior can take place in uniform manner in all directions, i.e. without any disturbing colour distortion betweenthe individual panes. The same applies regarding a uniform colour impression of the vehicle when viewed from the outside.

In many application~, including those described hereinbefore, it is necessary to thermall~ temper the glass carrier, which e.g.
takes place for increasing the mechanical stability, for preventing heat jumps and for reducing injury risks in the case of the glass breaking. Tempering is carried out by heating the almost exclusively used soda-lime-silica glass panes in air rapidly to a temperature above the glass transformation point, followed by rapid cooling. The temperatures required for tempering are in the range 580 to 680C and prefcrably 600 to 650 C. The same ~9~
- ; -temperature range is also required if the glass panes which comeflat from the glass manufacturing process undergo a bending process so that in certain ca~es, e.g. in the automobile field, bent glass plates are obtained. Hitherto the application of said colour-neutral metal coatings has taken place at the end of the tempering and/or bending process and the cooling of the pane~, use generally being made of vacuum coating proces~es.

This procedure of carrying out coating following the tempering and/or bending process has numerous disadvantages compared with a procedure in which initially the coating is applied and then the tempering and/or bending process is carried out. Thus, in the former case only cut sizes can be coated, because tempered panes cannot be cut. However, with regards to the coating procedure it is much more advantageous to coat standard sizes, particularly the lehr end sizes of glass production by the float process. In the latter case, it is much easier to solve the problems of a uniform coating thickness in the case of vacuum coatings than with cut sizes with corresponding gaps between the individual panes in the coating field. Tn addition, the transfer of such standard sizes through the coating plants i~ much less complicated than in the case of having to transfer individual pieces of different sizes.

Another disadvantage is that as a result of the high temperatures of the tempering and/or bending process impurities on the glass surface frequently form such a firm bond therewith that they cannot be removed during the following surface cleaning and before - ~ ~9~ o performing the coating process to the extent necessary for said coating process. They are quasi burned into the glass surface, which leads to a disturbing deterioration of the coating quality.

In the case of coating bent plates, the problem of obtaining an adequate coating uni~ormity is naturally particularly serious, because the angles and distances from the coating sources additionally change due to the curvature of the panes. In addition, the costs of vacuum coating plants for coating bent panes are much higher than for coatirg flat panes, because it is necessary for the inlet and outlet locks, as well as the locks between the different coating stations to be much wider than when coating flat glass.

lS Thus, considerable advantages are associated with a procedure in which flat glass, particularly having standard sizes, is coated and then tempered and/or bent, particularly after separating to cut sizes. However, this procedure has not hitherto been possible in the case of the metal coatings of metals or metal alloy* of elements with atomic numbers 22 to 28 preferred for colour neutrality reaeons, because the necessary temperatures above 580C lead to disturbing coating changes, part;cularly as a result of the oxidation of the coatings, as described e.g. in German patent application 17 71 223. The latter describes a method for producing oxide coatings, according to which the metal coatings or sub-oxidic coatings of these metals, particularly coatings from the group of metals cobalt, iron, manganese, cadmium, bismuth, copper, gold, lead and nickel , :

~?~9168 produced by vacuum evaporation undergo a heat treatment stage at temperatures between 315 and 677.5C and are consequently converted into the corresponding oxides. However, through the conversion into the oxides, the transmission of the coatings, particularly in the near infrared increases. This leads to an undesirable deterioration of the glare prevention action as compared with metal coatings.

In addition to the aforementioned metal coatings, combinations of these coatings with transparent oxide coatings ha~e been proposed. Thus, to the side of the metal coating remote from the glass carrier it is possible to provide a transparent oxide coating as a protective coating for improving the mechanical characteristics, or when constructed as a quarter-wavelength coating for the visible range as an antireflection coating for increasing the selective transmission. Such a coating arrange-ment is e.g. known from US patent 38 46 152. Tests have shown that even in the case of such an arrangement an adequate stability cannot be achieved if said coating arrangements are exposed to thermal stresses, such as occur during the tempering and~or bending proce~s.

For eliminatin~ the aforementioned difficulties, namely permitting the application of the coating prior to the tempering and/or bending process when using metals or metal alloys of elements with atomic numbers 22 to 28, it has already been proposed (German patent application P 35 44 840.7-45), prior to the tempering and/or bending process, to apply to the substantially flat glass carrier the metal coating with a preponderant content ~916l!3C~

of a metal or metal alloy from the elements ~-ith atomic numbers 22 to 28 of the periodic table and to the side remote from the glass carrier a protective coating of at least one metal oxide or mixed metal oxide which, based on a metal atom of the metal oxide or oxides, has an ox~gen deficit x of O.O5 S x < 0.4 and a thickness of lO to lOO nm and a co~position such that, during the tempering and/or bending process, there is no significant oxygen diffusion to the metal coating.

It is admittedly obvious for permitting this for making it possible to carry out the tempering and/or bending process follow~ng the application of the coating to use platinum, iridium or optionally rhodium as a result of their oxidation stability, this does not apply to transparent gold and/or silver coatings, because they are coloured in direct vision and/or in reflection and therefore do not have the desired neutrality for many applications. However, the use of the process known from French patent 12 71 584 of providing glass carriers with platinum or rhodium coatings prior to a tempering process and then to carry out the latter has not been successful in a method of the type on which the present application is based. For explanation purposes, it is pointed out that French patent 12 71 584 describes a procedure in which platinum or rhodium coatings, which in direct vision and reflection have the desired neutrality for many uses, have their adhesiveness improved by corresponding aftertreatment in air at elevated temperature, e.g. during a tempering process and it is also possible to apply to the precious metal coating a protective coating of an enamel or glaze, ~X916~

which can b~ burnt in in the furnace. If this process of providing the glass carrier with the platinum or rhodiurn coating and then carrying out a tempering and/or bending process is used with the coating thicknesses as provided in the method on which the present application is based, the tempering process leads to disturbing coating modifications. The coating turns cloudy, which can be detected as a disturbing stray light level, e.g. when illuminating with direct sunlight. Therefore such glass panes are unsuitable for glare prevention purposes in building or vehicle glazing systems. Moreover, particularly in the case of coated glass carriers with a light transmittance above approx-imately 4OX, based on the light transmittance of the uncoated glass carrier, there is an increase ~ the transmission for the spectral range of solar radiation and therefore a deterioration of the,glare preventing action due to the tempering and/or bending process.

The problem of the present invention is to so further develop the method on which the application is based that the disadvantages linked with coating the glass carrier only following the tempering and/or bending process are avoided and, without any risk of changes to the metal coating, it is possible to carry out the necessary coating measures prior to the tempering and/or bending process, whilst obtaining the relatively high transmission values.

According to the invention this problem is solved in that the metal coating i,s applied to the substantially flat glass carrier before the tempering and/or bending process and on the side of - ~X9~680 the metal coating remote from the glass carrier an oxide stabilizing coating from or with a preponderant content of at least one metal oxide or mixed metal oxide, preferably from the group Bi, In, Ni, Sb, Sn, Ta, Ti and Zn is applied with a thickness of 2 to 20 nm before the tempering and/or bending process.

The stabilizing coating can be applied in a thickness of max 15 nm.

According to the invention, the stabilizing coating is also applied in a thickness o~ max 12 nm.

The invention also proposes that In203, mixed oxides of ind~um and tin, Sb203 or Bi203 are ~sed for the stabilizing coating~

According to the invention, the general procedure is such that the coating of the transparent glass carrier takes place by vacuum coating.

It i9 pr~posed that the stabilizing coating is applied by reactive cathodic sputtering, particularly reactive magnetron cathodic sputtering.

The invention is based on the surprising finding that it is possible by applying the stabilizing coating to prevent the occurrence of cloudiness in the thin precious metal coating. The reasons for the action of the stabilizing coating are not kno~n.
It cannot be a protective action in the sense that through the ~9~6~

oxide coating the diffusion of oxygen from the air to the precious metal coating is prevented, becau~e in the case of such a mechanism it would be incomprehensible why thicker "open" precious metal coatings, as are used in the process of French patent 12 71 584, are not affected by the disturbing coating changes, so that therein and even without the presence of a stabilizing coating, as proposed by the invention, there can be a tempering of the coated glass carrier following the application of the metal coating.

It is also surpri9ing that for the action of the stabilizing coating it is merely necessary to have very small coating thicknesses, the necessary minimum being approximately 2 nm. This is advantageous, because in this range of limited coating thick-nesses, the optical data, particularly the neutrality in direct vision and reflection, of the metal coating are not d;sturbed by interference interaction with the dielectric stabilizing coating.
As is known, such visually disturbing interference effects only occur with coating thicknesses above 15 nm, particularly above 20 nm. The fact that even very small oxide coating thicknesses are sufficient for carrying out the method of the invention also leads to considerable advantages regarding the performance of the method, because the coating process can then be performed with considerable tolerances with respect to the coating thickness, without coating thickness fluctuations leading to a change in the technical data and the appearance of the coating.
This is a major advantage for coating large glass panes of the type almost exclusively used in the applications of interest here, because coating thickness uniformity problems generally increase ~?~9~6~
- 10 _ ~ith the pane sizes.

In the invention, it is optionally possible to provide between the glass carrier and the metal coating an additional oxide coating, in order to impro~e the coating adhesiveness, such oxide coatings being known per se e.g. from German application L 13 792 VIII d in the form of adhesive coatings for metal layers for improving the electrical conductivity of the latter. German Utility Model 17 34 744 already discloses a glass pane with a platinum coating and an oxidic protective coating applied thereto and which serves to protect the platinum coating against mechanical and chemical actions, without this literature reference disclosing the action of the inventively proposed stabilizing coating in the case of relatively thin metal coatings of the type provided in the inventive method.

In connection with the performance of the inventive method, coatings of In2O3, mixed oxide coatings of the metals indium and tin, Sb2O3 coatings and Bi2O3 coatings have proved particularly suitable for the stabilizing coating, becau~e inter alia this leads to a particularly hard and abrasion-resistance coating, such as is especially advantageous for the further handling of the glass panes after performing the tempering and/or bending process.

~part from platinum, which has proved to ~e particularly suitable as a msterial for the metal coating, iridium and optionall rhodium, as well as alloy coatings of platinum, iridium and optionally rhodiu~ have proved suitable. It is also possible to use alloy coatings in which less precious metals are added to the aforementioned metals or their alloys. However, these additions ~?~916f~0 must be so small that the precious metal character is largely retained, so that the maximum less precious metal additions represen~ approximately 50 atomic per cent according to the rule drawn up by Tamman (G. Tamman, "Lehrbuch der Metallkunde", Edition IV, 1932, Leopold Frost, Leipzig, p 428 ff).

According to the method of the invention, the coating is generally produced by vacuum coating. The coatings can be applied by evaporating from resistance-heated evaporator means or by electron beam e~aporation. Cathodic sputtering in the form of direct current or low frequency sputtering, but in particular high frequency and magnetron cathodic sputtering are also suitable.
The metal or metal alloy coatings can either be produced by direct e~aporation or sputtering in neutral atmosphere. The lS reactive e~aporation method is suitable for producing the oxide coatings. The reactive cathodic sputtering, particularly reactive magnetron cathodic sputtering, in which sputtering takes place of corresponding metal or metal alloy targets in an atmosphere inter alia containing oxygen is also suitable.
ZO

It is also pointed out that particularly when per~orming the process slowly, as is frequently the case during bending, the inventive method can also be advantageously used with light transmittance values of less than 30%, e.g. 20%, because this also leads to a favourable influence on the otherwise unavoidable clouding processes.

Further features and advantages of the invention can be gathered from the following description, in which inter alia 1 6~0 embodiments are explained in detail with reference to the drawings, wherein show:

Fig. 1 An embodiment of a glass pane which can be manufactured according to the inventive method in section and at right angles to the pane plane.

Fig. Z The spectral transmission curves of a glass pane manufactured according to the prior art before and after performing the tempering process.

As shown in fig. 1, the glass plate shown therein has a transparent soda-lime-silica glass carrier 10 carrying a platinum metal coating 12. On the side of metal coating 12 remote from glass carrier 10 is applied an In203 stabilizing coating 14.

Example 1 In a vacuum coating plant equipped with coating means for magnetron cathodic sputtering, the following coatings were successively applied to a 10 cm x 10 cm float glass pane. Firstly a plat~num coating 3.2 nm thick was applied by sputtering a platinum target in an argon atmosphere at a pressure of 5.10 3 mbar. To the platinum coating as the stabilizing coating was then applied an antimony oxide coating by the reactive sputtering of an antimony target in an argon-oxygen atmosphere with a 50%

oxygen proportion at a pressure of 5.10 3 mbar. The antimony oxide coating thickness was 6 nm.

The coated pane had a neutral appearance in both direct vision and reflection. The light transmittance of the coatedpane was ~L~9~6~

60%, whereas the uncoated pane had a light transmittance of 60%.

The coated pane was then heated in a tempering furnace to 600C
and cooled. There was substantially no change to the appearance and the light transmittance of the pane as a result of the tempering process.

Example 2 The procedure of example 1 was adopted, with the difference that no antimony oxide stabilizing coating was applied. In direct vision and in reflection, the coated pane had the ~ame neutral appearance as in example 1 and the light transmittance was 60X.

As in example 1, the coated pane was then tempered. Following this process, the coating was cloudy and appeared as a disturbing stray light level after illumination with a projection lamp. In addition, the light transmittance had increased to 68%.

Fig. 2 shows the spectral transmission curves prior to carrying out the tempering process (curve 1) and a~ter said process (curve 2). They show that the glare preventing action has been considerably reduced by tempering.

Example 3 In a ~acuum coating plant, as described in example 1, the following coatings were successively applied to a 10 cm x 10 cm float glass pane:

~9~6~0 , ll a 5 nm thic~ In203 co~ting by the reactive sputtering of an indil~ target at a pressure of 5.10 3 mbar in an argon-oxygen atmosphere of composition 60% Ar and 4~ 2~

a 7 nm platinum coating by sputtering a platinum target in an argon atmosphere at a pressure of 5.10 3 mbar, and a 5 nm thick In203 top coating by the reacti~e sputtering of an In target under the same conditions as for $he first In203 coating.

The coated pane had a light transmittance of 40% and had a neutral appearance in direct vision and reflection. The coated pane was then tempered as in example 1.

There was substantially no change to the appearance and light transmittance of the pane as a result of the tempering process.

ExamPle 4 As in example 3, a platinum coating was applied, but without the additional In203 coatings. Here again the light tran~mittance of the coated pane was 40%.

Although after tempering the light transmittance was still 40X, the coating was cloudy and this was ~isible as disturbing stray light when illwn~nated with a projecting lamp. Thus, in this form the coating is unsuitable for the indicated uses.

Example 5 A coating system as describedin example 3 was applied, but the 1?~31680 -- l 5 pure platinum was replaced by a coating of a platinum-silver alloy of composition 70 atomic % platinum and 30 atomic % silver in a thickness of 5 nm. The coated pane had a light transmittance of 51% and a neutral appearance both in direct ~ision and in reflection.

As in example 3, the appearance and light transmittance of the plane were substantially unchanged as a result of the tempering process.

The features of the invention disclosed in the above description, the claims and the drawings can be essential to the realization of the inYentive concept in its different embodiments, either singly or in random combinations.

Claims

WHAT IS CLAIMED:

1. A method for the manufacture of a tempered and/or bent glass pane of soda-lime-silica glass with reduced transmission for solar radiation, in which to at least one side of the transparent glass carrier is applied a metal coating of metal selected from platinum, iridium rhodium, alloys of these metals, or metal alloys with a preponderant proportion of at least one of these metals, in a thickness such that the light permeability of the laminate formed from the glass carrier and the metal coating is between 10 and 90% of that of the glass carrier alone and a tempering and/or bending process is performed in air at a temperature of 580 to 680°C, wherein the metal coating is applied to the substantially flat glass carrier before the tempering and/or bending process, and on the side of the metal coating remote from the glass carrier an oxide stabilizing coating from or with a preponderent content of at least one metal oxide or mixed metal oxide is applied with a thickness of 2 to 20 nm before! the tempering and/or bending process,

2. A method as claimed in claim 1, wherein the thickness of the metal cooling is such that the light permeability of the laminate is between 30% and 90% of that of the glass carrier alone.

3. A method as claimed in claim 1, wherein the tempering and/or bending process is performed at a temperature of 600 to 650°C.

4. A method as claimed in claim 2, wherein the tempering and/or bending process is performed at a temperature of 600 to 650°C.

A method as claimed in claim 1, wherein the oxide stabilizing coating is from the group Bi, In, Ni, Sb, Sn, Ta, Ti and Zu.

6. A method as claimed in claim 2, wherein the oxide statilizing coating is from the group Bi, In, Ni, Sb, Sn, Ta, Ti and Zu.

7. A method as claimed in claim 3, wherein the oxide statilizing coating is from the group Bi, In, Ni, Sb, Sn, Ta, Ti and Zu.

8. A method as claimed in claim 4, wherein the oxide statilizing coating is from the group Bi, In, Ni, Sb, Sn, Ta, Ti and.

9. A method according to claim 1, wherein the stabilizing coating is applied in a thickness of maximum 15 nm.

10. A method according to claim 1, wherein the stabilizing coating is applied in a thickness of maximum 12 nm.

11. A method according to any one of claims 2 to 8, wherein the stabilizing coating is applied in a thickness of maximum 15 nm.

12. A method according to any one of claims 2 to 8, wherein the stabilizing coating is applied in a thickness of maximum 12 nm.

13. A method according to any one of claims 1 to 10, wherein In2O3, mixed oxides of the metals indium and tin, Sb2O3 or Bi2O3 are used for the stabilizing coating.

14. A method according to any one of claims 1 to 10, wherein the transparent glass carrier is coated by vacuum coating.

15. A method according to any one of claims 1 to 10, wherein the stabilizing coating is applied by reactive cathodic sputtering.

16. A method according to any one of claims 1 to 10, wherein the stabilizing coating is applied by reactive magnetron cathodic sputtering.