DE2757750B2 - Heat-reflecting disk with a TiO 2 layer in rutile modification and process for its production - Google Patents

Description

The invention relates to a heat reflective Disc according to the preamble of claim 1 and a method for producing such a Washer according to the preamble of claim 7.

_{Heat-reflecting panes, in which a heat-reflecting TiO 2} layer is applied by vapor deposition of a titanium layer in a vacuum and subsequent oxidation of this layer at higher temperatures in air, are known and, for example, in a publication by G. Hass entitled “Preparation, Properties and Optical Applications of Thin Films of Titanium Dioxide "(G. Hass, Vacuum, VoI, 11, No. 4, pages 331-345 [1952]). Depending on the conditions under which the Ti layer is vapor-deposited in a vacuum, the subsequent oxidation of the Ti layer in air _{produces "white TiO 2} modifications. If the titanium is in a good vacuum, i.e. a vacuum of = 10" ⁵ mbar or better, rapidly deposited, resulting in formation of the rutile modification, while mbar at relatively slow evaporation in bad vacuum, for example about 10- ^4, the anatase form is formed. TiO ₂ layers produced in this way have found various optical applications for coating glass panes, for example as a light splitter and as a coating that reflects solar radiation, the layer thickness being a quarter-wavelength interference layer to achieve the highest possible reflection - based on the spectral range in which a modification of the reflection properties of the Substrate is desired - is formed.

A special application for heat-reflecting panes of the type mentioned is that such panes can be used in facade elements or parapet panels. In the case of parapet panels of this type, TiO ₂ -coated glass panes are desired, which are characterized by a high, color-neutral reflection - possibly with a slight shade of blue or yellow - in the visible spectral range. In such parapet panels, the TiO ₂ interference layer is generally arranged on the side of the building, while the back of the glass pane is provided with an opaque enamel or varnish in order to prevent the view of parts of the building behind the parapet panel.

3 4

In particular, for the last-mentioned application, layer changes only occur in rutile layers. The purpose is TiO ₂ layers with a rutile structure. Other vacuum evaporation conditions are of considerable advantage because TiO ₂ layers are used in rutile mode, in particular a poorer vacuum and / or a higher refractive index than anatase or slower evaporation speeds, with layers _{as a result of which higher TiO 2} layers with an anatase structure, which are very desirable in the case of facade 5, the oxidation in the manner already described leads to the elements or parapet panels, so reflection values can be achieved. In addition, has thus coated disks on larger cache Tempe shown that rutile layers temperatures much higher hardness as 550 ⁰ C and more, warm without it possess and abrasion resistance than anatase layers. the shift changes described comes. Therefore, panes in which the same difficulties, namely the rutile layers on the _{outside of the building, suffer from the TiO 2} interference layer changes, naturally occur with a rutile-modified layer, can occur immediately without also whenever further Thermal toughening of the exposed atmosphere can also damage the external atmosphere for a long time as described above. In addition, to be made for cleaning windshields, therefor, be voreingesetzt in the case of soda-lime-silicate glasses in the top of such disks or parapet plates for η manner indicated temperatures above aligemein standard of about outer glass surfaces detergent 55O ⁰ C, preferably about 570 to 62O ⁰ C, are required. These

In the case of various applications of _{layer changes that are disadvantageous with TiO 2} , the above gei occur in the coated panes. In the internal way, heating the panes to the temperatures required for thermal tempering, especially when used as a facade element 20, regardless of or parapet plate, it is necessary to temper the glass on whether the oxidation of the Ti layers is to comply with the safety regulations. TiO ₂ layers and the heating on the prestressing - Such prestressing is necessary if the temperature is carried out in one step or if the parapet plates provided with rutile layers are initially backed with Ti layers at a relatively low level: Due to the radiation-opaque 25 layers below 550 ⁰ C is oxidized and the enamel layer can in this case only then, if necessary after further exposure to sunlight, heat up the glass to such an extent that, without processing, the panes are heated to the temperatures required for the thermal tempering of the glass substrate. The glass is then toughened in the.

known way by heating the glass over the) o To solve the problem of heat-reflecting,

Transformation temperature to temperatures begin - especially as parapet panels or facade elements

With softening and subsequent shock-like elements, suitable disks of the type mentioned at the beginning

Cooling down. In the case of soda-lime-silicate glasses with the and a process for their production,

chemical composition of usual flat glasses in which the TiO2 layers at least predominantly

are for this purpose temperatures of about 570 to 620 ⁰ C 35 rutile structure and at which the occurrence of the

necessary. disturbing layer changes when heated

The biasing can in the production of wärmere- temperatures above 550 ⁰ C as done for inflecting discs of the type mentioned in rapid oxidation of the Ti layer necessary insbesonprinzipiell in two different ways. Once it is absolutely necessary for the thermal toughening, the toughening process is effectively prevented, the way with the oxidation of DE-OS 26 46 513, which is vapor-deposited in a vacuum, suggests that between the glass pane and the Ti layer combine. Of course, however, it is also possible for the TiO ₂ layer to not cause any interference, initially the vapor-deposited Ti layer is arranged next to the vapor-deposited silicon oxide layer, with temperatures sufficient for this, for example this method being characterized by the fact that 400 to 500 ° C. oxidize, then cool the glass pane provided with the glass pane with a TiO ₂ layer before the vapor deposition of the Ti layer, and finally vaporize the silicon oxide layer which does not cause any interference until in a further process step; and that the so coated a further furnace is heated to the heating for the glass pane to oxidize in air.
Biasing required temperature of - in the case of the present invention is that, given above of soda-lime-silicate glasses - 50 new to 62O ⁰ C and also DE-OS 26 46 513 to perform underlying about 570th Task as an alternative to the teaching given there

In principle, it is of course desirable to use the oxides mentioned in the characterizing part of claim 1

tion of the Ti layer to TiO ₂ in rutile modification in features. Accordingly, one stands out

to be able to carry out as short a time as possible. It is an inventive method for making a

known - G. Hass, Vacuum, Vol 11, No. 4, page 335, “heat-reflecting disk of the invention

Fig. 3 - that the oxidation takes place all the faster, kind by the characterizing part of claim 7

the higher the oxidation temperature is chosen. mentioned measures.

If, however, the oxidation temperature is increased in the particularly preferred embodiments of the known method to the values required per se for a fast merelecting disk and the method after the oxidation process, namely above the invention result from the corresponding half of about 550 ^° C., so Subclaims occur in the rutile layers.

Shift changes on. The layers become matt. The invention is based on the surprising finding

and cloudy and scatter both in transmission and in underlying that it is possible to remove the disadvantageous layer changes.

Reflection of light to such a considerable extent that the TiO2 layer with rutile structure changes

thus prepared discs for the aforementioned applications there heating to temperatures of above 550 ⁰ C, such as

application cases, in particular as parapet panels or they are particularly required for thermal prestressing

as facade elements, are no longer used, should be avoided if between the

can. Strangely enough, the aforementioned glass pane and the rutile layer form an intermediate layer

from T1O2 is arranged in anatase modification. the Both layers are created in such a way that on the glass pane first a first Ti layer and then relatively slowly in a relatively poor vacuum then a second Ti layer can be applied relatively quickly with a relatively good vacuum, wherein then the subsequent oxidation leads to the anatase intermediate layer on the glass pane from the first Ti layer and the rutile layer is formed from the second Ti layer.

It has been shown that by the measure according to the invention, between the glass pane and the rutile layer To provide an anatase layer, not only - as in DE-OS 26 46 513 - the disadvantages of the state the technology can be completely avoided, namely in the case of the oxidation or for thermal tempering required temperatures no layer changes occur, but that even with a large total thickness of the T1O2 coating of up to 0.06 μιτι, how to achieve a A color-neutral outer layer is desirable, no cracking or peeling the coating occur. Since the vapor deposition of the two Ti layers is advantageously the same, Titanium-filled vaporizer devices can be used, the application of the Overall coating with the invention is even lighter and more cost-effective than with the heat-reflecting one Disc and the method according to DE-OS 26 46 513. In addition, titanium is used as a coating material in Wire form available, while silicon monoxide is used as a vapor deposition material in granular form, see above that the weighing of the quantities of material required for charging the evaporator devices is facilitated in the invention. The double coating according to the invention shows the same hardness and Abrasion resistance as a rutile layer without anatase intermediate layer, as long as the rutile layer is thick at least about 0.008 μm is applied. All in all the thickness of the rutile layer within the total TiO2 coating should not be more than about 0.03 μm otherwise cracks could form in the rutile layer. The maximum allowable The thickness of the rutile layer depends slightly on that for the oxidation of the layers or for the thermal Tensioning selected temperature, namely the maximum allowable thickness is slightly less if this Temperatures are increased. Furthermore, the maximum allowable thickness will be a little smaller if this Temperatures are increased. Furthermore, the maximum permissible thickness of the rutile layer at which Exceeding cracking of the rutile layer could occur, slightly due to the surface condition of the glass before coating, namely in the sense that in the event of corrosion of the glass surface and Less careful cleaning of the glass surface also decreases the maximum permissible thickness.

A particular advantage of the coating according to the invention is that on the glass pane the T1O2 coating is applied directly, creating a gives particularly good adhesion. In addition, the not yet oxidized Ti layers also have one very good adhesion to the glass, which means that the Ti-coated panes can be handled up to the point of oxidation Ti layers is facilitated.

The person skilled in the art could not gain any suggestions for teaching the invention from the prior art. So is in DE-OS 15 96 816 a layer arrangement described, with a mixed layer on the glass pane of silicon oxide and titanium oxide is applied, whereupon only then a titanium oxide layer and finally a Silicon dioxide layer follow - in a similar way, ■ -> also CA-PS 4 64 446 shows layer arrangements in which A mixed layer of titanium oxide and silicon oxide as well as (one) pure one successively on a pane of glass Titanium oxide or silicon dioxide layer (s) are arranged, but these publications are a reference to

id the teaching of the invention, to avoid layer changes in panes of the initially mentioned type, in which the production of the TiOr layer in rutile modification is an intermediate layer to provide from T1O2 in anatase modification, not to

ii remove. The US-PS 24 78 817th which general the production of TiO2 layers in the immersion process relates, and the Czechoslovak patent specification PV 43 94-65, published in part in Glass technical reports Pll, February 1968, show no reference to the teaching according to the invention in which Production of TiO2 layers by oxidation in vacuum vapor-deposited Ti layers in this way proceed so that by appropriate choice of the evaporation conditions on the glass pane, an intermediate

: =, layer layer in anatase modification and only then an outer layer in rutile modification can be formed, which latter has the advantageous properties desired for the outer surface of the disk and discussed in detail above.

The following are embodiments of the invention explained in detail with reference to the schematic drawing.

The drawing, which consists of a single figure, shows the structure of a heat-resistant disk

r> according to the invention in section.

As can be seen in the drawing. comprises a heat reflective disc according to the invention Glass pane 10, in particular made of soda-lime-silicate glass, on which an intermediate layer follows one another 12 T1O2 in anatase modification and a TiO2 layer 14 in rutile modification are arranged. This layer arrangement can be produced in such a way that initially on the glass pane 10 a first Ti layer at a vacuum in the

• π order of 10 ~ ⁴ slowly and then a second Ti layer are evaporated mbar relatively quickly at a vacuum of the order of 10- ⁵ mbar relatively, after the two layers of a then by oxidation at

be oxidized at a temperature sufficient for this for anatase or rutile modification. The layer arrangement shown in the drawing consists of the exemplary embodiment described here made of thermally toughened glass, in other words, the glass pane is ^{heated to a temperature in the range from 570 to 620 °} C. after coating, here: 550 ^° C., and then heated to thermal Prestressing has been quenched. The procedure is preferably such that the glass pane provided with the two Ti layers is

bo equal to a temperature in the range from 570 to 620 ° C - in the case of soda-silicate glass - is heated, in which case both the conversion of the vapor-deposited Ti layers in the anatase layer 12 or in the rutile layer 14 as well as the heating of the

h5 glass pane 10 on the one for thermal toughening required temperature take place so that quenching can follow immediately. Disadvantageous shift changes which in this way in rutile modification

TiCV layer 14 produced could not be observed. Even in long-term studies, no changes to the Tio2 coating were found.

In the following two more examples are described in which once - Example 1 - according to the status the technology and on the other hand - Example 2 - was proceeded according to the teaching of the invention.

example 1

In a vacuum deposition, a float glass plate having a thickness of 8 mm and outer dimensions of 300 cm 245 cm χ initially at a pressure of 4 χ 10 ~ ² mbar purified in a conventional manner by the glow discharge. A Ti layer was then applied by vapor deposition at a pressure of 6.7 10 ⁵ mbar, the vapor deposition time being 35 seconds. The coated pane was then heated to 620 ° C. in a conventional thermal toughening furnace and then quenched. During the heating process, the titanium _{layer was oxidized to form a TiO 2} layer 0.047 µm thick with a rutile structure. However, the layer was cloudy and matt, so that the pane could not be used, since such panes, especially when used as a parapet panel or facade element, are not tolerated for architectural reasons.

Example 2

The procedure was as in Example 1, with the difference that after the glow purification initially at a pressure of 2 χ 10- ⁴ mbar at a deposition time of 2 minutes, a first Ti layer and then, after interrupting the Aufdampfvorganges and improve the vacuum, mbar were evaporated at a pressure of 6.7 χ 10 ~ ⁵ in a deposition time of 20 seconds, a second Ti layer. The pane coated in this way was then prestressed in the same way as in Example 1. The outer TiCV layer, which was created from the second Ti layer vapor-deposited under a good vacuum, also had a rutile structure. The thickness of the anatase layer was 0.024 μm and the thickness of the rutile layer was 0.025 μm. In contrast to the disk produced according to Example 1, the e. pane manufactured according to the invention completely clear after prestressing, so that the pane manufactured in this way could be used excellently as a parapet panel or facade element. The disc had a neutral color, shiny silver appearance. The reflectivity of the pane, based on the light sensitivity of the human eye, was 40%. For architectural reasons, the pane can be used particularly advantageously in conjunction with color-neutral insulating glass panes.

Hierza 1 sheet of drawings

Claims (11)

Patent claims: 1. Heat-reflecting pane, consisting of a pane of glass, in particular of soda-lime-silicate glass, with a TiO ₂ layer in rutile modification, which is produced by vapor deposition of a Ti layer in a vacuum and subsequent oxidation, is characterized in that between the glass pane (10) and the rutile layer (14) iu an intermediate layer (12) of TiO ₂ in anatase modification, likewise produced by vapor deposition of a Ti layer in a vacuum and subsequent oxidation, is arranged 2. Heat-reflecting pane according to claim 1, characterized in that the total thickness of the TiO ₂ coating consisting of the intermediate layer (12) and the rutile layer (14) is 0.03 to 0.06 μm 3. Heat-reflecting disk according to claim 2, characterized in that the intermediate layer (12) has a thickness of at least 0.003 μm. 4. Heat-reflecting disc according to claim 3, characterized in that the rutile layer (14) has a thickness of at least 0.008 and at most 0.03 μιπ. 5. Heat-reflecting disc according to claim 4, characterized in that the rutile layer (14) has a thickness of 0.022 to 0.025 μm. 6. Heat-reflecting pane according to one of the preceding claims, characterized in that that the glass pane (10) is thermally prestressed. 7. A method for producing a heat-reflecting panel according to any of the preceding v> claims, in which on a glass pane, in particular from soda-lime-silica glass, by vacuum evaporation, a Ti layer is applied and this is then oxidized at an elevated temperature to TiO ₂ , characterized in that a first Ti layer is initially deposited relatively slowly on the glass pane at a relatively poor vacuum of the order of 10 ~ ⁴ mbar and then a second Ti layer is vaporized relatively quickly at a relatively good vacuum of the order of ΙΟ- ^{5 mbar} will; and that the glass pane thus coated is heated in air to oxidize the first Ti layer to an intermediate layer of TiO ₂ in anatase modification and at the same time to oxidize the second Ti layer to a TiO ₂ layer in rutile modification (rutile layer). 8. The method according to claim 7, characterized in that the vapor deposition of the first Ti layer takes place in a vapor deposition time of more than 60 seconds and the vapor deposition of the second Ti layer in a vapor deposition time of less than 30 seconds; and that the pressure prevailing in the pressure during the vapor deposition Aufdamp'en the first Ti layer 1.33 to 2.67 χ 10 ~ ⁴ mbar and during vapor deposition of the second Ti layer is at most 8 χ is 10 ^-5 mbar. 9. The method according to claim 7 or 8, characterized in that both Ti layers one after the other evaporated using the same evaporator devices filled with Ti, wherein after the completion of the first Ti layer, the vapor deposition process is interrupted, then the vacuum improves and only then the second Ti layer is evaporated. 10. The method according to any one of claims 7 to 9, characterized in that the Ti-coated Glass pane for the oxidation of the Ti layers in air to a temperature of at least 550 ° C, preferably 570 to 620 ° C. 11. The method according to claim 10, characterized characterized in that the glass sheet after heating to the oxidation temperature for thermal toughening is quenched. IZ method according to one of claims 7 to 10, characterized in that the Ti-coated glass pane is first heated to a temperature sufficient to oxidize the Ti layers, then further processed and only in a further heating step for thermal toughening to a temperature of at least 550 ⁰ C, preferably 570 to 620 ° C, and then quenched.