Fire-resistant pane and fire-resistant glazing assembly

Abstract

The present invention relates to a fire-resistant pane, including at least one float glass pane with a tin bath side and at least one protective layer that is arranged on the tin bath side in a planar manner, wherein the float glass pane and the protective layer are thermally tempered or partially tempered together. At least one alkaline fire-resistant layer is arranged on the protective layer in a planar manner. The protective layer contains metal oxide, metal nitride, and/or mixtures or layered compounds thereof. At least one edge sealing is arranged directly on the protective layer.

Claims

1. A fire-resistant pane, comprising: a float glass pane with a tin bath side and a protective layer that is arranged on the tin bath side in a planar manner, wherein the float glass pane and the protective layer are thermally tempered or partially tempered together, at least one alkaline fire-resistant layer that is arranged on the protective layer in a planar manner, wherein the protective layer contains or comprises silicon nitride, and an edge sealing that is arranged directly on the protective layer.

2. The fire-resistant pane according to claim 1, wherein the edge sealing contains at least one of polysulfide, polyurethane, polysilicone, and reactive hotmelts.

3. The fire-resistant pane according to claim 1, wherein the fire-resistant layer contains at least one of alkali silicate, alkali phosphate, alkali tungstate, alkali molybdate, and/or mixtures or layered compounds thereof.

4. The fire-resistant pane according to claim 1, wherein the fire-resistant layer contains a hydrogel of at least one of cross-linked monomers and polymers.

5. The fire-resistant pane according to claim 1, wherein the protective layer contains tin-zinc oxide and the ratio of zinc:tin is from 5 wt.-%:95 wt.-% to 95 wt.-%:5 wt.-%.

6. The fire-resistant pane according to claim 1, wherein the protective layer contains at least one dopant.

7. The fire-resistant pane according to claim 1, wherein the protective layer is a multi-layer structure and wherein one protection sub-layer contains or is made of a metal nitride, and an other protection sub-layer contains or is made of a metal oxide.

8. The fire-resistant pane according to claim 1, wherein the protective layer has a thickness d from 2 nm to 500 nm.

9. The fire-resistant pane according to claim 1, wherein the float glass pane contains borosilicate glass, alumosilicate glass, alkaline earth silicate glass, and soda lime glass.

10. The fire-resistant pane according to claim 1, wherein the float glass pane has a thickness from 1 mm to 25 mm.

11. The fire-resistant pane according to claim 1, wherein one adhesion-improving layer or one adhesion-reducing layer is arranged between the protective layer and the fire-resistant layer.

12. The fire-resistant pane according to claim 1, wherein the fire-resistant layer contains a hydrogel of at least one of polyacrylamide, poly-N-methylolacrylamide, or polymerized 2-hydroxy-3-methacryloxy-propyl-trimethyl-ammonium chloride.

13. The fire-resistant pane according to claim 1, wherein the fire-resistant layer contains at least one of alkali polysilicate, alkali polyphosphate, alkali polytungstate, alkali polymolybdate, and mixtures or layered compounds thereof.

14. The fire-resistant pane according to claim 3, wherein the fire-resistant layer contains at least one of sodium, potassium, lithium, and mixtures thereof.

15. The fire-resistant pane according to claim 1, wherein the protective layer contains tin-zinc oxide and a ratio of zinc: tin is from 15 wt.-%:85 wt.-% to 70 wt. -%:30 wt.%.

16. The fire-resistant pane according to claim 1, wherein the protective layer contains at least one dopant and wherein the dopant is at least one of antimony, fluorine, silver, ruthenium, palladium, aluminum, and tantalum.

17. The fire-resistant pane according to claim 1, wherein the protective layer contains at least one dopant, and wherein a fraction of the dopant in a metal fraction of the protective layer is from 0 wt.-% to 10 wt.-% .

18. The fire-resistant pane according to claim 1, wherein the protective layer is a two-ply layer structure and wherein one protection sublayer contains or is made of a metal nitride and one protection sublayer contains or is made of a metal oxide.

19. The fire-resistant pane according to claim 1, wherein the protective layer is a multilayer structure and wherein one protection sublayer contains or is made of silicon nitride, and one protection sublayer contains or is made of a tin-zinc oxide or a doped tin-zinc oxide.

20. The fire-resistant pane according to claim 1, wherein the protective layer has a thickness from 5 nm to 50 nm.

21. The fire-resistant pane according to claim 1, wherein the fire-resistant layer has a thickness from 0.5 mm to 70 mm.

22. The fire-resistant pane according to claim 11, wherein the one adhesion-improving layer or one adhesion-reducing layer contains at least one organofunctional silane or at least one polymer-wax.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in detail in the following with reference to drawings and an example. The drawings are not completely true to scale. The invention is in no way restricted by the drawings. They depict:

(2) FIG. 1A a schematic cross-sectional view of a fire-resistant pane according to the invention,

(3) FIG. 1B a schematic plan view of the fire-resistant pane according to the invention of FIG. 1A,

(4) FIG. 2A a schematic cross-sectional view of a fire-resistant glazing assembly according to the invention,

(5) FIG. 2B a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly according to the invention,

(6) FIG. 3 a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly according to the invention,

(7) FIG. 4A a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly according to the invention,

(8) FIG. 4B a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly according to the invention,

(9) FIG. 5 a flowchart of an exemplary embodiment of the method according to the invention,

(10) FIG. 6 a diagram of the clouding of the fire-resistant pane according to the invention in comparison with the prior art,

(11) FIG. 7 a schematic cross-sectional view of another alternative exemplary embodiment of a fire-resistant pane according to the invention,

(12) FIG. 8 a schematic cross-sectional view of another alternative exemplary embodiment of a fire-resistant glazing assembly according to the invention, and

(13) FIG. 9A-D a schematic representation of the method for producing a fire-resistant glazing assembly according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(14) FIG. 1A depicts a schematic view of a fire-resistant pane according to the invention 10 in cross-section. FIG. 1B depicts a schematic view of the fire-resistant pane 10 in a plan view in the direction Ill. The fire-resistant pane 10 includes a float glass pane 1.1 with an atmosphere side I and a tin bath side II. The float glass pane 1.1 has, for example, a thickness b of 5 mm and dimensions of 2 m3 m. Of course, the float glass 1.1 can also have different thicknesses and dimensions adapted to the respective intended use.

(15) A protective layer 3.1 is arranged on the tin bath side II of the float glass pane 1.1 in a planar manner. The float glass pane 1.1 is thermally tempered or partially stressed together with the protective layer 3.1 such that the float glass pane 1.1 and the protective layer 3.1 bond fixedly to each other. A fire-resistant layer 3.1 made of an alkaline polysilicate is arranged on the protective layer 3.1. The protective layer 3.1 extends partially and preferably substantially completely over the entire tin bath side II of the float glass pane 1.1. The protective layer 3.1 extends, in particular, over the complete surface between the fire-resistant layer 2.1 and the float glass pane 1.1. It can thus be ensured that the surface of the tin bath side II of the float glass pane 1.1 is protected against the alkaline polysilicate of the fire-resistant layer 2.1.

(16) The protective layer 3.1 contains, for example, antimony-doped tin-zinc oxide and was deposited by cathode sputtering. The target for the deposition of the protective layer 3.1 contained 30 wt.-% zinc, 68 wt.-% tin, and 2 wt.-% antimony. The deposition took place under addition of oxygen as reaction gas during the cathode sputtering. The thickness d of the protective layer 3.1 is, for example, 25 nm.

(17) The fire-resistant layer 2.1 contains, for example, a hardened polysilicate, which is formed from an alkali silicate and at least one hardener, for example, from potassium silicate and colloidal silicic acid. In an alternative embodiment, the potassium silicate can also be produced directly from caustic potash solution and silicon dioxide. In the polysilicate, the molar ratio of silicon dioxide and potassium oxide (Si02:K20) is, for example, 4.7:1. Such a fire-resistant layer 2.1 is typically alkaline with a pH of 12. The thickness h of the fire-resistant layer 2.1 is, for example, 3 mm.

(18) An edge sealing 6 is arranged on the float glass pane 1.1 surrounding the fire-resistant layer 2.1 and along the edge of the float glass pane 1.1. The edge sealing 6 contains or is made, for example, of a sealant or adhesive based on polysulfide, polyurethane, polysilicone, or reactive hotmelts. In combination with protective layers 3.1 made of tin-zinc oxide, edge sealings 6 made of polysulfide have proved to be particularly advantageous, with good adhesion and long-term stability. The edge sealing 6 can be arranged directly on the float glass pane 1.1 with protective layer 3.1 according to the invention since, as a result of being tempered together, the protective layer 3.1 is particularly fixedly bonded to the float glass pane 1.1.

(19) FIG. 2A depicts a schematic cross-sectional view of a fire-resistant glazing assembly according to the invention. The fire-resistant glazing assembly 100 according to the invention includes, for example, a fire-resistant pane 10 according to the invention, as described in FIG. 1. Furthermore, the fire-resistant layer 2.1 of the fire-resistant pane 10 is bonded in a planar manner, on the side opposite the protective layer 3.1, to the atmosphere side I of a second float glass pane 1.2. The second float glass pane 1.2 corresponds in its characteristics, for example, to the float glass pane 1.1.

(20) Again, an edge sealing 6 is arranged between the float glass panes 1.1 and 1.2 surrounding the fire-resistant layer 2.1. The edge sealing 6 forms, together with the float glass panes 1.1 and 1.2, a hermetically sealed cavity, in which the fire-resistant layer 2.1 is protected against air and moisture from the environment. In order to keep the distance between the float glass panes 1.1 and 1.2 constant and stable during production and use, a spacer 5 can be arranged between the float glass panes 1.1 and 1.2. The spacer 5 is made, for example, of polyisobutylene or other suitable materials, and, in particular, plastics.

(21) FIG. 2B depicts a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly 100 according to the invention. The fire-resistant glazing assembly 100 according to the invention corresponds to that of FIG. 2A. To improve the properties in the event of fire, an adhesion-reducing layer 4 is arranged between the protective layer 3.1 and the fire-resistant layer 2.1 as well as between the fire-resistant layer 2.1 and the second float glass pane 1.2. The adhesion-reducing layer 4 contains, for example, a hydrophobic organofunctional silane. The adhesion-reducing layer 4 has the particular advantage that, in the event of fire, upon breakage of the float glass pane 1.1, 1.2, the individual fragments of the fire-resistant layer 3.1 can detach, without the continuity of the fire-resistant layer 3.1 being lost.

(22) FIG. 3 depicts a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly 100 according to the invention. The fire-resistant glazing assembly 100 according to the invention comprises, for example, a fire-resistant pane 10 according to the invention, as described in FIG. 1. Furthermore, the fire-resistant layer 2.1 of the fire-resistant pane 10 is bonded in a planar manner, via a second protective layer 3.2, to the tin bath side II of a second float glass pane 1.2, on the side opposite the protective layer 3.1. The second float glass pane 1.2 and the second protective layer 3.2 form, in turn, a fire-resistant pane 10.1 according to the invention with the fire-resistant layer 2.1. Since both the tin bath side II of the float glass pane 1.1 and the tin bath side II of the second float glass pane 1.2 are separated by a protective layer 3.1, 3.2 from the fire-resistant layer 2.1, clouding of the view through the fire-resistant glazing assembly 100 due to aging is prevented according to the invention.

(23) Such a fire-resistant glazing assembly 100 is suitable for independent use as an architectural element in a building or as a motor vehicle glazing assembly.

(24) FIG. 4A depicts a schematic cross-sectional view of an alternative exemplary embodiment of a fire-resistant glazing assembly 101 according to the invention, using the example of a triple glazing assembly with three float glass panes 1.1, 1.2, 1.3 and two fire-resistant layers 2.1, 2.2. The fire-resistant glazing assembly 101 according to the invention comprises, for example, a fire-resistant pane 10 according to the invention, as described in FIG. 1. Moreover, the fire-resistant layer 2.1 of the fire-resistant pane 10 is bonded in a planar manner, on the side opposite the protective layer 3.1, to the atmosphere side I of a second float glass pane 1.2. The second float glass pane 1.2 has on its tin bath side II a second protective layer 3.2 and is bonded via this to a second fire-resistant layer 2.2. The second float glass pane 1.2, the protective layer 3.2, and the fire-resistant layer 2.2 form, in turn, a fire-resistant pane II according to the invention. The side of the second fire resistant layer 2.2 facing away from the second protective layer 3.2 is bonded to the atmosphere side I of a third float glass pane 1.3.

(25) FIG. 4B depicts an alternative exemplary embodiment of a fire-resistant glazing assembly 101 according to the invention. The fire-resistant layer 2.1 of a fire-resistant pane 10 according to the invention is bonded to the atmosphere side I of a second float glass pane 1.2 in a planar manner. Moreover, the atmosphere side I of the float glass pane 1.1 is bonded to a second fire-resistant layer 2.2 in a planar manner. The second fire-resistant layer 2.2 is bonded to the atmosphere side I of a third float glass pane 1.3 in a planar manner. This exemplary embodiment has the particular advantage that only one protective layer 3.1 according to the invention is needed to produce an aging-resistant fire-resistant glazing assembly 101, since by means of a suitable arrangement of the outside float glass panes 1.2, 1.3, only the tin bath side II of the float glass pane 1.1 is arranged directly adjacent to a fire-resistant layer 2.1 without separation by glass.

(26) The triple glazing assemblies depicted in FIGS. 4A and 4B exhibit particularly high stability and fire resistance. Of course, analogously, fire-resistant panes with four or more float glass panes can be produced, wherein, for the prevention of clouding of the view due to aging according to the invention, a protective layer according to the invention is arranged between each fire-resistant layer and the tin bath side of a float glass pane arranged immediately adjacent thereto.

(27) FIG. 5 depicts a flowchart of an exemplary embodiment of the method according to the invention for producing a fire-resistant glazing assembly 100 according to the invention of FIG. 2.

(28) FIG. 6 depicts a diagram of the clouding in an aging test of fire-resistant panes 10 according to the invention compared to a fire-resistant pane according to the prior art as a comparative example. In the accelerated aging test, the respective float glass pane was immersed over a period of 4 hours and at a temperature of 80 in an aqueous solution of potassium silicate. The aqueous potassium silicate solution is the alkaline fraction in the production of a fire-resistant layer according to the invention made of an alkali polysilicate-hydrogel. The clouding was measured with a haze meter of the type Haze-Gard Plus of the company 8YK-Gardner.

(29) Example 1 is a float glass pane according to the invention, whose tin bath side 1I was coated with a protective layer made of tin-zinc oxide. The ratio of tin to zinc was 50 wt.-%:50 wt.-%. The thickness d of the protective layer was 25 nm. After the aging test, clouding of 0.3% was measured.

(30) Example 2 is a float glass pane according to the invention, whose tin bath side 1I was coated with a protective layer made of zinc oxide. The thickness d of the protective layer was 25 nm. After the aging test, clouding of 0.7% was measured.

(31) Example 3 is a float glass pane according to the invention, whose tin bath side II was coated with a protective layer made of indium-tin oxide (ITO). The ratio of indium to tin was 90 wt.-%:10 wt.-%. The thickness d of the protective layer was 25 nm. After the aging test, clouding of 0.4% was measured.

(32) The Comparative Example according to the prior art was a float glass pane, of which neither the atmosphere side I nor the tin bath side II was coated and, thus, both sides were exposed to the aqueous solution of potassium silicate. After the aging test, clouding of 8.9% was measured in the case of the Comparative Example.

(33) In the aging test presented, the atmosphere sides I of the float glass panes of the Examples 1 to 3 and of the Comparative Example were not protected by a protective layer according to the invention and, thus, were directly exposed to the aqueous solution of potassium silicate. It can therefore be concluded that the clouding is caused substantially by the contact of the tin bath side II with the aqueous solution of potassium silicate.

(34) Each of the protective layers according to the invention from Examples 1 to 3 reduced the clouding of the float glass pane compared to the Comparative Example according to the prior art without a protective layer 3 according to the invention to values<1%. In the case of the protective layer according to the invention made of tin-zinc oxide according to Example 1, the clouding was actually reduced by a factor of 89. This result was unexpected and surprising for the person skilled in the art.

(35) FIG. 7 depicts a schematic view of an alternative exemplary embodiment of a fire-resistant pane 10 according to the invention in cross-section. The float glass pane 1.1 and the fire-resistant layer 2.1 are implemented according to FIG. 1. The protective layer 3.1 is implemented as a two-ply layer structure composed of a first protective (sub)layer 3.1a and a second protective (sub)layer 3.1b. The protective (sub)layer 3.1a has a thickness d, of, for example, 8 nm and is made, for example, of a silicon nitride layer, and, in particular, of Si3N4. The protective (sub)layer 3.1b has a thickness dbof, for example, 15 nm and is made, for example, of a tin-zinc oxide layer, as was described in FIG. 1. The thickness d of the entire protective layer 3.1 was thus 23 nm.

(36) As investigations of the inventors revealed, already with a protective (sub)layer 3.1a made of silicon nitride that had a thickness d, of 3 nm, it was possible to obtain advantageously increased aging resistance and greatly reduced clouding. At the same time, it was possible to reduce the thickness of the tin-zinc oxide layer without degrading aging resistance or clouding.

(37) In this exemplary embodiment, the protective (sub)layer 3.1a made of silicon nitride is arranged directly on the tin bath side II of the float glass pane 1.1 and the (protective (sub)layer 3.1b made of tin-zinc oxide is arranged on the protective (sub)layer 3.1a made of silicon nitride. Of course, the order of the materials can also be permuted such that a layer made of tin-zinc oxide is arranged directly on the tin bath side of the float glass pane and a layer made of silicon nitride is arranged on the layer made of tin-zinc oxide.

(38) FIG. 8 depicts another alternative exemplary embodiment of a fire-resistant glazing assembly according to the invention 101. The fire-resistant glazing assembly 101 of FIG. 8 corresponds to the fire-resistant glazing assembly 101 of FIG. 4b, wherein only the protective layer 3.1 of FIG. 4b is implemented as a 2-ply layer structure made up of a protective (sub)layer 3.1a and a protective (sub)layer 3.1b. The protective (sub)layers 3.1a and 3.1b correspond, for example, to the layers of FIG. 7.

(39) Table 1 summarizes the results of aging tests and clouding tests for various exemplary embodiments of fire-resistant panes 10 according to the invention.

(40) TABLE-US-00001 TABLE 1 Layer Layer Resistance in the Material Thickness (n) Aging Test Clouding tin-zinc oxide (3.1) 25 nm (3.1) Good Slight silicon nitride (3.1a)/ 8 nm (3.1a)/ Very good Very slight tin-zinc oxide (3.1b) 15 nm (3.1b) silicon nitride (3.1a)/ 3 nm (3.1a)/ Good Slight tin-zinc oxide (3.1b) 15 nm (3.1b) tin-zinc oxide (3.1a)/ 15 nm (3.1a)/ Very good Very slight silicon nitride (3.1b) 8 nm (3.1b)

(41) The first column indicates the material of the protective layer 3.1 and the second column indicates the thickness. The protective layers 3.1 are in each case arranged directly on the float glass pane 1.1. The statement silicon nitride (3.1a)/tin-zinc oxide (3.1b) indicates that the protective layer 3.1 comprises a 2-ply layer structure. The first indicated protective (sub)layer 3.1a made of silicon nitride is arranged directly on the float glass pane 1.1 and the second protective (sub)layer 3.1b made of tin-zinc oxide is arranged directly on the first protective (sub)layer 3.1a. For the layer sequence tin-zinc oxide (3.1a)/silicon nitride (3.1b) the reverse order applies.

(42) Surprisingly, the layer sequence silicon nitride (3.1a)/tin-zinc oxide (3.1b) with layer thicknesses of 3 nm for the first protection (sub)layer 3.1a and 15 nm for the second protective (sub)layer 3.1b exhibited similarly good aging resistance and slight clouding as a single-ply protective layer 3.1 made of 25 nm tin-zinc oxide, although the overall thickness could be reduced from 25 nm to 18 nm. For layer thickness combinations of 8 nm for silicon nitride and 15 nm for tin-zinc oxide, the experiments actually revealed increased aging resistance and less clouding than with a single-ply protective layer 3.1 made of 25 nm tin-zinc oxide.

(43) As extensive investigations of the inventors revealed, the combination of a layer made of a metal nitride, such as silicon nitride, and a layer made of a metal oxide, such as zinc-tin oxide, is particularly advantageous in order to produce an aging-resistant fire-resistant glazing assembly and to prevent clouding of the tin bath side of a float glass pane in the case of contact with an alkaline fire-resistant layer.

(44) FIG. 9A-D depict the schematic sequence of an exemplary embodiment for producing a fire-resistant layer 100 according to the invention using four process steps. As depicted in FIG. 9A, in a first process step, a protective layer 3.1 is applied on the tin bath side II of a float glass pane 1.1, for example, by cathode sputtering. In another process step, the float glass pane 1.1 with the protective layer 3.1 arranged thereon is thermally tempered or partially tempered, for example, by shared heating and rapid cooling of the surfaces using a stream of cold air. The float glass pane 1.1 thus treated is depicted in FIG. 9B. By means of the shared thermal tempering or partial tempering, an intimate bond is formed between the float glass pane 1.1 and the protective layer 3.1.

(45) In the process step depicted in FIG. 9C, the thermally tempered or partially tempered float glass pane 1.1 and another float glass pane 1.2 are positioned at a fixed distance from each other. The float glass pane 1.2 is turned with its atmosphere side I and, therefore, the protective layer 3.1 facing the tin bath side II of the float glass pane 1.1. Of course, the float glass pane 1.2 can also have a protective layer on the tin bath side II that was thermally tempered or partially tempered together with the float glass pane 2.1 after application.

(46) The float glass panes 1.1 and 1.2 are held at a fixed distance from one another by an external device (not shown) such that a cavity 8 is formed between the float glass panes 1.1 and 1.2, with the distance predefining the thickness of the subsequent fire-resistant layer. A further fixing can preferably take place by means of one or a plurality of spacers 5. The spacers 5 preferably run along the entire circumference of the float glass panes 1.1 and 1.2 and leave open only a filling opening 7 on, for example, the top narrow side of the cavity 8. Moreover, the narrow sides of the cavity 8 between the float glass panes 1.1 and 1.2 are sealed by an edge sealing 6. The edge sealing 6 is made of a sealant, such as polysulfide. The edge sealing 6 is arranged on the full circumference of the cavity 8 with the exception of the region of the filling opening 7.

(47) In the process step depicted in FIG. 9D, a still liquid fire-resistant layer 2.1 is poured via the filling opening 7 into the cavity 8. The fire-resistant layer 2.1 is made, for example, of alkali silicate in the form of a potassium silicate and colloidal silicic acid and is prepared as a pourable compound which hardens to form a polysilicate with a molar ratio of Si02 to K20 of, for example, 4.7:1. The pourable compound is degassed in a known manner and poured into the cavity 8. The compound is fluid enough that it displaces the air present in the cavity 8 and forms no air inclusions. After a complete filling of the cavity 8, the filling opening 7 is sealed by the edge seal 6. Thus, the fire-resistant layer 2.1 is hermetically sealed against the environment. The fire-resistant glazing assembly 100 thus produced is stored in an appropriate position until the reaction process in the fire-resistant layer 2.1 has finished and the polysilicate is hardened.

(48) Table 2 summarizes the results of the aging tests on various exemplary embodiments of fire-resistant glazing assemblies 100 according to the invention. The examples presented correspond with the exception of the differences identified to the exemplary embodiment of FIG. 2A.

(49) TABLE-US-00002 Resistance and seal Fire-resistant glazing tightness of the edge assembly with: sealing in the aging test Clouding Example A Float glass pane 1.1 and Poor Slight protective layer 3.1 made of tin-zinc oxide on the tin bath side II, not tempered together Example B Float glass pane 1.1 and Very good Slight protective layer 3.1 made of tin-zinc oxide on the tin bath side II, tempered together

(50) The fire-resistant glazing assembly according to the invention of Example B contained a float glass pane 1.1 and a protective layer 3.1 made of tin-zinc oxide on the tin bath side II of the float glass pane 1.1. The float glass pane 1.1 and the protective layer 3.1 were thermally tempered together. This means that, first, the protective layer 3.1 was deposited on the tin bath side II of the float glass pane 1.1 and, then, the coated float glass pane 1.1 was thermally tempered.

(51) In contrast, in the case of the fire-resistant pane according to Example A, the float glass pane 1.1 was first thermally tempered, and, then, a protective layer 3.1 made of tin-zinc oxide was applied on the tin bath side II of the float glass pane 1.1.

(52) Both fire-resistant glazing assemblies exhibited only slight clouding during aging. The protective layers 3.1 made of tin-zinc oxide were able in each case to protect the tin bath sides II of the float glass panes 1.1 against the attack of the alkaline fire-resistant layers 2.1.

(53) However, in the aging test, significant differences appeared in the region of the edge sealing: In Example A, defects in the adhesion and seal tightness of the edge sealing could be noted. Thus, it was possible for air to penetrate into the interior of the fire-resistant glazing assembly; it was possible for water to escape from the fire-resistant compound and damage the fire-resistant glazing assemblies. Such fire-resistant glazing assemblies are not very useful. Consequently, such a protective layer in the region of the edge sealing must be removed with considerable effort, for example, by mechanical grinding or chemical etching, before the application of the edge sealing.

(54) In the case of Example B, the adhesion and seal tightness of the edge sealing was significantly improved. The adhesion of the edge sealing on the protective layer 3.1 of the float glass pane 1.1 tempered together was stable and did not lose its bonding to the float glass pane 1.1, even after many aging cycles. This can be explained by the fact that the float glass pane 1.1 and the protective layer 3.1 form a stable bond by being thermally tempered or partially tempered together that prevents detachment or dissolution of the protective layer 3.1 between the edge sealing 6 and the float glass pane 1.1. Complicated removal of the protective layer 3.1 in the area of the edge sealing is no longer necessary.

(55) This result was unexpected and surprising for the person skilled in the art.