EP1940612A1

EP1940612A1 - Fireproof glazing

Info

Publication number: EP1940612A1
Application number: EP06793604A
Authority: EP
Inventors: Bertrand Dury; Pierre Goelff
Original assignee: AGC Glass Europe SA
Current assignee: AGC Glass Europe SA
Priority date: 2005-09-22
Filing date: 2006-09-18
Publication date: 2008-07-09
Also published as: RU2008115104A; FR2890894B1; FR2890894A1; WO2007033950A1; RU2401374C2

Abstract

The invention concerns fireproof glass panes. The inventive glass panes comprising at least one hydrated alkaline silicate-based intumescent layer between two glass sheets wherein the composition of the intumescent layer, prior to its being used in the glazing is subjected to one or more treatments enabling the constituents of said composition likely to promote decomposition of water under the effect of UV radiation to be eliminated. The resulting glass panes are resistant to aging.

Description

Fire-resistant glazing

The present invention relates to transparent fireproof glazing comprising a layer of intumescent material based on hydrated alkali silicates.

Fireproof glazing comprising in addition to glass sheets, one or more sheets of intumescent material are widely used in the trade. They have various fire resistance qualities depending on their constitution. Apart from their quality of fire resistance they must also ensure a certain mechanical resistance. These two properties can be obtained by a suitable choice of structure including in particular several sheets of glass associated with several sheets of intumescent material.

For satisfactory use the products in question must be free from defects, and in particular from defects which impair their optical qualities. It is known among the possible defects for this type of products, that the most frequent concern the presence more or less apparent bubbles and / or a haze ("haze"). These defects appear most often to the test of aging. To be satisfactory it is appropriate that these products retain a minimum optical quality for at least a period of not less than 10 years. The presence of some bubbles or a very light veil, especially after a very long period of use is not prohibitive, but must remain very limited.

One factor known to promote accelerated aging is exposure to ultraviolet light. Given that the products in question are very often exposed to ultraviolet-rich radiation, especially to solar radiation, the preservation of optical qualities requires the implementation of specific provisions. Various means have been proposed to prevent the alteration of the optical properties of the glazings comprising layers based on hydrated alkali silicates, it being understood that the traditional clear glass sheets which envelop these layers, obviously do not constitute a sufficient barrier to ultraviolet rays.

Among the proposed means in particular is the use of a known sheet to form an effective UV filter, sheet whose primary utility is to confer glazing properties of mechanical strength. Polyvinyl butyral (PVB) sheets are particularly suitable. In particular, it is known that even at a relatively small thickness, of about 0.38 mm, more than 95% of the UV rays are stopped. However, the use of polymer sheets in fireproof glazing is not always appropriate. The presence of organic materials is preferably avoided in this type of products because of their fire behavior. Moreover, the implementation imposes a well-defined arrangement of this sheet on the path of the incident radiation so that it actually prevents UV rays before they reach the sensitive layer that must be protected.

Other proposals have been made which include using a thin layer of titanium oxide deposited on the glass sheet at least on the side of the incident light. The studies of the inventors have shown that the presence of a layer of this type in terms of UV protection is insufficient to prevent the degradation of the intumescent layer.

All prior proposals have the effect of filtering UV radiation to prevent them from reaching the intumescent composition of hydrated alkali silicates. The inventors sought a different kind of solution by trying to find out what were the mechanisms behind the observed degradation in order to be able to counter them effectively. The inventors' studies have shown, first of all, that the bubbles that could form in the intumescent material originated mainly from the decomposition of water associated with silicates. The bubbles in question are not vapor bubbles, but are composed mainly of hydrogen. The absence in these oxygen bubbles resulting from the decomposition of water is attributed by the inventors to the fact that it is easily absorbed in the silicate which is not the case of hydrogen.

Going further, the inventors investigated the causes of this decomposition of water. The analysis of the possible causes seems to be directed towards the presence of impurities in the industrial alkali silicates used, and in particular metallic impurities which are believed to be capable of catalyzing the decomposition observed.

Regardless of the accuracy of the possible causes indicated above, the inventors have been able to implement solutions capable of inhibiting or minimizing the decomposition of the water of the silicates, and therefore the formation of bubbles within the compositions. intumescent, even when they are exposed to prolonged UV rays.

The analysis of commercial alkali silicate compositions made by the inventors shows the presence of ions or metal particles capable of inducing the decomposition of water. As an indication, the main constituents present in a typical product are in a proportion by weight of:

Fe 0, 003%

Al 0, 022%

Ti 0, 005%

In practice the inventors propose to eliminate or "neutralize" the impurities in question. The means used for this are of two kinds, on the one hand for the elimination of these impurities which are often in the form of microparticles, the implementation of a filtration of the composition more extensive than that usually carried out in order to remove possible punctual defects of transparency, and secondly the neutralization of impurities by introduction into the intumescent composition of components inhibiting these impurities promoting the decomposition of water. Both means, namely sequestration and filtration, can be used separately or together.

The industrial silicate compositions and the various additives introduced are traditionally subjected to filtration aimed at eliminating any visible insolubilized particle. For reasons of convenient implementation, this filtration only concerns particles whose average dimensions are greater than about 20μ. Further filtration is necessarily more restrictive.

Typically, according to the invention, it is advantageous to carry out a filtration which guarantees the complete elimination (more than 95%) of particles of more than 10 μ and preferably of particles of 5 μ and more. Even more preferably, the filtration according to the invention makes it possible to remove particles of more than 1 μm for at least 95% of these particles. Filtration which targets even smaller particles is more difficult to achieve under industrial conditions even if it can provide additional improvement, especially since the possible addition of chelant, according to the invention, combined with filtration can effectively complete the protective effect obtained.

Given the nature of the elements promoting the decomposition of water, the inventors propose the introduction into the intumescent composition based on hydrated alkali silicates, compounds known to "sequester" or "chelate" the transition metals and especially the iron.

Products sequestering or chelating transition metals introduced into the compositions according to the invention must be usable under the specific conditions which are those of intumescent materials based on alkali silicates. In particular, they must be able to be used efficiently in a strongly alkaline medium (the pH of these compositions is of the order of 11). They must also be of a sufficiently hydrophilic nature, to be dissolved at effective levels in the composition.

Compounds which inhibit the decomposition of the alkali silicates constituting the intumescent materials must still not induce pronounced undesirable coloration at effective levels. To be perfectly satisfactory, the products according to the invention must be substantially "neutral" in coloring or slightly gray or bluish. They must also remain stable under conditions of use at normal temperatures, which can be relatively high when the windows are exposed to the sun, for example.

Agents meeting these criteria belong to different categories. It is possible in particular to use compounds based on amino-carboxylic acids, especially ethylene-diamine tetracetic acid.

(EDTA) diethylene tetramine pentaacetic acid (DTPA), (S, S) ethylene diamine-N, N'-disuccinic acid (EDDS), nitrilo triacetic acid (NTA), phosphates and phosphonates and in particular the phosphonates of amino-polycarboxylates, especially ethylene-diamine-tetramethylene phosphonic acid (EDTPM), amino-trimethylenephosphoic acid (ATMP), hexamethylenediamine-tetramethylenephosphonic acid (HEDP), diethylene triamine pentamethylene phosphonic acid (DTPMP), hydroxy carboxylic acids, especially gluconic acid or sodium gluconate, carbohydrate acrylates.

Apart from those metallic constituents indicated above which may favor the appearance of defects by decomposition of water, the analysis of the industrial silicate compositions still shows the presence of ions which are capable of reacting with the complexing agents used for "neutralize" the metals indicated above. These ions in themselves do not induce the decomposition of water but can also react with the complexing agents, thus requiring an additional amount of these agents so as to obtain the complete treatment of the transition metals present. In the composition of the analyzed product we find in particular:

That's 0.001%

Mg <0.001%

The complexing mode of the metals, and in particular the number of reactive sites of the complexing agents makes it possible to determine the relative proportions of these which must be present to completely inhibit the metals responsible for the alteration of the intumescent layers.

For the contents of the order of those indicated above, and preferably introducing a slightly greater amount than strictly necessary, the contents of complexing agents in the products according to the invention are advantageously between 0.1 and 2%. by weight of the intumescent layer. If it is possible, taking into account their solubility to introduce greater amounts of complexing agent, it is nevertheless preferable to limit these quantities, to minimize the possible coloration induced.

The choice of additives and / or filtration conditions according to the invention must necessarily go through an experimental verification of the various properties of these products under the actual conditions of use. The tests in question can be carried out routinely. It is to subject the composition prepared to accelerated aging UV, temperature of the order of 60 ⁰ C. The audit involves observing under these conditions if a disorder or bubbles appear within twenty days. The measurement is conducted empirically. In this measurement the product is illuminated by the side. The presence and quantity of bubbles and particles determines the amount of light scattered perpendicularly to the faces of the glass sheet.

The invention is described in more detail with reference to the drawings in which:

Figure 1 is a schematic sectional view showing a basic structure of an anti-fire glazing;

Figure 2 shows a fireproof glazing which a glass sheet is replaced by a laminated assembly;

FIG. 3 shows an anti-fire glazing comprising a UV protection layer;

FIG. 4 shows an embodiment of a double anti-fire glazing unit

Figure 5 is a graph showing two types of particle retention versus selected filters.

Traditionally different modes of production are used to constitute the fireproof glazing comprising these intumescent layers. The most usual mode is to apply a solution of the various constituents of the composition on a glass sheet, to proceed to the drying of this composition. The glass sheet coated with the dried intumescent layer is then assembled with another sheet of glass. Assemblies can also combine several sheets coated with intumescent layers.

Another embodiment consists in producing a film of intumescent material on a support independent of the glass sheets of the glazing. The film of intumescent material is either separated from its temporary support in the assembly with glass sheets, or this support, a film for example of polyethylene terephthalate glycol (PET) or polypropylene, is integrated with the glazing material intumescent. Another traditional method of constituting glazing consists in forming the material directly by gelling the hydrated alkali silicate between two glass sheets.

The invention is applicable in all these glazing production methods insofar as the sensitivity to UV aging is inherent in the nature of the silicates and the presence of impurities capable of promoting the decomposition of the water included in these silicates. constituting the intumescent material.

The type of glazing concerned by the invention is shown in section in FIG. 1. The fireproof glazing in its most basic configuration comprises two sheets of glass (1 and 2) joined together by means of a sheet of intumescent material. (3) consisting of hydrated alkali silicate.

The glass sheets are either of standard "float" glass of the soda-lime type or, if appropriate, of glass with a low thermal expansion coefficient of the borosilicate type.

The structures of commercial fire-resistant glazing can assemble several sheets of intumescent materials and a corresponding number of glass sheets. Similarly, the thickness of the glass sheets and that of the or, intumescent material sheets vary depending on the production methods and applications envisaged, the thickest structures, and those consisting of multiple sheets of glass and material. intumescent normally leading to the most fire resistant glazing.

Whatever the chosen structure, the question of transparency, and more specifically of the absence of appearance of bubbles or veil over time, remains attached to the presence of these sheets of intumescent material exposed to UV rays. To a certain extent, the greater the total thickness of the intumescent material, the more the defects related to aging alter the transparency of the glazing, and therefore more is needed to avoid the appearance of these defects.

In the form shown in Figure 1 the glass sheets are "simple". In some embodiments as in Figure 2, one or more "monolithic" glass sheets may be replaced by one or more laminated sheets consisting for example of two sheets of glass joined by means of a polyvinyl butyral (PVB) thermoplastic interlayer sheet ethylene vinyl acetate copolymer (EVA) etc. The use of sheets of this type is generally intended to improve the mechanical properties of the glazing. The properties of the constituent materials of these spacers, however, have a number of disadvantages when they are subjected to the test of fire, especially because they lead to a release of fumes from their decomposition. When they are present in a glazing, efforts are made to arrange them so that these disadvantages are minimized. In particular, they are preferably placed on the side of the glazing that is least likely to be exposed to fire or, in more complex structures comprising more than two glass sheets, they are possibly located in the center of these structures.

As indicated above, the PVB sheets incidentally constitute a very powerful filter against UV rays. The systematic use of these sheets as a protection against the degradation of the intumescent layers is however not generally desirable because of the difficulties indicated above with respect to the fire resistance of these materials, also because of its This is accompanied by an increase in the total thickness of the glazing, again because of the cost of the PVB sheets which constitutes an important element of the cost of the whole.

FIG. 2 shows a glazing consisting of a monolithic glass sheet (6), an intumescent layer (3), and a laminate consisting of two sheets of glass (1, 1 ') and a spacer ( 5). In practice on the side of the glazing comprising the laminate, the UV protection is normally provided by the interlayer sheet (5). In this case the use of a layer intumescent (3) comprising a metal inhibitor catalyzing the degradation of water is necessary only if these rays also come from the side having only the single sheet (6).

Figure 3 shows another embodiment of fireproof glazing comprising various provisions protecting the intumescent layer against UV aging. In the embodiment shown, it is a question of having a layer (4) which filters UVs at least partially. Of course and as before the UV filter layer does not protect the side of the glass sheet (2). The presence of the intumescent layer according to the invention is therefore necessary in the event that the UV rays can also come from this side or, when the layer (4) only partially filters the UV.

Figure 4 is a representation of a double glazing incorporating an anti-fire panel. In the case shown, the fireproof panel consisting of the two sheets of glass (1, 2) and the intumescent layer (3) is associated with a single sheet of glass (7), from which it is separated by a space (8). ) filled with possibly insulating gas in the usual manner of double glazing.

The combinations presented above are only indicative. All the assemblies made to constitute fire-resistant glazings can be reproduced by incorporating the intumescent layers of the invention.

The intumescent materials in question are of various natures. Their composition based on hydrated alkali silicates is distinguished, in particular by the nature of the silicates used. The most common are sodium silicates, but potassium silicates are also often used optionally mixed with sodium silicates. The choice of one or other of these alkalis also influences the proportions of the other constituents and in particular the water content.

Intumescent materials are further characterized by the relative proportions of Si and alkali present in the composition. This This report defines what is usually presented as reflecting the more or less "refractory" nature of these materials. Another significant feature of these materials is their water content, which is sometimes indirectly represented by the "loss on fire" of the product, which is the weight percentage of what is removed when the material is calcined. The water present in the intumescent material, releasing under the effect of heat, is responsible for the formation of the foam on which depends the quality of fire resistance.

Other constituents participate in the composition of these materials. These are various elements that either contribute to the improvement of the fireproof properties, or contribute to the stability of the product over time, or facilitate the production of these glazings. Among the most commonly used elements include polyol compounds and in particular glycerine which promotes in particular a certain plasticity of the intumescent material.

The nature and properties of the materials in question are the subject of many previous publications. As an indication, reference may in particular be made to patent publications: EP 1 027 404, FR 2 607 491 and FR 2 399 513.

Experimentally fireproof glazing consists of two sheets of glass each 3mm thick, and an intumescent layer of about 1 mm thick, hydrated sodium silicate. The alkali silicate layer has a glycerin content of 12% by weight. The water content of the layer is 28% and the molar ratio Si / Na is 3.5.

A sample of this glazing is subjected to UV exposure in a "Q-Panel" device for 1000 hours, corresponding to 10 years of natural aging.

The measurement is performed on a given constant sample area. It is performed on the light scattered by the bubbles and the veil. In a first series of tests according to the invention, EDTA is added to the intumescent layer. We note for an incorporation of

0.1% by weight of EDTA, a decrease in defects (bubbles and haze) of the order of 20% at the end of the test. A similar test is carried out by introducing 0.3% EDTA. Under these conditions the decrease in defects is of the order of 50%.

The introduction of EDTA thus makes it possible to significantly reduce the sensitivity of the layer of hydrated silicates to exposure to UV rays.

In a second test series 0.1% by weight is introduced into the intumescent layer of EDDS. The amount of defect after UV exposure is reduced to a quarter of the value obtained for the reference product.

The same experiment is repeated by introducing into the intumescent layer increasing amounts of the chelating agent sold under the name "Dequest FS 9510" by the company Solutia. The composition of this agent is based on diphosphonic acids known for sequestering in particular iron, including in strongly alkaline media.

Successively 0.3, 0.6 and 0.9% by weight of the agent are introduced into the composition of the intumescent layer. The content can be further increased because of the extensive miscibility of this compound with the silicate solutions. After exposure under the same conditions, the measurement of defects is only 25, 10 and 5% of the reference value respectively.

The introduction of the sequestering agent therefore makes it possible to minimize the occurrence of aging defects very evenly under the extreme conditions used.

The efficiency of filtration on the stability of the intumescent compositions is illustrated from two filtration modes, the result of which is represented in FIG. The graph represents the retention rate of the particles present in the composition as a function of the particle size given in micrometers. The curve (I) is of the type obtained with the filters traditionally used. For these filters the distribution of retained particles extends over a wide range of dimensions. The advantage of these filtrations is that they can be carried out particularly rapidly. In return it is found that a large fraction of the particles whose dimensions are smaller than 20μ, remains in the filtered composition.

Curve (II) is of the type obtained using a more selective filter. With this filter used according to the invention practically all the particles of more than 10μ are retained.

UV aging tests of traditional compositions (without addition of chelating agents transition metals) show a 66% decrease in defects in the compositions passed on the filters retaining all the particles greater than 10μ.

If the filtered compositions are subjected to the two modes presented, a thermal aging at 80 ^° C. shows this time that the compositions filtered under the conditions of the invention have a reduction of 75% of the defects.

The implementation of the methods for preventing degradation of the intumescent compositions may combine a more efficient filtration and the addition of chelating compounds to treat the elements not retained on the filters.

Claims

1. Fire-resistant glazing comprising at least one intumescent layer based on hydrated alkali silicate comprised between sheets of glass, in which the composition of the intumescent layer, prior to its implementation in the glazing is subjected to one or more treatments to eliminate the constituents of this composition may promote the decomposition of water under the effect of UV rays.

2. Glazing according to claim 1 wherein the constituents likely to promote the decomposition of water are the transition metals in the form of ions or particles.

3. Glazing according to one of the preceding claims wherein before its introduction into the glazing, the intumescent composition is filtered so as to remove at least 95% of the insoluble particles present of more than 10μ and preferably more than 5μ.

4. Glazing according to one of the preceding claims wherein the intumescent composition comprises an effective amount of at least one complexing agent for the transition metals may be present in this composition.

5. Glazing according to claim 4 wherein the complexing agent (s) present in the composition of the intumescent layer are chosen from those which are stable in a strongly basic medium.

6. Glazing according to one of claims 4 or 5 wherein the complexing agent (s) are chosen such that at effective concentrations they do not induce a coloration of the layer or at most a slight gray or bluish coloration.

7. Glazing according to one of claims 4 to 6 wherein the complexing agent (s) is (are) chosen from compounds of one of the following groups:

- amino-carboxylic acids and their salts - phosphonic acids and their salts

the hydroxy-carboxylates

carbohydrate acrylates

8. Glazing according to claim 7 wherein the intumescent layer contains at least one of the complexing agents of the group comprising: amino trimethylene phosphonic acid (ATMP), ethylene diamino tetramethylene phosphonic acid (EDTMP), hydroxymethylene acid 1, 1 diphosphonic acid (HMDP), hexamethylene diamino tetramethylene phosphonic acid (HEDTMP), diethylene triamino pentamethylene phosphonic acid (DTPMP), hydroxyethylidene diphosphonic acid (HEDP).

9. Glazing according to claim 7 wherein the intumescent layer contains at least one of the complexing agents of the group comprising: ethylene-diamine tetracetic acid (EDTA), diethylene tetramine pentaacetic acid (DTPA), acid ( S, S) ethylene diamine-N, N'-disuccinic (EDDS) nitrilo triacetic acid (NTA).

10. Glazing according to one of claims 4 to 9 wherein the intumescent layer contains the complexing agent (s) in sufficient weight to complex all of the transition metal ions contained in the alkali silicate composition.

11. Glazing according to claim 10 wherein the intumescent layer contains the complexing agent (s) in a weight proportion of 0.1 to 2%.

12. Intumescent material film based on hydrated alkali silicate whose composition, prior to its implementation in the glazing is subjected to one or more treatments allowing to eliminate constituents likely to promote the decomposition of water under the effect of UV rays.