WO2014154969A1

WO2014154969A1 - Fire-resistant glazing

Info

Publication number: WO2014154969A1
Application number: PCT/FR2014/050556
Authority: WO
Inventors: Régine FAURE; Vincent Rachet; Dominique Hourdet; Clémence WABLE
Original assignee: Saint-Gobain Glass France
Priority date: 2013-03-26
Filing date: 2014-03-12
Publication date: 2014-10-02
Also published as: FR3003797A1; FR3003797B1

Abstract

The present invention relates to a fire-resistant glazing comprising at least two glass sheets between which is positioned at least one transparent and intumescent layer which exhibits a low aptitude for hydrostatic creep. The transparent layer is composed of a hybrid hydrogel comprising the polymerization product of at least one alkali metal silicate hydrate, of at least one first monomer selected from the group consisting of acrylic acid, methacrylic acid and salts thereof, and of at least one second acrylamide or acrylate monomer selected from the group consisting of N,N-dimethylacrylamide, N-(2-hydroxyethyl)acrylamide, N,N'-methylenebisacrylamide, 2-methacrylamido-2-methylpropanesulphonic acid, N,N'-(1,2-dihydroxyethylene)bisacrylamide, 3-(methacryloylamino-N,N-dimethyl-N-sulphopropyl)-1-propanaminium hydroxide, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate and 1,6-hexanediol dimethacrylate. Another subject of the invention is a process for manufacturing said fire-resistant glazing.

Description

FIREPROOF GLAZING

The present invention relates to the field of fire protection glazing, also called "fireproof glazing".

The invention relates to an anti-fire glazing whose fireproof layer consists of an intumescent transparent layer having good resistance to hydrostatic creep.

The invention also relates to a method of manufacturing said fireproof glazing.

The fire-resistant glazings are generally in the form of a structure consisting of at least two glass sheets held substantially parallel by spacers disposed at the periphery, in which the free space between the sheets is filled with a transparent layer and at least one of the glass sheets is provided on its surface which is in contact with the transparent layer with a primer layer which improves the adhesion of the transparent layer to the glass.

The transparent layer may consist of a hydrated alkali metal polysilicate, in particular having an SiO ₂ : M ₂ O molar ratio greater than 2: 1 (where M denotes an alkali metal) (WO 94/04355), or a gel aqueous solution based on a crosslinked acrylic resin (EP 0 000 531) or a polymer derived from (meth) acrylamide (EP 0 590 978).

The primer layer is preferably based on a hydrophilic organic substance, for example a silane.

In case of fire, under the effect of heat, the transparent layer loses the water it contains and is transformed into a layer that opposes the transmission of thermal radiation, which ensures for a long time given period effective protection against the passage of heat. In particular, it is possible to extend the fire resistance time by increasing the number of glass sheets and transparent layers in the fireproof glazing. Compared to an organic polymer-based layer, the alkali metal polysilicate layer has the advantage of being intumescent and therefore forming, under the effect of heat and produced water vapor, a foam insulating silica and incombustible.

The polysilicate forming the above-mentioned transparent layer is in the form of a liquid of very high viscosity which tends to flow over time under the effect of its own weight, thus causing deformation (bending) of the glass sheets in the part low fire glazing.

To minimize the effect of the hydrostatic creep of the polysilicate, it is known to limit the distance between the two sheets of glass, especially by making it less than 6 millimeters.

It has also been proposed to solve the problem by modifying the composition of the transparent layer.

Thus, in KR 20100051929, the transparent layer comprises a hydrophilic precursor of a polymer, in particular an unsaturated carboxylic acid hydroxyalkyl ester, a thermally activatable polymerization initiator or ultraviolet radiation, silica, a solvent and optionally a glass adhesion promoter. Nevertheless, as demonstrated later, the layer is not intumescent.

In WO 201 1/045597, the intumescent transparent layer contains an alkali metal silicate and a foaming additive which contains a polymer and / or an oligomer and / or their salts, in particular a polymer of acrylic or methacrylic acid, a salt of sodium, potassium or lithium of acrylic or methacrylic acid or poly (meth) acrylamide.

In some "hot" countries where the ambient temperature exceeds

40 ° C, the effects of hydrostatic creep are exacerbated. Quickly after being installed, the fire-resistant glazing undergoes deformations that are accompanied by unacceptable optical distortions for the user. The solution of further reducing the thickness of the transparent layer makes it necessary to increase the number of sheets of glass and transparent layers together in order to maintain effective protection against fire. The glazing is weighed down what is not desired.

The object of the present invention is to propose an anti-fire glazing composed of at least two sheets of glass between which is disposed at less a transparent and intumescent layer which has a low hydrostatic creep ability. This glazing is a good compromise between fire resistance and resistance to hydrostatic creep.

This object is achieved according to the invention in that the transparent layer consists of a hybrid hydrogel comprising the polymerization product of at least one hydrated alkali metal silicate, at least a first monomer chosen from the group consisting of by acrylic acid, methacrylic acid and their salts, and at least one second acrylamide or acrylate monomer selected from the group consisting of Ν, Ν-dimethylacrylamide, N- (2-hydroxyethyl) acrylamide, Ν , 2'-methylene-bis-acrylamide, 2-methacrylamido-2-methylpropanesulphonic acid, N, N '- (1,2-dihydroxyethylene) bisacrylamide, 3- (methacryloylamino) -N, N- dimethyl-N-sulfopropyl) -1-propanaminium, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate and 1,6-hexanediol dimethacrylate.

The hydrogel forming the transparent layer is a hydride hydrogel because it consists of a mineral polymer, namely the alkali metal polysilicate, and an organic polymer, namely the polymer resulting from the co-polymerization of the first monomer and of the above-mentioned second acrylamide or acrylate monomer.

The organic polymer acts as an agent to consolidate and maintain a uniform distribution of the polysilicate within the hybrid hydrogel, which has the effect of preventing hydrostatic creep. In addition, the organic polymer gives the hybrid hydrogel elastic properties that allow it to deform under the effect of evaporation of water when the glazing is exposed to fire. The deformable character of the hybrid hydrogel makes possible its expansion and the formation of the intumescent layer.

The inorganic polymer and the organic polymer forming the hybrid hydrogel of the transparent layer are obtained by polymerization in situ from the corresponding precursors, that is to say the alkali metal silicate and the first and second monomers already mentioned.

The polysilicate is obtained from an alkali metal silicate having an SiO ₂ : M ₂ O molar ratio greater than 2: 1, preferably lower than at 25: 1, and which advantageously ranges from 2: 1 to 3: 1, M denoting an alkali metal.

The alkali metal silicate is selected from potassium, sodium and lithium silicates, and mixtures of these silicates. Preferably, the silicate is potassium silicate.

The amount of alkali metal silicate is 30 to 55% by weight of the precursor composition.

The hydrated alkali metal silicate can be obtained by introducing a base, such as potassium, sodium or lithium hydroxide, into an aqueous dispersion of silica particles, preferably in the form of nanoparticles.

The organic polymer is obtained from the first and second monomers mentioned above.

The first monomer consists of at least one monomer selected from the group consisting of acrylic acid, methacrylic acid and their salts, for example the potassium and / or sodium salts. The preferred monomer is the potassium salt of acrylic acid or methacrylic acid.

The first monomer represents 5 to 15% by weight of the precursor composition.

The second monomer consists of at least one acrylamide or acrylate monomer chosen from the group of compounds defined above. This monomer acts as a crosslinking agent and makes it possible to form with the first monomer a polymeric network having a certain elasticity which strengthens the cohesion of the polysilicate and prevents it from flowing. The preferred monomer is N, N'-methylene-bis-acrylamide.

The amount of second monomer represents 0.65 to 20% of the weight of the first monomer, preferably 2 to 10%.

In general, the polymerization of the aforementioned precursors is carried out in the presence of an initiator, preferably a thermally activatable initiator, such as potassium persulfate, benzoyl peroxide and azobisisobutyronitrile. The preferred initiator is potassium persulfate.

The initiator is present in the precursor composition in a proportion of 0.01 to 0.1% by weight. The precursor composition is advantageously prepared in the following manner.

In a first step, a solution is prepared by introducing the first and second monomers into an aqueous solution of a base.

In a second step, an alkali metal silicate suspension is prepared by adding particulate silica to an aqueous solution of a base. The silica may be preliminarily subjected to a vacuum treatment, in particular at a pressure of the order of 100 mbar, for a time sufficient to eliminate any gas bubbles in the final suspension.

The solution and the suspension are mixed and, preferably, the mixture thus obtained is treated under vacuum, for example at a pressure comparable to that mentioned in the preceding paragraph, for a period which can vary from 15 to 180 minutes, preferably approximately 60 minutes. . Then, the polymerization initiator is added to the mixture.

The amount of water in the precursor composition ranges from 28 to 70

% in weight. The amount of water is the same in the hybrid hydrogel which constitutes the transparent and intumescent layer of the final glazing.

The amount of water must be sufficient so that the composition is not too viscous and can be poured (or "poured") into the free space between the glass sheets. It must also allow the production of sufficient steam under the effect of heat to foam the transparent layer so that it can play its role of fire protection.

The method of manufacturing the aforementioned fire-resistant glazing is another object of the invention.

This method comprises the steps of a) assembling at least two glass sheets peripherally on its four sides by means of at least one joint so as to provide a free space between said sheets while leaving an opening in the thickness seal to allow filling of said free space, b) filling said free space with the precursor composition, c) sealing the opening with a seal identical to that of step a), and d) subjecting the assembly to a heat treatment to obtain the polymerization of the precursors to form a hybrid hydrogel. The glass sheets may have a thickness that varies from 2 to 8 mm, preferably from 4 to 6 mm. Advantageously, each sheet has the same thickness.

The glass may be a silico-soda-lime glass obtained by floating on a tin bath (according to the "float" method), a borosilicate glass or any other type of transparent glass. The glass sheet may have undergone heat quenching treatment to enhance its mechanical properties.

The glass sheets are arranged such that their main faces are substantially parallel and are kept at a distance from each other, for example by means of a spacer frame. The sheets are generally joined to each other by a seal applied to the periphery of said sheets, all the way around, while providing an opening in the thickness of the joint to allow the filling of the space between the sheets. of glass by the composition of precursors. The gasket is preferably liquid and gas tight, and has the property of being able to adhere to the glass.

The filling with the precursor composition is generally carried out by "casting", that is to say by letting said composition flow by gravity into the space between the glass sheets. During the filling step, the assembled glass sheets are preferably arranged on an inclined plane or placed in a vertical position so as to avoid the presence of air in the lower part of the glazing.

Step c) consists of sealing the opening at the gasket joint identical to that of step a). The space between the glass sheets filled with the precursor composition is also hermetically sealed.

The heat treatment of step d) is carried out at a temperature ranging from 60 to 100 ° C, preferably 70 to 90 ° C, for a time sufficient to obtain the polymerization of the first and second monomers. By way of example, the duration varies from 1 to 20 hours.

Before assembling the glass sheets, it is preferable that the face of each glass sheet intended to be in contact with the hybrid hydrogel in the final glazing is treated with an adhesion promoting silane, for example vinyltriethoxysilane or gamma-aminopropyltriethoxysilane. The following examples illustrate the invention without limiting it.

In these examples, the following tests were used:

- Foaming test

A sample of the clear coat composition (cylinder 3 cm in diameter and 3 cm in height) is placed in an oven at 600 ° C for 5 minutes. The initial volume (Vi) and the final volume (Vf) of the sample are measured and the foaming rate is calculated according to the following formula: (Vi / Vf) x 100.

- Creep test

A sample of the transparent layer composition (cylinder of

8.8 mm in diameter and 10 mm in height) is immersed in paraffin oil, liquid at 25 ° C, contained in a container. The sample is arranged so that a circular face rests on the inner part forming the bottom of the container and the opposite face is in contact with a constant load equal to 0.6 N for a period of 20 and 100 hours.

The initial height (h ₀ ) and the height at time t (h _t ) of the sample are measured, and the percentage of strain is calculated according to the following formula (ho - h _t ) x 100 / h ₀

- Temperature resistance test

The clearcoat composition is deposited on the entire surface of a glass sheet. The transparent layer is exposed to a source of heat and the evolution of the temperature of the glass on the unexposed side of the heat as a function of time is measured. The time corresponding to a glass temperature equal to 140 ° C. is determined.

EXAMPLE 1

A precursor composition comprising the following constituents in the following proportions (in% by weight) is prepared:

- 4.78% acrylic acid

0.3% of N, N'-methylene-bis-acrylamide

- 51% of a silica sol (silica content: 30%)

- 14.4% potash

- 0.02% potassium persulfate

- 29.5% water The precursor composition is prepared in two stages. Initially, a solution containing acrylic acid, Ν, Ν'-methylene-bis-acrylamide, a portion of potassium hydroxide (3.71%) and water is prepared.

A suspension containing the silica sol and the remainder of the potash (10.69%) is then prepared.

The solution is poured into the suspension, the resulting mixture is treated under vacuum (100 mbar) for 45 minutes and potassium persulfate is then added.

The foaming rate is equal to 680%.

By way of comparison, Example 1 of KR 20100051929 was reproduced.

The composition contains (in% by weight):

- 20% polyethylene glycol acrylate

- 51% of a silica sol (silica content: 30%)

- 1% potassium persulfate

- 9% ethylene glycol

- 19% water

After the foaming test, it is found that the sample is in flame at the exit of the oven: the organic part burns leaving a silica solid, friable and having a reduced volume of 83% with respect to the initial volume.

By way of comparison, Examples 25 and 27 of WO have been reproduced

201 1/045597 and a conventional clear coat composition (Reference) which contains (in% by weight): 47% silica, 16% potash and 37% water.

The results obtained after submission to the creep test are given in Table 1 below.

Table 1

Percentage of deformation

20 hours 100 hours

Ex. 1 0 0

Ex 25 (comparative) 58 73

Ex. 27 (comparative) 17 38

Reference 80 83 EXAMPLE 2

The procedure is carried out under the conditions of Example 1 to prepare a precursor composition comprising the following constituents in the following proportions (in% by weight):

- 5.00% acrylic acid

0.30% of N, N'-methylene-bis-acrylamide

- 25.00% silica

- 15.00% potash

- 0.02% potassium persulfate

- 54.68% water

A (1 1 cm x 12 cm) sheet of a counter-mold (distance: 12 mm) is equipped and the precursor composition is poured into the space between the sheet and the mold. The assembly is subjected to heat treatment at 80 ° C. for 10 hours and the temperature resistance test is carried out.

By way of comparison, a glass sheet provided with a 6 mm thick transparent layer based on potassium silicate from the composition (reference) described in Example 1 is prepared under the same conditions.

The glass sheet according to the invention withstands the temperature of 140 ° C for 35 minutes while the reference sheet withstands 46 minutes.

The transparent layer according to the invention constitutes a good compromise between the fire resistance and the hydrostatic creep resistance.

Claims

1. Fire-resistant glazing consisting of at least two sheets of glass between which is disposed at least one transparent and intumescent layer, characterized in that said layer consists of a hybrid hydrogel which comprises the polymerization product of at least one silicate of hydrated alkali metal, at least one first monomer selected from the group consisting of acrylic acid, methacrylic acid and their salts, and at least one second acrylamide or acrylate monomer selected from the group consisting of N, N-dimethylacrylamide, N- (2-hydroxyethyl) acrylamide, N, N'-methylene-bis-acrylamide, 2-methacrylamido-2-methylpropanesulphonic acid, N, N '- (1, 2- dihydroxyethylene) bisacrylamide, 3- (methacryloylamino-N, N-dimethyl-N-sulfopropyl) -1-propanaminium hydroxide, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate.

2. Glazing according to claim 1, characterized in that the alkali metal silicate has an SiO ₂ : M ₂ O molar ratio of greater than 2: 1, preferably less than 25: 1, and which advantageously ranges from 2: 1 to 3 : 1, M denoting an alkali metal.

3. Glazing according to claim 1 or 2, characterized in that the silicate is selected from potassium silicates, sodium and lithium, and mixtures of these silicates.

4. Glazing according to one of claims 1 to 3, characterized in that the hybrid hydrogel contains 28 to 70% by weight of water.

5. Method of manufacturing the glazing according to one of claims 1 to

4, characterized in that it comprises the steps of

a) assembling at least two glass sheets peripherally on its four sides through at least one joint so as to provide a free space between said sheets, while leaving an opening in the thickness of the joint to allow the filling said free space,

b) filling all or part of said free space with a hybrid hydrogel precursor composition comprising a hydrated alkali metal silicate, a first monomer selected from the group consisting of acrylic acid, methacrylic acid and their salts, and at least one second monomer acrylamide or acrylate selected from the group consisting of N, N-dimethylacrylamide, N- (2-hydroxyethyl) acrylamide, N, N'-methylene-bis-acrylamide, 2-methacrylamido-2-methylpropane sulfonic acid, N, N '- (1,2-dihydroxyethylene) bisacrylamide, 3- (methacryloylamino-N, N-dimethyl-N-sulfopropyl) -1-propananniniunn hydroxide, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate and 1,6-hexanediol dimethacrylate,

c) sealing the opening with a seal identical to that of step a), and

d) subjecting the assembly to a heat treatment to obtain polymerization of the precursors to form a hybrid hydrogel.

6. Process according to claim 5, characterized in that the alkali metal silicate represents 30 to 55% of the weight of the precursor composition.

7. Process according to claim 5 or 6, characterized in that the first monomer represents 5 to 15% by weight of the precursor composition.

8. Process according to one of Claims 5 to 7, characterized in that the second monomer represents 0.65 to 20% of the weight of the first monomer, preferably 2 to 10%.

9. Method according to one of claims 5 to 8, characterized in that the precursor composition further contains a thermally activatable initiator.

10. Method according to one of claims 5 to 9, characterized in that the heat treatment of step d) is carried out at a temperature ranging from 60 to 100 ° C, preferably 70 to 90 ° C.

1 1. Process according to Claim 10, characterized in that the duration of the heat treatment varies from 1 to 20 hours.