Fire resistant interlayer

Abstract

The composition for preparation of a fire resistant interlayer includes an aqueous alkali silicate solution and a silicon dioxide compound. The composition has a molar ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O) of larger than 2. The composition further includes a stabilisation agent and the stabilisation agent includes zinc (Zn).

Claims

1. A composition for preparation of a fire resistant interlayer comprising an aqueous alkali silicate solution and a silicon dioxide compound, wherein the composition has a molar ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O) of larger than 2, wherein the composition comprises a stabilisation agent wherein the stabilisation agent comprises zinc (Zn), whereby the composition comprises 0.0005 mol/kc to 0.003 mol/kc zinc.

2. The composition according to claim 1, wherein the composition has a molar ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O) of 4-6 and a freezing point of 15 C. to 9 C.

3. The composition according to claim 1, further comprising an antifreeze agent.

4. The composition according to claim 3, wherein at least one on the following statements is true: the antifreeze agent is mono ethylene glycol (MEG); the composition comprises 0.5% to 15% antifreeze agent; the composition comprises 0.5% to 15% mono ethylene glycol (MEG).

5. The aqueous alkali silicate solution according to claim 3, wherein the stabilisation agent comprises zinc-ions.

6. The composition according to claim 5, wherein the stabilization agent comprises Zn2+-ions.

7. The composition according to claim 6, wherein the stabilization agent comprises at least one of zinc sulphate, zinc halide, zinc carbonate, zinc acetate, zinc oxide, zinc hydroxide, zincate, zinc nitrate, zinc chlorate, zinc phosphate, zinc molybdate, zinc cyanide, zinc arsenite, zinc arsenate and zinc chromate, zinc sulphide or a mixture thereof.

8. The composition according to claim 1, wherein the stabilisation agent comprises zinc-ions.

9. The composition according to claim 8, wherein the stabilization agent comprises Zn2+-ions.

10. The composition according to claim 1, wherein the composition has a molar ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O) of larger than 2.5.

11. The composition according to claim 1, wherein the composition has a molar ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O) of larger than 4.

12. The composition according to claim 1, wherein the stabilization agent comprises at least one of zinc sulphate, zinc halide, zinc carbonate, zinc acetate, zinc oxide, zinc hydroxide, zincate, zinc nitrate, zinc chlorate, zinc phosphate, zinc molybdate, zinc cyanide, zinc arsenite, zinc arsenate and zinc chromate, zinc sulphide or a mixture thereof.

13. A fire resistant interlayer, wherein the fire resistant interlayer is arrangeable between at least two support elements, and wherein the fire resistant interlayer is made using a composition according to claim 1.

14. A fire resistant element comprising at least two support elements and a transparent fire resistant interlayer according to claim 13, wherein fire resistant interlayer is arranged between two essentially parallel support elements.

15. A method for manufacturing a fire resistant element according to claim 14, comprising the steps of: providing at least a first and a second support element; assembling the first support element, the second support element and sealing means such that the first support element and the second support element are spaced apart from one another and form together with the sealing means an internal space with an opening; providing an aqueous alkali silicate solution; providing a silicon dioxide compound; providing a stabilisation agent, the stabilisation agent comprising at least one of zinc, zinc-ions, and Zn2+-ions; mixing the aqueous alkali silicate solution, the silicon dioxide compound and the stabilisation agent as a composition; filling the composition into the internal space; closing the opening of the internal space.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject matter of the invention will be explained in more detail in the following text with reference to exemplary embodiments which are illustrated in the attached drawings, in which:

(2) FIG. 1 shows three container with mixed compositions a) freshly, b) after seven days and c) after 14 days of a durability test;

(3) FIG. 2 shows a diagram depicting the development of the freezing point (FP) due to addition of mono ethylene glycol (MEG) and zinc to a composition;

(4) FIG. 3 shows a diagram depicting the effect of additives (ADD) on the freezing point (FP) of a composition;

(5) FIG. 4 shows a cured composition;

(6) FIG. 5 shows the effect of zinc as stabilisation agent in a composition with two containers including a composition a) after 1 day and b) after 14 days of a quick aging test.

DETAILED DESCRIPTION OF THE INVENTION

(7) The reference symbols used in the drawings, and their meanings, are listed in summary form in the list of reference symbols. In principle, identical parts are provided with the same reference symbols in the figures.

(8) FIG. 1 shows three containers with mixed compositions of an aqueous alkali silicate solution and a silicon dioxide compound. The composition has a molar ratio (M) of silicon dioxide (SiO2) to alkali metal oxide (M2O) of larger than 4.77, abbreviated: M4.77. The composition further includes 4.5 w % mono ethylene glycol (MEG) (w % is given as weight percent).

(9) The container to the left serves as reference (REF), where no further additives (ADD) are added. The container to the right includes an additional 5 Vol % zinc sulphate (ZnSO.sub.4) solution in the composition, wherein the zinc sulphate has a concentration of 0.05 mol/L. The container in the middle includes an additional 5 Vol % zinc sulphate (ZnSO.sub.4) solution with a concentration of 0.1 mol/L in the composition.

(10) The freshly mixed composition in all three containers as shown in FIG. 1a is transparent. After applying the three containers to elevated temperatures of 80 C. for a seven days (FIG. 1b) the reference sample (REF) to the left (without zinc) reveals a significant clouding and turbidity. The both samples with added zinc (right5 Vol % 0.05 M ZnSO4; middle5 Vol % 0.1 M ZnSO4) surprisingly revealed that the addition of zinc to a composition of the alkali silicate solution and the silicon dioxide compound improved the aging stability of the composition, as the composition remained transparent.

(11) After further seven days of applying elevated temperatures of 80 C. (FIG. 1c) the reference sample (without zinc) to the left shows even more clouding and turbidity. However, after a total of 14 days of applying elevated temperatures of 80 C. also the samples with additional 5 Vol % 0.05 M ZnSO4 solution (right) and 5 Vol % of 0.1 M ZnSO4 solution (middle) show some clouding and turbidity.

(12) Overall, the zinc acts as a stabilisation agent and reduces clouding and turbidity of the composition including aqueous alkali silicate solution and a silicon dioxide compound.

(13) FIG. 2 depicts a diagram showing the freezing point (FP) of the composition of aqueous alkali silicate solution and a silicon dioxide compound for several samples with addition of mono ethylene glycol (MEG) and zinc.

(14) The freezing point (FP) is the temperature at which the composition freezes and builds crystals, in particular ice crystals. The decreased freezing point is advantageous when the composition is applied as fire resistant interlayer in a fire resistant element. This is because a freezing of the composition can impair the quality of the fire resistant interlayer or fire resistant element, in particular of a fire resistant glazing that is to be applied in cold regions. A once frozen element might not be full transparent after unfreezing.

(15) The molar ratio of silicon dioxide (SiO2) to alkali metal oxide (M2O), also called modulus, is a measure for the dimensional stability of the composition. The higher modulus the higher is the dimensional stability. Accordingly, a large modulus is desired. Nevertheless, a large modulus leads to an undesired increase of the freezing point of the composition. The increased freezing point (FP) can be surprisingly be counterbalanced by controlled the addition of zinc to the composition.

(16) FIG. 2 shows the freezing point of compositions with three different moduli, namely a high modulus of 5.6 (empty signs [circle and square ]), a modulus of 5.4 (filled signs [circle .circle-solid., square .square-solid. and triangle .box-tangle-solidup.]) and a lower modulus of 5.07 (grey rhombus [.diamond-solid.]) as reference.

(17) The compositions were modified by adding certain, fixed amounts of mono ethylene glycol (MEG) as antifreeze agent. For samples with a modulus of 5.6 a MEG content of 1% and 2% was tested. Samples with a modulus of 5.4 were tested with a MEG content of 4.5%. The content is given as share of the total volume of the composition (Vol %).

(18) In further samples the stabilisation agent zinc was added to the composition (square and triangle). The compositions include per 100 g 5 mL of a zinc sulphate solution with a concentration of 0.05 mol/L (square [.square-solid.modulus=5.6; modulus=5.4]) or with a concentration of 0.1 mol/L (triangle [.box-tangle-solidup.modulus=5.6]). This corresponds to an overall zinc concentration of 0.025 mol/L or 0.005 mol/L in den composition.

(19) It can surprisingly be seen, that the addition of zinc results in a reduction of the freezing point (FP) for all compositions, independent of the modulus of the composition and independent from the content of the antifreeze agent MEG (difference between circle and square). Furthermore, FIG. 2 reveals that with the addition of 5 mL per 100 g composition of 0.05 molar zinc solution the freezing point of a reference sample with a lower modulus (modulus (reference)=5.07) can be approached. This is illustrated by the close proximity of the grey rhombus (.diamond-solid.modulus=5.07, no zinc) and the squares (.square-solid.modulus=5.6, c(Zn)=0.025 mol/L; modulus=5.4, c(Zn)=0.025 mol/L).

(20) Additionally, it can be shown that a further increase of the zinc concentration in the composition does not lead to a further decrease of the freezing point, as expected by the skilled person, but rather causes a slight increase of the freezing point ([.box-tangle-solidup.modulus=5.6, c(Zn)=0.005 mol/L). Accordingly, the effect of the additional zinc in the composition surprisingly only leads to a decrease of the freezing point in a certain range of the zinc concentration.

(21) In order to verify the positive effect of zinc on the freezing point reference measurements without zinc were performed as shown in FIG. 3. FIG. 3 depicts the freezing point (FP) of several compositions with different additives (ADD) in different shares. As explained above, the share of the additive (ADD) is given in Vol %.

(22) All measurements were performed on compositions with a modulus of 5.07. In a first set of samples the amount of MEG as additive is increased from 0% to 4.5% (circles.circle-solid. [ADD=MEG]). For this set a systematic decrease of the freezing point of the composition is observed. In a second set of samples the amount of MEG is hold constant at 4.5% and water (H2O) is added as additive. The corresponding results are shown as triangles (.box-tangle-solidup.ADD=H2O+4.5% MEG). For this set of samples, a slight increase of the freezing point is observed. The pure addition of 4.5% of water as additive (ADD) is shown a square (.square-solid.ADD=H2O).

(23) From the results depicted in FIG. 3 it becomes clear that an addition of a solution to a composition containing MEG and not containing zinc leads to a decrease of the freezing. In contrast to that the addition of zinc leads to a decrease of the freezing point (FP) as shown in FIG. 2.

(24) FIG. 4 shows a transparent composition including an aqueous alkali silicate solution and a silicon dioxide compound with a modulus of 4.77 and with 4.5% MEG. The alkali silicate solution was supplemented with zinc as stabilisation agent and was aged for three days at 80 C. This illustrates the stabilisation effect of zinc on the aqueous alkali silicate solution.

(25) FIG. 5 two containers with a composition including an aqueous alkali silicate solution and a silicon dioxide compound. The composition has a modulus of 4.77 and includes 4.5% MEG. The composition in the left container includes 5 Vol % water and the composition in the right container includes 5 Vol % of a 0.3 molar zinc sulphate solution.

(26) FIG. 5a) shows a freshly mixed and 5b) the composition after 14 days of a quick aging test at elevated temperatures of 80 C. It can be clearly seen, that zinc improves the stability of the composition and reduces the clouding and turbidity of the composition.

(27) While the invention has been described in present preferred embodiments of the invention, it is distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practised within the scope of the claims.