AQUEOUS SILICA DISPERSION WITH LONG SHELF LIFE FOR FIRE-RESISTANT GLASS

Abstract

The invention relates to aqueous silica dispersion with a pH in the range from 8 to 14, comprising a base chosen from the group consisting of alkali metal hydroxides, (akyl)ammonium hydroxides or a mixture thereof, at least 35% by weight of silica particles surface-treated with an amino-organosilane (I) and/or a product of hydrolysis of compound of formula (I), 3% to 35% by weight of at least one polyol, 20% to 60% by weight of water, preparation of such dispersion and the use thereof in fire-resistant glass.

Claims

1-15. (canceled)

16. An aqueous silica dispersion, comprising; at least 35% by weight of silica particles surface-treated with an organosilane; 3% to 35% by weight of at least one polyol; 20% to 60% by weight of water; a base chosen from the group consisting of alkali metal hydroxides, amines, amino alcohols, (akyl)ammonium hydroxides or a mixture thereof; wherein the organosilane is a compound of formula (I) and/or a product of hydrolysis of compound of formula (I): ##STR00002## wherein:
0≤h≤2; Si(A).sub.h(X).sub.3-h is a silane functional group; A is H or a branched or unbranched C.sub.1 to C.sub.4 alkyl residue; X is selected from Cl or a group OY, wherein Y is H or a C.sub.1 to C.sub.30 branched or unbranched alkyl-, alkenyl-, aryl-, or aralkyl-group, branched or unbranched C.sub.2 to C.sub.30 alkylether-group or branched or unbranched C.sub.2 to C.sub.30 alkylpolyether-group or a mixture thereof, B is a branched or unbranched, aliphatic, aromatic or mixed aliphatic-aromatic C.sub.1 to C.sub.30 carbon-based group, which may contain N, S and/or O heteroatoms; each of R.sup.1 and R.sup.2 is independently H or branched or unbranched, aliphatic, aromatic or mixed aliphatic-aromatic C.sub.1 to C.sub.30 carbon-based group; and wherein the pH of the dispersion is in the range from 8 to 14.

17. The aqueous silica dispersion of claim 16, wherein the silica is a fumed silica.

18. The aqueous silica dispersion of claim 16, wherein the silica has a BET surface area of 30 m.sup.2/g to 60 m.sup.2/g.

19. The aqueous silica dispersion of claim 16, wherein the polyol is glycerol, ethylene glycol, trimethylolpropane, pentaerythritol, sorbitol, polyvinyl alcohol, polyethylene glycol or a mixture thereof.

20. The aqueous silica dispersion of claim 16, wherein the base is potassium hydroxide, sodium hydroxide or lithium hydroxide.

21. The aqueous silica dispersion of claim 16, wherein the number mean aggregate diameter of the silica particles in the dispersion is less than 200 nm.

22. The aqueous silica dispersion of claim 16, wherein the pH of the dispersion is in the range of 10 to 13.

23. The aqueous silica dispersion of claim 16, comprising from 1 mmol to 60 mmol of the organosilane of formula (I) and/or the units derived from the organosilane of formula (I) per 100 g of the dispersion.

24. The aqueous silica dispersion of claim 16, wherein said aqueous silica dispersion comprises 38% to 60% by weight of pyrogenically prepared silica surface-treated with an organosilane of formula (I) and/or a product of hydrolysis of compound of formula (I), and having a BET surface area of 30 m.sup.2/g to 60 m.sup.2/g; 5% to 25% by weight of glycerol, 25% to 50% by weight of water, 0.3% to 0.7% by weight of KOH.

25. The aqueous silica dispersion claim 16, wherein in the organosilane of formula (I):
0≤h≤2; A is H, CH.sub.3 or C.sub.2H.sub.5; B is a branched or unbranched, aliphatic, aromatic or mixed aliphatic-aromatic C.sub.1 to C.sub.6 carbon-based group; X is Cl, OCH.sub.3 or OC.sub.2H.sub.5.

26. The aqueous silica dispersion of claim 16, wherein, in the organosilane of formula (I), R.sup.1═R.sup.2═H.

27. The aqueous silica dispersion of claim 16, wherein the organosilane is chosen from the group consisting of 3-aminopropyl triethoxysilane (AMEO), 3-aminopropyl trimethoxysilane (AMMO), 3-aminopropyl-methyl-diethoxysilane, N-(2-aminoethyl)-N′-(3-(trimethoxysilyl)propyl)ethylenediamine (TRIAMO), products of hydrolysis thereof and mixtures thereof.

28. The aqueous silica dispersion of claim 27, wherein the polyol is glycerol, ethylene glycol, trimethylolpropane, pentaerythritol, sorbitol, polyvinyl alcohol, polyethylene glycol or a mixture thereof.

29. The aqueous silica dispersion of claim 28, wherein the base is potassium hydroxide, sodium hydroxide or lithium hydroxide.

30. The aqueous silica dispersion of claim 29, wherein the number mean aggregate diameter of the silica particles in the dispersion is less than 200 nm.

31. The aqueous silica dispersion of claim 28, wherein said aqueous silica dispersion comprises 38% to 60% by weight of pyrogenically prepared silica surface-treated with an organosilane of formula (I) and/or a product of hydrolysis of compound of formula (I), and having a BET surface area of 30 m.sup.2/g to 60 m.sup.2/g; 5% to 25% by weight of glycerol, 25% to 50% by weight of water, 0.3% to 0.7% by weight of KOH.

32. The aqueous silica dispersion of claim 28, wherein in the organosilane of formula (I)
0≤h≤2 A is H, CH.sub.3 or C.sub.2H.sub.5, B is a branched or unbranched, aliphatic, aromatic or mixed aliphatic-aromatic C.sub.1 to C.sub.6 carbon-based group, X is Cl, OCH.sub.3 or OC.sub.2H.sub.5.

33. The aqueous silica dispersion of claim 28, wherein, in the organosilane of formula (I), R.sup.1═R.sup.2═H.

34. A process for the preparation of the aqueous silica dispersion of claim 16, wherein a dispersion, comprising: at least 35% by weight of surface-untreated silica powder; 3% to 35% by weight of at least one polyol; 20% to 60% by weight of water is treated with 0.05% to 10% by weight relative to the weight of the resulting aqueous dispersion, of an organosilane of formula (I) and/or a product of hydrolysis of compound of formula (I).

35. A process for the preparation of the aqueous silica dispersion of claim 16, wherein the silica surface-treated with an organosilane of formula (I) and/or a product of hydrolysis of compound of formula (I) is mixed with water and the polyol.

Description

EXAMPLES

Example 1: Dispersions Prepared with Aged Sample of Fumed Silica

[0071] Fumed silica (AEROSIL® OX50, BET=50 m.sup.2/g, manufacturer: Evonik Resource Efficiency GmbH) was stored for a period of over 4 years under ambient conditions (25° C., 1 atm) and then was used to prepare a silica dispersion with the following composition:

[0072] 1037.2 g (33.15 wt. %) deionized water

[0073] 538.2 g (17.20 wt. %) glycerin

[0074] 1508.4 g (48.20 wt. %) fumed silica (AEROSIL® OX50 stored for more than 4 years at ambient conditions)

[0075] 45.5 g (1.45 wt. %) KOH solution (30 wt. % KOH in deionized water).

[0076] Preparation of the dispersion was carried out substantially according to the procedure described in Example 1 of WO 2006002773 A1 but with smaller laboratory scale equipment. More specifically, 917.7 grams of deionized water and 226.2 grams of glycerin were introduced in a double wall high-grade steel mixing container cooled with line water. While mixing at approximately 2000 rpm with a Dispermat model AE-3M dissolver equipped with a 75 mm diameter dissolver wheel, 1508.4 g of AEROSIL® OX50 were manually added over a time of 20 minutes. The mixing was continued for another 15 minutes after which the solution was homogenized for 30 minutes at 7000 rpm with an IKA Ultra-Turrax T 50 Disperser equipped with a rotor-stator dispersion tool model S 50 N-G 45 G.

[0077] The batch size of the prepared dispersion was 3 kg. From this master batch, four identical samples (dispersion samples 1.1 to 1.4) each of 300 g were then taken.

Example 1a (Comparative Example—Without Amino Silane)

[0078] A 250 mL wide neck glass bottle containing 300 g of dispersion sample 1.1 was placed on a magnetic stirrer and heated at 55° C. for 1 hour while stirring. Stirring speed was maintained as high as possible without causing magnetic stirring rod to jump. The sample was then cooled down to room temperature (25° C.) and stored at this temperature. Eight days later, 148 g of the sample were placed in a 250 mL polyethylene (PE) cup. While mixing at 490 rpm with a Heidolph R2R 5021 stirrer mounting a blade stirrer, 52 g of 50 wt. % KOH solution were added at once and the mixing was continued for another 10 minutes. The mixture was degassed in a rotary evaporator under vacuum for 12 minutes. In the first two minutes the absolute pressure was gradually reduced from atmospheric to 65 mbar and then it was maintained at 65 mbar for another 10 minutes. The water bath temperature was maintained at 50° C. for the whole period of 12 minutes. The milky mixture was then used to fill 5 small (10 mL) transparent glass bottles. The bottles were cured in an oven at 75° C. for 8 hours. After curing, the content of all the bottles was transparent and solid in appearance but showed many small bubbles.

[0079] Due to the presence of these air bubbles, the thus prepared cured product is not suitable for use in transparent fire resistant glasses.

Example 1b (According to the Invention)

[0080] 6.46 g of 3-aminopropyl trimethoxysilane (Dynasylan® AMMO, manufacturer Evonik Resource Efficiency GmbH) was slowly added to 300 g of the stirred dispersion sample prepared in example 1 (sample 1.2) at 25° C. Further treatment of the dispersion was exactly the same as described in example 1a.

[0081] After curing, the content of all the 10 mL bottles was transparent and solid in appearance. No air bubbles could be seen.

[0082] FIG. 1 shows the dispersion sample 1.1 (example 1a) without an amino silane (left) and dispersion sample 1.2 (example 1b) with AMMO (right).

Example 1c (According to the Invention)

[0083] 7.5 g of N-(2-aminoethyl)-N′-(3-(trimethoxysilyl)propyl)ethylenediamine (Dynasylan® TRIAMO, manufacturer Evonik Resource Efficiency GmbH) was slowly added to 300 g of the stirred dispersion sample prepared in example 1 (sample 1.2) at 25° C. Further treatment of the dispersion was exactly the same as described in example 1a.

[0084] After curing, the content of all the 10 mL bottles was transparent and solid in appearance. No air bubbles could be seen.

Example 1d (According to the Invention)

[0085] 5.0 g of N-(2-aminoethyl)-N′-(3-(trimethoxysilyl)propyl)ethylenediamine (Dynasylan® TRIAMO, manufacturer Evonik Resource Efficiency GmbH) was slowly added to 300 g of the stirred dispersion sample prepared in example 1 (sample 1.2) at 25° C. Further treatment of the dispersion was exactly the same as described in example 1a.

[0086] After curing, the content of all the 10 mL bottles was transparent and solid in appearance. No air bubbles could be seen.

Example 1e (According to the Invention): The Effect of Treating Aged Fumed Silica with AMEO Before Preparation of Dispersion

[0087] AEROSIL® OX50 from the same batch as used in example 1 (stored for over four years) was treated with 3-aminopropyl triethoxysilane (Dynasylan® AMEO, manufacturer Evonik Resource Efficiency GmbH) following the procedure similar to that described in EP 0466958 A1. The AMEO-treated fumed silica was then used to make a silica dispersion with the following composition:

[0088] 160.0 g (32.52 wt. %) deionized water,

[0089] 89.7 g (17.36 wt. %) glycerin,

[0090] 251.4 g (48.60 wt. %) AMEO-treated fumed silica,

[0091] 7.58 g (1.47 wt. %) KOH solution (30 wt. % KOH in deionized water)

[0092] Preparation of the dispersion was carried out similarly to the procedure described in Example 1. More specifically, 153 grams of deionized water and 37.7 grams of glycerin were introduced in a double wall high-grade steel mixing container cooled with line water. While mixing at approximately 1700 rpm with a Dispermat model AE-3M dissolver equipped with a 75 mm diameter dissolver wheel, the first 90 g of the AMEO-treated AEROSIL® OX50 then 7.58 g of 30% KOH solution, and finally the remaining 161.4 g of AMEO-treated AEROSIL® OX50 were manually added. The mixing was continued for another 15 minutes after which the remaining 15 g of deionized water was added and the solution was homogenized for 45 minutes at 4000 rpm with an IKA Ultra-Turrax T 50 disperser equipped with a rotor-stator dispersion tool model S 50 N-G 45 G.

[0093] Further treatment of the dispersion was exactly the same as described in example 1a. After curing, the content of all of the 10 mL bottles was transparent and solid in appearance. No air bubbles could be seen.

[0094] As it can be seen from examples 1 and 1a, the use of aged fumed silica material in alkali silica dispersions containing glycerin may lead to a massive air bubble formation, which would preclude the use of such stored silica samples for preparing transparent fire resistant glasses. On the other hand, the use of particular amino silanes (examples 1b-1d) allow using of such aged fumed silica samples to prepare bubble-free silica dispersions suitable for use in transparent fire retardant glasses. The treatment of fumed silica with an amino silane can be carried out directly in the dispersion (examples 1b-1d) as well as separately, before forming the silica dispersion (example 1e).

Example 2: The Effect of Adding AMEO to an “Old” Silica Dispersion

[0095] A silica dispersion was prepared with the following composition:

[0096] 764 kg (31.30 wt. %) deionized water

[0097] 397 kg (19.43 wt. %) glycerin

[0098] 1125 kg (48.24 wt. %) fumed silica (AEROSIL® OX50, BET=50 m.sup.2/g, manufacturer: Evonik Resource Efficiency GmbH)

[0099] 24.0 kg (1.03 wt. %) KOH solution (50 wt. % KOH in deionized water)

[0100] Preparation of the dispersion was carried out according to the procedure analogous to that described in Example 1 of WO 2006002773 A1 but on a larger scale.

[0101] The dispersion was stored for 1 year and 11 months at ambient conditions (25° C., 1 atm). After this storage time, two samples (dispersion samples 2.1 and 2.2) each of 300 g, were taken.

Example 2a (Comparative Example)

[0102] A 250 ml PE cup containing 148 g of dispersion sample 2.1 was mixed with KOH solution (50 wt. % KOH in deionized water) in a mixing ratio of 74 wt. % silica dispersion/26 wt. % KOH solution. The mixture was degassed under vacuum for 12 minutes in a rotary evaporator for 12 minutes. In the first 2 minutes, the absolute pressure was gradually reduced from atmospheric to 65 mbar and then it was maintained at 65 mbar for 10 minutes. The water bath temperature was maintained at 50° C. for the whole period of 12 minutes. The milky mixture was then used to fill 4 small (10 mL) transparent glass bottles. The bottles were cured in an oven at 75° C. for 8 hours. After curing, the content of all the bottles was transparent and solid in appearance but showed many small bubbles.

[0103] Due to the presence of these air bubbles, the thus prepared cured product is not suitable for use in transparent fire resistant glasses.

Example 2b (According to the Invention)

[0104] 6.3 g of 3-aminopropyl triethoxysilane (Dynasylan® AMEO, manufacturer Evonik Resource Efficiency GmbH) was slowly added to 300 g of the stirred dispersion sample prepared in example 2 (dispersion sample 2.2) at 25° C. The dispersion sample was then heated to 55° C. for 1 hour while continuing to stir, then cooled down to 25° C. and stored at this temperature for 8 days. Further treatment of the dispersion was exactly the same as described in example 2a.

[0105] After curing, the content of all the 10 mL bottles was transparent and solid in appearance. No air bubbles could be seen.

[0106] As it can be seen from examples 2 and 2a, the use of aged alkali silica dispersions containing glycerin may lead to a massive air bubble formation, which would preclude the use of such stored silica dispersions in transparent fire resistant glasses. On the other hand, the use of amino silane AMEO (example 2b) allow using of such aged fumed silica dispersions to prepare bubble-free cured silica dispersions suitable for use in transparent fire retardant glasses.

Example 3 (Comparative Example): The Effect of Ageing of a Reference Silica Dispersion on a Fire Resistant Windows

[0107] A silica dispersion was prepared with the following composition:

[0108] 131.65 kg deionized water corresponding to 33.47 wt. %

[0109] 67.73 kg (17.22 wt. %) glycerin

[0110] 189.83 kg (48.26 wt. %) freshly prepared fumed silica (AEROSIL® OX50, BET=50 m.sup.2/g, manufacturer: Evonik Resource Efficiency GmbH).

[0111] 4.14 kg (1.05 wt. %) KOH solution (30 wt. % KOH in deionized water)

[0112] Preparation of the dispersion was carried out according to the procedure described in Example 1 of WO 2006002773 A1.

[0113] The dispersion was then stored at ambient conditions (25° C., 1 atm). A first sample of this dispersion (sample 3.1) was taken after 11 days of storage, a second sample (sample 3.2) after 6 months of storage, and a third sample (sample 3.3) after 11 months of storage. Each sample was used to produce the fire-resistant interlayer in a fire-resistant glass windows of size 100 cm×100 cm.

[0114] The procedure used to prepare fire-resistant interlayer was as follows:

[0115] 7.74 kg of the dispersion prepared in example 3 was placed in a double mantel mixing reactor equipped with temperature control and a vacuum pump which was capable of evacuating the empty reactor to an absolute pressure below 100 mbar. 2.76 kg of KOH solution (50 wt. % KOH in deionized water), were gradually added to the reactor while mixing (weight ratio of dispersion to KOH solution was 73.7:26.3, wt %:wt %). The mixture was degassed under vacuum for 15 minutes, while the temperature was maintained between 45° C. and 50° C., after which it was quickly cooled down to room temperature. The degassing was continued at room temperature (25° C.) for another 40 minutes after which the still fluid mixture was used to fill the cavity between two thermally tempered glass plates, which were pre-assembled together with suitable spacer sealant and spacer materials. The size of each glass plate was 100 cm×100 cm×5 mm and they were assembled together so that the two inner faces were 6 mm apart. The mixture was introduced through an opening in the sealant material. Once the space between the glass plates was filled, the opening in the sealant was sealed and the window was placed in horizontal position in a curing oven. The window was then heated at 75° C. for 15 hours. The results were as follows:

[0116] The window obtained with the dispersion sample stored for 11 days (sample 3.1) was clear, transparent and bubble-free.

[0117] The window obtained with the dispersion sample stored for 6 months (sample 3.2) was clear and transparent, but contained a few small bubbles.

[0118] The window obtained with the dispersion sample stored for 11 months (sample 3.3) was clear and transparent, but contained many bubbles.

Example 4 (According to the Invention): The Effect of Ageing of a Silica Dispersion Containing AMEO on a Fire Resistant Windows

[0119] A silica dispersion was prepared with the following composition:

[0120] 33.87 kg deionized water corresponding to 32.17 wt. %

[0121] 17.94 kg (17.04 wt. %) glycerin

[0122] 50.28 kg (47.75 wt. %) fresh fumed silica (AEROSIL® OX50, BET=50 m.sup.2/g, manufacturer: Evonik Resource Efficiency GmbH)

[0123] 1.13 kg (1.05 wt. %) KOH solution (30 wt. % KOH in deionized water)

[0124] 2.08 kg (1.98 wt. %) 3-aminopropyl triethoxysilane (Dynasylan® AMEO, manufacturer Evonik Resource Efficiency GmbH).

[0125] Preparation of the dispersion was carried out according to the procedure described in Example 1 of WO 2006002773 A1. While stirring, Amino silane (AMEO) was slowly added to the dispersion containing all other components The dispersion was heated and maintained at a temperature of 55° C. while stirring for 1 hour after which it was stored at ambient conditions. A first sample of this dispersion (sample 4.1) was taken after 11 days of storage, a second sample (sample 4.2) after 6 months of storage, and a third sample (sample 4.3) after 11 months of storage. Each sample was used to produce the fire-resistant interlayer in a fire-resistant glass windows of size 100 cm×100 cm. The same procedure for preparation of fire-resistant interlayer as described in example 3, was used.

[0126] The window obtained with the dispersion sample stored for 11 days (sample 4.1) was clear, transparent and bubble free.

[0127] The window obtained with the dispersion sample stored for 6 months (sample 4.2) was clear, transparent, and bubble free.

[0128] The window obtained with the dispersion sample stored for 11 months (sample 4.3) was clear, transparent, and still bubble free.

[0129] The examples 3 and 4 show that the results obtained in examples 2a and 2b on a 10 mL scale can be reproduced on a large scale, in real fire-resistant glasses. Examples 3 and 4 show that storage of a silica dispersion not containing an amino silane over the time of 11 days to 6 months could lead to a slight deterioration in quality of the prepared windows, whereas storage for 11 months leads to considerable air bubble formation and makes such dispersions not suitable for use in transparent fire-resistant windows.

Example 5: Fire Test of Glass Plate Made with Silica Dispersion Containing AMEO

[0130] A window prepared as in example 4 was mounted in a frame and tested in a furnace. The furnace was heated according to the standard temperature curve defined in EN 1363-1. The window resisted 39.7 minutes of thermal treatment according to EN 1364-1 thereby achieving requirements for classification EI30.