CA2109715A1 - Process for the preparation of silica aerogel-like material - Google Patents
Process for the preparation of silica aerogel-like materialInfo
- Publication number
- CA2109715A1 CA2109715A1 CA002109715A CA2109715A CA2109715A1 CA 2109715 A1 CA2109715 A1 CA 2109715A1 CA 002109715 A CA002109715 A CA 002109715A CA 2109715 A CA2109715 A CA 2109715A CA 2109715 A1 CA2109715 A1 CA 2109715A1
- Authority
- CA
- Canada
- Prior art keywords
- alcogel
- contact
- silica
- solution
- tetraalkoxysilane
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/16—Preparation of silica xerogels
- C01B33/163—Preparation of silica xerogels by hydrolysis of organosilicon compounds, e.g. ethyl orthosilicate
Abstract
A process for the preparation of silica xerogel by hydrolysis and polycondensation of a tetraalkoxysilane to form an alcogel which is a silica skeleton surrounded by an aqueous methanol, whereafter the aqueous methanol is removed by evaporation. The alcogel formed is brought in contact with a solution of tetraalkoxysilane, the contact is maintained at or above room temperature to strengthen the silica skeleton, whereafter the gel is dried slowly at or above room temperature and at about atmospheric pressure. Before the alcogel is brought in contact with the solution of tetraalkoxylsilane it may be washed with a solution (e.g. aqueous methanol) to change the composition of the aqueous alcohol surrounding the silica skeleton or to change the functional groups on the surface of the alcogel.
Description
W092/20623 PCT/NO92/0~96 210971~ ~
Process for the preparation of a silica aerogel-like material.
This invention relates to a process for the preparation of a material similar to silica aerogel. Silica aerogel is a porous material of a very low density and it contains up to 99% of air. The type of silica aerogel prepared according to the present i~vention is normally calIed silica xerogel. Due its high porosity, the material has excellent heat insulating properties, and since the pore size of the material is smaller than the wave length of visible light, it is also trans~arent.
Typical properties of silica aerogel are as follows: -Density: 70 - 25Q kg/m3 ~;
Re~ractive index: 1.02 - 1.05 Thermal conductivity in air: 0.021 W/mK at 20C
Thermal conductivity in vacuum: 0.~08 W/mK at 20C
Particle size: 4 - 7 nm Pore size: 10 - 20 nm ~ransmittance 88% for 10 mm thickness . ~-Silica aerogel has an insulating property which is approximately twice as good as that of rockwool, and since it is also transparent, it may be used as insulation in windo~s.
Due to its porosity silica xerogel/aerogel has also a very high capacity for sucking up liquid and may also be used as starting material for composite materials and carrier for catalyst and liquids, e.g. electrolytes.
Originally, sodium silicate-hydrate was used as starting material for the preparation of silica aerogel, and in a hydrogen chlo~ide catalysed reaction between the silicate and water an aquagel was formed. However, this preparation route is very time-consuming since the a~uagel has to be washed with alcohol before the drying step may take plare. The drying process is necessary to remove preferably alI liguid, leaving only the desired silica network.
.
210~7 15 More recently tetramethoxysilane, Si(OCH3)4, TMOS, has also been used as starting material for the preparation of silica aerogel. TMOS is a suitable starting material since it is easy to handle, easy to prepare in pure form and easy to hydrolyse.
However, it is toxic and expensive. The alcogel formation takes place by a direct acid- and/or base-catalysed hydrolysis of TMOS in a so-called sol-gel technology. The alcogel formed is a silica skeleton surrounded by aqeous methanol. The problem which then arises is to remove the aqueous methanol from the silica skeleton to obtain the aerogel.
In order to prepare the desired aerogel, it is as mentioned above, necessary to remove the liquid surrounding the silica skeleton, and this may be done by eliminating or at least reducing the capillary forces working in the alcogel when the liquid front w}thdraws, or the network may be stengthenéd so that the pores do not collapse when the liquid is removed.
`
Two drying procedures are possible where the capillary forces are e~iminated:
a) Supercritical drying where the solvent in liquid phase is transformed to the gaseous phase under elevated pressure in an autoclave at a temperature~above the critical point of the solvent. A modification of this drying method is to extract the solvent with another compound such as CO2, which has lower critical point. Supercritical drying is a somewhat dangerous method because the large amounts of methanol which is expelled may lead to an explosion if there is a leak.
b) Freeze dryingr where the alcogel is frozen to becom@
!, solid, whereafter the solvent is subjected to sublimation under reduced pressure.
In the third possible method, viz.
c) Air drying and direct evaporation of the solvent where the liquid phase is transformed to gaseous phase, the drying W092/20623 PCT/~09?/00096 2~371~
process will normally lead to collapse of the pores and crack formation in the gel due to capillary forces. In the literature, the addition a DCCA (Drying Control Chemical Additive) to the sol has been reported, to obtain a narrow pore size distribution and hence a reduction in the differential strain in the alcogel, whereby cracking is considerably reduced. However, the resulting silica xerogel will have a relatively high density, e.g. about 1,4 g/cm3.
Strictly speaking, only preparation method a) will result in an aerogel. In the other two methods b) and c) there will be obtained a gel which may be described as silica cryogel and silica xerogel respectively, which may have approximately the same properties as silica aerogel.
Drying method a) with supercritical drying results in an aerogel with low density and relatively good optical properties, but the method is expen~ive and dangerous due to the high pressure and the high temperature during drying. In`
the production of tiles for use as insulation in windows it will be necessary with an autoclave which will represent a considerable element of risk during operation due to large amounts of methanol which can be ignited. By using e.g. C02 as medium during the supercritical drying, an extraction of the solvent is necessary.
Drying method b) is cheap, but due to volume expansion of the solvent during crystallisation (i.e. freezing), the result may easily be cracking of the gel during the drying.
Drying method c) normally takes place with a large shrinkage of the gel due to a collapse of the gel structure. In the preparation of high density glass by sintering from these xerogels which are not particularly reactive, it is problematic to remove organic residues, i.e. DCCA.
The purpose of the present invention is to pro~ide a process for preparing silica xerogel (aerogel) having a relatively low 21()~7~
density (i.e. below 0.5 g/c~.3) and such that the material is suitable as a heat insulating material.
According to present invention there is provided a new and improved process for the preparation of silica xerogel of lo~
density by hydrolysis and polycondensation of a tetraalkoxysilane, to form a an alcogel which is a silica skelet~n surrounded by aqueous alcohol. The process is characterised by the fact that the alcogel formed is contacted with a solution of a tetraalkoxysilane. The contact is maintained at or above room temperature to stabilise the silica skeleton, whereafter the alcogel is slowly dryed at or above room temperature and at above approximately atmospheric pressure. Before the alcogel is contacted with the solution of tetraalkoxysilane it may be suitable to contact the alcogel with a liquid~to wash the gel (in order to change the composition of the aqueous alcohol surrounding the silica skeleton) and to replace functional groups on the surface.
This liquid may e.g. consist of a mixture of water and alcohol, preferably about 40~ methanol. This liquid may also be replaced several times. The liquid added for washing may have a temperature up to the boiling point, preferably room temperature.
Suitably tetrametoxysilane is used for preparing the alcogel, whereafter the gel formed is contacted with a solution of tetraethoxysilane, e.g. in a lower alcohol, particularly methanol, The contact between the alcogel and the later added teraalkoxysilane is suitably maintained for a sufficiently long time for a strengthening of the gel network to take place, e.g. from 6 hours to 16 days, at a temperature which does not represent any risk for the alcogel, preferably from 20 to 200C, particularly 40-80C. An increased ageing time results in the largest pores in the product, i.e the lowest density. The washing of the alcogel with liquid, e.g aqueous Y~O 92/20623 PC~r/N 092/00096 21û~715 alcohol results in less shrinking of the gel and larger pores.
The alcohol used is normally a mono-, di- or trihydric alkanol, particularly with 1-10 C-atoms, preferably methanol.
It is of essential importance that the drying takes place under controlled conditions, since a to quick drying may lead to collapse. Controlled drying may be accomplished by allowing it to take place in an atmosphere which contains components which are present in the liquid surrounding the silica skeleton, or components formed from said liquid at higher temperature. The drying may e.g. take place in a chamber with such an atmosphere, or it may take place while the alcogel is kept almost completely covered, e.g. up to 99~, whereby the same effect is obtained~ The drying is suitably carried out at a temperature in the range 40 - 200C. The drying temperature may also be gradually varied from room temperature to the boiling point of aqueous alcohol.
.~ .
The thereby formed xerogel has a low density (e.g. 0,5 g/cm3 or lower) and has also a homogeneous structure.
Exam~le 1 An alcogel was prepared by hydrolysis and polycondensation of TMOS. The hydro~ysis took place with NH40H as catalyst, a stoichiometric amount of water (TMOS:water, molar ratio 1:4), and with methanol as a solvent. The gel formation took place at approximately 0C. The alcogel was cast in PyrexJteflon moulds with a removable bottom of Nescofilm. After up to several hours standing in completely covered condition after the gel formation, the mould with the alcogel was immersed in - an ageing solution of tetraethoxysilane (TEOS~ and methanol.
The mould was~removed from the bath after approximately 24 hours, and the bath was then kept covered for additional 24 hours. During the entire periode of immersing and continued storage, the temperature was kept at about 60C. The gel was then covered to an extent of 97% and was dried at about 60C
and a pressure of one atmosphere. The drying resulted in a monolithic gel having a density in the range 0.42 - 0.73 g/cm3. Different molar ratios between TEOS and methanol in the ageing solutions were used. The density decreases linearly, and correspondingly the pore size increases with increasing amount of TEOS in the ageing liquid and increased time in this liquid. The shrinkage of the alcogel during the drying is in the range 15 - 30% depending on the molar ratio and ageing time. The surface area of the xerogel is in the range 600 -650 m2/g. The thermal conductivity of the silica xerogelmaterial formed has been measured down to 0.024+0.004 W/mK at 45C.- -Example 2 An alcogel was prepared as described in Example 1. After up toseveral hours of standing in covered condition the mouled with the alcogel was immersed in liquid consisting of methanol and water (e.g. 30 volume % of water). The liquid mixture was changed three times with 24 hours intervals. The alcogel in the liquid mixtures was kept at room temperatuxe during the entire washing. After four days the washing solution was replaced by a solution of tetraethoxysilane as in Example 1.
The rest is as in Example 1.
The treatment of the alcogel in the solution of water and methanol causes less shrinkage of the alcogel during drying.
The shrinkage of the alcogel during drying is about 13~. The thermal conductivity of the silica xerogel prepared has been measured down to 0.028+0.04W/mK.
The surface area decreases and the pore size increases linearly with increasing amount of water in the liquid mixture used for washing the alcogel.
Example 3 The same procedure as in Examples 1 and 2, but methanol was replaced by ethanol in the liquid mixture used during the - 7 2 10 g 7 1 ~
washing and as solvent for the tetraalkoxysilane used to stengthen the gel network.
Process for the preparation of a silica aerogel-like material.
This invention relates to a process for the preparation of a material similar to silica aerogel. Silica aerogel is a porous material of a very low density and it contains up to 99% of air. The type of silica aerogel prepared according to the present i~vention is normally calIed silica xerogel. Due its high porosity, the material has excellent heat insulating properties, and since the pore size of the material is smaller than the wave length of visible light, it is also trans~arent.
Typical properties of silica aerogel are as follows: -Density: 70 - 25Q kg/m3 ~;
Re~ractive index: 1.02 - 1.05 Thermal conductivity in air: 0.021 W/mK at 20C
Thermal conductivity in vacuum: 0.~08 W/mK at 20C
Particle size: 4 - 7 nm Pore size: 10 - 20 nm ~ransmittance 88% for 10 mm thickness . ~-Silica aerogel has an insulating property which is approximately twice as good as that of rockwool, and since it is also transparent, it may be used as insulation in windo~s.
Due to its porosity silica xerogel/aerogel has also a very high capacity for sucking up liquid and may also be used as starting material for composite materials and carrier for catalyst and liquids, e.g. electrolytes.
Originally, sodium silicate-hydrate was used as starting material for the preparation of silica aerogel, and in a hydrogen chlo~ide catalysed reaction between the silicate and water an aquagel was formed. However, this preparation route is very time-consuming since the a~uagel has to be washed with alcohol before the drying step may take plare. The drying process is necessary to remove preferably alI liguid, leaving only the desired silica network.
.
210~7 15 More recently tetramethoxysilane, Si(OCH3)4, TMOS, has also been used as starting material for the preparation of silica aerogel. TMOS is a suitable starting material since it is easy to handle, easy to prepare in pure form and easy to hydrolyse.
However, it is toxic and expensive. The alcogel formation takes place by a direct acid- and/or base-catalysed hydrolysis of TMOS in a so-called sol-gel technology. The alcogel formed is a silica skeleton surrounded by aqeous methanol. The problem which then arises is to remove the aqueous methanol from the silica skeleton to obtain the aerogel.
In order to prepare the desired aerogel, it is as mentioned above, necessary to remove the liquid surrounding the silica skeleton, and this may be done by eliminating or at least reducing the capillary forces working in the alcogel when the liquid front w}thdraws, or the network may be stengthenéd so that the pores do not collapse when the liquid is removed.
`
Two drying procedures are possible where the capillary forces are e~iminated:
a) Supercritical drying where the solvent in liquid phase is transformed to the gaseous phase under elevated pressure in an autoclave at a temperature~above the critical point of the solvent. A modification of this drying method is to extract the solvent with another compound such as CO2, which has lower critical point. Supercritical drying is a somewhat dangerous method because the large amounts of methanol which is expelled may lead to an explosion if there is a leak.
b) Freeze dryingr where the alcogel is frozen to becom@
!, solid, whereafter the solvent is subjected to sublimation under reduced pressure.
In the third possible method, viz.
c) Air drying and direct evaporation of the solvent where the liquid phase is transformed to gaseous phase, the drying W092/20623 PCT/~09?/00096 2~371~
process will normally lead to collapse of the pores and crack formation in the gel due to capillary forces. In the literature, the addition a DCCA (Drying Control Chemical Additive) to the sol has been reported, to obtain a narrow pore size distribution and hence a reduction in the differential strain in the alcogel, whereby cracking is considerably reduced. However, the resulting silica xerogel will have a relatively high density, e.g. about 1,4 g/cm3.
Strictly speaking, only preparation method a) will result in an aerogel. In the other two methods b) and c) there will be obtained a gel which may be described as silica cryogel and silica xerogel respectively, which may have approximately the same properties as silica aerogel.
Drying method a) with supercritical drying results in an aerogel with low density and relatively good optical properties, but the method is expen~ive and dangerous due to the high pressure and the high temperature during drying. In`
the production of tiles for use as insulation in windows it will be necessary with an autoclave which will represent a considerable element of risk during operation due to large amounts of methanol which can be ignited. By using e.g. C02 as medium during the supercritical drying, an extraction of the solvent is necessary.
Drying method b) is cheap, but due to volume expansion of the solvent during crystallisation (i.e. freezing), the result may easily be cracking of the gel during the drying.
Drying method c) normally takes place with a large shrinkage of the gel due to a collapse of the gel structure. In the preparation of high density glass by sintering from these xerogels which are not particularly reactive, it is problematic to remove organic residues, i.e. DCCA.
The purpose of the present invention is to pro~ide a process for preparing silica xerogel (aerogel) having a relatively low 21()~7~
density (i.e. below 0.5 g/c~.3) and such that the material is suitable as a heat insulating material.
According to present invention there is provided a new and improved process for the preparation of silica xerogel of lo~
density by hydrolysis and polycondensation of a tetraalkoxysilane, to form a an alcogel which is a silica skelet~n surrounded by aqueous alcohol. The process is characterised by the fact that the alcogel formed is contacted with a solution of a tetraalkoxysilane. The contact is maintained at or above room temperature to stabilise the silica skeleton, whereafter the alcogel is slowly dryed at or above room temperature and at above approximately atmospheric pressure. Before the alcogel is contacted with the solution of tetraalkoxysilane it may be suitable to contact the alcogel with a liquid~to wash the gel (in order to change the composition of the aqueous alcohol surrounding the silica skeleton) and to replace functional groups on the surface.
This liquid may e.g. consist of a mixture of water and alcohol, preferably about 40~ methanol. This liquid may also be replaced several times. The liquid added for washing may have a temperature up to the boiling point, preferably room temperature.
Suitably tetrametoxysilane is used for preparing the alcogel, whereafter the gel formed is contacted with a solution of tetraethoxysilane, e.g. in a lower alcohol, particularly methanol, The contact between the alcogel and the later added teraalkoxysilane is suitably maintained for a sufficiently long time for a strengthening of the gel network to take place, e.g. from 6 hours to 16 days, at a temperature which does not represent any risk for the alcogel, preferably from 20 to 200C, particularly 40-80C. An increased ageing time results in the largest pores in the product, i.e the lowest density. The washing of the alcogel with liquid, e.g aqueous Y~O 92/20623 PC~r/N 092/00096 21û~715 alcohol results in less shrinking of the gel and larger pores.
The alcohol used is normally a mono-, di- or trihydric alkanol, particularly with 1-10 C-atoms, preferably methanol.
It is of essential importance that the drying takes place under controlled conditions, since a to quick drying may lead to collapse. Controlled drying may be accomplished by allowing it to take place in an atmosphere which contains components which are present in the liquid surrounding the silica skeleton, or components formed from said liquid at higher temperature. The drying may e.g. take place in a chamber with such an atmosphere, or it may take place while the alcogel is kept almost completely covered, e.g. up to 99~, whereby the same effect is obtained~ The drying is suitably carried out at a temperature in the range 40 - 200C. The drying temperature may also be gradually varied from room temperature to the boiling point of aqueous alcohol.
.~ .
The thereby formed xerogel has a low density (e.g. 0,5 g/cm3 or lower) and has also a homogeneous structure.
Exam~le 1 An alcogel was prepared by hydrolysis and polycondensation of TMOS. The hydro~ysis took place with NH40H as catalyst, a stoichiometric amount of water (TMOS:water, molar ratio 1:4), and with methanol as a solvent. The gel formation took place at approximately 0C. The alcogel was cast in PyrexJteflon moulds with a removable bottom of Nescofilm. After up to several hours standing in completely covered condition after the gel formation, the mould with the alcogel was immersed in - an ageing solution of tetraethoxysilane (TEOS~ and methanol.
The mould was~removed from the bath after approximately 24 hours, and the bath was then kept covered for additional 24 hours. During the entire periode of immersing and continued storage, the temperature was kept at about 60C. The gel was then covered to an extent of 97% and was dried at about 60C
and a pressure of one atmosphere. The drying resulted in a monolithic gel having a density in the range 0.42 - 0.73 g/cm3. Different molar ratios between TEOS and methanol in the ageing solutions were used. The density decreases linearly, and correspondingly the pore size increases with increasing amount of TEOS in the ageing liquid and increased time in this liquid. The shrinkage of the alcogel during the drying is in the range 15 - 30% depending on the molar ratio and ageing time. The surface area of the xerogel is in the range 600 -650 m2/g. The thermal conductivity of the silica xerogelmaterial formed has been measured down to 0.024+0.004 W/mK at 45C.- -Example 2 An alcogel was prepared as described in Example 1. After up toseveral hours of standing in covered condition the mouled with the alcogel was immersed in liquid consisting of methanol and water (e.g. 30 volume % of water). The liquid mixture was changed three times with 24 hours intervals. The alcogel in the liquid mixtures was kept at room temperatuxe during the entire washing. After four days the washing solution was replaced by a solution of tetraethoxysilane as in Example 1.
The rest is as in Example 1.
The treatment of the alcogel in the solution of water and methanol causes less shrinkage of the alcogel during drying.
The shrinkage of the alcogel during drying is about 13~. The thermal conductivity of the silica xerogel prepared has been measured down to 0.028+0.04W/mK.
The surface area decreases and the pore size increases linearly with increasing amount of water in the liquid mixture used for washing the alcogel.
Example 3 The same procedure as in Examples 1 and 2, but methanol was replaced by ethanol in the liquid mixture used during the - 7 2 10 g 7 1 ~
washing and as solvent for the tetraalkoxysilane used to stengthen the gel network.
Claims (7)
1. A process for the preparation of silica xerogel (aerogel) by hydrolysis and polycondensation of a tetraalkoxysilane to form an alcogel which is a silica skeleton surrounded by an aqueous alcohol, whereafter aqueous alcohol is removed by evaporation:
c h a r a c t e r i z e d i n t h a t the formed alcogel is brought in contact with a solution of tetraalkoxysilane, the contact is maintained at or above room temperature to stengten the silica skeleton, whereafter the gel is dried slowly at or above room temperature at approximately atmospheric pressure.
c h a r a c t e r i z e d i n t h a t the formed alcogel is brought in contact with a solution of tetraalkoxysilane, the contact is maintained at or above room temperature to stengten the silica skeleton, whereafter the gel is dried slowly at or above room temperature at approximately atmospheric pressure.
2. The process of claim 1, c h a r a c t e r i z e d i n t h a t the alcogel is brought in contact with a solution of tetraalkoxysilane, preferably in an alcohol.
3. The process of any of claims 1 and 2, c h a r a c t e r i z e d i n t h a t the alcogel before further contact is washed with an optionally aqueous alcohol.
4. The process of any of claims 1 - 3, c h a r a c t e r i z e d i n t h a t tetramethoxysilane is used for the preparation of the alcogel, which is then brought in contact with a solution of tetraethoxysilane in an alcohol, especially methanol.
5. The process of any of claims 1 - 4, c h a r a c t e r i z e d i n t h a t the contact between the alcogel and the solution of tetraalkoxysilane is maintained at a temperature in the range 20 - 200°C for a period from 6 hours to 16 days.
6. The process of claim 5, c h a r a c t e r i z e d i n t h a t the subsequent drying is performed within the temperature range 40 - 200°C.
7. The process of claim 6, c h a r a c t e r i z e d i n t h a t the drying takes place in an atmosphere which contains components present in the liquid surrounding the silica skeleton, or components which may be formed from the said liquid at higher temperatures, for example by covering up to 99% of the gel surface during drying.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NO912006 | 1991-05-24 | ||
| NO912006A NO912006D0 (en) | 1991-05-24 | 1991-05-24 | PROCEDURE FOR THE MANUFACTURE OF A SILICA-AEROGEL-LIKE MATERIAL. |
| PCT/NO1992/000096 WO1992020623A1 (en) | 1991-05-24 | 1992-05-22 | Process for the preparation of a silica aerogel-like material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2109715A1 true CA2109715A1 (en) | 1992-11-26 |
Family
ID=19894166
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002109715A Abandoned CA2109715A1 (en) | 1991-05-24 | 1992-05-22 | Process for the preparation of silica aerogel-like material |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0646097A1 (en) |
| JP (1) | JPH06510268A (en) |
| BR (1) | BR9206051A (en) |
| CA (1) | CA2109715A1 (en) |
| FI (1) | FI935203A (en) |
| NO (2) | NO912006D0 (en) |
| WO (1) | WO1992020623A1 (en) |
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| DE4439217A1 (en) * | 1994-11-03 | 1996-05-09 | Hoechst Ag | Process for the production of aerogels |
| DE19538333A1 (en) * | 1995-10-14 | 1997-04-17 | Basf Ag | Process for the subcritical production of aerogels |
| US6764690B2 (en) | 1996-05-29 | 2004-07-20 | Delsitech Oy | Dissolvable oxides for biological applications |
| DE19718740A1 (en) | 1997-05-02 | 1998-11-05 | Hoechst Ag | Process for the granulation of aerogels |
| DE19718741A1 (en) | 1997-05-02 | 1998-11-05 | Hoechst Ag | Process for compacting aerogels |
| DE19756633A1 (en) | 1997-12-19 | 1999-06-24 | Hoechst Ag | Lyogels and aerogels subcritically dried in a packed bed with minimal particle breakdown |
| DE19801004A1 (en) | 1998-01-14 | 1999-07-15 | Cabot Corp | Production of spherical lyogel useful as precursor for permanently hydrophobic aerogel |
| JP2002517585A (en) | 1998-06-05 | 2002-06-18 | カボット・コーポレーション | Nanoporous interpenetrating organic-inorganic network |
| US6239243B1 (en) * | 1999-06-10 | 2001-05-29 | Dow Corning Corporation | Method for preparing hydrophilic silica gels with high pore volume |
| ES2174680B1 (en) * | 1999-09-03 | 2004-09-16 | Consejo Superior De Investigaciones Cientificas | LOW DENSITY INORGANIC-ORGANIC TERMOHIBRIDED MATERIALS AND THEIR OBTAINING PROCEDURE. |
| GB0025940D0 (en) * | 2000-10-24 | 2000-12-13 | Secr Defence | Solvogels & a method of manufacturing the same |
| JP4170734B2 (en) | 2002-11-13 | 2008-10-22 | 信越化学工業株式会社 | Composition for forming porous film, porous film and method for producing the same, interlayer insulating film, and semiconductor device |
| US8034749B2 (en) | 2002-12-31 | 2011-10-11 | Baker Hughes Incorporated | Aerogels effective to reduce drilling fluid density |
| US10149825B2 (en) | 2004-02-27 | 2018-12-11 | Delsitech Oy | Method for preparing adjustably bioresorbable sol-gel derived SiO2 |
| FR2873677B1 (en) * | 2004-07-29 | 2007-08-17 | Armines Ass Pour La Rech Et Le | PROCESS FOR THE PREPARATION OF HYDROPHOBIC SILICA SEROGELS |
| PT103257B (en) | 2005-04-05 | 2007-05-31 | Inst Superior Tecnico | METHOD OF SUBCRYTIC PRODUCTION OF SYMBOLS AND ALTERNATIVE AEROGISES HYBRID OF MODIFIED SILICA AND LATEX WITH ALCOXYSILAN GROUPS |
| WO2007024925A2 (en) * | 2005-08-25 | 2007-03-01 | Keller Companies, Inc. | Aerogel and method of manufacturing same |
| DE102008056987A1 (en) * | 2008-11-12 | 2010-05-20 | Rwe Power Ag | insulating cartridge |
| DE102009053782A1 (en) * | 2009-11-19 | 2011-06-01 | BSH Bosch und Siemens Hausgeräte GmbH | Porous SiO2 xerogel with characteristic pore size, its drying-stable precursors and its application |
| DE102009053784A1 (en) * | 2009-11-19 | 2011-05-26 | BSH Bosch und Siemens Hausgeräte GmbH | A method for producing a porous pore size SiO 2 xerogel by a bottom-up method via a precursor having organic solid skeletal supports |
| PT106781A (en) | 2013-02-15 | 2014-08-18 | Inst Superior Técnico | FLEXIBLE HYBRID AERIALS PREPARED IN SUBCRYTIC CONDITIONS AND PREPARATION PROCESS FOR THE SAME |
| JP6191012B2 (en) * | 2013-12-12 | 2017-09-06 | パナソニックＩｐマネジメント株式会社 | Insulation |
| US10889501B2 (en) | 2016-02-24 | 2021-01-12 | Massachusetts Institute Of Technology | Solar thermal aerogel receiver and materials therefor |
| KR102092769B1 (en) | 2016-09-12 | 2020-03-24 | 주식회사 엘지화학 | Method of preparing for silica aerogel and silica aerogel prepared by the same |
| KR102092770B1 (en) | 2016-09-12 | 2020-03-24 | 주식회사 엘지화학 | Method of preparing for silica aerogel and silica aerogel prepared by the same |
| EP3677618A4 (en) * | 2017-09-01 | 2021-05-26 | AGC Inc. | Methods for producing wet gel and xerogel |
| WO2019210051A1 (en) | 2018-04-25 | 2019-10-31 | Massachusetts Institute Of Technology | Energy efficient soundproofing window retrofits |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE422045C (en) * | 1979-04-30 | 1984-12-11 | Guy Von Dardel | VIEW TO MAKE SILICA EROGEL IN THE FORM OF A SIGNIFICANT CRACKLESS, PREFERRED TRANSPARENT BLOCK AND USE OF THE SAME IN SOLAR PANELS |
| US4402927A (en) * | 1980-04-22 | 1983-09-06 | Dardel Guy Von | Silica aerogel |
| DE3616133A1 (en) * | 1985-09-25 | 1987-11-19 | Merck Patent Gmbh | SPHERICAL SIO (DOWN ARROW) 2 (DOWN ARROW) PARTICLES |
| DD283701A7 (en) * | 1988-09-26 | 1990-10-24 | Veb Leuna-Werke "Walter Ulbricht",Dd | METHOD AND DEVICE FOR PRODUCING ORGANICALLY MODIFIED SILICA TAGS |
-
1991
- 1991-05-24 NO NO912006A patent/NO912006D0/en unknown
-
1992
- 1992-05-22 EP EP92910393A patent/EP0646097A1/en not_active Ceased
- 1992-05-22 JP JP4510552A patent/JPH06510268A/en active Pending
- 1992-05-22 CA CA002109715A patent/CA2109715A1/en not_active Abandoned
- 1992-05-22 BR BR9206051A patent/BR9206051A/en not_active Application Discontinuation
- 1992-05-22 WO PCT/NO1992/000096 patent/WO1992020623A1/en not_active Application Discontinuation
-
1993
- 1993-11-23 FI FI935203A patent/FI935203A/en not_active Application Discontinuation
- 1993-11-23 NO NO934233A patent/NO934233D0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NO934233L (en) | 1993-11-23 |
| FI935203A0 (en) | 1993-11-23 |
| BR9206051A (en) | 1994-11-15 |
| AU1785292A (en) | 1992-12-30 |
| AU662147B2 (en) | 1995-08-24 |
| NO912006D0 (en) | 1991-05-24 |
| WO1992020623A1 (en) | 1992-11-26 |
| NO934233D0 (en) | 1993-11-23 |
| EP0646097A1 (en) | 1995-04-05 |
| JPH06510268A (en) | 1994-11-17 |
| FI935203A (en) | 1994-01-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |