Verfahren zur Herstellung von organisch modifizierten Aerogelen unter Verwendung von Alkoholen, bei dem gebildeten Salze ausgefällt werden
摘要
The invention concerns a process for preparing organically modified aerogels, in which: a) a silicic acid sol with a pH </= 4.0 is produced from an aqueous potassium silicate solution using at least one organic and/or inorganic acid; b) the resultant silicic acid sol is polycondensed by the addition of a base to form a SiO2 gel; c) the gel produced in step b) is washed with an organic solvent until the water content of the gel is </= 5 wt %; d) the gel obtained in step c) is surface-modified with at least one C1-6 alcohol; and e) the surface-modified gel obtained in step d) is dried. The process is characterized in that the at least one acid forms with the potassium silicate cations salts which are difficult to dissolve in the silicic acid sol. Before step b), the resultant salts which are difficult to dissolve are precipitated to the greatest possible extent and separated from the silicic acid sol.
