Process for the preparation of xerogels

Details Process for the preparation of xerogels Process for the preparation of xerogels

1995-06-28

1997-07-15

Kim, Christopher

Distillation: processes, separatory

Adding material to distilland except water or steam per se

Organic compound

423338, 502233, B01D 334, C01B 3312

Patent

active

056479620

ABSTRACT:
The invention relates to modified SiO.sub.2 gels (xerogels), the preparation thereof and the use thereof as thermal insulators. The xerogels are prepared by acidifying an aqueous waterglass solution, polycondensing the silicic acid produced thereby, by adding a base, to an SiO.sub.2 gel, removing the water from the resulting gel by extractive distillation with an organic solvent which forms with water an azeotrope which separates on cooling into two phases, reacting the gel with a silylating agent, and then drying at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used for removing the water.

REFERENCES:
patent: 3801705 (1974-04-01), Krekeler et al.
patent: 3846537 (1974-11-01), Marotta
patent: 4042770 (1977-08-01), Bachl et al.
patent: 4190457 (1980-02-01), McDaniel
patent: 4382070 (1983-05-01), Novak et al.
patent: 4649037 (1987-03-01), Marsh et al.
patent: 4975405 (1990-12-01), Okamura et al.
patent: 5122291 (1992-06-01), Wolff et al.
patent: 5275796 (1994-01-01), Tillotson et al.
Chemisches Zentralblatt, No. 20, 1965, Berlin, pp. 87-90 by F. Polak et al.
Chemical Abstracts, vol. 81, No. 14, Oct. 7, 1974, Columbus, Ohio, Abstract No. 82740a by J. Viska et al.

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