Method for producing aerogels and aerogels obtained using said method

Patent metadata

Field	Value
Publication number	US-12378128-B2
Application number	US-201917291565-A
Country	US
Kind code	B2
Filing date	Nov 6, 2019
Priority date	Nov 13, 2018
Publication date	Aug 5, 2025
Grant date	Aug 5, 2025

Abstract

The invention relates to a method for producing an aerogel under increased pressure, to the aerogel obtained using said method and to their use.

First claim

The invention claimed is:

1. A method for producing a silica aerogel, comprising:
(a) introducing droplets of a sol into an apparatus subjected to a pressure of more than 30 bar to form a particulate lyogel, wherein:
the sol has a pH greater than 7 and is a solution or dispersion of a precursor in a solvent or dispersant,
the apparatus contains compressed carbon dioxide and formation of the particulate lyogel is initiated by a pH shift of the sol due to the compressed carbon dioxide, and
the sol has not been pre-gelled or partially gelled by an acid or base before being introduced into the apparatus; and

(b) following step (a), performing a solvent exchange of the lyogel.

2. The method according to claim 1 , wherein:
the pressure in step (a) is more than 40 bar; and/or
step (a) is carried out at a temperature above 50° C.

3. The method according to claim 1 , further comprising converting the lyogel into an aerogel by removing a solvent or dispersant of the solvent exchange of step (b) from the lyogel at a pressure of more than 50 bar.

4. The method according to claim 1 , wherein the precursor is selected from silicic acids, colloidal silicic acid, colloidal silica, silanes, silica sols, tetraalkoxysilanes, siloxanes and mixtures thereof.

5. The method according to claim 1 , wherein the sol comprises a hydrophobing silanizing agent.

6. The method according to claim 1 , wherein the solvent exchange occurs by contacting the lyogel with an organic solvent.

7. The method according to claim 6 , wherein the organic solvent is brought into contact with the lyogel together with a hydrophobing agent.

8. The method according to claim 7 , further comprising, subsequent to contact with the organic solvent and hydrophobing agent, converting the lyogel into an aerogel.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Hintemann Damian
• Kilzer Andreas
• Mölders Nils
• Renner Manfred
• Sengespeick Andreas
• Weidner Eckhard
• Weishaupt Oliver

Classifications

• C01P2006/32

  Thermal properties · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01P2004/32

  Spheres · CPC title

• C01B33/159

  Coating or hydrophobisation · CPC title

• C01B33/1546

  the first formed hydrosol being converted to a hydrogel by introduction into an organic medium immiscible or only partly miscible with water · CPC title