Method for producing silica aerogel and silica aerogel produced thereby

Patent metadata

Field	Value
Publication number	US-11279622-B2
Application number	US-201716069677-A
Country	US
Kind code	B2
Filing date	Sep 12, 2017
Priority date	Sep 12, 2016
Publication date	Mar 22, 2022
Grant date	Mar 22, 2022

Abstract

The present invention relates to a method for producing a silica aerogel and a silica aerogel produced thereby. The present invention provides a two-step process of a nucleation step of forming silica colloid particles by using a low-concentration silica precursor and a growth step of further adding a relatively high-concentration silica precursor to form a silica wet gel by using the silica colloid particles as a seed. Thus, the present invention provides a method for producing a silica aerogel of which mechanical stability is improved to enhance pore characteristics, and physical properties are readily controllable, and also provides a silica aerogel produced thereby.

First claim

The invention claimed is:

1. A method for producing a silica aerogel, comprising:
1) adding an acid catalyst and a first water glass solution to a reactor to prepare a water glass dispersion solution for forming silica colloid particles;
2) adding a surface modifier solution to the water glass dispersion solution for forming silica colloid particles, to form the silica colloid particles;
3) mixing an acid catalyst with a second water glass solution to prepare a water glass dispersion solution for forming a silica wet gel;
4) adding the water glass dispersion solution for forming the silica wet gel to the reactor including the silica colloid particles to form the silica wet gel; and
5) drying the silica wet gel; wherein the first water glass solution and the second water glass solution contain a silicon dioxide.

2. The method of claim 1 , wherein a concentration of the silicon dioxide in the second water glass solution is equal to or greater than a concentration of the silicon dioxide in the first water glass solution.

3. The method of claim 1 , wherein a concentration of the silicon dioxide in the first water glass solution is 0.01 to 2 wt %.

4. The method of claim 1 , wherein a concentration of the silicon dioxide in the second water glass solution is 1 to 11 wt %.

5. The method of claim 1 , wherein a concentration ratio of the silicon dioxide in the first water glass solution to the silicon dioxide in the second water glass solution is 1:1 to 1:1100.

6. The method of claim 1 , wherein the acid catalyst in step 1) and the acid catalyst in step 3) are selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid and hydrofluoric acid.

7. The method of claim 1 , wherein the surface modifier solution is a solution in which a surface modifier is added to a nonpolar organic solvent.

8. The method of claim 7 , wherein the surface modifier is at least one selected from the group consisting of trimethylchlorosilane (TMCS), hexamethyldisilazane (HMDS), methyltrimethoxysilane, trimethylethoxysilane, ethyltriethoxysilane, and phenyltriethoxysilane.

9. The method of claim 7 , wherein the nonpolar organic solvent is at least one selected from the group consisting of hexane, heptane, toluene, and xylene.

10. The method of claim 1 , wherein the surface modifier solution is added in an amount that a molar ratio of a surface modifier to a silicon dioxide in the first water glass solution becomes 0.05 to 20.

11. The method of claim 1 , wherein gelation, solvent exchange, and surface modification are simultaneously performed in step 4).

12. The method of claim 1 , wherein the silica wet gel is grown by using the silica colloid particles as a seed.

13. The method of claim 1 further comprising, during step 4), a step of adding an ammonium hydroxide (NH 4 OH).

14. The method of claim 13 , wherein the ammonium hydroxide is added in an amount that a molar ratio of the ammonium hydroxide to the silicon dioxide in the second water glass solution becomes 0.5 to 25.

15. A silica aerogel produced by the method of claim 1 .

Assignees

• Lg Chemical Ltd

Inventors

• Kim Young Hun
• Lee Je Kyun

Classifications

• C01B33/145 Primary

  Preparation of hydroorganosols, organosols or dispersions in an organic medium · CPC title

• C01B33/157

  After-treatment of gels · CPC title

• C01B33/1585 Primary

  Dehydration into aerogels · CPC title

• C01B33/155

  Preparation of hydroorganogels or organogels · CPC title

• C01B33/154

  by acidic treatment of aqueous silicate solutions · CPC title