Method for preparing hydrophobic silica aerogel

Patent metadata

Field	Value
Publication number	US-2016280557-A1
Application number	US-201514653189-A
Country	US
Kind code	A1
Filing date	Feb 4, 2015
Priority date	Feb 6, 2014
Publication date	Sep 29, 2016
Grant date	—

Abstract

Provided are a method for preparing a hydrophobic silica aerogel by the combined use of a first surface modifier and a second surface modifier, and a hydrophobic silica aerogel prepared by using the method. A hydrophobic silica aerogel having excellent physical properties and pore characteristics as well as a high degree of hydrophobicity may be prepared with high efficiency by the preparation method according to the present invention.

First claim

1 . A method for preparing a hydrophobic silica aerogel, the method comprising:
preparing a hydrophobic silica wet gel by adding a first surface modifier, a second surface modifier, a non-polar organic solvent, and an inorganic acid to a water glass solution and performing a reaction; and washing and drying the hydrophobic silica wet gel, wherein the first surface modifier comprises two or more hydrophobic groups in one molecule, and the second surface modifier comprises two or more reactive groups reactable with a hydrophilic group on a surface of silica.

2 . The method of claim 1 , wherein the water glass solution comprises silica in an amount of 0.1 wt % to 30 wt %.

3 . The method of claim 1 , wherein the water glass solution and the first surface modifier are added in a volume ratio of 1:0.03 to 1:0.15.

4 . The method of claim 1 , wherein the water glass solution and the second surface modifier are added in a volume ratio of 1:0.001 to 1:0.05.

5 . The method of claim 1 , wherein the first surface modifier and the second surface modifier are materials that are not hydrated; and
the water glass solution comprises silica in an amount of 0.1 wt % to 10 wt %.

6 . The method of claim 1 , wherein at least one of the first surface modifier and the second surface modifier is a hydrated material; and
the water glass solution comprises silica in an amount of 3 wt % to 30 wt %.

7 . The method of claim 1 , wherein the first surface modifier and the second surface modifier are added in a volume ratio of 1:0.01 to 1:0.9.

8 . The method of claim 1 , wherein the first surface modifier comprises any one selected from the group consisting of an akyldisilazane-based compound and a hydrate thereof, or a mixture of two or more thereof.

9 . The method of claim 1 , wherein the first surface modifier comprises any one selected from the group consisting of an akyldisilazane-based compound of Chemical Formula 1 and a hydrate thereof, or a mixture of two or more thereof:

wherein, in Chemical Formula 1, R 1 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R 2 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms and, in R 1 and R 2 , at least two functional groups are alkyl groups.

10 . The method of claim 1 , wherein the first surface modifier comprises any one selected from the group consisting of hexaalkyldisilazane, tetraalkyldisilazane, and a hydrate thereof, or a mixture of two or more thereof.

11 . The method of claim 1 , wherein the first surface modifier comprises any one selected from the group consisting of hexamethyldisilazane and hydrated hexamethyldisilazane, or a mixture thereof.

12 . The method of claim 1 , wherein the second surface modifier comprises any one selected from the group consisting of an alkoxysilane-based compound including two or more alkoxy groups in one molecule and a hydrate thereof, or a mixture of two or more thereof.

13 . The method of claim 1 , wherein the second surface modifier comprises any one selected from the group consisting of an alkoxysilane-based compound of Chemical Formula 2 and a hydrate thereof, or a mixture of two or more thereof:

wherein, in Chemical Formula 2, R 21 to R 24 each independently represent an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and at least two of R 21 to R 24 are alkoxy groups.

14 . The method of claim 1 , wherein the second surface modifier comprises any one selected from the group consisting of alkyltrialkoxysilane, dialkyldialkoxysilane, and a hydrate thereof, or a mixture of two or more thereof.

15 . The method of claim 1 , wherein the second surface modifier comprises any one selected from the group consisting of methyltrimethoxysilane, dimethyldimethoxysilane, and a hydrate thereof, or a mixture of two or more thereof.

16 . The method of claim 1 , wherein the non-polar organic solvent comprises any one selected from the group consisting of hexane, heptane, toluene, and xylene, or a mixture of two or more thereof.

17 . The method of claim 1 , wherein the water glass solution and the non-polar organic solvent are added in a volume ratio of 1:1 to 1:2.

18 . The method of claim 1 , wherein the inorganic acid comprises any one selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, acetic acid, and hydrofluoric acid, or a mixture of two or more thereof.

19 . The method of claim 1 , wherein the preparing of the hydrophobic silica wet gel is performed in a temperature range of 40° C. to 60° C.

20 . The method of claim 1 , wherein solvent substitution, surface modification, and gelation are simultaneously performed during the preparation of the hydrophobic silica wet gel.

21 . The method of claim 1 , wherein the hydrophobic silica wet gel is prepared by adding a non-polar organic solvent to a water glass solution to prepare a water glass-non-polar organic solvent layer separation composition which includes a water glass solution layer and a non-polar organic solvent layer; and adding a first surface modifier, a second surface modifier, and an inorganic acid to the water glass-non-polar organic solvent layer separation composition and performing a reaction.

22 . The method of claim 21 , wherein the first surface modifier, the second surface modifier, and the inorganic acid are simultaneously added or sequentially added to the water glass-non-polar organic solvent layer separation composition.

23 . The method of claim 21 , wherein the inorganic acid is added in two divided portions to the water glass-non-polar organic solvent layer separation composition.

24 . The method of claim 1 , wherein the hydrophobic silica wet gel is prepared by adding a non-polar organic solvent to a water glass solution to prepare a water glass-non-polar organic solvent layer separation composition which includes a water glass solution layer and a non-polar organic solvent layer; adding a first surface modifier and an inorganic acid to the water glass-non-polar organic solvent layer separation composition and reacting to prepare a first surface-modified silica wet gel; and adding an inorganic acid and a second surface modifier to the first surface-modified silica wet gel and performing a reaction.

25 . The method of claim 1 , wherein the hydrophobic silica wet gel is prepared by passing a water glass solution through an ion exchange resin to prepare a silica sol; and adding an inorganic acid, a first surface modifier, a second surface modifier, and a non-polar organic solvent to the silica sol and performing a reaction.

26 . The method of claim 25 , wherein the inorganic acid, the first surface modifier, the second surface modifier, and the non-polar organic solvent are simultaneously added or sequentially added to the silica sol.

27 . The method of claim 25 , wherein the ion exchange resin is selected from the group consisting of a cation exchange resin, an anion exchange resin, or an amphoteric ion exchange resin.

28 . The method of claim 25 , wherein the ion exchange resin is a strong acidic cation exchange resin.

Assignees

• Lg Chemical Ltd

Inventors

• Kim Mi Ri
• Oh Kyoung Shill
• Klm Ye Hon
• Cho Dong Hyun
• klm Young Sam

Classifications

• C01P2006/17

  Pore diameter distribution · CPC title

• C01B33/166

  by acidification of silicate in the presence of an inert organic phase · CPC title

• B01J13/0091

  Preparation of aerogels, e.g. xerogels · CPC title

• C01P2006/16

  Pore diameter · CPC title

• C01P2006/32

  Thermal properties · CPC title