Silica wet gel and aerogel

Patent metadata

Field	Value
Publication number	US-2023286812-A1
Application number	US-202318181357-A
Country	US
Kind code	A1
Filing date	Mar 9, 2023
Priority date	Mar 9, 2022
Publication date	Sep 14, 2023
Grant date	—

Abstract

The invention provides silica wet gel, silica aerogel, and methods that can be used to form an enhanced silica aerogel sheet having fewer optical defects along with other desirable properties.

First claim

We claim:

1 . A silica aerogel formed from a precursor material comprising methyl silicate 51 and having a haze of less than 2.5%, a visible transmission greater than or equal to 98%, a thermal conductivity of less than 20 mW/m*K, and a global structural similarity index measure of greater than or equal to 0.80.

2 . The silica aerogel of claim 1 wherein the haze is less than 1.75%.

3 . The silica aerogel of claim 1 wherein the thermal conductivity is less than 13 mW/m*K.

4 . The silica aerogel of claim 1 wherein the silica aerogel is in the form of a silica aerogel sheet.

5 . The silica aerogel of claim 1 wherein the silica aerogel is devoid of structural nonuniformities that create optical distortion lines visible to the naked eye.

6 . The silica aerogel of claim 1 wherein the silica aerogel is prepared by a method comprising the steps of:
preparing a first solution by mixing methyl silicate 51 and methanol;
preparing a second solution by mixing ammonium hydroxide and water;
mixing the first solution and the second solution together to form the precursor material;
allowing components in the precursor material to react to form silica wet gel; and
drying the silica wet gel to form the silica aerogel.

7 . The silica aerogel of claim 6 wherein the precursor material has a weight percent ratio of the methyl silicate 51:water of between 0.25:1 and 2:1.

8 . The silica aerogel of claim 7 wherein the weight percent ratio of the methyl silicate 51:water for the precursor material is between 0.5:1 and 1:1.

9 . The silica aerogel of claim 6 wherein the precursor material comprises:
methyl silicate 51 at a weight percent of greater than or equal to 15% and less than or equal to 24%;
methanol at a weight percent of greater than or equal to 60% and less than or equal to 68%;
water at a weight percent of greater than or equal to 15% and less than or equal to 17%; and
ammonium hydroxide at a weight percent of greater than or equal to 0.08% and less than or equal to 0.2%.

10 . The silica aerogel of claim 9 wherein the precursor material comprises:
methyl silicate 51 at a weight percent of greater than or equal to 15.28% and less than or equal to 19%;
methanol at a weight percent of greater than or equal to 65.16% and less than or equal to 68.52%;
water at a weight percent of greater than or equal to 15.68% and less than or equal to 16.04%; and
ammonium hydroxide at a weight percent of greater than or equal to 0.15% and less than or equal to 0.17%.

11 . The silica aerogel of claim 6 wherein the precursor material is devoid of N,N-dimethylformamide.

12 . A method of making silica aerogel, comprising the steps of:
preparing a first solution by mixing methyl silicate 51 and methanol; preparing a second solution by mixing ammonium hydroxide and water; mixing the first solution and the second solution together to form a precursor material, such that the precursor material comprises methyl silicate 51 at a weight percent of greater than or equal to 15% and less than or equal to 24%; allowing components in the precursor material to react to form silica wet gel; and drying the silica wet gel to form silica aerogel.

13 . The method of claim 12 wherein the weight percent of the methyl silicate 51 in the precursor material is greater than or equal to 15.28% and less than or equal to 19%.

14 . The method of claim 12 wherein the precursor material comprises:
methyl silicate 51 at a weight percent of greater than or equal to 15% and less than or equal to 24%;
methanol at a weight percent of greater than or equal to 60% and less than or equal to 68%; water at a weight percent of greater than or equal to 15% and less than or equal to 17%; and
ammonium hydroxide at a weight percent of greater than or equal to 0.08% and less than or equal to 0.2%.

15 . The method of claim 12 wherein the precursor material comprises:
methyl silicate 51 at a weight percent of greater than or equal to 15.28% and less than or equal to 19%;
methanol at a weight percent of greater than or equal to 65.16% and less than or equal to 68.52%;
water at a weight percent of greater than or equal to 15.68% and less than or equal to 16.04%; and
ammonium hydroxide at a weight percent of greater than or equal to 0.15% and less than or equal to 0.17%.

16 . The method of claim 12 wherein a weight percent ratio of the methyl silicate 51:water for the precursor material is between 0.25:1 and 2:1.

17 . The method of claim 16 wherein the weight percent ratio of the methyl silicate 51:water for the precursor material is between 0.5:1 and 1:1.

18 . The method of claim 12 wherein the first solution comprises methyl silicate 51 at a weight percent of greater than or equal to 15% and less than or equal to 30% and methanol at a weight percent of greater than or equal to 60% and less than or equal to 90%, and the second solution comprises ammonium hydroxide at a weight percent of greater than or equal to 0.5% and less than or equal to 1% and water at a weight percent of greater than or equal to 99% and less than 100%.

19 . The method of claim 12 wherein the precursor material is devoid of N,N-dimethylformamide.

20 . The method of claim 12 wherein the silica aerogel has a haze of less than 1.75%, a visible transmission of greater than 98%, a thermal conductivity of less than 13 mW/m*K, and a global structural similarity index measure of greater than 0.80.

21 . The method of claim 12 wherein the silica aerogel is devoid of structural nonuniformities that create optical distortion lines visible to the naked eye.

22 . The method of claim 12 wherein the method further comprises the steps of:
depositing the silica wet gel onto a substrate to form a silica wet gel sheet; and
wherein said drying the silica wet gel to form the silica aerogel comprises drying the silica wet gel sheet to form the silica aerogel as a silica aerogel sheet.

Assignees

• Cardinal Cg Co

Inventors

• Chowdhury Reaz Ahmed
• Arifuzzaman Mohammad
• Kitzman Kellen
• Myli Kari B

Classifications

• 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

• B32B5/18 Primary

  characterised by features of a layer {of} foamed material · CPC title

• B32B2419/00

  Buildings or parts thereof · CPC title

• B32B2307/304

  Insulating · CPC title

• B32B2266/126

  Aerogel, i.e. a supercritically dried gel · CPC title