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A method for rapid preparation of hydrophobic silica airgel by subcritical drying of methanol

A water-based silicon oxide and aerogel technology, which is applied in the direction of silicon oxide and silicon dioxide, can solve the problems of potential safety hazards, long preparation time, high energy consumption, etc., to ensure hydrophobicity, save time and energy costs, and save The effect of the surface modification process

Active Publication Date: 2017-11-07
IBIH ADVANCED MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the critical temperature and pressure of methanol are 240°C and 7.95MPa respectively. To make the whole system fully reach the supercritical state of methanol, the heating source will be close to 300°C, and the pressure will be close to 20MPa, which will cause the following problems: 1) high cost energy consumption; 2) huge potential safety hazard; 3) long preparation time

Method used

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  • A method for rapid preparation of hydrophobic silica airgel by subcritical drying of methanol
  • A method for rapid preparation of hydrophobic silica airgel by subcritical drying of methanol

Examples

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Effect test

Embodiment 1

[0046] Sol-gel preparation: Mix 150 grams of methyl orthosilicate (28% wt) and 50 grams of methyl triethoxysilane, add 50 grams of deionized water, stir at a constant speed for about 10-40 minutes, and prepare a silicon solution Extract 500 grams of industrial methanol with a content of 99.5%, add it into the silicon solution prepared in the previous step at a uniform speed, drop into 1M hydrochloric acid aqueous solution after stirring, stir evenly, make the pH value reach about 2, and stir at a constant speed for 1 hour to fully hydrolyze. Then add 1M aqueous sodium hydroxide solution dropwise at 30°C to increase the pH value, stir evenly, and let stand for 10-60 minutes to form a gel. Subcritical drying can be performed after aging the gel at 50°C for 5 hours.

[0047] Subcritical drying: put the aged gel in an autoclave, immerse and close the autoclave with industrial methanol, slowly raise the temperature of the autoclave to about 190°C, and keep the pressure inside the a...

Embodiment 2

[0049] Sol-gel preparation: Take 100 grams of methyl orthosilicate (28%wt) and mix 25 grams of dimethyldiethoxysilane, add 20 grams of deionized water and stir at a constant speed for about 10-40 minutes, then prepare Silicon solution; extract 300 grams of industrial methanol with a content of 99.5%, add it into the silicon solution prepared in the previous step at a uniform speed, and then drop in 1M hydrochloric acid aqueous solution after stirring evenly, so that the pH value reaches about 2, and stir at a constant speed for 1 hour to fully hydrolysis. In an environment at 35°C, drop 1M ammonia solution to increase the pH value to 7.4, stir evenly to prepare a silica sol, inject the silica sol into a glass fiber blanket with a length, width, and thickness of 20cm, 20cm, and 1cm, and let it stand After about 10-60 minutes, the gel glass fiber composite blanket is made. Place the gel glass fiber composite blanket in an aging kettle at 50°C for 8 hours.

[0050] Subcritical ...

Embodiment 3

[0052] Sol-gel preparation: Mix 200 grams of ethyl orthosilicate (28%wt) and 50 grams of methyltriethoxysilane, add 25 grams of deionized water and stir at a constant speed for about 10-40 minutes, then prepare a silicon solution Extract 500 grams of industrial methanol with a content of 99.5%, add it into the silicon solution prepared in the previous step at a uniform speed, drop into 1M hydrochloric acid aqueous solution after stirring, stir evenly, make the pH value reach about 2, and stir at a constant speed for 1 hour to fully hydrolyze. Then add 1M aqueous sodium hydroxide solution dropwise at 30°C to increase the pH value, stir evenly, and let stand for 10-60 minutes to form a gel. Subcritical drying can be performed after aging the gel at 65°C for 4 hours.

[0053] Subcritical drying: put the aged gel in an autoclave, immerse and close the autoclave with industrial methanol, slowly raise the temperature of the autoclave to about 190°C, and keep the pressure inside the ...

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Abstract

The invention relates to a method for preparing hydrophobic silicon oxide airgel by using methanol subcritical drying, comprising the steps of: (1) fully hydrolyzing the proportioning solution of silicate and ethoxysilane in methanol environment through an acid catalyst; (2) Adding an alkali catalyst, the near-neutral or alkaline sol then forms a wet gel; or after obtaining a near-neutral or alkaline sol, it is combined with inorganic fibers to prepare a gel fiber composite material and aged; after aging, it is extracted with methanol Drying in the device; (3) heating and pressurizing to the subcritical state of methanol, separating and extracting the methanol in the pores of the dry hydrophobic silica airgel, cooling down, releasing the pressure, and standing still to obtain the hydrophobic silica airgel . The method of the present invention saves the solvent replacement link, saves time and energy costs; the drying temperature is 180-200°C, the pressure is 5-6MPa, and the energy consumption is greatly reduced; methanol provides part of the hydrophobic group for the body, and the silicon source introduces An appropriate amount of methylethoxysilane ensures the hydrophobicity of the product.

Description

technical field [0001] The invention relates to the field of airgel production, in particular to a method for rapidly preparing hydrophobic silica airgel by using methanol subcritical drying and an airgel product prepared by the method. Background technique [0002] Airgel is known as one of the ten most potential new materials in the future. Because of its porosity as high as 95%, thermal conductivity and density as low as 0.01W / m. It has unparalleled advantages in noise reduction and sound insulation, and will definitely contribute to energy conservation and emission reduction in the future. [0003] Airgel was invented by Professor Kistler of Stanford University in 1931, using water glass as a silicon source, and aerogel was prepared by sol-gel process, but the process is complicated and has not been applied. [0004] In the 1960s, Nicolaon et al. used silicon alkoxide as a precursor to prepare wet gel by sol-gel process, and then made it by supercritical drying (SCFD) p...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/16C04B30/02
Inventor 田雷董海兵
Owner IBIH ADVANCED MATERIALS CO LTD
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