Method for preparing elastic silica aerogel bulk material with toughness

Abstract

The invention relates to a method for preparing an elastic silica aerogel bulk material with toughness. The method comprises the following steps of (1), preparation of a silica sol; (2), preparation of a gel: taking a certain amount of precursor solution of which reaction is completed, adding dropwise an alkaline catalyst to adjust the pH value, and stirring rapidly for a certain time; (3), slowlyinjecting the prepared gel into a mold; (4), placing at a certain temperature for a period of time, aging, curing the gel and shaping; (5), drying: drying the obtained gel to obtain the hydrophobic silica aerogel insulating block material. The method has the advantages of simple process, low cost, controllable reaction condition and excellent product performance, the prepared elastic silica aerogel block material has a complete block structure, very small shrinkage and stable shrinkage ratio and can adapt to mold preparation requirements, and the usability of profiled products in the field ofinsulation can be fully met by controlling the appropriate enlargement of the mold.

Description

technical field

[0001] The invention relates to an elastic airgel thermal insulation material and a preparation method thereof, in particular to a preparation method of an elastic silica airgel block material with toughness. Background technique

[0002] SiO2 airgel is a lightweight nanoporous amorphous solid material with excellent thermal insulation performance, its porosity is as high as 80-99.8%, the typical size of the pores is 1-100nm, and the specific surface area is 200-1000m2 / g , while the density can reach 3Kg / m3, and the thermal conductivity at room temperature can be as low as 0.012W / (m·k). application potential. However, due to the large specific surface area, porosity and low density of SiO2 airgel, its strength is very low, and its inherent brittleness and poor mechanical properties greatly limit the application of airgel materials in some fields.

[0003] The Chinese patent with publication number CN 101973752A provides a glass fiber reinforced silica airge...

Examples

Embodiment 1

[0035] Mix methyl orthosilicate and hexadecyltrimethoxysilane at a molar ratio of 1:1, and then fully mix and stir this mixture with methanol and water at a molar ratio of 2:10:3 , with 2mol / L of H 2 SO 4 Slowly drop the solution into the uniformly mixed solution, and change the dropwise addition while stirring, adjust the pH value of the solution to 3, and add the flame retardant into the solution at a ratio of 5g of ammonium polyphosphate per 1L of silica sol; The good solution was kept stirring at 40°C for 5 hours to prepare the precursor solution. Take a certain amount of precursor solution, mix it thoroughly and evenly, adjust the pH value of the solution to 6 with hexamethyldisilazane, add it while stirring, and pour it into the pre-prepared, cleaned and dried mold. The mold was then placed in a 40°C water bath, and a silica gel was formed after 2 hours. Change to aging in a 60°C water bath for 12 hours. The mold is taken out, and the airgel block is taken out from t...

Embodiment 2

[0037] Mix and stir ethyl orthosilicate and dodecyltrimethoxysilane at a molar ratio of 1:2, then fully mix and stir this mixture with ethanol and water at a molar ratio of 3:20:4 , use 2mol / L HCl solution to slowly drop into the uniformly mixed solution, add dropwise while stirring, adjust the pH value of the solution to 4, and add the flame retardant at a ratio of 5g of melamine phosphate per 1L of silica sol solution; then the prepared solution was continuously stirred at 40° C. for 5 hours to obtain a precursor solution. Take a certain amount of precursor solution, fully mix and stir evenly, then adjust the pH value of the solution to 6 with 10% ammonia water, add it while stirring, and pour it into the pre-prepared, cleaned and dried mold. The mold was then placed in a 50°C water bath, and a silica gel was formed after 1 hour. Aged in a 60°C water bath for 6 hours. The mold is taken out, and the airgel block is taken out from the mold, and the hydrophobic airgel block m...

Embodiment 3

[0039] Mix and stir methyl orthosilicate and octadecyltrimethoxysilane at a molar ratio of 1:1, then fully mix and stir this mixture with methanol and water at a molar ratio of 2:20:5, Slowly drop 2mol / L HNO3 solution into the uniformly mixed solution, add dropwise while stirring, adjust the pH value of the solution to 3, and add the flame retardant to the solution at a ratio of 5g polyphosphate per 1L silica sol in; then the prepared solution was continuously stirred at 40° C. for 5 hours to obtain a precursor solution. Take a certain amount of precursor solution, fully mix and stir evenly, then adjust the pH value to 6 with 0.5Mol / L solution, add it while stirring, and pour it into the pre-prepared, cleaned and dried mold. The mold was then placed in a 40°C water bath, and a silica gel was formed after 2 hours. Aged in a 60°C water bath for 12 hours. The mold is taken out, and the airgel block is taken out from the mold, and the hydrophobic airgel block material is obtaine...

technical field

[0001] The invention relates to an elastic airgel thermal insulation material and a preparation method thereof, in particular to a preparation method of an elastic silica airgel block material with toughness. Background technique

[0002] SiO2 airgel is a lightweight nanoporous amorphous solid material with excellent thermal insulation performance, its porosity is as high as 80-99.8%, the typical size of the pores is 1-100nm, and the specific surface area is 200-1000m2 / g , while the density can reach 3Kg / m3, and the thermal conductivity at room temperature can be as low as 0.012W / (m·k). application potential. However, due to the large specific surface area, porosity and low density of SiO2 airgel, its strength is very low, and its inherent brittleness and poor mechanical properties greatly limit the application of airgel materials in some fields.

[0003] The Chinese patent with publication number CN 101973752A provides a glass fiber reinforced silica airge...

Examples

Embodiment 1

[0035] Mix methyl orthosilicate and hexadecyltrimethoxysilane at a molar ratio of 1:1, and then fully mix and stir this mixture with methanol and water at a molar ratio of 2:10:3 , with 2mol / L of H 2 SO 4 Slowly drop the solution into the uniformly mixed solution, and change the dropwise addition while stirring, adjust the pH value of the solution to 3, and add the flame retardant into the solution at a ratio of 5g of ammonium polyphosphate per 1L of silica sol; The good solution was kept stirring at 40°C for 5 hours to prepare the precursor solution. Take a certain amount of precursor solution, mix it thoroughly and evenly, adjust the pH value of the solution to 6 with hexamethyldisilazane, add it while stirring, and pour it into the pre-prepared, cleaned and dried mold. The mold was then placed in a 40°C water bath, and a silica gel was formed after 2 hours. Change to aging in a 60°C water bath for 12 hours. The mold is taken out, and the airgel block is taken out from t...

Embodiment 2

[0037] Mix and stir ethyl orthosilicate and dodecyltrimethoxysilane at a molar ratio of 1:2, then fully mix and stir this mixture with ethanol and water at a molar ratio of 3:20:4 , use 2mol / L HCl solution to slowly drop into the uniformly mixed solution, add dropwise while stirring, adjust the pH value of the solution to 4, and add the flame retardant at a ratio of 5g of melamine phosphate per 1L of silica sol solution; then the prepared solution was continuously stirred at 40° C. for 5 hours to obtain a precursor solution. Take a certain amount of precursor solution, fully mix and stir evenly, then adjust the pH value of the solution to 6 with 10% ammonia water, add it while stirring, and pour it into the pre-prepared, cleaned and dried mold. The mold was then placed in a 50°C water bath, and a silica gel was formed after 1 hour. Aged in a 60°C water bath for 6 hours. The mold is taken out, and the airgel block is taken out from the mold, and the hydrophobic airgel block m...

Embodiment 3

[0039] Mix and stir methyl orthosilicate and octadecyltrimethoxysilane at a molar ratio of 1:1, then fully mix and stir this mixture with methanol and water at a molar ratio of 2:20:5, Slowly drop 2mol / L HNO3 solution into the uniformly mixed solution, add dropwise while stirring, adjust the pH value of the solution to 3, and add the flame retardant to the solution at a ratio of 5g polyphosphate per 1L silica sol in; then the prepared solution was continuously stirred at 40° C. for 5 hours to obtain a precursor solution. Take a certain amount of precursor solution, fully mix and stir evenly, then adjust the pH value to 6 with 0.5Mol / L solution, add it while stirring, and pour it into the pre-prepared, cleaned and dried mold. The mold was then placed in a 40°C water bath, and a silica gel was formed after 2 hours. Aged in a 60°C water bath for 12 hours. The mold is taken out, and the airgel block is taken out from the mold, and the hydrophobic airgel block material is obtaine...