Clumpy hydrophobic phenolic resin/silicon dioxide compounded aerogel and preparation method thereof

[0035] The present invention also provides a method for preparing any of the above block hydrophobic phenolic resin/silica composite aerogels, the method comprising the following steps:

[0036] (1) Mix a certain amount of phenols, aldehydes, aminosilanes and siloxanes with one or two hydrocarbon groups, distilled water and alcohols, and stir for 10 to 120 minutes to obtain a transparent sol; among them, phenols, aldehydes, The molar ratio of aminosilane, siloxane containing one or two hydrocarbon groups, distilled water, and alcohols is 1:(0.5~7.5):(0.1~3.5):(0.1~8.5):(1.5~45):(10 ~70), wherein the molar ratio of aminosilane is preferably 0.7-2.5, the molar ratio of distilled water is preferably 18-45, and the molar ratio of alcohols is preferably 20-50;

[0037] (2) Gelation of the above transparent sol, the gelation temperature is 20~95℃, preferably the gelation temperature is 60~70℃, and the gelation time is 1~20h to obtain a phenolic resin/silica composite Wet gel

[0038] (3) The gel obtained in step (2) is naturally dried or heated under normal pressure to prepare a block hydrophobic phenolic resin/silica composite aerogel.

[0039] The phenols described in step (1) are phenol, o-cresol, p-cresol, m-cresol, 2,6-xylenol, 2,5-xylenol, 3,4-xylenol, 2, At least one of 3,5-trimethylphenol, 3,5-xylenol, and resorcinol.

[0040] The aldehydes in step (1) are at least one of formaldehyde, furfural, 5-hydroxymethylfurfural, 5-bromofurfural, 5-methylfurfural, 5-phenyl-2-furfural and 3-furfural.

[0041] The aminosilane described in step (1) is 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-aminopropyldimethyl Methoxysilane, N-aminoethyl-3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 3-aminopropyl At least one of methyldiethoxysilane.

[0042] The siloxane containing one or two hydrocarbon groups described in step (1) is methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane , Ethyltrimethoxysilane, Diethyldimethoxysilane, Diethyldiethoxysilane, Vinyltrimethoxysilane, Vinyltriethoxysilane, Methylvinyldimethoxysilane , Hexamethyldisiloxane, octyltriethoxysilane, chloropropyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, ethyltrichlorosilane, diethyldichloride At least one of silanes. Preferably at least one of methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane .

[0043] The alcohol described in step (1) is at least one of methanol, ethanol, propanol, isopropanol, butanol, and tert-butanol.

[0044] The drying temperature in step (3) is 20 to 200°C, and the drying time is 1 to 72 hours.

[0045] Compared with the prior art, the advantages of the present invention are:

[0046] (1) The method of the present invention is carried out under normal pressure, does not require supercritical equipment, has simple process, low cost and high safety;

[0047] (2) In addition, the method of the present invention does not require subsequent organic solvent exchange and surface hydrophobic modification treatment, and the production cycle is short, which is convenient for industrial production;

[0048] (3) The composite aerogel prepared by the present invention has good hydrophobicity and agglomeration, and can be widely used in building thermal insulation, sewage treatment, petrochemical industry, catalyst carrier, solar energy collection and many other fields.

[0049] figure 1 It is a photo of the bulk phenolic resin/silica composite aerogel prepared in one embodiment of the present invention;

[0050] figure 2 It is a photo of the contact angle of distilled water on the bulk phenolic resin/silica composite aerogel prepared in one embodiment of the present invention, the contact angle is 168°;

[0051] image 3 It is a scanning electron micrograph of a bulk phenolic resin/silica composite aerogel prepared in an embodiment of the present invention;

[0052] Figure 4 Is the pore size distribution diagram of the bulk phenolic resin/silica composite aerogel prepared in an embodiment of the present invention;

[0053] Figure 5 It is a graph of weight loss in the air of the bulk phenolic resin/silica composite aerogel prepared in an embodiment of the present invention, and the mass percentage of silica is 20%.

[0055] Example 1

[0056] Mix 1.5g of phenol, 1.5g of formaldehyde, 2.5g of 3-aminopropyltrimethoxysilane, 3.0g of methyltrimethoxysilane, 5.0g of distilled water, and 20g of ethanol. Stir and mix thoroughly for 10 minutes to obtain a transparent sol, gel at 50℃ 10h to get wet gel. The wet gel was dried at 50°C under normal pressure for 48 hours to obtain a phenolic resin/silica composite aerogel. The density of the above phenolic resin/silica composite aerogel is 0.20 g·cm -3 , Porosity 88.2%, BET specific surface area is 200m 2 ·G -1 , The contact angle formed by distilled water with the surface is 128°, the pore size distribution is 10-100nm, the elastic modulus is 5MPa, the compressive strength is 11.5MPa, and the thermal conductivity is 0.035W·m -1 ·K -1 , The silica content is 35%. From figure 1 It can be seen that the composite aerogel is a block and the actual color is beige.

[0057] Example 2

[0058] Mix 1.5g of phenol, 2.0g of formaldehyde, 2.5g of 3-aminopropyltrimethoxysilane, 3.5g of methyltriethoxysilane, 5.0g of distilled water, and 25g of ethanol. Stir and mix thoroughly for 50min to obtain a transparent sol, which is condensed at 60°C. Glue for 5h to get a wet gel. The wet gel was dried at 40°C under normal pressure for 48 hours to obtain a phenolic resin/silica composite aerogel. The density of the above phenolic resin/silica composite aerogel is 0.15 g·cm -3 , Porosity is 91.0%, BET specific surface area is 570m 2 ·G -1 ,From figure 2 It can be seen that the contact angle formed by distilled water and the surface is 138°, from image 3 with Figure 4 It can be seen that the pore size distribution is 7~120nm, the elastic modulus is 2MPa, the compressive strength is 3.5MPa, and the thermal conductivity is 0.03W·m -1 ·K -1 , The silica content is 47%.