Preparation method of rigid silicon dioxide aerogel insulating board

Abstract

The invention provides a preparation method of a high-strength low-carbon environment-friendly rigid silicon dioxide aerogel insulating board, which comprises the following steps: (1) taking 68-120g of sodium water glass with the modulus of 3.1-3.6, adding 100-200g of pure water, and stirring uniformly to obtain diluted water glass; (2) weighing 25-100g of 40 wt% sulfuric acid, adding 10-40g of ethanol, and stirring uniformly to obtain a sulfuric acid solution; (3) mixing the diluted water glass and sulfuric acid solution, and regulating the pH value to 3.5-4.5 to obtain a sol; (4) pouring the sol into a reinforcing-fiber-filled mold, gelatinating the sol after 10-15 minutes, and standing for 2-10 hours while keeping at the temperature of 50-80 DEG C, thereby obtaining a gel board; (5) carrying out integrated aging and acid alcohol treatment on the alcoholic aquagel board; (6) putting the gel board subjected to acid alcohol treatment into 1000-250ml of trimethylethoxy silane, treating at room temperature, and completing hydrophobic modification and gel drainage in one step within 6-10 hours; and (7) after the drainage is finished, drying the wet gel board with hot nitrogen or carbon dioxide.

Description

technical field [0001] The invention relates to a preparation method of an aerogel insulation board, in particular to a preparation method of a rigid silica aerogel insulation board. Background technique [0002] There are many types of building insulation materials, which can be divided into two categories: organic and inorganic. Organic materials mainly include molded polystyrene foam (EPS), extruded polystyrene foam (XPS), polyurethane rigid foam and phenolic insulation boards. Organic materials are cheap and have good thermal insulation effects, but the fire resistance of the materials is low. For example, EPS boards are flammable materials, and most materials will produce thick smoke during a fire. Inorganic thermal insulation materials mainly include rock wool, foamed concrete, expanded perlite and hollow glass beads. Inorganic thermal insulation material has a large capacity and poor thermal insulation effect; but it is fire-retardant, anti-aging, and has stable p...

AI Technical Summary

Problems solved by technology

No matter what kind of supercritical drying process, there are problems such as complex equipment, high energy consumption, long production time, and expensive manufacturing costs.

The airgel materials sold on the market mostly use tetraethyl orthosilicate as the silicon source, and trimethylchlorosilane as the hydrophobic material, which contains chloride ions that severely corrode stainless steel, and cannot be used in the fields of nuclear power and liquefied natural gas.

At the same time, the airgel thermal insulation blankets sold on the market have low strength and are not resistant to bending. They are easily broken and delaminated when torn by external forces, which limits the wide-scale application of this type of material in the construction field.

[0014] Atmospheric pressure drying technology is an important means of large-scale industrial production of airgel materials. The previous normal pressure drying technology required tedious water washing, solvent exchange, and surface modification, which limited the development of this type of technology.

For example, patent 101671029 first mixes ethyl orthosilicate, absolute ethanol, oxalic acid and water and then conducts a hydrolysis reaction for 48-60 hours, wherein the molar ratio of ethyl orthosilicate to water is 1:1, and ethyl orthosilicate and no The molar ratio of water to ethanol is 1:7, and the molar ratio of tetraethyl orthosilicate to oxalic acid is 1:9×10-4; secondly, add water, N,N-dimethylformamide and ammonia water, let stand 24-48h to get the gel; 3. Place the gel prepared in step 2 in a drying oven at 20-60°C for 2-6h, and then place it in an aqueous solution with a volume concentration of 80% ethanol at 40-60°C Aging treatment for 12-24 hours, and then placed in a mixed solution of tetraethyl orthosilicate and ethanol with a volume ratio of 1:5, aging treatment for 12-24 hours at 40-60°C; 4. The gel after aging treatment Put it into isopropanol for solvent replacement for 4-8 hours, then put it into a mixture of isopropanol and n-hexane with a volume ratio of 1-4:5 for solvent replacement 1-5 times, each time for 4-8 hours, and then put it into Perform solvent replacement in n-hexane for 4-8 hours, then use a mixture of trimethylchlorosilane and n-hexane with a volume ratio of 1:1-50 to modify the surface until it is completely transparent, and then use isopropanol with a volume ratio of 1:1-50 and Wash with n-hexane mixture for 4-8 hours, and then wash with n-hexane for 4-8 hours; 5. Dry the gel after step 4 at 40-80°C for 6-10 hours to obtain airgel. The process is extremely cumbersome. Chlorine-containing and toxic trimethylchlorosilane is used as a modifier, which is not suitable for industrial production

[0015] Patent CN101691227 first prepares wet gel with tetraethyl orthosilicate and methyltrimethoxysilane or methyltriethoxysilane; then soaks the wet gel in an ethanol atmosphere and leaves it to age; after aging, soak the gel In the mixed solution of trimethylchlorosilane, absolute ethanol and n-hexane; then take out the gel in the mixed solution of trimethylchlorosilane, absolute ethanol and n-hexane, and wash it with n-hexane to remove the residue on the surface of the sample Mix the solution and soak it in n-hexane; then dry it to obtain the silica airgel material, the process is also very cumbersome