Method for preparing fiber-containing silicon dioxide aerogel composite thermal insulation material

Abstract

The invention relates to a method for preparing a fiber-containing silicon dioxide aerogel composite thermal insulation material. The method is mainly characterized by comprising the following steps of: adding fiber and an infrared sunscreen agent into aerogel precursor solution to form composite gel, and treating the composite gel to obtain fiber-containing silicon dioxide aerogel composite powder; and adding a little binding agent and performing compression molding by adopting a half-dry pressing method, and performing heat treatment to obtain composite products in various shapes. By adopting a technical route for preparing the composite powder and molding by adopting the half-dry pressing method, products in complex shapes are easy to produce, supercritical drying at high cost and in danger of high pressure is avoided, and the method is easy for mass production. By taking industrial silica sol and industrial spirit as main raw materials for preparing silicon dioxide aerogel, addinga drying controlled chemical additive, the infrared sunscreen agent and the fiber in turn and finally slowly adding the industrial spirit until gelling, the fiber and the infrared sunscreen agent canbe fully and uniformly mixed with the aerogel in the composite powder, the thermal insulation of the materials is improved, and a higher-strength light thermal insulation material is prepared.

Description

Technical field: [0001] The invention relates to a preparation method of a silica airgel composite thermal insulation material containing fibers, belonging to the field of thermal insulation materials. technical background: [0002] The unique nanoporous structure of silica airgel material makes the pore diameter smaller than the mean free path of gas molecules, thereby limiting the convective heat transfer of gas molecules, while the ultra-high porosity limits the solid-phase heat transfer of the material. In addition, , the high-temperature radiation heat transfer of the material can be reduced by adding an appropriate amount of infrared opacifying agent. Therefore, silica airgel is considered to be the solid material with the best thermal insulation performance at present, and has broad application prospects in the field of thermal insulation materials. However, Due to the huge surface tension of the silica airgel material during the drying process, the material itself ha...

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Problems solved by technology

[0002] The unique nanoporous structure of silica airgel material makes the pore diameter smaller than the mean free path of gas molecules, thereby limiting the convective heat transfer of gas molecules, while the ultra-high porosity limits the solid-phase heat transfer of the material. In addition, , the high-temperature radiation heat transfer of the material can be reduced by adding an appropriate amount of infrared opacifying agent. Therefore, silica airgel is considered to be the solid material with the best thermal insulation performance at present, and has broad application prospects in the field of thermal insulation materials. However, Due to the huge surface tension of the silica airgel material during the drying process, the material itself has defects, and the extremely low density results in low inherent strength, high brittleness and easy cracking of the silica airgel material, which limits its use. use in practice

(Chinese Patent No. 95197068.2 "A Composite Material Containing Airgel, Its Preparation Method and Application", No. 96196879.6 "Composite Material Containing Airgel and Adhesive, Its Preparation Method and Application"), but due to air condensation The density of the rubber powder is extremely small, and it is difficult to mix evenly with fibers and infrared opacifiers. The fibers and infrared opacifiers cannot be fully dispersed, and it is difficult to ensure the heat insulation performance and mechanical strength of the product.

Especially when using an organic binder, when the operating temperature exceeds 300°C, the binder will burn and volatilize, resulting in a sharp drop in the high-temperature mechanical strength of the material

Two, by adding short fiber (inorganic reinforcement) and infrared opacifying agent into the airgel precursor solution and then forming a gel, and then obtaining the material by supercritical drying (Chinese Patent No. 97106652.3 "Modified Nano Thermal Insulation Material and Production Technology 》), although the prepared material has a certain strength and good thermal insulation, but the material strength is still difficult to meet the harsh requirements of actual use and the supercritical drying process limits its large-scale application and production

The composite materials prepared by the methods described in 3 and 4 all have good mechanical strength and thermal insulation, but the process is complex and cumbersome, and the material manufacturing cost is high. In addition, the drying process adopts a supercritical method, which limits large-scale production and application

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