Aerogel Composite Material Production via Subcritical Drying
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Solution Overview
Problem
Current methods for producing aerogels are complex, costly, and not environmentally friendly, especially when scaling up, and they lack stability with acid-sensitive fibers like rock wool, leading to inefficient thermal insulation due to high thermal conductivity and mechanical instability.
Innovation Solution
A method involving the hydrolysis of organosilane compounds to produce a siliceous sol, followed by gelation, hydrophobization with hexamethyldisiloxane and nitric acid, and subcritical drying, allowing for high porosity and low thermal conductivity aerogels that can incorporate rock wool fibers without dissolving them, thus achieving a cost-effective and environmentally friendly industrial-scale production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supercritical drying is used to produce aerogels with high porosity and low density, then the aerogel achieves excellent thermal insulation properties, but the process becomes complex and unsuitable for large-scale production
Solution Approach 1:
The patent changes the drying parameters from supercritical conditions to subcritical conditions (below 150°C at normal pressure), making the process suitable for industrial scale while maintaining aerogel quality. This parameter change resolves the contradiction between achieving high thermal insulation performance and maintaining process simplicity for large-scale production.
2Ease of manufacture
If trimethylchlorosilane is used for hydrophobic treatment to enable subcritical drying, then aerogel production becomes simpler and more scalable, but hydrochloric acid is released which attacks rock wool fibers
Solution Approach 1:
The patent replaces the problematic trimethylchlorosilane with hexamethyldisiloxane, which does not release harmful hydrochloric acid during hydrophobic treatment. This substitution eliminates the harmful effect on rock wool fibers while maintaining the benefits of subcritical drying and industrial scalability.
3Stability of the object's composition
If glass wool fibers are used instead of rock wool to avoid acid attack, then fiber stability is improved, but fire resistance and temperature resistance decrease
Solution Approach 1:
By replacing trimethylchlorosilane with hexamethyldisiloxane for hydrophobic treatment, the patent eliminates hydrochloric acid release, thereby allowing rock wool fibers to be used without degradation. This enables the use of rock wool's superior fire resistance and temperature resistance properties while maintaining fiber stability through the acid-free hydrophobic treatment process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of highly porous aerogels with thermal conductivity below 18 mW/mK and high stability, suitable for industrial-scale manufacturing, using rock wool fibers for enhanced fire resistance and thermal performance.
Implementation Method 1
the surface of the gel is made hydrophobic with surface-modifying compounds in order to reduce the capillary pressure in the pores of the gel before drying
Implementation Method 2
The trimethylchlorosilane reacts with the OH groups of the silicate surface of the gel, with elimination of HCl
Implementation Method 3
a procedure was developed, according to which a subcritical drying of the gel below 150 °C in the circulating air flow and at normal pressure is possible
Implementation Method 4
A method involving the hydrolysis of organosilane compounds to produce a siliceous sol, followed by gelation, hydrophobization with hexamethyldisiloxane and nitric acid
Data Source
AI summary
The present invention relates to a method for aerogel production and to a composite material produced by said method and comprising an aerogel and mineral fibers. An aerogel material produced on the basis of silicate with a coefficient of thermal conductivity of < 18 mW/mK is obtainable by rendering it hydrophobic with HMDSO in the presence of nitric acid.