| 摘要 |
PROBLEM TO BE SOLVED: To solve problems about safety in a high pressure of supercritical drying when a wet gel is dried and problems that a long treating time for aging and hydrophobizing treatments is required when the shrinkage is suppressed by the aging and hydrophobizing treatments. SOLUTION: A wet gel is dried by controlling the degree of heating up within the range so as not to suddenly raise the pressure in relation to the temperature and pressure of a heat-up vaporizing part. In the process, the pressure is regulated, as necessary, by feeding a pressurized gas. Thereby, the surface tension can be lowered to reduce a capillary force when a liquid in holes is vaporized by a pressure rise at the minimum. As a result, the shrinkage of the gel during the drying can be suppressed. In the process, a high pressure such as supercritical drying is not used and even the time of aging and hydrophobizing treatments can be reduced. The efficiency of production can be improved and the cost can be reduced.
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