シリカエアロゲル/ポリウレタンフォー厶コンポジット断熱材の調製と耐久性評価

摘要

Polyurethane foam (PUF)/silica aerogel composites were successfijlly prepared as a heat insulating material by the supercritical carbon dioxide drying of PUFs filled with silica aerogels. PUF/silica aerogel composites were flexible and their thermal conductivities were as low as for the silica aerogel. The durability of PUF/silica aerogel composites was improved by using hydrophobic silica aerogel. PUF/hydrophobic silica aerogel composites were aged at 70°C and 95℅ RH. PUF/hydrophilic silica aerogel composite easily adsorbed water. Simultaneously, the volume shrank and the thermal conductivity of the composite drastically increased. On the other hand, PUF /hydrophobic silica aerogel composite was stable even at high temperature and in humidity conditions. After 10 weeks, the thermal conductivity of the composite hardly increased.%シリカエアロゲルの断熱材としての応用を目的に，シリカエアロゲルとポリウレタンフォームを複合化したコンポジット断熱材の作製を行った.コンポジット断熱材の作製にはまずシリカ湿潤ゲルをゾル-ゲル反応中に軟質ポリウレタンフォームに含浸した.さらにその後に超臨界乾燥を行いポリウレタンフォーム中でシリカエアロゲルを作製することで複合化した.コンポジット断熱材は柔軟で屈曲性を有し，さらにシリカエアロゲルと同程度の熱伝導率を有していた.また，複合化するシリカエアロゲルを疎水化することで耐湿性が向上し，70℃・95℅RHの高温高湿条件下でも10週間後の熱伝導率が0.002W/(m・K)の増大に留まった.本手法がシリカエアロゲルの断熱材への応用に対して有用な手段であることを確認した.