超臨界二酸化炭素中での籾殻シリカ疎水化とその建材不透水化への応用

摘要

Rice husk is a major agricultural waste in many areas where rice is yielded as a main agricultural product. The fact that it can be used as a superior source of amorphous silica via thorough pyrolysis of the organic moieties contained in raw rice husk should be highlighted. Unless high purity of silica is required, rice husk ash silica can serve as our industrial silica-based materials. As Husui et al recently reported, rice husk ash silica can be used as the substrate for surface-hydrophobizing agents. They could render the concrete surface superhydrophobic by smearing rice husk ash powder which was surface-hydrophobizied with perfluorosilane coupling agent 1) . From the practical viewpoint, surface hydrophobization for building materials is intended to prolong the service life of them since it contributes to preventing rainwater from undergoing gradual ingress into concrete. In the present work, we aimed to use alkyl- or phenyl- trimethoxysilanes as the surface- hydrophobizing agent since they are much less costly than perfluorosilane used in the work by Husui and his coworkers.