| abstract |
A water-proofing sheet having high hydraulic pressure resistance and high moisture permeability and having a wet type coagulation polyurethane film on the surface of a cloth. A clay organic composite member containing quaternary ammonium ions introduced between layers of swellable laminar silicates is dispersed in the wet coagulation polyurethane film 0.5 to 20 wt% on the basis of the solid content of the polyurethane, the hydraulic pressure resistance is at least 5,000 mm and permeability is at least 8,000 g/m² 24 hrs. Polyurethane is dissolved in a solvent consisting mainly of a nitrogen-containing polar solvent, and a solution prepared by dispersing the clay organic composite member containing the quaternary ammonium ions between the layers of the swellable laminar silicate 0.5 to 20 wt% on the basis of the solid content of the polyurethane is applied to a cloth, and the cloth is immersed in a coagulation bath to coagulate the polyurethane. Thereafter, washing with water and drying are carried out to prepare the water-proofing sheet. |