| Summary |
This report summarizes the results of the studies on the dirt-repellency of membrane materials.
As the surface treatment materials for coated fabrics，one hundred percent fluorocarbon-resin clearly reduced dirt-repellency. Moreover， a top-coated titanium dioxide(Ti02) photocatalyst markedly improved the dirt-.repellency of coated fabrics.
Influence of location was investigated by an outdoor exposure test. The degree of dirt depends on the locations. Membrane materials were the most polluted in Tokyo and Osaka. An apparatus for accelerating the dirt process was developed and the results obtained by this apparatus were in fair agreement with the results of the outdoor exposure test. The relationship between the angle of the side wall and the rain water dirt streaks was investigated by the outdoor exposure test. When the exposure angle of the side wall against the horizontal plane exceeded 65 degrees，rain water dirt streaks appeared.
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