| 摘要 |
PURPOSE: To obtain a cover material for preventing the penetration of rainwater capable of ensuring the safety against a fire by laminating a protective layer composed of unvulcanized rubber having weatherability and low viscosity to the single surface of a sealant layer based on a rubbery elastomer and having salt blocking properties and waterproofness and laminating a skin layer to the surface thereof. CONSTITUTION: A cover material preventing the penetration of rainwater from the outside protruding region of the bottom part of an outdoor storage tank to prevent the corrosion of the lower part of the tank caused by water or salt injury is obtained by laminating a tape or sheet like protective layer composed of unvulacnized rubber to the single surface of a tape or sheet like sealant layer and further laminating a skin layer composed of paper, a nonwoven fabric, a fabric or a plastic film to the surface of the protective layer 3. The sealant layer 2 is composed of a waterproof compsn. having salt blocking properties with chlorine ion transmissivity of 0.05×10<-3> mg/cm<2> day or less and water absorption of 1% or less and based on a rubbery elastomer such as NR, butyl rubber, polyisobutylene or silicone rubber.
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