| 摘要 |
PROBLEM TO BE SOLVED: To provide a cover material which is heat-bonded to a vessel and can be reattached to the aperture of the vessel through pressure bonding after being partially separated from the vessel to cover the aperture of the vessel. SOLUTION: A cover material 1 comprises, successively from the outer surface, a paper layer, an adhesive layer, an aluminum foil layer and a heat- sensitive adhesive layer which exerts an adhesive property by heating, wherein the heat-sensitive adhesive layer is formed in a circular manner covering the entire surface of the aluminum foil layer or the entire heat-bonding portion of the cover material which is heat-bonded to a vessel. Here, the heat-sensitive adhesive layer 14 has a sea and island structure which comprises a sea portion comprising a water-soluble resin and an island portion comprising a resin having a glass transition temperature of -20 deg.C or lower obtained by emulsion polymerization of a radical-polymerizable monomer. When heated, the sea and the island portions become inverted to exert an adhesion property.
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