US Patent 6956070 Water-soluble film and package using the same

The present invention provides a water-soluble film which comprises a modified polyvinyl alcohol containing an N-vinylamide monomer unit in an amount of 1 to 10 mole percent, and a carboxyl group and a lactone group in a total amount of 0.020 to 4.0 mole percent in the molecule, and having a degree of polymerization of 300 to 3000, and a degree of hydrolysis of 75 to 99.5 mole percent. Further, the present invention provides a package obtained by packaging an acidic substance, a chlorine-containing compound, or the like using the water-soluble film.