Patent ID: 7501176

Claim:
A film comprising at least a multivalent metal salt of a polycarboxylate-based polymer (A), and a multivalent metal in an amount which is in a range of 1 to 5 chemical equivalents relative to all the carboxyl groups contained in the polycarboxylate-based polymer (A), wherein a density of the film is in a range of 1.80 to 2.89 g/cm 3 , wherein a thickness of the film is in a range of 0.001 um to 1 mm, wherein a surface ratio α [the peak surface S 1 (3700 to 2500 cm −1 )/a peak surface S 2 (1800 to 1500 cm −1 )] of an infrared absorption spectrum of the film is not larger than 2.5, and wherein a peak ratio β [the peak A 1 (1560 cm −1 )/the peak A 2 (1700 cm −1 )] of the infrared absorption spectrum is not smaller than 1.2.