US Patent 7713602 Packaging materials and packing containers using the same

Packaging containers for foods in which the contents can be safely kept and which give no metallic residue after incineration. A bag made of a film material wherein a light-blocking printed layer (4) having a sepia printed layer (7) is provided on the internal face of the bag. The color of the sepia printed layer (7) is controlled to give a color hue of 5R to 10R in the Mansell color system, a lightness of 5 to 7 and a chroma of 0 to 3, while the light (300 to 800 nm) permeability of the packing material (1) is controlled to 10% or less.